# Jones and Shipman 540P Rebuild



## deema

I thought I’d share my adventures with a new to me surface grinder. I’ve done a lot of woodworking machine restorations, and only dabbled a bit with metal working machines, so this is a first! Now, I know less than would fit in the back of a postage stamp about grinding, but I do have jobs that would be far better / easier with a surface grinder.

this is what it looked like in one piece!


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## deema

So the tear down begins. The table is only connected by the hydraulic piston arms, one either side. There are 4 bolts holding it on. You can’t lift the machine using the table or the piston arms will bend and need replacing. The piston is the bit with bits of tissue stuffed in the hydraulic ports. You can see at either end the two blocks that hold the table to to the rest of the machine.


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## deema

I don’t have a manual for this machine, if anyone has one and could send me a copy that would be really appreciated.
The hydraulic ram came off next. A few bolts and then it’s just a case of easing it iff the pins carefully.














The table is extremely heavy, two man lift or preferably some form of lifting device. Anyway, with that off you arrive at what I’m going to call the cross slide carriage.


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## deema

I’m posting photos which I took, so the photos may show the machine with parts removed that I haven’t yet described. I hadn’t considered doing a thread when I was pulling it apart. They may appear more than once!

I bought the machine described as being well maintained! Well, when I started to look at it and take it apart, that clearly as a stretch. The spindle has no discernible end end play. (You place a clock on the nose of the spindle and push the spindle in and note the deflection) there was none to speak off, well, about 1 micron; so good enough. The taper on the spindle was in good condition, and run out was again negligible, possibly 1 micron. (Clock on the side of the spindle and the spindle turned)

The cross slide is…….well………fluggered! The scale is in hundreds of a thou (microns there abouts) and there is just a bit of backlash, well around 3mm! The screw is a 5 TPI acme…..so almost completely worn through.

The hydraulic fluid looks like lapping paste, and the stuff on the ways was thick black with grinding dust. There are still witness marks of the scrapping evident on almost the entire length of the ways, which suggests that the state of the machine is something that’s happened recently.


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## TFrench

Watching with much interest! One of these is definitely on my list in the future if I can figure out how to fit it in the workshop. There's some very useful stuff on practical machinist about them - I'm sure someone on there will have the manual. I think a company called andmar are the people to go to for spares on these.


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## Fergie 307

You really don't want to plug hydraulics with tissue. You would be surprised how much of a nuisance a bit of fluff can cause. One easy way of doing it is to cut the finger off a plastic glove, stuff that with tissue and use it in the hole.


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## deema

Fergie 307 said:


> You really don't want to plug hydraulics with tissue. You would be surprised how much of a nuisance a bit of fluff can cause. One easy way of doing it is to cut the finger off a plastic glove, stuff that with tissue and use it in the hole.


Thanks Fergie, that’s appreciate, hadn’t thought about that, I will use your trick going forward.


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## NetBlindPaul

Fergie 307 said:


> You really don't want to plug hydraulics with tissue. You would be surprised how much of a nuisance a bit of fluff can cause. One easy way of doing it is to cut the finger off a plastic glove, stuff that with tissue and use it in the hole.


Plugging ports with tissue would have resulted in disciplinary action when I worked for a global hydraulics OEM, unless the device was being dismantled for repair, and the tissue was only being used to stop oil from dribbling out before cleaning and dismantling.


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## Fergie 307

NetBlindPaul said:


> Plugging ports with tissue would have resulted in disciplinary action when I worked for a global hydraulics OEM, unless the device was being dismantled for repair, and the tissue was only being used to stop oil from dribbling out before cleaning and dismantling.


Same here when I used to work on hydraulic pumps for tractors and such. Now I have a jar full of assorted plastic blanking plugs taken from various new or refurbished brake and hydraulic cylinders over the years.


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## Dalboy

When I finished work I cleared out my toolbox to find loads of the plastic plugs which I used to cover the ends of connectors if I had to go and get a replacement hose made especially if it burst on a very muddy site


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## deema

It’s been a while since I did an update, cleaning the machine is tedious and not very inspiring!

Let’s start with the sump, or hydraulic tank that’s located inside the bottom of the machine. Getting the tank out of the machine full of hydraulic fluid is “fun”. It must weigh over 50Kg when full! You have to remove the two hydraulic hoses and disconnect the wiring to the motor before it will squeeze through the door. To get at the hydraulic hoses you need to remove the front switch panel. I’d recommend draining as much of the fluid as possible before attempting this. The pump itself can be used to pump it out…..but it’s at a pressure so not feeling that brave I used a manual pump.

A few pictures of the gubbins after I’d initially cleaned them…..well wiped off the majority of the thick goo so you can actually hopefully recognise a few of the parts. It’s a simple system, a 4 pole motor drives through a chain and sprocket a pump to provide hydraulic pressure for the system. The manual says the oil should be changed annually, but I think this has been in the tank for the full 50 years of its life! I know that I used just paper towel to block the ports but the photos were before the brilliant advise already provided. In later photos I’ve headed the recommendatio.








So first order of the day was to disassemble and start cleaning!

The tank looks a bit better after a spring clean.





The oil sits in the tank and the actual pump system sits on a platform connected through anti vibration pads that connect to the three tabs around the tank.

The platform is a casting, machined and ribbed for additional strength. It’s a substantial piece, not just a thin metal fabrication we would find today. The slots on the left are T slots that are used to connect and slide the motor to tension the chain.












