Jones and Shipman 540P Rebuild (Round 2)

[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.

 

[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.

 

[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.

 

[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.

 

[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.

 

[Fergie 307]

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.

 

[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.

 

[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.

 

[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.

 

[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.

 

[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.

 

[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.

 

[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.

 

[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.

 

[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.

 

[NetBlindPaul]

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.

 

[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.

 

[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.

 

[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.

 

[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.