Lathe Thread Stop

[ZigFireParticipant @zigfire]

Hi,

Was looking at some of the vids on the Start Model Engineering” site (a great site btw) and the gentleman there talked about the lathe he was using having a thread stop.

 

I understand the concept, but unfortunately my lathe is not fitted with such a stop.

 

Question being has anyone designed such a beast for retro fitment to a cross slide as I reckon this would be a pretty handy thing to have.

 

Cheers

Michael

[ZigFireParticipant @zigfire]

[TerrydParticipant @terryd72465]

Hi Michael,

 

I’m not sure exactly what you mean by a ‘thread stop’. I had a Boxford which had an attachment to provide a stop on the cross slide for use when cutting threads. It consists of a simple clamp which fixes to the cross slide dovetails with a sliding screw which screws into a tapped hole in the end of the cross slide itself. In practice it allows you to set a stop when cutting then it is possible to withdraw the tool, rewind cross slide and then reset the tool to it’s original setting. It is, as you say very useful.

 

In the picture below you cannot see the grub screw which secures the clamp to the dovetail. It is fitted into a threaded hole in the LH side of the clamp and presses on a slug of metal the end of which is shaped to the angle of the dovetail which does the clamping to avoid damage to the dovetail itself. I can’t show a picture of the parts as the device was lost in a workshop fire last year.

 

The cut of course is put on with the top slide

 

 

 

Hope this helps,

 

Best regards

 

Terry

Edited By Terryd on 13/03/2011 10:31:37

[ZigFireParticipant @zigfire]

Hi Terry,

 

Yes you nailed in your description what I meant by “thread stop”.

Thanks for the image, I should be able to adapt something similar and as you say, very useful as I do cut alot of threads.

 

Thanks for the post.

 

Cheers Michael

[TerrydParticipant @terryd72465]

Hi Michael,

 

Glad it may be useful, it really is quite a simple device to use and works beautifully. Here is a picture of the Boxford carriage which i found, it shows clearly the threaded hole in the cross slide for the threaded part of the sliding stop bolt. It makes it quite easy to visualise the operation of the device.

 

 

Best Regards

 

Terry

[John Somers 2Participant @johnsomers2]

Hi Michael

 

I wonder if you may have been confusing the thread stop with the carriage stop featured on my site (Scroll down to item 7 for more info).

 

John Somers

[TerrydParticipant @terryd72465]

Hi John,

 

Michael did mention a stop for the cross slide, not the carriage. Such a stop is used when making metric threads. It enables the top slide to be withdrawn using the cross slide, the lathe reversed to the beginning and then the tool can be returned to it’s correct registration ready for the next cut which is put on using the top slide.

 

Best regards

 

Terry

[John Somers 2Participant @johnsomers2]

Thanks Terry

Yes I can see that but I don’t think there is any reference on my site to a cross slide stop, maybe there should be as I can see it being as useful as a carriage stop for certain machining applications.

So much still to learn !

John

[TerrydParticipant @terryd72465]

Hi Michael, John,

 

I managed to retrieve my cross slide (thread) stop after salvaging it from a workshop fire. I intend to clean it up when I get my workshop rebuilt. I’ve posted a picture below of the disassembled stop showing the component parts. Note the thrust pin (for want of a better description) is angled to match the dovetail to prevent damage. The reduced diameter section allows the ‘thrust pin’ to be made captive so that it isn’t lost when removed from the lathe.

 

 

 

Best regards

 

Terry

Edited By Terryd on 16/03/2011 17:15:55

[ZigFireParticipant @zigfire]

Posted by John Somers 1 on 16/03/2011 16:11:26:

Hi Michael

 

I wonder if you may have been confusing the thread stop with the carriage stop featured on my site (Scroll down to item 7 for more info).

 

John Somers

Hi John,

 

It was mentioned in your tutorials under “Lathe Lessons” number two I believe.

 

Cheers Michael

[ZigFireParticipant @zigfire]

Posted by John Somers 1 on 16/03/2011 16:53:09:
Thanks Terry

Yes I can see that but I don’t think there is any reference on my site to a cross slide stop, maybe there should be as I can see it being as useful as a carriage stop for certain machining applications.