The sprockets and chain were worn out. The tips of the teeth on the sprockets were sharp enough to cut any unwary fingers venturing close. I’ve popped the dimensions of the two sprockets on the old units and shown them against the new ones Ive replaced them with. The new sprockets have tapered locking bushes to fit the spindles. I used Reynolds simplex roller chain 3/8” pitch and appropriate sprockets.

I took the motor apart and replaced the bearings. Might as well as they are cheap and it helped cleaning up the motor. These were replaced with SKF sealed for life bearings.




















The sprockets are shown as I originally put them on, however, they foul the shroud this way around, and I subsequently reversed them. Made fitting them a little tricky to tighten up the grub screws, but there is enough room for a standard Allen key.
I didn’t take apart the pump, it has a few gaskets and seals inside it which I can’t find spares for. Ideally I would want to do this as I’m sure it’s full of crud. If anyone has taken this apart and knows where to get seals from please give me a shout out. I could use gasket compound ratter than gaskets. At the moment the plan is to flush it through with fresh hydraulic fluid.

I checked the dynamic balance of the new sprockets, and found that they were very good. Only a little adjustment being required to achieve almost imperceptible vibration.


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## deema

The platform is mounted to the tank on Metalastik anti vibration feet. You can buy the ‘original’ parts from either Precision Machinery (£47 / each) or Andmar (£12 each) the prices are correct as of May 2021 and didn’t include VAT or delivery ouch…….so I bought male bobbin anti vibration units from WDS components for a lot less! with M8 threaded ends and a load carrying capacity of 18.8kg, the platform assembly weighs 27KG so dividing it my 3 gives circa 10KG Per foot. Usually, I understand you add 60% for extreme conditions and these were the closet I could find. The alternative was feet with exactly 10KG maximum load and I was sure the motor would cause the load to be biased towards the foot closest to it.




With the feet I could now mount the platform to the tank and pop the shroud over the gubbins.















The chain is tightened to allow a maximum of 5mm movement on the middle between the two sprockets (according to the manual). The sprockets must be aligned or the chain will wear very quickly. Achieving this is difficult!! There is a lot of play in the T nuts and getting the chain tight and aligned is frustrating and time consuming……or it was for me!

I have copies of the manuals for all three variants of the machine, and I’m using specifications from all three as the level of detail in each is different. However, it’s clear that very little changed between each iteration of the machine which is a very good sign that they got it right the first time. The tank arrangement wasn’t changed and the hydraulic oil specification remained the same.






The shroud just sits on the tank and isn’t touching it connected to the platform. It’s important to ensure the the oiler pipe is positioned over the chain to lubricate it. It comes from a feed off the pump. The small basket is where the hydraulic fluid returns to before dripping into the tank.

The tank hold approximately 18 litres and requires Vacuoline 1405 which can be bought from Westway lubricants in a 20 litre drum Which is handy.

The shroud has a handy spy hole that allows you to see that the chain lubricator is working. There is a small adjuster on the pump to alter the flow as needed. The pump should be set to 6.8 bar pressure with a maximum pressure of 8.3bar. I haven’t tested this…..yet! Advise on a setup to text the pressure would be appreciate, I’m no hydraulic expert. 

The assembled tank is very very heavy and that’s without 18 litres of hydraulic fluid sloshing around inside it. I can perhaps understand why draining this is a chore and not often done.


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## deema

So, after posting the details of the tank, it’s got me thinking. Perhaps I really should take apart the pump? Here is a schematic of what I will find inside. Now, as I’ve previously said, hydraulics are something relatively new to me, and I don’t know a lot about them. I haven’t so far had a need to poke my fingers into hydraulics, but I’m very very aware how dangerous a squirt of it can be if you get it wrong! So, I’m very cautious about playing with this stuff, I don’t want to have bits of me cut off due to having it inadvertently injected into me!!



E
So, here are my thoughts, hopefully any hydraulic experts can correct my perceptions.
There appears to be just three sealing parts, two copper gaskets and a stuffing ring. I think I can reuse everything? I dont think I will need to replace the copper gaskets as long as I carefully mark which side , way around they are and pop them back in the same way? Not sure what the stuffing ring is made from but hopefully that is just some form of fibre rope?.

There are two pipes up to the machine from the pump. It looks like there are two pressure pipes into the machine, from reading other posts I think the centre one is the high pressure port and the one above the Exhaust pipe (S) is a low pressure outlet. So firstly, any experts, does this sound about right? Can you see any issues in taking this apart and rebuilding it? Anything I should be careful about / pointers for reassembly?


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## Cabinetman

I’m sorry I can’t advise, just watch in wonderment. Can’t wait to see when you move onto the top half of the machine. Ian


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## TFrench

I'm certainly no expert but here's my thoughts - if these gaskets aren't available from the specialists, I'd say they're probably fine to reuse. Thousands (hundreds of thousands?) of these machines were made over the years and if they were a common service item, they'd be available. Possibly worth annealing them when they're out to soften them up?


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## deema

Thanks TFrench for you perspective, still wondering what to do and hoping for a few more comments.


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## deema

So, while I’m pondering what to do with the hydraulic pump, I though I’d add a bit more on what I’ve been doing.

The next bit up is the cross slide carriage system. This is the most complex bit of the table arrangement, but built extremely well and very robustly. Initially let’s look at the automatic cross slide movement system. A schematic of what this consists of is below.




Although it looks complex, it’s not difficult to take apart and reassemble.

