Jock Miller's Taper Turning Attachment.

I'm having trouble visualizing this. Does the base (Part A) for the guide bar move in an arc when the cross slide is moved toward the operator to put on the cut? If so, does this not cause a small change in the angle of the taper with each succeeding cut? Thanks.

Jim

For anyone who isn't quite sure how it works, a block with two dovetail slides (D) fits on top of the cross-slide. A long plate (A) aligned with the bed slides in one dovetail, anchored at the far end of the bed by a long bar (L).

A guide bar (B) on top of the plate that can be angled for positive or negative tapers moves a dedicated top slide (F) in and out along the other dovetail.

To answer the question, no the cut is put on with the cross slide without affecting the angle. Although moving the cross-slide back and forth may move the carriage slightly closer or further away from the tailstock (very little because of the length of the anchor) the angle is only set by the angle of the guide bar, item B.

Neil

I would have been glad of a GA drawing.

+1 for a GA, it would have been more useful than the oversize parts drawings.

I have been perusing the much anticipated article as I too have an M250. In Jocks original article MEW259, he mentioned that the unit used an idea borrowed from an Emco taper turning attachment regarding the crosslide leadscew - forgive the paraphrasing as I do not have the article in front of me.

As I understand it usually when using a TT attachment the crosslide feedscrew is disconnected e.g. the Myford device. I got the impression from MEW 259 that this was unnecessary with Jocks design.

I was expecting in MEW264 for the leadscrew arrangement to be explained / detailed but have not come across it, perhaps it is obvious to the more technically minded.

<moved to where the explanation is by Neil>

Given that the article was much awaited, I hope that there will be a string of constructors eager to get started adapting the design to their machines or to suit their preferred methods of construction. I hope that this thread can be used to discuss designs / construction / show progress.

Tony

Edited By Neil Wyatt on 26/01/2018 12:58:40

I agree a GA would have helped, but getting thing sorted this far was a story in itself.

I think Item F was drawn for a 1/2 A4 page but I don't think the others are oversize; to squeeze into less space we would have had to cross the page join.

Neil

A simpler explanation:

Instead of moving the crosslide in and out, a second slide is fitted on top which is moved in and out by an angled guide bar mounted on a base which is anchored at its far end to the lathe bed.

Neil

Thank you for all the comments. I think I've got it now, I was failing to note that the yoke or clevis connecting the anchor link to part A could pivot. Sometimes I can't see the forest for the trees!

Congratulations to Mr. Miller on a very clever piece of work. My only suggestion would be to add a reference surface to part A so that a sine bar could be used to set the angle the guide bar.

Jim

Thanks Neil glad it was't just me. I like the idea of the reference surface.

Yes thanks for the explanation Neil, I should have said that earlier. This is the first taper attachment plan I've ever seen that didn't require either a telescoping crossfeed screw, or disconnecting the screw.

Jim

I'm assembling material for this - is anyone else planiing to build one ?

Cost of material is going to be high but as M250 taper turning attachements are as rare as rocking horse droppings it will be worth it.

Tony

The GA seems an ideal thing to put as a download on this site, single page PDF, meaningless to someone who's not read the article in MEW.

Regards,

Richard.

Cheeky! You want me to commission a GA just for the benefit of those who don't buy the magazines

Neil

No. Quite the opposite. The GA without the piece parts would be quite difficult to use, much more to the benefit of those who did buy the magazine. Just thinking that the web site could be used as an extension to the magazine for bits where there wasn't room to include them. I did, as others have said, think it'd have been useful to see a GA in the magazine, but could see there was no room.

Ah well, idea successfully squished.

Regards,

Richard.

I always try to make sure we have an extra bit of 'web content' for each magazine.

It was something of a mission for all involved to get the device into print, I really didn't want to further impose as it would be asking a lot of Jock and Peter to generate an additional GA.

I might be able to sketch the working principle.

Neil

Possibly a few more photos of the completed unit in various states of undress and an overall shot of the unit with the one guide bar and mounting posted on here would clarify the overall concept without needing extra drawings?

I will be drawing this up - don't know if I'll go as far as a GA as I think I've gor my head around it now.

I'm currenlt slicing up a large lump of MS for the bed clamp (sorry don't have the drawing in front of me to recall what letter s assigned to that parti. I'm going down the machine from solid route as I have the material and do not weld.

If anyone can follow what I'm talking about the bed clamp has a matching plate, the drawings call for holes in both parts to be M8 clearance - I would have thought that the lower piece would have been threaded M8 to save fiddling with nuts on the underside at the back of the lathe bed, any thoughts ?

Its been asked before!

That's how the original was made, probably to make sure there was clearance to ensure the clamp is located by the dowels not the screws. Using the arrangement you suggest should work fine.

Neil

If anyone's still having trouble getting their head around the layout of this attachment, here's an 'exploded' diagram (from the Emco V13 manual) of the device that inspired Jock.

Note that Emco chose rollers, rather than Jock's slippers, to follow the 'sine bar'. One roller is mounted on an eccentric pin (9) for clearance adjustment.

I am local to Jock and know him well and really must visit him again soon. If more questions appear here, I'll get answers directly from him and post them - hopefully within a fortnight or so.

Hope this helps.

[Note to Editor - please can you encourage contributors to provide GA drawings routinely for all but the simplest projects, instead of unnecessary instructions on the most basic workshop techniques and photos of drill bits going into metal, etc.?]

Possibly the most ignored paragraph in my article guidelines:

A general arrangement drawing is always welcome for any complex project and if one is not supplied I may request one. If you use first or third angle projections, please make it clear which is used on the drawing with the little ‘bucket’ symbol.

Neil