Dr Al's Latest Folly

[Dapph2]

I've spent a couple of hours looking at your lathe build .
One thing stands out to me well two things ..both your tool rests are round bar . It's easy to slip off them and poke the wood .

A few weeks ago I was given a lesson by a guy in his 80's ( I'm 75) who has turned wood since he was about 8 yrs old.
Whilst having a MYFORD ML8 wood lathe it's not able to be set up at present ( awaiting a new mancupboard ) so I used my antique metal lathe that does not have a coolant system . The day before i met him I made a bodged up tool rest out of round stock welded to some angle iron & bolted it across the ways . I turned up some gash soft deal to make some 10 mm plugging . they were as rough as a the proverbial badgers Arrrrz.

When I gave him the plugging he said , Can I see your lathe " ? In the mancupboard he watched me make some more rough plugging . One thing he said was always place the chisel on the wood with the cutting tip a couple of inches forward and above the center line as it will rattle & bounce if the wood is not round this will stop you digging the chisel in ..

The next was the tool rest he said a round bar will allow you to slip forward with the chisel again causing digging in and variable depths of cut. . MY MYFORD rests are a different shank than the one I made so I ground the round bars off and welded on 1/2 " angle iron pieces . Suddenly things became a lot easier as having a finger against the crook of the angle stopped a lot of unwanted movement .
The lathe in the picture with the curved blade facing you on the rest is what he considered to be the best rests ( same as on the MYFORD )

 

[Dr.Al]

I've spent a couple of hours looking at your lathe build .
One thing stands out to me well two things ..both your tool rests are round bar . It's easy to slip off them and poke the wood .

They've got a round profile, but they're not round: they're a quarter of a circle (ish). This is the cross-section:

They were the closest shape I could (easily) get to relative to the one recommended in what I gather is the "bible" of woodturning, the book by Keith Rowley. This is his recommended tool rest shape:

I'm not sure I really understand the "slip off them and poke the wood" thing. What do you mean? I don't think I've ever slipped off the tool rest so I don't really follow.

Certainly making them out of angle would have been a heck of a lot easier! I might have a go with an angle-iron rest when the lathe is eventually back together again but that'll be a few weeks yet I expect.

 

[Dapph2]

Here is the MYford ML8 tool rest there are two one about 4 inches long and the other 8 inches long
eBay item number:357669611308

The curve is a finger fantastic resting place whilst you hold the chisel in your hand .

IIRC the Axminster's company made Youtubes use them and also recommend them .

 

[Dr.Al]

Today was all about the tailstock. When I made the tailstock originally, I just used what is essentially a nut to fix it in place. It wasn't quite as low-tech as a nut: it was a cylinder of steel with a thread tapped in the bottom and a sliding tommy bar going through it. Tightening and loosening the tailstock was a case of spinning the tommy bar round clockwise or anticlockwise.

That worked okay, but the box section that forms the bed isn't perfectly even and in some places I'd find myself needing to move the nut by as much as half of a turn, at which point I had to slide the tommy bar across. Not exactly a major issue (it certainly hasn't stopped me making stuff with the lathe), but a cam-lock tailstock would be nicer.

It's not the first time I've made one (I upgraded my first metalworking mini-lathe to have a cam-lock tailstock) so I had a fairly good idea of what I was doing before I started. When I did the original cam-lock tailstock for the mini-lathe, I followed a design I found on-line but it broke after a year or so and I ended up beefing it up a bit. For this one I decided to err on the side of strong!

I started with these three bits of EN1A:

They're 20 mm, 30 mm and 50 mm diameter. I later also used a bit of 10 mm diameter EN1A as well. I started with the largest piece, which was faced off on both ends and then drilled and bored out to 30 mm to a depth of 40 mm (in the 45 mm long piece):

The 30 mm bar got the outside surface cleaned up and then I drilled and tapped a shallow M10 hole in the bottom:

With those simple jobs done, it was over to the milling machine. I started with the bigger bit, which got drilled through 11.5 mm and also got a through 5 mm hole, which was partially tapped M6 in the more accessible side (the other side got partially tapped after it was removed from the mill vice):

The M6 thread there is for a short grub screw. The only purpose of the grub screw is to block the hole and stop sawdust from getting in (hence it only being partially tapped: the grub screw will tighten into the hole without protruding into the bore or out of the outside diameter).

I only actually wanted an M6 hole for a blanking plug on one side of the part but the side I wanted it on was the underside and I wanted it to be parallel with the other hole so it seemed easiest just to drill all the way through and add a blanking grub screw on both sides.