This is the unit after it was cleaned, oiled and reassembled. I will be using pictures of cleaned and as was pictures mixed up, depending on what I had taken. Apologies.
The unit comes apart firstly into two main pieces with a gentle pull, which disengages the locking system from an internal ring. The star knob on the front has first to be removed.





Front face with the Star knob removed.





Back of the unit.





the unit pulled apart into two pieces








You can see the two faces that are joined together. The lower of the two pieces (top item in the photo) contains the pawls that allow the cross slide of the unit either towards the user or away from them.
The top piece (lower item in photo) has the geared ring that the micro adjust worm engages with. This is 80 teeth for the imperial machine like mine and 100 for the metric version. The spigot sticking out is what engages with the pawls to engage either move in / out or disengage them completely.

The front comes away from the worm drive ring, again a gentle pull.


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## deema

A photo of the worm gear removed. The Star knob pulls the spigot you can see against the back of a recess in the worm gear and locks the assembly to allow the micro adjust to actuate movement in the table. If it’s not locked the micro adjust just spins, and this is how it should be left most of the time. The spigot thread on mins is just about worn out, and at some point I will make a new one; but that’s for another day!






The next part is to remove the circlip and washer to break the last pieces apart.






The pawls are held I’m by two pins that simply push out, they are not a press fit. The two pawls are identical and have a small spring held within a pocket. No real energy to worry about when taking apart. The brass lever that determines the amount of movement the carriage makes at the end if each table stroke is also held by a pin that just pushes out.









You can see the bottom of the pawl pins in the next photo.





The lever that activates the automatic movement and actuates the pawls has indents for a ball bearing to snap into to give a positive location when selecting the three positions. Mine didn’t have any ‘snap’ action. The lever is held onto the actuator by a tapered pin. The lever has a recess for the spring and ball bearing. When I took mine apart I found the ball bearing had worn such that half of it was missing. It was a half moon shape. I bought a pack of 5mm ball bearings to replace it.

Although I noted the orientation of the actuator, the tapered pin would only go back in when it was orientated correctly.








A light oil if you all the parts and reassemble was simply the reverse. The only ‘tricky’ bit is getting the lever to re-engage with the pawls. I found by just gently turning the lever back and forth it would work it way back into place and allow the parts to reassemble without any issues .


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## deema

Next part to undergo decontamination was the fine adjust for the cross slide. The schematic for the assembly is shown below. The previous Posts Ive worked on item A / J. This will be looking at item E. a more detailed schematic of the system is shown in the lower diagram.








In order to remove the ratchet system A, you need to remove the fine or micro adjust. A grub screw (D) is removed and the dial can then be pulled off. Next are six bolts folding the two boss ends into place (C). Once these are removed a genital tapping on the end of the shaft where the dial has been removed will push out the system. The star knob needs to be loose on the ratchet mechanism. I used a puch to push out the top boss.








The worm has two thrust races, one that sits under the knob and the other a I’ve the worm gear……not as shown in the layout, but the assembly is shown correctly in the last picture where I’v temporarily put it back together again.


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## deema

The last handle is the manual table traverse. Again starting from the schematic





The handwheel is held into the cross slide by a grub screw that can be seen in the photo below. Once released, the mechanism just pulls out.





Taking apart the handle starts with a nut in the centre of the had wheel (M) , which allows the front end to be pulled off. Three screws (O) around the collar of the handwheel allow the shield to be removed.
Taking out the bolt (G) gives access to the spring and ball bearing) once these have been removed the shaft (A) can be pulled out.






The tubular guard is some kind of material, not sure what, but as far as I can discern it’s just to stop rubbish ingress into this region.
There is a single oil seal at the handle end which I couldn’t work out why there wasn’t one at the other end initially. Looking at how it works, hydraulic oil drips into the central table space and a groove channels some of it to enter the open end. The shaft has a groove running all the way down it to allow the hydraulic oil to lubricate the mechanism. It’s clear that levelling this machine will be vital to ensure that the hydraulic oil runs properly to lubricate everything correctly.


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## deema

The next part is where I’m again having a good think about what to do. So, any input / advise / opinions would be appreciated. The Hydraulic valve block Is something I’ve been leaving and putting to one side for sometime. The question is, should I take it apart and clean it, or just try flushing it through in place?? The good news is I can get replacement seals for all the bits. Hurray! If I take the plunge and pull it apart.


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## deema

I’ve so far cleaned the valve block, well the bits I can get at. One of the valve guides was broken and I’ve made a replacement. Well I made two, the first made of stainless steel I orientated the mounting holes 90 degrees wrong! So, the second was made of just ordinary steel as drilling a small hole through the base of the guide a long way in SS wasn’t fun first time around.

Not sure how the original cast guide was broken as it’s buried under a plate that covers the gubbins. The plate is circa 3mm steel that covers it, so nothing could have knocked it. The broken part was still present and trapped beneath the plate which was handy to take dimensions off. The part has a small spigot on the underside.

The orginal broken part is in the left, the new fitted part in the centre, and the billie do 1st attempt on the right!……I’ve just noticed that the part it fitted the wrong way around! 

Ive taken out and cleaned all the valve stems, they were dirty indicating that the inside of the block is also dirty and needs a clean.
Getting the stems back in, especially the one with the ball bearing under it was interesting. I eventually used a bit of grease to hold the spring in place whilst I lowered the stem into the hole onto the ball. Im hoping the grease won’t affect anything.


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## Fergie 307

I would be inclined to leave the pump alone, if there is a problem with it once you have the machine up and running, then you can take it apart. They tend to go on and on provided the oil is clean.


