I really didn't expect that to work...

[Dr.Al]

This was an experiment, mostly to work out ergonomics and dimensions before designing something suitable for machining from lots of bits of aluminium. However, I think I won't bother with the aluminium now.

The experiment started with two left-over bits of walnut (from when I made a lot of chisel handles a couple of years ago):



They both got turned into cylinders with a roughing gouge:



I then got the spindle gouge out and attacked one of them in a rather random manner and with no particular shape in mind:



Off the lathe it came and a contraption that was almost entirely made by my 3D printer got mounted onto the lathe:



The only bits not 3D-printed are a cheap insert cutter from ridethebevel.co.uk, the four steel bars along with the LM10UU linear bearings that run on them, the two centres (turned on the metalworking lathe) and lots and lots and lots and lots of brass threaded inserts and steel screws. The linear bearings allow the tall bit of the assembly to move smoothly along and across the bed. The tool post thing has a pointy-out bit that touches the first (lower) turned part and stops the tool post (and hence the cutter) from moving too far in.

I was expecting it to shake itself apart or just vibrate too much to be of any use, but it just worked, with the cutter easily skimming down the workpiece to the right size:



The finish isn't amazing, but it's good enough that it wouldn't take much sanding. If/when I use it for real, I'll probably leave sanding of the "master" part until I've done all the duplicates and then everything will be sanded from the same base shape. A more direct comparison of the two parts:



Tonight I'll print version 2 with a few minor changes (mainly increasing the maximum part diameter to about 70 mm instead of the current 40 mm, but also making the tool post and cross-slide narrower). One nice thing about the design (and my new big 3D printer) is that all the parts fit easily on the printer bed in one go:

 

[Cabinetman]

Very clever indeed Al, and yes I like that it’s all on one “page”

 

[AndyT]

Very ingenious - but mind you don't design yourself out of your hobby!

 

[AndyP]

Nice one Al, why do you need so many identical spindles?
I have a design for a lathe duplicator with a far off hope of making a chess set one day.

 

[Dr.Al]

Nice one Al, why do you need so many identical spindles?

Honestly... I'm not really sure. The inspiration for it came when I was making drawer knobs for a recent box. It took me a few attempts to get two matching knobs. If that sort of thing comes up again (and especially if there are only two of them), I'll probably still make them all manually (rather than using the duplicator) but it nevertheless made me curious to see whether I could design one for my lathe.

The other possibility that I've been pondering is making a mug tree. That would have six (probably) spindles that I'd want to be fairly similar to one another. The duplicator would be very useful for that.

I have a design for a lathe duplicator with a far off hope of making a chess set one day.

That's one thing that doesn't tempt me in the slightest, but I'll still look forward to seeing what you make!

 

[Jonathan]

Al Very clever! Reminds me of an old Spanish wood turner I use to use, you had to supply him the design of the turning on 10mm MDF he then made it into a template for his copy lathe to follow. Bed on this machine was from memory about 2 meters long, he used to make the tulipwood pilasters for my furniture.

 

[AndyP]

Don’t hold your breath Al.
Here is the design I was hoping to copy

So far all I have made is the base.

 

[Accipiter]

That's a great 'jig' for duplicates. Very clever indeed

 

[Dr.Al]

Don’t hold your breath Al.
Here is the design I was hoping to copy

So far all I have made is the base.

That's interesting to see. I possibly over-constrained mine by keeping the tool on what I think of as the Y axis, whereas that one has a freely moveable base. I deliberately didn't look at online examples before starting as I wanted to see what I could come up with on my own.

For now, mine does everything I need it to do (although I'll admit that's not much!). I can always tweak it later if I ever need to. It'd be very easy to make the tool rotatable.

 

[AndyT]

Naahh... That's one way to make a chess set, but you don't need so many bits and pieces really...

 

[Cabinetman]

That's interesting to see. I possibly over-constrained mine by keeping the tool on what I think of as the Y axis, whereas that one has a freely moveable base. I deliberately didn't look at online examples before starting as I wanted to see what I could come up with on my own.

For now, mine does everything I need it to do (although I'll admit that's not much!). I can always tweak it later if I ever need to. It'd be very easy to make the tool rotatable.

I applaud your inventive streak Al, back when I was inventing things I really hated to see that it had already been done!

 

[Dr.Al]

Version 2 has been printed and fitted:



View from the rear of the lathe:


As you can see, the tool post now rotates, thanks to a conical washer in the base:



It's stiff, but I see that as a good thing: less likely to rotate when I don't want it to.

After the first test, I also had to replace a part that I never expected to last at all:



The steel replacement was made from a bit of 10 mm square bar using hacksaw, file, pillar drill and M4 tap.

To test out version 2, I thought I'd print a template instead of using a turned part:



With a template like that and the rotating head, I can hold a bit of wood in the chuck and turn to match:



I'm pleased with how it's turned out. I might do a version 3, but the only thing I'll change is to round over the corners of the lower part of the tool post (and perhaps the base that it slides along). That'll give a bit more clearance from the reference part when rotating the tool.

In practice, I'm not really expecting to use this very much. It's been a fun design challenge to come up with a design, but I'd rather be doing things manually and I'd rather be making one-offs rather than lots of the same. Nevertheless, I'm sure it'll come in handy now and then. Given how infrequently I expect to use it, it was nice to be able to print the parts rather than spending ages plodding away with the milling machine chewing up aluminium.

 

[Woolf]

Very neat.
How do you fit the brass inserts?

 

[Dr.Al]

Very neat.
How do you fit the brass inserts?

With a (gas powered) soldering iron. One of these, for which I turned some very simple brass ends.