The bigger hole is to be 16 mm on the upper side and 12 mm on the lower side. For the upper side, I made the 16 mm hole with an end mill:

For the lower side, I converted the 11.5 mm drilled hole into a 12 mm hole with a reamer:

The outside surface of this part has some light surface rust. Since it was a short piece when I first started working on it, I couldn't turn the outside surface (as it was gripped in the jaws). I don't need a turned finish, I just want the rust gone. Rather than making something custom to hold on the inside bore, I thought I'd make use of the stub spindle I made a few days ago:

I fitted one of my woodworking chucks to that spindle and fitted some jaws that I recently bought second-hand on ebay. Conveniently, they're designed to hold on a 30 mm bore:

I don't think that would be a very good set-up for taking any substantial cuts with a lathe tool, but it was fine for spinning the part round and cleaning up the outside with 240 grit emery cloth:

The other part already had a smooth outside surface as it had been given a skim cut on the lathe, but it still needed the cross holes, this time a 16 mm hole all the way through and a smaller M5 hole half-way through:

That M5 hole will have a grub screw in, which will lock a bit of threaded rod into the tapped hole in the bottom; removing the M6 blanking plug in the outer part will allow access to the grub screw if I want to remove the threaded rod later.

The next job was to work on the tailstock. This needed a 20 mm hole drilled in the rear face. I say drilled, but I had to use slot drills and end mills for this job as the surface is sloped and hence a drill bit wouldn't have worked.

While I had it clamped in the mill vice, I also drilled and tapped an M5 hole down in the corner:

The final significant job was the cam. This started off as 20 mm EN1A, which got turned down to 16 mm for a bit and then turned down to 12 mm for a bit. The tailstock live centre was then removed and the end got an M5 tapped hole made in the end:

It then got remounted in the lathe but with a couple of feeler gauge sheets (totalling 1 mm thickness) in between one of the jaws and the part. I could then skim most of that 16 mm diameter down a bit more, resulting in an offset section that will lift and release the 30 mm diameter nut.

The other end got mounted in a collet and tidied up a bit and then it got taken over to the milling machine to gain a tapped cross-hole:

Without taking any photos, I made a couple of other simple pieces: a 10 mm shaft with an M8 thread on each end and a 16 mm tapering knob with and M8 tapped hole in the end:

They get assembled like this:

I also made a very simple small stub shaft (just a bit of 10 mm steel with a counterbored hole in it for an M5 retaining screw) to go into the tapped hole in the corner of the back of the tailstock. It was then time for a test drive. The lathe bed is in pieces at the moment, so I just got the welded box section pieces and clamped them on top of some pieces of wood on the bench. That was good enough to test the operation:

This photo from the rear of the lathe shows the cam in the unlocked position, resting on that little stub shaft (which stops it dropping further down behind the lathe and potentially starting to lock again):

This photo shows the cam in the locked position. It seems to hold onto the bed extremely rigidly and, if necessary, it could still be rotated further if more locking force were ever required:

That's all the changes I'm making to the tailstock, except that I'm planning to paint it (and other parts). I might try and deal with the weld bead on the back of the tailstock before painting (if I can find a good way to get a grinder of some sort to it - my angle grinder flap disc wouldn't get in there). It's not the end of the world if I don't though.

The next job will probably be to work on the banjo. I'm thinking I might add a cam-lock to the tool post mount as well (there's already a cam-lock securing the banjo to the bed).

 

[Dapph2]

Today was all about the tailstock. When I made the tailstock originally, I just used what is essentially a nut to fix it in place. It wasn't quite as low-tech as a nut: it was a cylinder of steel with a thread tapped in the bottom and a sliding tommy bar going through it. Tightening and loosening the tailstock was a case of spinning the tommy bar round clockwise or anticlockwise.

That worked okay, but the box section that forms the bed isn't perfectly even and in some places I'd find myself needing to move the nut by as much as half of a turn, at which point I had to slide the tommy bar across. Not exactly a major issue (it certainly hasn't stopped me making stuff with the lathe), but a cam-lock tailstock would be nicer.

It's not the first time I've made one (I upgraded my first metalworking mini-lathe to have a cam-lock tailstock) so I had a fairly good idea of what I was doing before I started. When I did the original cam-lock tailstock for the mini-lathe, I followed a design I found on-line but it broke after a year or so and I ended up beefing it up a bit. For this one I decided to err on the side of strong!