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## deema

Thanks Fergie, appreciate it, trouble is the oil wasn't clean, in fact it was like mud! Now to be fair, that could be the sediment stirred up when I collected / transported the machine. I’ve been playing with the piston and the oil that came out of that was clean.


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## deema

For completeness, so you can see how much has been done of the cross saddle, here is a schematic of the components 





Got a little further, started to look at the piston. The schematic for it is






The piston is a sealed unit, so I decided to check the oil coming out of it before deciding whether to tear it apart. If I were to do so, I’d replace the piston seals which are a known consumable and available. The oil was nice and yellow, the correct colour…..at least to me it was a yellow colour, I’m not good with colours!

The piston received a thorough clean, however the nut and threaded nut collar were jammed on one end. No coaxing would make the nut collar wind off. So, nothing for it as I didn’t want to damage the piston rod it had to be broken off. A groove either side of the nut was cut carefully with the angle grinder, not deep enough to encounter the thread, and then my large nut breaker split it off.







This left the threaded piston rod intact. However something had caused the jam. Measuring the threads using the 3 wire method and checking the OD and pitch came out that the thread is a 3/8“ 20 TPI BSWF thread. For good measure I used a die to run down each thread and then made two new threaded collars, the other was a bit mangled.




This shows the end, it hadn’t been cleaned at this stage.


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## Fergie 307

deema said:


> Thanks Fergie, appreciate it, trouble is the oil wasn't clean, in fact it was like mud! Now to be fair, that could be the sediment stirred up when I collected / transported the machine. I’ve been playing with the piston and the oil that came out of that was clean.


I would still be inclined to flush it through and then see if it works ok, which it probably will. If the oil coming out when you flush it is clean then you should be ok. Nice job so far though, nice to see someone taking the trouble to do a proper job of it. Looks like it's in pretty good shape. Reminds me of my old Harrison lathe, looked awful at first sight, but under all the dirt it was in really good condition.


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## deema

A bit of cleaning of the main table came next. Underneath the years of grime it wasn’t too bad. No rust which was good to see. I believe the machine had predominan been run dry as it came with the dust extractor but no coolant system.







The ways are worn, only time will tell how they will affect the overall grinding accuracy. I’m considering scraping them, however it’s not something I’ve ever done before, and I suspect a grinder isn’t the mostly appropriate first project to learn on! If there are any scraping experts / knowledgeable people near Chester, who would be kind enough to help me / show me how to scrape I would be both eternally grateful and provide good hospitality…..,.plenty of cold fluids and nurishmeant!





the other end



middle bit








Here I’ve laid the piston onto the table to adjust the end bolts far easier now than trying to do it when I reassemble it.





The two ends of the piston are bolted to the ends of the table. Any backlash is taken out by the just tightening the nuts on the two pistons. This is all that holds the table onto the machine. If you try lifting it with the table you will bend / destroy the piston rods.


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## deema

The last bit I have to do before putting the table arrangement back together is to sort out the cross slide lead screw. Mine is completely worn out. There is over 3mm of backlash! not bad for a machine that has a handle indented in thousands of an inch.
The obligatory schematic





Replacements are available





However, they are eye watering expensive, I’ve been quoted £681 delivered including VAT. I will have a look at making a new one, but I am bracing myself that I might need to buy one!

So this is what it looked like when I fished it out of the machine.



















Its clear that it hadn’t been lubricated in a very long time and grime had just built up and worn the bronze nut and the Acme thread away.


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## NetBlindPaul

Grease + grinding swarf = lapping paste!
I’ve seen it too many times.
The accuracy of the positioning is going to be dependent on the accuracy of the leadscrew.
Can you investigate a ballscrew?
As far as scraping the slides go, it’s possible, but not easy, and yes I have done it, and yes it was on a grinder, but not a surface grinder, my employer made CNC generally cylindrical grinders of various types.


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## deema

Thanks Paul
A ball screw sounds like a good idea, can they handle a dirty environment? A bit of reading I have done suggests they needed to be kept clean? The 540 basically allows the hydraulic fluid to flow over most of the surfaces to wash away grinding dust and it seems to drip everywhere. I’d appreciate your perspective / experience in using them…..as I have a total of zero.


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## deema

Jumping back to the cross slide, the actuator that stops the automatic feed if the cross slide I haven't previously shown.

This is the mechanism, it’s held together by a bar that is fixed using a grub screw.




Looking at the area with the lever removed.





The lever has a square nut in the end of it which is adjustable. The nut sits in this space and activated the yellow lever. It’s a bit tricky to get back together and get out.






The lever and bits where you can see the square nut.


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## deema

Back to the cross slide lead screw. After cleaning it up, it looks like this
Apart from the Acme thread, the thread for the retaining nut and the end that sits into a bush, the rest looks as though it has no wear. 






I think this helps illustrate just how much wear to the Acme thread there has been.






The thread in the nut is also badly worn. 





Most places I’ve seen reference to the pitch of the Acme thread on other forums suggests is a single right hand thread 5TPI Acme. Well, mine is different, and I actually think the other references are also wrong. The thread is (now I’m not sure if I’m correctly stating it) is a 2.5TPI twin threaded I.e, the tooth form is 5TPI Acme right hand thread. If you look at the nut you can see the two thread starts. As all the other references state it to be 5TPI I double checked both by measuring how far the nut moves with 2.5 turns of the handle, and by checking the dial calibration (1 turn is 400 thou) and using a 5TPI ACME thread gauge. So, I’m confident in what I believe it to be.

