Boxford BUD saddle clamp

[Daniel BrannanParticipant @danielbrannan48897]

Hi

I recently got hold of a filthy 1963 Boxford BUD mki which I’ve stripped, cleaned and put back together and is working well. However I noticed the saddle tries to lift at the front under load and so it occurred to me that I probably missed a piece when reassembling; namely a saddle clamp of some description. However I have no recollection whatsoever of removing this and so what it would look like. I did however find this:

 

 

Would that be the right bit? The cutout fits under the edge of the way and the hole seems to line up with the hole in the saddle next to the right hand apron bolt. However the boxford parts diagram is vague and shows a piece which looks nothing like this. If it is the correct part, how the hell is it adjusted? Is there some adjusting mechanism I’ve lost? Or do you just crudely shove a bolt through it and tighten it so there’s just enough torque to take prevent it lifting but still allow it to slide?

 

thank you kindly for your help

 

regards

 

Dan

[Grindstone CowboyParticipant @grindstonecowboy]

That’s not the saddle clamp, looks more like the clamp for the tailstock barrel (although I think that step should be more rounded. The saddle clamp is a rectangular cast piece with a threaded hole and a couple of odd lumps (number 140 on the parts list here). Adjusted by a square-headed bolt coming down from above. However, I don’t think you should be getting any lifting at the front when cutting normally, even with no saddle clamp fitted, as cutting forces should be pushing the front of the saddle down onto the prismatic ways. One thing to check is that the saddle gib (number 27 on the list) at the rear is properly adjusted.

Rob

Links to https://www.scribd.com/document/806450030/Boxford-Lathes-Parts-List-II-incl-dismantling-instr

[BazyleParticipant @bazyle]

Not standard part. The normal clamp is held by a socket head set screw from the top going into a rectangular cast iron rectangular plate. So if it is undone too much  the plate drops off and maybe gets chucked with some swarf so the owner rigs up something else.
The saddle shouldn’t lift at the front under load – this is a clamp not a sliding retention piece like you have along the rear shear.

[Clive Brown 1Participant @clivebrown1]

The Boxford does have a saddle clamp on the front shear but its purpose is to lock the saddle to prevent longitudinal movement, not to prevent lift under load. It is located on the front right-hand corner of the saddle. There is a plate to prevent saddle lift under the rear shear adjusted by a couple of bolts with spring wahers.

I can’t suggest a reason for the front of the saddle lifting as you describe when the load is downwards.

[Daniel BrannanParticipant @danielbrannan48897]

Thanks for all the replies. In that case I’m pretty sure the cast piece you all spoke of didn’t come with it so I’ll try source one from ostia tools. With regards the gib at the back – I only vaguely set this when I put it all back together so I’ll revisit that

thanks again

[PeteParticipant @pete41194]

You’d have to verify the parts on the exploded view Grindstone Cowboy linked to are still present in your own lathe Dan. As others have said, those aren’t meant to clamp the carriage down in any way, there simply in place to prevent any lifting of the carriage. If my interpretation of the drawings are correct, then it’s part #27 at the rear of the carriage and #140 at the front that are designed to prevent excess lifting at either end of the carriage. A carriage lock would be used when facing a part to prevent the carriage from being pushed back.

On a brand new lathe, there would be a very small clearance between the lip of #27 & #140 of only a very few thousandths of an inch and the bottom of the lathes bed ways. That allows the carriage to travel longitudinally along the lathe bed without any binding. The more bed and carriage wear there is, the more clearance there will be between those plate lips and the bottom of the lathe bed ways. However you still can’t re-machine the parts to tighten that clearance any more or you will have binding at the far less worn tail stock end of the lathe bed. And as others have already mentioned, I can’t visualize why your seeing even by eye the carriage lifting under any cutting loads. Something definitely isn’t correct.

Unless there’s parts missing or an incorrect reassembly I can’t visualize. The only other possibility I can think of is your lathes upper way surfaces and bottom ways on your carriage are extremely worn and allowing the carriage to rock up and down. And if that is the cause? A full lathe bed and carriage way regrinding with possibly additional scraping might be the only fix. Even that causes further issues with realigning the lead screw further down to then match the half nuts new and lowered elevation position. Depending how much grinding was needed, something like a Moglice, Turcite, Rulon product might be used to build the carriage ways back up. But likely only a machine tool re-builder could advise you properly about what might be required.

Pulling the tail stock and removing the carriage, then using something like a metal yard or meter scale as your straight edge and held tightly against the side of the lathes front V way and the same on the rear flat way against the mostly unworn tail stock end should give you a fairly good indication of the amount of bed wear you have at the head stock end. Feeler gauges between the worn bed and the edge of the straight edge would get you a fairly close estimate of the amount of bed wear. There’s no simple or easy method of gauging the amount of wear on those bottom carriage way surfaces that I know of. And unfortunately, bed wear of that amount would also mean the tail stocks bottom way surfaces, cross and top slide ways will also need re-grinding and maybe scraping.