I started with these three bits of EN1A:

They're 20 mm, 30 mm and 50 mm diameter. I later also used a bit of 10 mm diameter EN1A as well. I started with the largest piece, which was faced off on both ends and then drilled and bored out to 30 mm to a depth of 40 mm (in the 45 mm long piece):

The 30 mm bar got the outside surface cleaned up and then I drilled and tapped a shallow M10 hole in the bottom:

With those simple jobs done, it was over to the milling machine. I started with the bigger bit, which got drilled through 11.5 mm and also got a through 5 mm hole, which was partially tapped M6 in the more accessible side (the other side got partially tapped after it was removed from the mill vice):

The M6 thread there is for a short grub screw. The only purpose of the grub screw is to block the hole and stop sawdust from getting in (hence it only being partially tapped: the grub screw will tighten into the hole without protruding into the bore or out of the outside diameter).

I only actually wanted an M6 hole for a blanking plug on one side of the part but the side I wanted it on was the underside and I wanted it to be parallel with the other hole so it seemed easiest just to drill all the way through and add a blanking grub screw on both sides.

The bigger hole is to be 16 mm on the upper side and 12 mm on the lower side. For the upper side, I made the 16 mm hole with an end mill:

For the lower side, I converted the 11.5 mm drilled hole into a 12 mm hole with a reamer:

The outside surface of this part has some light surface rust. Since it was a short piece when I first started working on it, I couldn't turn the outside surface (as it was gripped in the jaws). I don't need a turned finish, I just want the rust gone. Rather than making something custom to hold on the inside bore, I thought I'd make use of the stub spindle I made a few days ago:

I fitted one of my woodworking chucks to that spindle and fitted some jaws that I recently bought second-hand on ebay. Conveniently, they're designed to hold on a 30 mm bore:

I don't think that would be a very good set-up for taking any substantial cuts with a lathe tool, but it was fine for spinning the part round and cleaning up the outside with 240 grit emery cloth:

The other part already had a smooth outside surface as it had been given a skim cut on the lathe, but it still needed the cross holes, this time a 16 mm hole all the way through and a smaller M5 hole half-way through:

That M5 hole will have a grub screw in, which will lock a bit of threaded rod into the tapped hole in the bottom; removing the M6 blanking plug in the outer part will allow access to the grub screw if I want to remove the threaded rod later.

The next job was to work on the tailstock. This needed a 20 mm hole drilled in the rear face. I say drilled, but I had to use slot drills and end mills for this job as the surface is sloped and hence a drill bit wouldn't have worked.

While I had it clamped in the mill vice, I also drilled and tapped an M5 hole down in the corner:

The final significant job was the cam. This started off as 20 mm EN1A, which got turned down to 16 mm for a bit and then turned down to 12 mm for a bit. The tailstock live centre was then removed and the end got an M5 tapped hole made in the end:

It then got remounted in the lathe but with a couple of feeler gauge sheets (totalling 1 mm thickness) in between one of the jaws and the part. I could then skim most of that 16 mm diameter down a bit more, resulting in an offset section that will lift and release the 30 mm diameter nut.

The other end got mounted in a collet and tidied up a bit and then it got taken over to the milling machine to gain a tapped cross-hole:

Without taking any photos, I made a couple of other simple pieces: a 10 mm shaft with an M8 thread on each end and a 16 mm tapering knob with and M8 tapped hole in the end:

They get assembled like this:

I also made a very simple small stub shaft (just a bit of 10 mm steel with a counterbored hole in it for an M5 retaining screw) to go into the tapped hole in the corner of the back of the tailstock. It was then time for a test drive. The lathe bed is in pieces at the moment, so I just got the welded box section pieces and clamped them on top of some pieces of wood on the bench. That was good enough to test the operation:

This photo from the rear of the lathe shows the cam in the unlocked position, resting on that little stub shaft (which stops it dropping further down behind the lathe and potentially starting to lock again):

This photo shows the cam in the locked position. It seems to hold onto the bed extremely rigidly and, if necessary, it could still be rotated further if more locking force were ever required:

That's all the changes I'm making to the tailstock, except that I'm planning to paint it (and other parts). I might try and deal with the weld bead on the back of the tailstock before painting (if I can find a good way to get a grinder of some sort to it - my angle grinder flap disc wouldn't get in there). It's not the end of the world if I don't though.

The next job will probably be to work on the banjo. I'm thinking I might add a cam-lock to the tool post mount as well (there's already a cam-lock securing the banjo to the bed).

Very nice . I may make a cam lock for the metal lathe as it us usually tighten so much with a 1/2 whit spanner then turn the jaw through 180 and finish off tightening . .

 

[Dr.Al]

Very nice . I may make a cam lock for the metal lathe as it us usually tighten so much with a 1/2 whit spanner then turn the jaw through 180 and finish off tightening . .