The next step will be to measure and draw up the parts. However, my lathe will not cut a 2.5TPI thread, so without some new change gears I’m going to have to come up with a plan. Ideally I think I’d like to make the leadscrew in two pieces and connect them together with say a taper pin. The first part will be all the detail that goes through the handle mechanism, the second part will be the Acme or some other threaded bar. In theory at least, when it wears out again, it will be far easier to replace just the threaded portion. Any suggestions for making this would be welcomed.

Ideally I would like the handle calibration to match the thread. So either I need a matching Acme thread, or alternatively some other thread say trapezoidal or ball screw and then get the handle calibration ring changed to match (they will be metric) The machine came with a DRO for this axis, so it doesn’t have to match, but the purest in me would like it to.


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## deema

A bit more measuring of the leadscrew to see what room I have to play with.
The central pocket is where the lead screw sits, the lead screw can’t be seen when the casting is popped back onto the machine. so first job is to temporarily put the screw back in.





This is the arrangement of the bearings that fit on the end of the leadscrew.




and this is with them placed on the shaft. The shaft now just goes through the casting and you thread on the nut and bolt it all in place.






This is the front with it all bolted up.




Just for anyone doing a similar task, I’ve put the rachet system on. This just slips over the shaft with a key to engage it. The nut on the end removes backlash / secured the ratchet mechanism in place.






The following is the nut that secures everything which then has a cap that fits over it and is secured with 3 cal screws.




This is the lead screw in place. I have 3mm of head room underneath between the bottom surface of the casting and the top of the nut, and plenty of room either side. The idea I have is to adapt this nut to take a standard off the shelf nut.


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## deema

Some close up of the cross slide ways. Not very good at all! They are worn and scratched, the hydraulic oil wasn’t making its way into them properly due to the ports through the casting being blocked. Hydrualic oil gets pumped into the table slides and then drains down onto the cross slide ways. The ways are both V shaped.


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## deema

The last job with the cross slide lead screw was to remove the end bush which appears to be solid bronze. It was a,so badly worn…a real rattling fit!

I made a quick and dirty bush puller. The puller is a threaded insert that pushes against the bush with a collar on the other side. The collar supports a large washer through which the bolt passes and then screws into the insert. As the bolt pulls on the insert it pulls the bush out.




This is the bush after I’d removed it. I’m had a hole for oil to weep in from the grease nipples on top of the casting.


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## NetBlindPaul

deema said:


> Thanks Paul
> A ball screw sounds like a good idea, can they handle a dirty environment? A bit of reading I have done suggests they needed to be kept clean? The 540 basically allows the hydraulic fluid to flow over most of the surfaces to wash away grinding dust and it seems to drip everywhere. I’d appreciate your perspective / experience in using them…..as I have a total of zero.


They aren't good in a dirty environment, but, then again we used to use the same waylube oil for the ballscrews and the slides, and the system was unfiltered, and re-circulating.
Some areas were total loss, others weren't, which might be a better description.
You might have a problem with alignments if you go ballscrew, now I've thought a little more about it.
They need to be rigid and aligned correctly not to suffer from premature wear.
The hydraulic fluid shouldn't be "washing away" the grinding swarf, the two should, "strictly speaking", never meet.
With hindsight, I think you would be better off sticking with a leadscrew.
Are you sure that is an Acme (29 deg.) rather than a square thread?
I can't tell from the pics, but a lot of leadscrews are square, not Acme.


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## deema

Thanks Paul, appreciate your perspective on the ball screws. The thread is definitely Acme, and a very unusual size for 3/4”. I had hoped I could buy it ‘off the shelf’ to make replacing it an easy exercise. Unfortunately I can’t find anything thats an exact match of the pitch. So the choice is going to be either use trapezoidal which I can get in 10(2) 21mm which will just fit (nearly 2.5TPI), get some made, or find some change gears for my Cholchester Student as the quick change gear cutting box only goes down to 5TPI. ……or bite the bullet and pay for a replacement.


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## deema

Going back to the hydraulics, I’d appreciate some help and guidance. I’m struggling to identify the thread on the fittings connecting the hoses to the pump. I want to both test the pressure being created and fit a permanent pressure gauge without interfering with the hydraulic pipes as I understand they act as accumulators. They thread seems measure (male end) 18mm (OD not PCD) at the top and appears to taper to 17.5mm with a 1.5mm pitch. Are they metric M18 pipe fittings of 1/2” NPT or something else??
The pipe has a 1/2” bore and is clamped into the pipes that use ferrules to seal with a nut into the pump.


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## deema

It’s been a while since I last did an update. 
Lets talk nuts, and leadscrews. In looking at the original design of the lead screw nut, I was surprised to find that it was designed to fail! The lead screw has a two threads and only one of these is fed by the oil port. The other thread has no access to oil. I had imagined that the single oil delivery port to the thread would have been sufficiently wide to straddle both threads, but no, it is drilled to precisely encounter the centre of one thread only.
Making a replacment, rather than spending circa £700 on a new replacement nut the lead screw I wanted oil to be delivered to both threads. I also wanted the thread bar and the nut to be easily replaceable. It would have been ideal to have found off the shelf parts that would have nit needed any machining and just fitted into the carriers I make. However, I couldn’t find anything that was sufficiently close to allow this.
I bought a trapezoidal lead screw and nut from Accu, which were extremely quick to deliver and the parts were excellent quality




I bought 22mm diameter, 10mm pitch Trapzoidal bar with a Bronze flanged nut for £69.30 delivered, which I thought was very reasonable.