[HollowpointParticipant @hollowpoint]

Check that the apron and saddle are screwed together tight at the front and that the clamp at the rear is sufficiently tight. They are the two most likely causes.

[Grindstone CowboyParticipant @grindstonecowboy]

Sorry Pete, I agree with most of what you’ve said there, but the part #140 saddle clamp/carriage lock (as Bazyle and Clive also said, and yourself at one point) is only there to prevent movement when facing, not to be adjusted with minimal clearance to prevent lift. It could be removed completely without ill-effect, apart from inabilty to lock the saddle, of course.

There isn’t anything at the front of the saddle to adjust or that holds it down other than gravity and normal cutting forces. Thinking about it, and in addition to your very valid points about wear, a bent or badly misaligned leadscrew could feasibly cause vertical movement of the front of the saddle – although it would have to be quite a severe bend – so that’s something else Daniel could check.

Rob

[Speedy Builder5Participant @speedybuilder5]

This is what it should look like.

[John HinkleyParticipant @johnhinkley26699]

I think the others, more experienced than me, have probably provided you with an answer to your original question, however, I would add that I have only experienced lift at the front of the saddle when I was in the early throes of learning to use my Asian 9 x20 lathe and that was due to setting a parting blade (slightly) above the centreline.  This caused the tool to “ride up” on the workpiece and force the tool holder-top slide-cross slide-saddle assembly to lift momentarily.  Scared the life out me when it happened!  It didn’t happen again.  I’d learnt my lesson.

John

 

[Daniel BrannanParticipant @danielbrannan48897]

This is exactly what I needed @speedy builder 5. Thank you. With regard to the other questions about my lift issues – I noticed it primarily when boring and taking a little too much off at a time. The pressure of the tool and the leverage from the length of it, caused that end of the saddle to twist round and ride up the v way slightly. I then investigated and was able to lift the front of the saddle by hand. I will check the rear gib/clamp this afternoon and report back

With regard to wear, when I first got the lathe I put a magnetic dti base on the saddle and moved the saddle slowly down the bed with the dti measuring against the front edge of the v way and got no measurable deviation. I know this isn’t a perfect method but it gave me confidence the ways weren’t totally worn out

[Dave HalfordParticipant @davehalford22513]

On the rear clamp all you probably need to do is flip the plate over to put the unworn side into use.

If you snug the front carriage clamp it stops the twisting effect from the handwheel (on mine anyway.)

[old martParticipant @oldmart]

The Smart & Brown model A has a saddle lock similar to Speedy Builders one illustrated and I made a second one to fit at the rear of the saddle so that when parting off the carriage gets held with greater security using both. This is even more appreciated when using the rear inverted parting off block fixed directly to the cross slide which puts lifting forces into the carriage.

Because of very great bed wear at the left hand end, the running clamps for the saddle have to be set rather loose or the travel is restricted at the unworn right hand end. Not a great problem except when parting off and using round insert tooling.

[PeteParticipant @pete41194]

I wasn’t sure if I was interpenetrating those drawings correctly Grindstone Cowboy. Then as you’ve said for the Boxford BUD lathes, there aren’t any front guide blocks. And what I thought that #140 part was is just the lower part of the carriage clamp? However I just noticed something I hadn’t before. It appears these Boxford lathes guide the carriage’s longitudinal movement with both the front and rear V ways. My lathes only use the front V way and the rear flat way for the carriage, and their tail stocks use the rear V and front flat way.

If your bed and carriage way wear is that little Daniel your very fortunate and that isn’t the cause of your lifting issues. I have no experience with your particular lathe, so at best I can only make general guesses.

Logically and it seems from what you’ve said, your carriage is moving upwards far more than what should be expected. And since there isn’t any guide blocks for the front of the carriage, I’m finding it difficult to understand Boxfords logic for not including them in the design. However they knew what they were doing about lathe design more than well, and I don’t. But that might be due to your carriage using both V ways? I’ve never owned or used a lathe like that so even this is just a guess.

And GC raises another good point, a bent lead screw would be another item to check. With a used lathe and with who knows what was done or incorrectly assembled before you bought it, there could be other reasons. I’d doubt it’s possible to get the half nuts vertical elevation that far out during reassembly. And other issues would show up as well. But with the lathe assembled and the carriage in the middle of the bed length with the half nuts closed. Is there any visual downwards pointing bow on the lead screw?

[Grindstone CowboyParticipant @grindstonecowboy]

Hi Pete

They aren’t the clearest of drawings, are they? Yes, #140 is just the cast plate that Speedy Builder kindly provided a photo of, and the saddle uses both Vs (the tailstock uses one V and a flat). Agreed, Boxford probably had a pretty good idea of what worked and what didn’t in normal use – one of the reasons I’ve never been tempted to run in reverse with an inverted parting tool at the front of the work, the screwed chuck being the other.

Rob

[Author]

Posts