So much still to learn !

John

Posted by Terryd on 16/03/2011 17:14:56:

Hi Michael, John,

 

I managed to retrieve my cross slide (thread) stop after salvaging it from a workshop fire. I intend to clean it up when I get my workshop rebuilt. I’ve posted a picture below of the disassembled stop showing the component parts. Note the thrust pin (for want of a better description) is angled to match the dovetail to prevent damage. The reduced diameter section allows the ‘thrust pin’ to be made captive so that it isn’t lost when removed from the lathe.

 

 

 

Best regards

 

Terry

Edited By Terryd on 16/03/2011 17:15:55

 

That’s great Terry and thanks for the picture of the lathe as well, much appreciated. Looks Like I have a little project to perform this weekend.

 

Cheers

Michael

[TerrydParticipant @terryd72465]

Hi Michael,

 

Have fun, it’s a very useful addition to the lathe and a very uncomplicated design unlike some other attachments I’ve seen. If you need any dimensions etc let me know.

 

Regards

 

Terry

[egaParticipant @ega]

There is an "improved" shop-made version of this device on eBay:

https://www.ebay.co.uk/itm/RARE-THREAD-CUTTING-STOP-FOR-BOXFORD-LATHE-AND-CLONES/232998436967?hash=item363fca0067:g:4dQAAOSw9z1b5KHr:rk:1f:0

[Pete RimmerParticipant @peterimmer30576]

The CVA/Monarch lathe comes with a threading stop built-in. It allows two turns of the cross slide for fast retraction then 2 turns in again to meet the same mark. Advancing the tool into the cut is done by swinging the top slide around.

[Neil WyattModerator @neilwyatt]

GHT came up with a very nice retracting topslide.

I must make one of Mike Cox's swing up screwcutting toolholders from MEW 178, even simpler to use.

Neil

[egaParticipant @ega]

Posted by Neil Wyatt on 21/11/2018 15:20:30:

GHT came up with a very nice retracting topslide.

I must make one of Mike Cox's swing up screwcutting toolholders from MEW 178, even simpler to use.

Neil

The GHT topslide also incorporated a forward stop ie a "thread stop". My kit for the GHT item is still gestating but I did make Mike Cox's device – another excellent project from him. The swing up action on mine is still rather stiff ie it's reluctant to go down again for the next cutting pass and I have added a knob to help with this.

[egaParticipant @ega]

There was a recent post deploring the industry's failure to provide cross slide stops on our lathes and I was prompted by this to continue with a long-dormant project for the S7. I had considered an ingenious micro-adjustable device by Tubal Cain and other devices which looked likely to get in the way and opted for a rod projecting from the rear of the slide with a simple clamp which buts against a plate screwed to the back face of the slide:

The Boxford style device mentioned above seemed suitable for the Willson slant bed (the two rectangular holes in the cast iron block are a legacy from its former role as the base to a fixed steady and are not part of the design):

There is a potential problem with both kinds of stop in that the cross slide can "bump" the stop by a thou or so and thus inadvertently alter the infeed; the plastic washer on the cap head screw is an attempt to mitigate this. Both stops are stops are still "under development" but seem likely to simplify screw cutting with set over top slide.

The swing-up tool needs no stop, of course, but does require the ability to stop the lathe and reverse without mishap.

[not done it yetParticipant @notdoneityet]

The ‘potential’ problem should easily be overcome with a lock-nut?

[egaParticipant @ega]

Posted by not done it yet on 06/02/2019 19:02:11:

The ‘potential’ problem should easily be overcome with a lock-nut?

Thanks for the suggestion.

In fact, the screw is tightly driven into the cross slide casting and bottoms in the tapped hole. A lock nut might help but it would be necessary to remove the red felt wiper and cover. I think that any movement is in the block itself and I might add a couple of vertical pusher screws at opposite end to the gib which clamps the block.

PS Just noticed a redundant "are stops" in my last but one paragraph.

Edited By ega on 06/02/2019 19:33:36

[Author]

Posts