Portable (bench-top) Workbench

[Dr Al]

Next up was the jam bar. This one took a bit of thought!

I started by digging out some bits of steel that were the right size to make sure the nut would sit in the middle of the jam bar. I clamped them in place using a spare half-nut as a spacer:

I could then fit the proper nut and clamp it in the right place:

The rest was easy. I was extra careful with the weld on the outer face as the jam shaft in the body may run near that and I didn't want it to get stuck on a sticky-out bit.

After letting everything cool down, I could put the two pieces together to mark up for the hinge. This is where I realised that I'd put the tube hinge blocks on the wrong way round! Thankfully the hinge hole is intended to be central, so I can just chamfer the other corner.

Before that, I marked up where the hole for the hinge will be:

I then used a spare half-nut and a short length of threaded rod to clamp everything together in the milling vice:

It was then fairly straightforward to spot drill and drill through the 5 mm hole for the hinge bar:

 

[Dr Al]

The tube went back into the milling vice and I cut another chamfer:

Finally, the hinge bar could be inserted (it's loose at the moment, but I'll sort that out later) and a magnet pressed into the hole (again loose at the moment, but I'll glue it later). The assembled lock piece:

I'm very happy to say that it works! This is what it looks like locked:

This is what it looks like unlocked:

Here are a couple of videos that hopefully show it working (the first one was taken with my phone held in the bench vice!):

 

[Dr Al]

Not much of any interest to report this afternoon. Most of the time was spent finishing all the bits that make up the other two lock pieces for the vice mechanisms: I didn't bother with photos as they look the same as the ones I made for the first lock piece. They're all made now and will be welded together tomorrow all being well.

While I was in batch production mode, I also made the front and back plates for the vice mechanism bodies. I fitted a stop on the vice, fitted the first plate and used an edge finder to zero the DRO. The position of the holes is critical relative to each other, but not that critical relative to the sides, so a stop on the vice is easily good enough for repeatability.

Then for each plate I spotted the holes with a spot drill:

Then drilled out the holes; three of them look like this:

Two of them look like this:

One of them looks like this:

That's it for now. I'll need to clean the mill scale off all the body parts before I weld them, but otherwise it should all come together fairly quickly tomorrow hopefully.

Then I've just got a bucket load of turned parts to make, but that's my favourite type of metalwork, so I'm not complaining!

 

[Dr Al]

Most of today was spent welding (and waiting for recently welded parts to cool down!) but I also did a bit of turning. I started by making a couple of simple bushes out of a bit of rusty steel I had in the scrap bin:

These go together with a bit of M8 threaded rod to make some train wheels!

They then go in between the two halves of a vice mechanism body and hold the two big holes in alignment. The jam bar (a bit of 6 mm steel bar) is also inserted to make sure those two holes stay lined up too.

First body welded:

All the parts for all the vice mechanisms are now complete and tested:

The jam bars and hinge bars are still loose at the moment; I need to decide whether to bother cutting them to length (or just leave them overhanging a bit) and then I'll fix them in with Loctite 603 probably.

Here you can see the reason I added extra holes in the outer plate. With hindsight it probably would have been better to make them big enough for a long T20 bit for my impact driver, but I'm sure I'll cope doing it by hand!

Finally, I started the first bit from the very large amount of turning I have to do. I started with the slotted bushes that go in the moving jaw of the dual-screw vice. These are turned as simple cylinders and then I'll stick them on the mill and make the central hole into a slot as well as adding a hole for a pin to keep them aligned in the jaw.

I haven't done much in the way of CAD based design of metal things; I generally just make it up as I go along. These (60 mm diameter) bits looked a lot bigger in the flesh than they did on the screen! I also discovered the disadvantage of getting lots of free brass: this stuff is horrible to turn: it produces lots of stringy bits of swarf, more like aluminium than brass. I guess it might be aluminium bronze (which I've got a little of, also for free) as that turns in a similar way to this; alternatively it might just be a non-free-cutting grade of brass.

Either way I'm hoping that the other big bits of brass (which look a bit different) that I've got are a nicer grade that produces little chips more easily. The 31.25 mm stuff that I got out of the same skip as the 63.5 mm stuff was a nice free-cutting grade. I'm also hoping that this isn't too difficult to mill.

 

[Cabinetman]

I wish I could say stop it Al, you’re making me feel deficient having never learned to do metalwork, but all power to your elbow, can’t wait to see it finished, - hope it works! Ian

 

[JoshD]

Wow, I'm blown away by this, looks amazing! But one question: did you consider using lead screw with trapezoidal thread (like this) instead of M20? I would have thought that the deeper thread would make your half-nut more secure, but perhaps it would less readily disengage? It would also have given you a choice of pitch. BUt of course if your rule is to only use what you already have then M20 it is ....