So, now need to make these look alike








The lead screw reaquires a machined front end that is then connected to the threaded bar. The connection is with a roll pin and a grub screw (to hold it for drilling)




The old and new parts side by side





Test assembly 




Now for the nut holder

The bore is just a sliding fit with the nut body, that way the retaining bolts don’t influence its position. It’s impossible to access the bolts when everything is assembled, so no opportunity to allow the nut to self align and then tighten down the retaining bolts. 
There is a groove under on the back face of the carrier to retain the o ring and it is compressed by the body of the nut. The front face has an o ring groove within the body.

The nut has had 6mm removed from the face of the flange, and cross drilled to align with the oil chamber. In my design both threads are lubricated. I also had to knock off the sides of the flange to make it fit properly.


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## deema

The original nut has a proboscis on the face not shown. This allows the thread to be extended and is accommodated into a recess on the cross slide cast body. The main body of the nut acts as a stop for the end of travel. This is why the new arrangement has the bronze nut protruding through the steel retaining body.


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## deema

There are parts of the design of this machine that seem unusual to me. The lubrication of the cross slide has been troubling me for some time. The main table has hydraulic fluid pumped into the ways to both provide lubricant and also to wash away anything that gets into them. I would have expected that the cross slide table ways would also be similarly lubricated, but they aren’t. The cross slide ways rely on the hydraulic oil from both the table ways and any leaks from the piston dribbling down into them.

The photo shows the two holes that the hydraulic oil has to flow down to the ways. I had assumed there would be a drilled gallery to these, but there isn’t.






These holes sit right beneath the main table actuating cylinder, so there is no access to them for a user to lubricate them. It’s just a rough cast area, so unless the grinder is precisely level, and with luck the cast body is also level, the hydraulic oil, will not lubrucate one side.

This is where the two holes come out, either side of the V ways, there are two V ways, one on each side, so 4 drain holes in total.





To add to the mystery, there is also a reservoir cast into the body to lubricate the manual table actuator, and also a collector to feed oil back down the drain pipe to the hydraulic tank. These are shown with arrows showing the way the oil will flow.





So, I cannot see how it’s possible to be certain that either of both of the cross slide ways will receive any lubrication. If anyone has any better knowledge / observations I’d appreciate your input. This is a design that hasn’t changed much and the machines are know to be reliable / accurate for years. I’m wondering if I’m missing something?


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## TFrench

Is it just a case that theres so much oil running about then its likely to get some at some point? 
Did you manage to find your leadscrew and nut to match the old one? So all the graduations on the dial will still be right?


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## AndyPandy64

I had to replace my cross slide screw and nut on my 540. You are correct, it is a 2.5tpi multi start thread. If you use a 5tpi screw you will have to turn the handle twice as much for the same distance.

I've got a Colchester student 1800 and by some miracle I figured out that you can do a multi start thread on it (only 2 threads) by using odd and even numbers on the thread dial. A lucky find for me since its not documented

I bored out the nut and made a insert that I threaded. It ended up being an extremely thin walled part and I had be careful with holding it in the chuck because the more thread I took the thinner the wall became and the more the chuck squeezed it. Ended up using a long piece and holding it in the chuck about half way and only threading the end that was not held by the chuck. Must admit I was quite chuffed with myself since it was the first thread I'd had to make in anger !!! Probably took me a day in total, including lots of practice parts in steel

If I can do it, anyone can. And best of all it cost next to nothing all. Maybe £30 in total


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## AndyPandy64

I modelled both the cross feed screw and nut insert a few years ago and the below are links to Fusion 360 models of both the Cross Feed Screw and the nut insert in case anyone needs them

Note the thread on both is not a two start ACME thread. I just modelled something

Nut insert
Screw

I've attached F360 model and drawings

I was to scared to drill the 5mm diameter 110mm deep grease hole. In my defence I dont have a bit long enough. And I dont use it that often


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## Jordhandson

good post well done


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## TFrench

Deema, massive thanks in order for this thread. I've just got one of these and having prior knowledge of what I was diving into from this thread have made it much easier!


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## deema

TFrench, you don’t have one if there aren't any pictures! 
I’m delighted the thread was of help to you.


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## TFrench

I just need to find time to sort my pictures out into a proper post, but here she is coming out of the van. Suspect my poor van was a bit overloaded with this one!


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## Saxguy

This has to be the best helpful thread Ive ever seen on the J&S 540.


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## hennebury

Great thread, nice machine. You have to be a bit of a detective to do machinery rebuilds, I get nervous going on if I don't understand something. Really interested in seeing the rest of the rebuild. I have a German grinder, not overly impressed with the design, so I look forward to seeing how yours is all done.


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## Saxguy

hennebury said:


> Great thread, nice machine. You have to be a bit of a detective to do machinery rebuilds, I get nervous going on if I don't understand something. Really interested in seeing the rest of the rebuild. I have a German grinder, not overly impressed with the design, so I look forward to seeing how yours is all done.



