Cutting long tapers using homemade top/compound slide

[Square PegParticipant @squarepeg53768]

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.

[Square PegParticipant @squarepeg53768]

[Mick B1Participant @mickb1]

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 2Participant @alanwaddington2]

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

[Square PegParticipant @squarepeg53768]

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 martParticipant @oldmart]

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

[egaParticipant @ega]

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

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

[egaParticipant @ega]

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 2Participant @alanwaddington2]

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.

[SpurryParticipant @spurry]

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 PegParticipant @squarepeg53768]

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…

[DC31kParticipant @dc31k]

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.

[DC31kParticipant @dc31k]

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 PegParticipant @squarepeg53768]

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

[Neil WyattModerator @neilwyatt]

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 LewisParticipant @howardlewis46836]

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 B1Participant @mickb1]

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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