 

[Dr Al]

I wish I could say stop it Al, you’re making me feel deficient having never learned to do metalwork, but all power to your elbow, can’t wait to see it finished, - hope it works! Ian

Thanks Ian. I've been doing metalwork for a lot of years now, so that's the bit I find easiest to be honest. It's this wood stuff that takes a bit more thought!

Wow, I'm blown away by this, looks amazing! But one question: did you consider using lead screw with trapezoidal thread (like this) instead of M20? I would have thought that the deeper thread would make your half-nut more secure, but perhaps it would less readily disengage? It would also have given you a choice of pitch. BUt of course if your rule is to only use what you already have then M20 it is ....

I did think about it, but there were a few reasons I stuck with M20. Firstly simplicity/cost: I had some M20 threaded rod & some 20 mm ID tube and that seemed ideal. Secondly, I don't think the extra strength is really needed in this application. It's a vice for holding wooden bits, so it's not going to take the punishment that my metalworking vices do (and one of them has triangular-form threads). Assuming I can get 20 mm OD trapezoidal threaded rod & a sensible size nut, it wouldn't be that hard to swap it out if there ever is a problem, but for now I'm betting that it'll be fine.

 

[Dr Al]

Thanks Ian. I've been doing metalwork for a lot of years now, so that's the bit I find easiest to be honest. It's this wood stuff that takes a bit more thought!



I did think about it, but there were a few reasons I stuck with M20. Firstly simplicity/cost: I had some M20 threaded rod & some 20 mm ID tube and that seemed ideal. Secondly, I don't think the extra strength is really needed in this application. It's a vice for holding wooden bits, so it's not going to take the punishment that my metalworking vices do (and one of them has triangular-form threads). Assuming I can get 20 mm OD trapezoidal threaded rod & a sensible size nut, it wouldn't be that hard to swap it out if there ever is a problem, but for now I'm betting that it'll be fine.

Also, trapezoidal lead screws tend to be much coarser pitch than metric threaded rod, so the nut would have to be much longer to get a decent number of "teeth" engaged.

 

[Dr Al]

I realised I didn't post a photo of the slot bushes in the state they were in after turning:

I'll start with a small update on the material. With the parts a fairly simple shape (i.e. before the slot was milled in them), I measured the OD, ID and length carefully and put them together on the kitchen scales. A simple calculation gave the density as 7.45 kg/m³. That's much more in the bronze range than the brass one, so I suspect these are some sort of bronze. One reference I used quoted aluminium bronze as 7.7 kg/m³ and generic tin-based "bronze" as 7.4 to 8.9 kg/m³; another quoted generic tin-based bronze the same but aluminium bronze as 7.8 to 8.6 kg/m³. Who knows, but it's certainly not heavy enough to be brass.

To make the slots, I started by mounting a bush in the milling vice. I'd intended to do this with a v-block between the moving jaw and the bush, but none of my v-blocks are big enough, so I just clamped it as if it were a bit of flat bar and hoped for the best! I used a DTI to find the exact centre of the bush:

Then put a big milling cutter in an ER40 collet. This cutter is somewhere in the region of 24 mm, but it's not an exact number: I think it was a 24 mm or 25 mm cutter that had been resharpened a few times when I bought it second hand.

I started opening out the slot by repeatedly moving the table over (in X) by a millimetre and then gradually plunging the cutter down. I did this until I'd reached ±8 mm.

I then moved the cutter over in tiny amounts in the Y direction and took passes all the way around the slot. This was intended to open the slot out and also smooth it up at the same time. Smoothing it up was a bit optimistic: I ended up with lots of chatter at the ends of the slot:

When I did the second bush, I used a slightly different technique - doing more of the plunge cuts and then only using the X feed to clean up the material between the circles made by the plunge cuts. I thought this would leave a much worse finish but it actually looked really good.

After cutting the slot, I spotted and drilled the 5 mm hole that is used with a dowel pin to make sure the slot is horizontal when it's inserted in the moving jaw.

I deburred both bushes and then for the bush that had lots of chatter, I then wrapped a bit of wet & dry paper round a 22 mm bar of steel and cleaned it up a bit:

The other one didn't need any clean up at all. The end result of that was that the slots are slightly different sizes (about 0.1 mm), so I'll probably make the tubes that run inside the bushes to match each individual bush (and make sure I put it all together the right way round!)