That's what my mini-lathe was like. It was a pain when working up close to the carriage.

 

[Dr.Al]

I didn't feel quite ready to work on the banjo yet (still more thinking to do) so I thought I'd get on with another job. I stared with another bit of left-over 50 mm EN1A bar, which got faced, skimmed and drilled 13 mm:

After chopping it off with the horizontal bandsaw, I mounted it back in the chuck with a 3D-printed "spider" and cleaned up the sawn-off face:

Next up was a big bit of skip-dive stainless steel. That got held in the outside jaws of the three-jaw chuck:

I then cleaned up one face...

... then flipped it over, cleaned up the second face (bringing it down in thickness as far as I could without hitting the jaws) and then again drilled 13 mm through:

I knocked up this quick and simple jig for holding both parts on the milling machine. The end has been reduced to 13 mm for a short section and it has an M8 tapped hole in the end:

The lathe axis got centred on the axis of that 13 mm section and then I mounted the 50 mm piece on the jig and drilled and counterbored for M5 cap screws:

That part then got removed and the bigger one fitted and this time I drilled and tapped M5:

The last milling job for now was to mount the smaller piece on end and cross-drill and tap M8:

M8 is a bit excessive for a part that thickness, but it has the advantage that the grub screw has a 4 mm AF hex socket in it, which is the same as that in an M5 cap screw or an M6 countersunk screw. Wherever possible, I'm using those types of screws on the lathe so that a single Allen key can be used for as much as possible.

Four M5 cap screws could now be used to join the two parts together:

I tightened those cap screws up as much as I could: all being well they'll never be undone.

With the two parts joined together, I mounted the assembly back on the lathe (gripping on the outside of the smaller diameter part) and (very slowly) bringing the larger part to final thickness (8 mm) and diameter (142 mm), before boring out the centre hole to 20 mm:

That took most of the morning (I had to run the lathe quite slowly or it would run out of power trying to cut near the outer diameter of that stainless disc) so I've stopped for lunch now. More to follow...

 

[Dr.Al]

After running some errands, this afternoon saw the completion of this part. I started by making a new jig, which was simply a bit of steel with a 20 mm section turned on the end, a 24 mm section turned concentric with that (the diameter of the latter didn't matter, it just had to be concentric) and an M8 hole tapped in the end:

In that photo I'm parting off the bit that hasn't had any turning done on it. That "jig" got held in a collet chuck and the workpiece got clamped down to it. I then used the "PCD" (pitch circle diameter) function of the digital read-out, in combination with an 3 mm spotting drill, to mark out 24 holes, evenly spaced around the outside (on a 120 mm diameter):

They all then got drilled out 2.5 mm and then every other one got drilled out 7.6 mm, deburred with a countersink and then reamed to 8 mm:

I put an M3 tap in the chuck but turned it by hand (there's no way I'm power-tapping M3 in stainless steel!) to turn the remaining holes into through threaded ones:

With all the holes drilled and reamed or tapped, that was the piece almost complete.

I used the pillar drill with a countersink bit to deburr the reverse side of the part and then used the laser function of my new-ish 3D-printer to engrave and cut out two mirrored pieces from some 1.6 mm thick black-on-white laser laminate:

Unsurprisingly, the laser won't countersink holes, so I did that on the pillar drill:

With that, the part is complete, both sides shown in this composite image:

You may notice that the screws holding the acrylic down look a bit odd. I don't have any short enough screws to have one coming in from each side in every hole so for now I've just used a longer one in every other hole. I've got quite a few different screws to get hold of so I'll place an order with KayFast in the next day or so.

In case you haven't already guessed what this is for, this is a dividing attachment for the lathe. It'll get mounted on the rear of the spindle. There will be a sliding bar in the new lid of the headstock (using one of the two holes I drilled in the lid that had to be 60 mm from the spindle axis) that will (hopefully) slide into the holes on this dividing plate and will lock the spindle's rotation, allowing me to add features that are evenly spaced around a turned part.

For interest, the other hole in the lid that also had to be 60 mm from the lathe axis is just for a mounting screw. The only reason it had to be 60 mm from the lathe axis is so that I can stick an Allen key through one of the dividing plate holes in order to loosen/tighten the screw.

 

[Dr.Al]

The last couple of days have been all about the new tool post clamp mechanism. There were two aims in this modification. The first was to replace the screw that is used to lock the tool post in place with a cam mechanism, which should make it possible to move the lever further away from the tool post (and hence the spinning workpiece). At the moment it points to the left slightly so I sometimes feel the need to stop the lathe before adjusting the toolpost screw just because of hand/spinning-bowl proximity.

