Repeatable turning - now with pictures!

[TheTiddles]

I'm normally too proud to admit such things but it appears I'm not as good at turning as I remember. I haven't done any in ages and over the last couple of evenings I've stripped my lathe apart (a very old Elu db180) shortened it so it's easier to fit on my bench and roughed back a load of spindles of beech to work on.

Today I decided to finish off the drawer pulls for my tool cabinet, I started it in February so I want it done now, incidentally that was February last year... I made about twenty, they're all a little bit different and the standard is crappy. I used to make larger things so most of my tools are a bit large, but still, I was hoping for better. I need six pairs of pulls, incrementing slightly in size as they go with with the drawers. With my stock of spindles exhausted I've decided to look into making a rough copying attachment that I can adjust to increase the size of the parts and hopefully get the proportions consistent, has anyone done anything like this? The task afterwards is tool handles and I'm not going to be happy if I blow all my nicely dried hornbeam making hamster bedding.

Any ideas? I'm half considering making a router lathe but this seems like more work than modifying my lathe just for these few items

Aidan

 

[9fingers]

Hi Aidan,

You could consider a mechanical pantograph device for scaling but quite a bit of effort.

If you are partway down the copy lathe solution then you could scale paper patterns on a photocopier or within the driver for your printer.
Then stick them onto 6mm mdf or acrylic sheet. Cut out on a scroll saw to make your follower templates.

Make the follower pin as small diameter as possible for best fidelity to the pattern. Slip a piece of tube over the pin for roughing cuts and slide off to finish.

hth

Bob

 

[wizer]

why not just make the paper templates and use them to check your work as you do it by hand ? I'm sure you'll get there with a bit of patience. Building a copying attachment or a router lathe is a bit extreme for one set of knobs

 

[DaveL]

Hi Aidan,

I would not try for them being all exact copies, just very similar, that shows they are hand turned. Not mass produced on a cnc machine along with 1000's of others. #-o

Toms idea is good, cut the profile you want in cardboard and mark the transitions on your work to guide yourself.

 

[TheTiddles]

...with a bit of patience

With what?!

This cabinet's the centrepiece of my man-cave and I've never been too keen on the idea of making things wonky to show you've made them yourself, surely it's a bit of a statement about your work if you have to do that?

Anyway, I'm going to get some templates cut and try that one whilst I work on the copy-attachement. It only needs to be a small one for tool handles and so on. WIP coming soon...

Aidan

 

[wizer]

...with a bit of patience

With what?!

Sorry I didn't realise who I was speaking to! I do agree that wonky just looks wonky, not hand made.

You could always have them outsourced ?

 

[TheTiddles]

Right, not had much time today but here's what I've tried...

Start with two pieces of plastic, just some scraps I have kicking around, first thing is to stick them together with a couple of bit of double sided tape, not much, it doesn't give good location between two parts, just a enough to hold them together otherwise you will end up breaking the parts to get them apart, drill them for locating dowels whilst the work is in progress, 3mm should do it,

Next, drill out the bulk of the material

and cut out the chunk in between, well, I need a new blade for this soon anyway

and the rest

Right, a small bearing I had kicking around, some more dowel pins and some nuts, screws and washers we have this, the astute amongst you should by now see the first shortcoming

So, a bit if my lovely hornbeam on the spinney thing and off we go

I played around a bit and then took ten cuts to measure consistency, the dimension we are looking for is 37mm as set on the tool.

So, results are
36.50
36.52 Mean 36.25
36.24 SD 0.26
36.32
36.28
36.12
36.06
36.14
35.74
36.60

Humpf, not what I was after. The results are good down to number 10 but then that jump looks to me like it wasn't something slipping down which is easier to address.

Still, never one to let things go to waste, the weekends dross makes a great degu toy!

Better luck next time, quite a few improvements to be made

Aidan

 

[Jake]

Clever Rexroth sled.

 

[TheTiddles]

Clever Rexroth sled.

Sorry buddy, I only speak English! :lol:

What's a Rexroth Sled?

Aidan

 

[Shultzy]

Tiddles, I think what you need is the attachment on this parting tool, but I'm not sure if these are supplied together.

http://www.craft-supplies.co.uk/cgi-bin ... 0|user||2|

 

[TheTiddles]

That's the sort of thing I was copying, though the cheeks either side of the bearing limit the depth of cut to just a few mm. I'm part way down an x/y follower at the moment, unlikely to finish it this week but hopefully it will do what I want it to

Aidan

 

[Richard Findley]

Hi Aidan,

That's a smart looking tool you've made. I'd say one of the main problems with using it would be an inability to get a good bevel rubbing cut? I always use vernier calipers:

Much easier and far more adjustable!!

Mind you, you are worrying over a maximum of 1mm difference. This is really nothing in turning terms, certainly not noticable on a set of knobs!!

Good luck with it,

Richard

 

[Jake]

Clever Rexroth sled.

Sorry buddy, I only speak English! :lol:

What's a Rexroth Sled?

Aidan

Isn't that a Bosch Rexroth extrusion you are using as a cross-cut sled?

 

[TheTiddles]

Clever Rexroth sled.

Sorry buddy, I only speak English! :lol:

What's a Rexroth Sled?

Aidan

Isn't that a Bosch Rexroth extrusion you are using as a cross-cut sled?

I wish! That's the standard extruded jobby on an Axminster TS200, same profile as the Bosch standard stuff, but about 1/100th the quality, you can bend it with finger pressure. Now if I had access to offcuts of machine building stuff I'd be made, however I don't, so it's clear acrylic and aluminium for the parts and an indexable carbide insert for me.

The sizing tool is ok for about two hours work, it's definitely not going to last more than a week or two before it's recycled. I like the idea of using calipers but I always find that I get close then overshoot the target with that method, though this is down to my technique. That and one slip and your calipers are flung across the shop and after that they're toast, I imagine you have a cheap set for that method?

As for 1mm being acceptable tolerance... not in my garage! Though seriously, it's more the profile between the points that shows up the inconsistency more than the actual measurements of the peaks, hence the desire for a copy attachment. When it comes to the tool handles I'm going to want that 1mm at the most, in the hand I'd notice much less than that, even though these are handles for my ****** chisels so they match the nice ones...

Aidan