The finished bushes - I'm really glad these are complete as I was dreading that milling operation.

They even fit!

 

[Dr Al]

Most of the rest of the parts will be made entirely on the lathe. This is all of the turned parts in the project (excluding the aluminium hand wheels, which will also need a bit of tweaking to modify the central hole):

The long ones are the simplest: three bits of threaded rod with a small plain section turned on one end of each and three bits of 30 mm OD, 20 mm ID tube cut to length (and maybe faced on the lathe for neatness). I'll start with the brass bits:

As you can see from the picture, most of these (and one of the steel parts) are variants of the same idea, a simple flanged bush like this:

Most of the other parts are just tubes.

There's lots of variation in all the dimensions, but the process of manufacture is going to be much the same for all of them, so I won't include many photos. I'm going to start with the rail slide bushes for the standard vice (the long ones near the bottom-right of the pictures above). Of all the parts in the design, these are probably the most critical: if they're too loose, the vice will "rack" badly when tightening or in the extreme it could jam as the jaws are pulled in out of parallel. If they're too tight, the vice won't move at all. As soon as these are made, I'll put them in the fixed jaw and attach the rails to the moving jaw and see how it all feels.

After filling one of my bins brim full with nasty bronze swarf, I fitted one of the other bars of skip "brass" in the lathe and did a quick test cut:

Much better! That should be much more pleasant to turn when I get started on the rail bushes.

I also received the hand wheels in the post today. They'll need a bit of machining to open up the internal hole, but otherwise I'll pretty much use them as is (still debating whether to paint them black - I hate painting!). When I ordered them I was debating whether to go with aluminium or cast iron and went with aluminium for cost reasons. Having seen how much all the bits I've made weigh, I think the choice of aluminium may have been a very good one - I just entered some approximate density figures for all the parts in the CAD model and it estimated 28 kg for the finished bench!

 

[Dr Al]

I've had a couple of evenings where I had to do things that weren't in the workshop (boo, hiss!), but was back out and turning brass again this evening. As I said in an earlier post, a lot of the parts are going to look very similar in terms of the process, so I probably won't post many pictures, but I thought I'd do a detailed write-up of the first one.

Sorry if this is a bit dull: a lot of the pictures look fairly similar!

I'm starting with the vice rail bushes. The steel tube that I'm using as the rails need to be a smooth and easy sliding fit in the hole through the middle of the bush, so I took my time on this one. After making these bushes I'll probably be able to make the other parts a lot quicker.

The end face was relatively flat already, so I didn't bother facing before starting the process. I went straight for a centre drill:

Then drilled out 12 mm:

Followed by 19.5 mm (just because it's a size of Morse taper drill bit I have for some reason):

... and finally 25 mm, which is my biggest drill bit:

I then set up a large boring bar such it stuck out from the tool holder slightly more than the target depth of the hole:

Then used the power feed to enlarge the hole to the desired depth.

As I got closer to the finished dimension, I used a (cheap and very nasty) bore gauge to measure the inside diameter.

I measured with some digital calipers as at this point accuracy isn't that important. This was the last measurement I made, substantially smaller than the 30 mm target.

I stopped boring at this point (with the hole under-size).

 

[Dr Al]

I then put my upside-down tool in the tool post, set the lathe to run backwards and faced off the end:

I then turned the outside diameter down to about 0.5 mm over the target diameter (40 mm).

Once that was done, I wandered off and did some tidying at the other end of the workshop for half an hour while the workpiece cooled down. It's probably not **that** critical for this application (it's not exactly a bearing fit or anything), but I wanted to give myself the best chance.

Once it was back down to room temperature (which didn't take that long as it hadn't actually got that hot), I took a final pass on the outside diameter and then faced the inside surface of the flange:

This seemed a good time for a test fit of the outside diameter in the fixed jaw:

The boring bar then went back onto the tool post and I took a lot of passes (with repeated "spring" passes at each setting of the cross-slide) to gradually sneak up on the final diameter.

As I got close, I used the steel tube as a reference, rather than relying on the bore gauge to measure the size.

Finally, I chamfered the end to tidy it up a bit. I also chamfered the inside edge, but I just did that with a hand held deburring tool while spinning the chuck with my other hand.

 

[Dr Al]

Anyone still reading this?!?!

The part then came off the lathe and I scribbled over it in pen and marked the intended length of the flange. I then clamped it in the bandsaw vice and sawed off the excess:

Then it was back in the chuck for facing and turning the outside diameter of the flange down to 50 mm.

