Taper Attachment Advise / Help

This topic has 8 replies, 6 voices, and was last updated 13 February 2013 at 14:19 by Baldric.

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12 February 2013 at 22:22 #111929
Rick Spaidal
Participant
@rickspaidal44040
I just purchased a taper attachment for a 13×40 lathe from EBAY, my lathe is a 13×40 except it is not setup to accept one yet,
there are no mounting holes or bolts in the rear of the saddle to mount the attachment to.
My question is how accurately do I need to make the taper attachment parallel to the ways, does it have to exact to within a thou .001"
if I don't remove the saddle and hand drill and tap the mounting holes I may not get it within a 1/16" will it still work OK or should I go
to all the trouble of completely dismantling the carriage/saddle so I can locate it exactly?
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12 February 2013 at 22:22 #6577
Rick Spaidal
Participant
@rickspaidal44040
13 February 2013 at 10:47 #111951
Brian Wood
Participant
@brianwood45127
Hello Rick,

I am not familiar with 13×40 lathes, nor a taper turning attachment to fit one, so I can only offer some general advice

First of all, the attachment mounts onto the lathe bed, NOT the saddle. Most are based on a dovetailed guide that can be locked to different shallow angles by bolting at each end into its mounting brackets, The dovetail will guide a block that is then attached up to the saddle via a stout coupling piece and a bracket onto the rear of the saddle so that guiding movements are directly into the saddle.

NOTE You must disconnect the normal saddle feedscrew arrangement so that all the saddle motion is from the taper guide alone. Failure to do that will result in a full on jam and damage to all sorts of things.

There should be a number of machined mounting points on the rear of the lathe bed upon which to mount the attachment, these may take the form of a fully machined surface running the full length of the bed, or a number of individual pads as on Myford lathes. There will be threaded mounting holes to match the spacing in the attachment you have bought. After fitting the attachment it will then be parallel to the bedways both across the lathe and vertically to within fairly tight limits in each direction.

The attachment should have come complete with all the bolting needed, and the stout block to transmit motion from the guide upwards to another substantial bracket or fitting that bolts to the saddle.

If you have all that then you are partway there. Taper angles should be engraved on one mounting for the guide so that you can preset for small angles.

The range of mounting holes along the rear of the lathe will allow you to make tapers at variou positions along the bed by moving the attachment to each section.

Take a look at my photos of the version I made for my Myford, it has all the essentials I've just outlined, but it is a full length version and not mounted as the genuine Myford version. which is about 8 inches long.

I hope that gives you some help. They are interesting things to watch in use.

Brian
13 February 2013 at 11:22 #111959
Swarf, Mostly!
Participant
@swarfmostly
Hi there, Rick and Brian,

Brian, you wrote 'saddle' but I think you meant 'cross-slide'.

Best regards,

Swarf, Mostly!
13 February 2013 at 11:31 #111961
Baldric
Participant
@baldric
Posted by Brian Wood on 13/02/2013 10:47:12:

Hello Rick,

I am not familiar with 13×40 lathes, nor a taper turning attachment to fit one, so I can only offer some general advice

First of all, the attachment mounts onto the lathe bed, NOT the saddle.

I am also not familiar with the 13×40 lathe so can't offer specific help on that, but do have a boxford, see **LINK** this does bolt to the saddle and the bed.

I also have use of an Elliot, from memory on that you don't disconnect the leadscrew nut, this means you can still use the cross slide feed to apply a cut.

Baldric
13 February 2013 at 12:49 #111966
David Littlewood
Participant
@davidlittlewood51847
Baldric,

I think there must be some confusion of nomenclature here. To use this type of attachment, you must* remove the cross-slide leadscrew as its position needs to be controlled by the taper bar. As Brian said, if you don't, there will be a massive smash up. You apply progressive cuts with the topslide, not the cross-slide. The Boxford attaachment is slightly different in that it looks to replace the cross-slide altogether (which of course automatically removes the cross-slide leadscrew from the equation).

On another note, most makers, and users, seem to assume that the taper guide bar and the slider which travels on it need to be dovetailed. This is quite unecessary; a rectangular bar is perfectly sufficient, as the rigid coupling with the cross-slide prevents any vertical movement. This is much easier to make in the home workshop. The Hemingway kit works on this basis (at least mine did, but that was 20 years ago).

*The only exception to this is if you have the type with a telescopic cross-slide leadscrew, as in the case of the one for the Harrison M300. If you have one of these – lucky you – then you need to follow its own instructions.

David

Edited By David Littlewood on 13/02/2013 12:51:38
13 February 2013 at 13:01 #111968
John McNamara
Participant
@johnmcnamara74883
Hi All

Some better end lathes us a teloscopic screw. a lot easier to set up.

Try the foolowing Google search.

taper attachment teloscopic screw

Cheers

John McNamara
13 February 2013 at 13:12 #111969
Brian Wood
Participant
@brianwood45127
Hello Swarf,

Thank you for pointing out my mistake, it is the cross-slide that is guided with the degree of cut controlled by the tposlide as David says.

Sorry for the confusion

Brian
13 February 2013 at 14:19 #111977
Baldric
Participant
@baldric
Posted by David Littlewood on 13/02/2013 12:49:15:

*The only exception to this is if you have the type with a telescopic cross-slide leadscrew, as in the case of the one for the Harrison M300. If you have one of these – lucky you – then you need to follow its own instructions.

David

Edited By David Littlewood on 13/02/2013 12:51:38

I think the Elliot is another exception. As I said I don't know the details about the 13×40, so I would advise trying to get the manula or be carefull, but not that different machines do it in different ways.

For info,the Boxford has a replacement cross slide that stays on the machine, you do have to remove the cross slide nut to use the taper turning attachment and replace it to use the crosss slide as normal. The down side is that the cross slide doesn't have t-slots in it.

Baldric
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