I love delving into projects such as this. Yes, I'm a sick puppy!
Its so much easier now we have digital cameras and the internet mind you. Used to have a jotter and a pencil and hope for the best!
You couldn't have said it better when you said that you need to be a bit of a detective. You look for things like witness marks, scuffs and scrapes, and they all tell a story, especially when reassembling (if you haven't polished them all up that is!) 
Get yourself a whole load of plastic boxes with the clip on lids. As well as different size plastic bins too (fish bins sometimes they are called), and with lids if possible.
As you start to disassemble, photograph and video the whole job, or at least areas where you are likely to have to remember, ie stacked washers/bearings/gears etc etc. Nothing more terrifying than having stripped down a gearbox, and a month later trying to remember what order the whole lots goes back in! 
And then use the various boxes for each 'part' of the machine. eg handle & cross screw assembly. Large parts in one of the large bins, and the smaller parts inside a small container placed with the larger parts in the large bin, and so on. LABEL THE BOXES/PARTS ACCORDINGLY. 
Then make a note of whats in the boxes, along with any suspicious findings (sometimes things have been adulterated and/or reassembled incorrectly before you even get them!).
Also, make sure you have, or think you have, the right tools to do the job before you start. Also, space. Assess how much space you think you will need, then double it!
Then..... let the fun begin!


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## Badee

deema said:


> Jumping back to the cross slide, the actuator that stops the automatic feed if the cross slide I haven't previously shown.
> View attachment 113582


Once the grub screw is removed, the shaft should slide out, right? I don't see anywhere to tap it out from behind, but don't want to grip the end and potentially damage it - yes, mine feels wedged in there. Any advice on removing this?


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## Badee

deema said:


> A bit more measuring of the leadscrew to see what room I have to play with.
> The central pocket is where the lead screw sits, the lead screw can’t be seen when the casting is popped back onto the machine. so first job is to temporarily put the screw back in.
> 
> View attachment 113586


My next question involves removing this cross saddle. I see 2 hoses connected to it if I shine a light past the valve block, which I'm assuming is the hydraulic oil feed (and drain?) lines to the cylinder block. I see yours are plugged in the image above. But I don't see a way of removing this saddle. Is it bolted down at some point (where it is still allowed to move forwards and back)? Or is it just one heavy casting that needs to be lifted?


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## deema

The saddle is just ‘sat’ on the slides. Extremely heavy, and lifts off when the hoses are disconnected.


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## deema

Badee said:


> Once the grub screw is removed, the shaft should slide out, right? I don't see anywhere to tap it out from behind, but don't want to grip the end and potentially damage it - yes, mine feels wedged in there. Any advice on removing this?


Yep, it’s not easy to get it out. You don’t need to remove it to lift off the saddle. I did so just to clean around it.


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## AndyPandy64

deema said:


> Thanks Paul, appreciate your perspective on the ball screws. The thread is definitely Acme, and a very unusual size for 3/4”. I had hoped I could buy it ‘off the shelf’ to make replacing it an easy exercise. Unfortunately I can’t find anything thats an exact match of the pitch. So the choice is going to be either use trapezoidal which I can get in 10(2) 21mm which will just fit (nearly 2.5TPI), get some made, or find some change gears for my Cholchester Student as the quick change gear cutting box only goes down to 5TPI. ……or bite the bullet and pay for a replacement.


I see you have a Colchester Student. I've got a Student 1800 and had the same problem. You are correct that the thread is a two start 2.5tpi ACME. I found out the hard way, but fortunately had just made a test nut to check the fit on the unworn ends of the lead screw

I found, by accident (or ignorance) that I can easily cut a two start 2.5tpi thread on my Colchester Student 1800. First set everything up to cut 2.5tpi as per the front plate. Then to get the two starts I just used alternative odd numbers on the thread dial, ie '1' for one thread and '3' for the other. Appears to be a non documented feature. Or just a lucky find

I bored out the bronze nut and made a threaded sleeve which I Loctited in place

Scarily this was my first every thread I cut on my mid life crisis lathe. Its not a great thread, to much play (didn't factor in tool wear), but it works well enough that I am still using the screw and nut 3 years later


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## J-G

AndyPandy64 said:


> I found, by accident (or ignorance) that I can easily cut a two start 2.5tpi thread on my Colchester Student 1800. First set everything up to cut 2.5tpi as per the front plate. Then to get the two starts I just used alternative odd numbers on the thread dial, ie '1' for one thread and '3' for the other. Appears to be a non documented feature. Or just a lucky find


??? That doesn't ring true. If you set up for a 2.5tpi thread (0.4" pitch) then that is what you will get - you could get a two start thread but the pitch will be 5 tpi (0.2") and you would have to use a half size tool and only cut 0.105" deep.

Since this is your first thread, you may of course be confused by thread nomenclature and are quoting the 'Lead' of the two start thread rather than the TPI (Pitch).


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## AndyPandy64

J-G said:


> ??? That doesn't ring true. If you set up for a 2.5tpi thread (0.4" pitch) then that is what you will get - you could get a two start thread but the pitch will be 5 tpi (0.2") and you would have to use a half size tool and only cut 0.105" deep.
> 
> Since this is your first thread, you may of course be confused by thread nomenclature and are quoting the 'Lead' of the two start thread rather than the TPI (Pitch).


You are probably correct

I measured the cross lead screw thread with a pitch gage, its a 5tpi thread. So my practice nut was a 5tpi. I was then confused then it did not fit on to the old lead screw. Eventually I figured out its was a two start 2.5tpi thread. If, on my Student 1800 you set it up for 2.5tpi and cut a two start thread you end up with what appears to be a single 5tpi thread.