Finally I used my very small chamfering tool to chamfer both outside corners of the flange and again used a hand-held deburring tool to chamfer the corner of the bore.

Et voila!

Test fit in the fixed jaw with the tube inserted.

My next job is to make another one exactly the same. After that I've got a few more parts to make, but none of them are anywhere near as critical. There are a couple with critical bores, but the actual dimension isn't important, just the fact that they're parallel. I'll (later) make the steel bits that slide in the bore and I'll size them to suit the sizes of the bores in the brass parts - it's much easier to measure the OD repeatedly during turning, so I'd rather do it that way round given the choice.

 

[Dr Al]

I spent this afternoon turning lots and lots of brass. I started by putting the vice rail bush in the photocopier:

With both of them complete I could do a quick test fit of the standard vice parts to make sure it slides okay. It's difficult to tell at the moment (without the screw present), but it certainly moves, so that's a good start!

I then got going on the other (simpler) flanged bushes. These were made in a similar way to the vice rail bushes with a few minor differences:

1. Accuracy was far less important, so I bored the hole out in one go (rather than letting it cool down part way through).
2. The parts are much shorter, so I turned the larger diameter at the same time as the smaller diameter.
3. I parted the pieces off in the lathe rather than using the bandsaw. I still flipped them round and faced the parted-off end, but doing it this way was a bit quicker and didn't involve worrying about how to hold relatively short, stepped pieces in the bandsaw:

The first one I made was the bearing for the thread in the standard vice. This one will have a (similar looking) steel part running inside it to give a (hopefully) smooth action to the screw and also to make sure the jaw moves in and out with the movement of the screw:

There were then three identical flanged bushes in which the threaded rod will slide. The bore of these is 19.8 mm as the threaded rod I've got seems to be 19.7 mm diameter.

Slightly irritatingly, I dropped one of the flanges on the floor and it got a "dink" in one end. I've decided not to worry about it as this dink is in the end that's hidden between the inside face of the fixed jaw and the steel body of the vice mechanism. No-one will ever see it.

 

[Dr Al]

Here are all of the brass parts fitted (but not adhered) into their holes:

This test did highlight some issues unfortunately. For two of the parts (one of the thread bushes for the dual-screw vice and the central bearing for the standard vice), the larger hole in which the flange sits isn't concentric with the central bore. It's not actually that important as it's the central bore that has to be (and is) in the right place to ensure it works properly, it just means that there's a small (0.5 mm maybe?) gap visible on one side of the bush.

This is one of those things that no-one other than me will ever notice (especially once the hand wheel and washer are there), but I'm trying to work out how much it's going to annoy me and whether to do anything about it (and if so, what). The only thought I've had at the moment is to mount the parts back in the mill vice, use a DTI on the inner bore of the brass bush to get the XY table in exactly the right place and then make the hole a bit bigger (somehow - I suspect my boring head would leave an awfully ragged edge). I could then add a contrasting wood (if it's thin and I can figure out how to make it) or aluminium ring around the brass part to make it look deliberate!

I'll ponder on that one; I think it will be a heck of a lot of work...

With all the brass parts made, I did a test assembly of the bench to see what it's looking like.

I also gave the lathe a bit of a clear up and put all the swarf in some freezer bags for saving. I think I've produced more brass swarf in the last two days than I have in the rest of my metalworking life put together.

That lot weighs just over 7.9 kg!

With all the turned brass bits complete, the next job is probably to work on the steel pieces:

Three of these (the darker coloured two tubes on the left and the lighter coloured flanged tube on the right) have threaded holes through, one has some counterbored holes drilled in an awkward location (because this part was an afterthought!), one is a simple washer and four are an attempt at a couple of pseudo-spherical-washers to allow angular clamping. I'll leave those latter parts to last as (if they don't work) they can be replaced with plain washers as I don't expect to do much angular clamping.

 

[Dr Al]

I woke up this morning firmly of the opinion that the non-concentricity of the hole on the moving jaw of the standard vice was something I can't live with. The one on the fixed jaw of the dual-screw vice I think I can - it's only really visible if you look really closely, unlike the one on the moving jaw which is a much bigger gap and looks (in my opinion) awful.

To that end, I started this morning by getting a big of steel the same size as the inner bore of the brass insert and drilling and tapping it for an M5 screw.

I then fitted an M5 cap screw into one of the threaded holes on my router that is designed for holding guide bushes in place:

I could then screw the block of steel into place.

Sliding the brass "bearing housing" onto the bush allowed me to pick a router bit that wouldn't quite touch the brass.