The second aim is to reduce the height of the clamping part slightly. The current one sticks up 25 mm above the banjo; the new one 20 mm.

I started by spending quite a while with the CAD model:

This cut-away animation shows how the new mechanism is intended to work (this loops on my website, but I can't figure out how to make that happen on the forum):

The first job was to make the cuboid that will form the body of the tool post clamp. That started as a slice off the end of a bar of 25 × 50 mm hot rolled steel:

It took a few hours of milling to clean all the hot rolled surfaces and reduce the size down to 20 × 49 × 70 mm, after which I had this shiny block:

This morning I started by drilling the hole in the end of the block (through which the brass clamping piece will slide). That was relatively straightforward, being a 12 mm hole to 49 mm depth and a 16 mm hole to 39 mm depth:

The holes in the top surface were also quite straightforward: three counterbored holes for M6 cap screws and a reamed 16 mm hole intersecting with that first hole I drilled:

The clamping piece was made from brass (which seems to look like copper in the next photo, but that's just the lighting/camera being odd). The body got turned down to 16 mm and the end turned down to 12 mm:

I did a quick test fit in the steel block to make sure it was looking okay before I took it out of the lathe's chuck:

To match the curve in the tool post's shaft, I mounted the brass piece in the milling vice with a collet chuck and used a 16 mm end mill to cut into the end:

I wanted to drill the last hole in the big block with the two parts together. If I pushed the brass piece into the hole and just attacked it with a drill bit, the hole could end up at the wrong angle and more than likely in the wrong place as well. If I put a 16 mm bar in the hole and clamped the brass piece to that, it would ensure the right orientation but the brass clamp would never move deep enough into the hole to actually clamp.

As an alternative, I dug out an off-cut and turned a section down to 16 mm before reducing the central portion a bit further (to 15 mm diameter):

That half millimetre reduction in radius means that, when clamped together, the hole in the brass piece was drilled with a bit of a protrusion into the tool post hole:

The first two parts complete:

Making the cam followed much the same process as the last one, with the first two diameters and the tapped hole in the end done as usual in the lathe before making the cam with some feeler gauge pieces shoved between one of the jaws and the part:

After drilling and tapping the cross hole for the tommy bar and finishing the bar to length, I found that the cam needed a bit of tweaking, so I put it back in the lathe (with some copper tape protecting the part from the jaws) and took 0.1 mm deep cuts at a time, testing with the rest of the assembly and the tool post after each cut:

With that, all the core parts were made and it was clamping the tool post very effectively. However, when the cam is unlocked, there's nothing stopping the brass clamping piece wandering into the tool post hole and hence stopping the tool post from being inserted. Fortunately, I'd thought of that beforehand: what it needs is a spring (if you go back to the cross section animation at the start of this post, you'll see a convenient gap has been left for a spring to sit in).

A few years ago, I made a spring calculator for calculating the right arbor size for making a custom spring out of piano wire. Despite having made that calculator, I've never actually made a spring before: I always intended to but never really had a need for a custom spring. This seemed the perfect opportunity.

The process is very simple. You set up the calculator for the diameter of piano wire you have, pick a target diameter and other parameters that matter to you (e.g. pitch, length) and it tells you the arbor size on which to wind your spring. The arbor is a simple bit of steel with a hole drilled through the end:

The wire gets fed through something clamped in the tool post (I used a bit of plastic with a hole drilled through) and through the cross-hole:

After turning the spindle a couple of times by hand to make the end coils, you engage the lead screw half-nuts (with the leadscrew set up for the desired pitch) and then keep turning the spindle by hand. Once you've got the length you want, you disengage the lead screw half-nuts and do a couple more turns for the other end:

After trimming off the excess with some heavy duty side cutters, I slid it onto the brass bit and it was a perfect fit (so the calculator seems to have got the arbor size spot on):

After assembling it again, I put the tool post clamp block in the bench vice and tried it out. If you look into the hole in the first half of this short video, you can see the brass clamp moving in (under the cam force) and out (under the spring force):

The last thing to do was drill and tap an extra hole (located with a transfer punch after tightening the other two screws) in the banjo:

Complete:

I may shorten the brass clamp (so it doesn't stick out the side as far) at some point, but I'm going to leave it as-is for now. It's not doing any harm as far as I can see and it'll give me something to grab onto if I ever need to for some currently unforeseeable reason. I'd also like to round off a few sharp corners at some point (although I can't got that far as there are a lot of screw head counterbores that are very close to the edge).