But yes. first thread and know nothing about 'thread nomenclature' or much else for that matter

Like I say more my dumb luck finding out my Student 1800 will do very odd two start threads. That was the bit of info I was try to pass on


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## J-G

AndyPandy64 said:


> You are probably correct
> 
> I measured the cross lead screw thread with a pitch gage, its a 5tpi thread. So my practice nut was a 5tpi. I was then confused then it did not fit on to the old lead screw. Eventually I figured out its was a two start 2.5tpi thread. If, on my Student 1800 you set it up for 2.5tpi and cut a two start thread you end up with what appears to be a single 5tpi thread.
> 
> But yes. first thread and know nothing about 'thread nomenclature' or much else for that matter
> 
> Like I say more my dumb luck finding out my Student 1800 will do very odd two start threads. That was the bit of info I was try to pass on


First - That's one hell of a thread for your first !! - Since you admit that you are new to threads, I presume that you may not even know the correct flank angle of an ACME thread -- this may also be why you think that you omitted to consider 'Tool wear'. To measure the wear after cutting a single thread in Bronze, would be difficult even with the most sophisticated inspection equipment, so I suggest that you have cut it too deep or not at 29°

There's nothing unusual about an OD of 3/4" - though that Dia. would normally be a 6tpi ACME - as it happens ACME threads are very much designed to transmit power, and 2 start more so, therefore all the 'standards' go out of the window.

What dia. did you machine the 'bore' to? And how deep did you make the final cut? - - - For a full depth thread the bore should have been ~ 0.55" and the thread depth 0.1" but since it is two start, you should have also taken note of the Helix Angle when selecting the tool. With a 5tpi Lead and 0.75" OD the helix angle is close to a massive 11° 5' so if you were using a 'standard' ACME Thread Chaser the clearance should have been modified - there would have been 'rubbing' on the flank which would affect the thread form - potentially causing the poor fit.


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## sawtooth-9

I have restored two surface grinders, but nowhere near the quality of this gear.
NEVER let it go


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## AndyPandy64

J-G said:


> First - That's one hell of a thread for your first !! - Since you admit that you are new to threads, I presume that you may not even know the correct flank angle of an ACME thread -- this may also be why you think that you omitted to consider 'Tool wear'. To measure the wear after cutting a single thread in Bronze, would be difficult even with the most sophisticated inspection equipment, so I suggest that you have cut it too deep or not at 29°
> 
> There's nothing unusual about an OD of 3/4" - though that Dia. would normally be a 6tpi ACME - as it happens ACME threads are very much designed to transmit power, and 2 start more so, therefore all the 'standards' go out of the window.
> 
> What dia. did you machine the 'bore' to? And how deep did you make the final cut? - - - For a full depth thread the bore should have been ~ 0.55" and the thread depth 0.1" but since it is two start, you should have also taken note of the Helix Angle when selecting the tool. With a 5tpi Lead and 0.75" OD the helix angle is close to a massive 11° 5' so if you were using a 'standard' ACME Thread Chaser the clearance should have been modified - there would have been 'rubbing' on the flank which would affect the thread form - potentially causing the poor fit.


Thanks J-G. I think you have identified my problem. Helix/clearance angle

The shaft OD is 7/8 but everything about the thread is ACME 5tpi. Tool geometry, apparent pitch, DoC, etc. ie 0.110 DoC. Just its a two-start thread

I got all the data from the Machinist Handbook

My plan was to first cut the internal thread to fit the ends of the existing lead screw where the threads are not worn. Then cut the thread on the new lead screw to fit the new nut. So going by the book was not strictly required. I hoped this would allow for my complete lack of experience

I thought I'd factored everything in, including an undocumented way of cutting two-start threads on my 1800

But I had not considered the helix angle. I've just checked the tool I ground and whilst it fits perfectly on the 1x5tpi test thread, it does rub on the two-start 2.5tpi thread. I've just put the test single start 5tpi next to the original screw and the difference in helix angle is so obvious. 5tpi helix angle is about 5° against the helix angle on the two-start is about 10°

Not a problem for the internal thread since I was using old J&S boring bar which takes a 1/8 (maybe bigger, but min size for a 5tpi AMCE thread) HSS which I ground. I think the helix/clearance angle did not matter because the tool size was so small. But for the external I ground a 3/8 HSS blank and I’ve just checked and the clearance angle is about 6°

Your explanation helped a lot. Time to make another one I think

This time I might also be brave enough to drill the 3.5” deep ¼” oil hole in the end !!!


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## J-G

Good - at least my input seems to have been useful. I have written a program (under Windows) to calculate the various dimensions of many Thread Forms, inc. ACME & Trapizoidal, which you may like - send me a PM if you are interested.

At 7/8" Ø the Helix angle on a 2 start 0.2" pitch is 9° 19' 47" - single start would be 4° 41' 46".

The DoC for the external thread should be 0.105". If you have the top-slide set over at 14½° the total travel should be 0.108". It's quite a challenge to measure the root Ø but if you can devise a method that should be 0.665". Internal threads are not generally full depth - the OD has to be correct (or marginally oversize) - but the root is usually larger than 'Nominal'.

The most important dimension is the Effective Ø which ( for a Class 2G fit) is 0.7693". Measuring that is probably more complex that you yet appreciate. The best way is the Three Wire method - which is what my program is designed for. Over 0.1" 'wires', the mic reading should be between 0.8876" and 0.8929" (2G fit).

The pragmatic approach (make the nut to fit the existing first) may well be your best course of action but considering the type of machine that you are refurbishing it might be prudent to strive for the highest accuracy and to make the new lead-screw first and make the nut fit that.


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