I could then drop the whole lot onto the moving jaw to rout a circle:

That left a small ridge all the way around the inside of the hole.

Which I took off with a chisel.

 

[Dr Al]

Last year for my other half's birthday, I made her some brass pattern weights and a stand for them to sit on. When I was making the stand I had a test run for the base and wasn't very happy with it, so it got tossed into the "might-be-useful-at-some-point" drawer. Today it was useful!

I fitted the four jaw chuck to the lathe, covered the ways with a big rag and fitted the offcut of American Black Walnut.

I used the same bargain-basement Forstner bit that I'd used for the original hole to make a central hole that should fit the brass bearing housing thing.

I then faced the block off and turned a portion to size. Facing left a pretty awful finish, but then I was using a tool ground for aluminium, not walnut!

With the block removed from the lathe, I gave it a bit of a rub with some sandpaper.

I then used a saw to separate the ring from the rest of the block.

That could then be glued into place, sanded side down.

Once the glue was dry, I used my flush trim saw to trim it down to length. The masking tape was intended to lift the saw up a bit and make sure it was still proud after trimming:

That didn't work especially well and I managed to undercut the walnut a bit, so I used a #5 plane and planed the whole surface of the moving jaw down until everything was flush:

Here it is with the brass bearing block in place. I'm much happier with how this looks. It'll probably look even better if I oil the moving jaw.

The brass is now slightly proud of the surface of the wood, but I quite like how that looks and, being on the outside of the jaw, it won't affect function.

 

[Dr Al]

With the concentricity problem fixed, I could get on with some of the steel parts. I started by putting a bit of 50 mm EN1A into the three jaw chuck and pulling out my infrequently used fixed steady. The stock is too big to go through the bore of the chuck and it would be quite wasteful to cut a length off as I'd need an extra bit to be held in the chuck and that extra bit might end up being too short to be useful.

With that all set up (and well lubricated), I spot drilled the centre point, then drilled it out 6 mm, 12 mm and 16 mm to a depth of about 70 mm.

I then bored the hole to 17.75 mm, which is tapping size for 70% thread engagement on a M20×2.5 threaded hole.

I then set the lathe up for thread cutting and used the only tool I could find in my collection that would cut an internal thread with such a coarse pitch. Unfortunately, it's a right-hand threading tool so I had to cut the thread in this blind hole with the lathe running forwards and the tool the normal way up. I generally prefer to cut threads with the lathe running backwards as the tool exits the hole at the end of the cut rather than (potentially) running into the bottom of the hole.

I didn't enjoy that much (I much prefer finer pitch threads!) and it's making me rethink the equivalent parts for the dual-screw vice. I may either decide to do them as simple plain sleeves and epoxy them in place or I might buy a tap to make life a bit easier.

Anyway, with that done, I faced the end and turned a short section on the end (to get rid of the rusty surface on the end of the bar):

I then parted off...

... pausing part way through the parting operation to chamfer the edges:

The parted off face needs a bit of work (my parting results are a bit hit-and-miss), but that'll do for now...

 

[Dr Al]

I then slid the travelling steady along a bit and turned the body of the threaded sleeve down to 25.5 mm.

Then it was time for lunch while it all cooled down. My first postprandial task was then to take the final cuts to bring the shaft down to be a smooth running fit in the bearing housing thing.

A quick chamfer of the exposed corners...

... and it was ready for a test fit of the sleeve.

The test fit showed that it was about 0.5 mm longer than the bearing housing. It needs to be longer so that it doesn't jam up when everything's tightened up, but that was a bit too loose so I faced the end a little and brought the difference down to about 0.15 mm.

I then inserted a short length of threaded rod into the hole:

I could then mount the parted off washer onto the end and sort out the rough face.

To finish off the lathe work on these parts, I put my home-made ER40 collet chuck in the headstock and faced the outside edge to the right length and chamfered.

 

[Dr Al]

The threaded sleeve was then mounted in a collet block on the milling machine and two holes were spotted and drilled. These will be used with an angle-grinder style pin spanner to tighten the sleeve onto the threaded rod.

Similarly, I mounted the washer in the mill vice and milled a couple of flats:

These are all the parts that make up the bearing for the standard vice:

Here they are mounted onto a bit of threaded rod to show how they fit together - in this set-up, the brass part can spin freely.

This is what they look like in the moving jaw - the brass part will be glued into the moving jaw but the other parts will be free to rotate.

Here you can see the pin spanner holes in the threaded sleeve and where they'll sit on the inside face of the moving jaw. The face of the threaded sleeve is slightly below the surface of the beech.