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Cutting long tapers using homemade top/compound slide

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Square Peg02/04/2020 14:52:34
10 forum posts

I often need to clean up tapered tools for jewelers and silversmiths and am limited by the 3" of travel on my topslide. I was wondering if making a longer top slide was a viable solution. I was thinking of powering the slide by using a small 3-phase motor and VFD. It seems simple enough but was wondering why nobody seems to use that method.

Mick B102/04/2020 15:03:20
1552 forum posts
83 photos

From your last pic, you seem to me to be doing nicely wiv wotcha got.

I'm guessing that the drawback to an extra long topslide is the potential mutual obstruction between topslide handwheel at full retraction and tailstock, unless you have a chatter-prone tool projection at the toolpost, or some special toolholding arrangment to counter that.

Alan Waddington 202/04/2020 15:31:36
496 forum posts
87 photos

Unless im misunderstanding the problem, why not just make a taper turning attachment ?

Square Peg02/04/2020 15:57:26
10 forum posts
Posted by Alan Waddington 2 on 02/04/2020 15:31:36:

Unless im misunderstanding the problem, why not just make a taper turning attachment ?

Cuz I've got no idea how they work!

old mart02/04/2020 15:59:53
1538 forum posts
136 photos

I think you are already using the best method that your lathe is capable of. A longer top slide will run into problems of lack of stiffness. That leaves the possibility of making a taper turning attachment, it might be feasible if you have milling facilities. For a taper turning attachment to work, you have to disconnect the cross slide leadscrew. The cross slide has an  extension to the rear which slides along a track angled the required amount to be parallel to the taper. When you move the saddle, the tool follows the required taper. The link might help to visualise how they work. Ignore the tailstock types, they will not do what you require.

 

https://www.google.co.uk/search?q=lathe+taper+turning+attachment&tbm=isch&source=iu&ictx=1&fir=duKOMIMNYJEaTM%253A%252CZVsM7gq3HZF_kM%252C_&vet=1&usg=AI4_-kSAOvL7HAUA0QdtZH6lXcstFwK4SQ&sa=X&ved=2ahUKEwiN16nMgsroAhUqQxUIHXDKCF0Q_h0wAHoECAUQBA#imgrc=duKOMIMNYJEaTM: 

Edited By old mart on 02/04/2020 16:11:15

ega02/04/2020 16:18:47
1633 forum posts
137 photos

In default of a TTA I have fitted a spare ML7 cross slide to my S7 cross slide:

b0010136.jpg

Fine adjustment of the "top slide" is via the gadget installed in the front tee slot.

Edited By ega on 02/04/2020 16:19:18

ega02/04/2020 16:28:45
1633 forum posts
137 photos

PS I haven't used this setup for some time but, looking at the photo, I can see that the "top slide" gib is on the wrong side for taper boring, something to bear in mind for the future. That said, I don't recall any problem of lack of adequate stiffness.

Alan Waddington 202/04/2020 18:41:24
496 forum posts
87 photos
Posted by Square Peg on 02/04/2020 15:57:26:
Posted by Alan Waddington 2 on 02/04/2020 15:31:36:

Unless im misunderstanding the problem, why not just make a taper turning attachment ?

Cuz I've got no idea how they work!

Google is your friend........got to be easier than what your doing now.

Is it a Harrison L5 or L5a ? If so pretty sure iv’e got a genuine Harrison taper turning attachment tucked away somewhere.

Spurry02/04/2020 19:01:31
187 forum posts
62 photos

Although not extending the range of the top slide, I have used an allen screw into the handle retaining shaft, powered by a bit of allen key in a variable speed electric drill.

Much less tedious than turning by hand.

Pete

Square Peg02/04/2020 19:29:41
10 forum posts
Posted by Alan Waddington 2 on 02/04/2020 18:41:24:
Posted by Square Peg on 02/04/2020 15:57:26:
Posted by Alan Waddington 2 on 02/04/2020 15:31:36:

Is it a Harrison L5 or L5a ? If so pretty sure iv’e got a genuine Harrison taper turning attachment tucked away somewhere.

It's a new fangled 140...

DC31k02/04/2020 20:35:04
182 forum posts

How accurate does the taper need to be? A great deal of the complexity of a full-blown taper attachment is in the adjustment mechanism. If you do not need such fine control of the angle, a much simplified version is reasonably easy to make. It would be more like a copy turning attachment where the pattern is straight-edged.

I would use some of the cheap round rail and bearing/slider that you see on low end CNC machines. Glue it to the back of the bed, set the angle good enough, disconnect the cross-slide feedscrew and have at it. Put on the cut with the compound slide.

Even simpler is just to spring load the cross slide against a straight piece of flat bar set at the correct angle. You might be able to set up the straight bar such that it is clamped to the bed just above the cross slide and let the non-moving part of the compound ride along it.

DC31k02/04/2020 20:45:17
182 forum posts

Sorry to follow up so soon, but it might be worth perusing this thread:

https://www.model-engineer.co.uk/forums/postings.asp?th=110851

Our very own Jason makes some very relevant points that will greatly assist your situation.

Square Peg07/04/2020 13:20:39
10 forum posts

Thanks for the replies, I think I may have a go at making one if I can't find one to buy...

Neil Wyatt07/04/2020 19:05:56
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17729 forum posts
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Posted by Spurry on 02/04/2020 19:01:31:

Although not extending the range of the top slide, I have used an allen screw into the handle retaining shaft, powered by a bit of allen key in a variable speed electric drill.

Much less tedious than turning by hand.

Pete

Me too

Steadier as well

Neil

Howard Lewis07/04/2020 22:47:57
3148 forum posts
2 photos

If you want to turn a long taper, you can offsetb the tailstock (Don't forget to realign it afterwards )

Or you could fit a Boring head in then Tailstock With the slide horizontal ) and use the adjuster to offset a small, specially made centre. No Boring Head,? There have been designs for a Tailstock mounted slide which does the same thing. I think that Dave Clark made one up for his mini lathe and featured it in an narticle in MEW, some time ago.

It might be worth doing a dummy run to ensure that the offset is correct to produce the taper that you require.

Howard

Mick B107/04/2020 22:55:18
1552 forum posts
83 photos
Posted by Howard Lewis on 07/04/2020 22:47:57:

If you want to turn a long taper, you can offsetb the tailstock (Don't forget to realign it afterwards )

...

OK, but the OP's illustrated piece would need a pretty big offset and also present what look like serious issues gripping the headstock end on the slant.

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