Saddle stop

[Bo’sunParticipant @bosun58570]

It would appear that many lathe owners make their own saddle stops. This then begs the question "why don't the lathe manufacturers make them?". I suspect it's because of the prism angle, although it looks to be 90 degrees, it varies quite a bit. Even within the same range of machines. Mine is 92 deg. but I've also seen 94 deg. and 88.4 deg. All on Weiss machines.

Any suggestions why this should be? It must make manufacturing more tricky, having to match the bedway and saddle. Surely 90 deg. would be the sensible option?

[Bo’sunParticipant @bosun58570]

Bedway angle?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bo'sun on 08/11/2020 10:02:11:

It would appear that many lathe owners make their own saddle stops. This then begs the question "why don't the lathe manufacturers make them?". I suspect it's because of the prism angle, although it looks to be 90 degrees, it varies quite a bit. Even within the same range of machines. Mine is 92 deg. but I've also seen 94 deg. and 88.4 deg. All on Weiss machines.

Any suggestions why this should be? It must make manufacturing more tricky, having to match the bedway and saddle. Surely 90 deg. would be the sensible option?

.

I can only assume that the beds are made in batches … and that the angle depends on the setting of the grinder.

Seems a little strange, but I suppose Weiss is not overly concerned by ‘interchangeability’ of components.

Incidentally : Does “All on Weiss machines.” mean … of the same model ?

MichaelG.

[Bo’sunParticipant @bosun58570]

Hi Michael,

Two of the angles were Warco WM250's and the other a US machine that bears a cunning resemblance to the WM250V.

[Anonymous]

Posted by Bo'sun on 08/11/2020 10:02:11:

It would appear that many lathe owners make their own saddle stops. This then begs the question "why don't the lathe manufacturers make them?".

…………..

Surely 90 deg. would be the sensible option?

Industrial lathe manufacturers do make them, although I'm still on the lookout for a secondhand multistop unit for my lathe at a price I can justify. They're a nice to have but not essential for me.

An included angle of 90° is not optimum for the Vs on a lathe bed. Acute is better so that any sideways or twisting forces are resisted without too much of the force being resolved upwards. I've just measured the Vs on my industrial (Harrison) lathe; they're 70° included. I'd be surprised if Harrison beds were anything other than 70° over a production run.

Andrew

[egaParticipant @ega]

Lathe manufacturers certainly do make saddle stops. The expensive Myford version (flat bed) fixes to the rear of the bed in a position which seems less than optimal given the direction of the forces involved.

A stop is a near-necessity on a manual lathe.

[JourneymanParticipant @journeyman]

Have a look at this THREAD it may or may not help.

John

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Bo'sun on 08/11/2020 10:39:24:

Hi Michael,

Two of the angles were Warco WM250's and the other a US machine that bears a cunning resemblance to the WM250V.

.

Thanks for the clarification

MichaelG.

[Tony Pratt 1Participant @tonypratt1]

Machine tools are or should be made to a properly dimensioned & toleranced drawing so interchangeability of parts & accessories will not be a problem.

Tony

[Clive FosterParticipant @clivefoster55965]

Interesting.

My indispensable 6 way stop of unknown origin has been on 4 lathes in my hands and seemed to fit the beds perfectly adequately. No idea what it was made for but its worked fine on my SouthBend Model A 9" (too big for the machine really), SouthBend Heavy 10, Pratt & Whitney Model B and Smart & Brown 1024. I never bothered to check angles, just used it.

One day I shall finish the design of Clives improved version with a built in microswitch for automatic stop on the 1024 VSL. Which has direct drive an no clutch.

If angle variation were an issue it would get some floating D shape rails let into the Vee sides to self adjust over small variations. Brass I thing to avoid marking the beds. Maybe 1/4" on the flats would be fine for adequate grip.

Hafta say I'd always thought bed Vee angle was either a symmetrical 90° or the very asymmetric shallow one side steep the other shape adopted by some makes when the design staff started overthinking angular force distribution. Always though that, like many clever schemes, the shallow & steep combination advantages are more theoretical than real. If its not a gap bed then Holbrook style long way covers pretty much completely protecting the ways so decent, clean lubrication is assured seemed a better way of refining things. Way I see it is that if the forces resolved to the bed were that large that such refinements were important the any conventional toolbit would be snapped clean off the moment it hit the work. Even on a superlathe its still a relatively slender cantilever.

Close to 90°and variable between machines / production batches is just plain careless on the makers part. Rule 1 of production engineering is to use reliable jigs and gauges for repeat set ups.

Clive

Edited By Clive Foster on 08/11/2020 11:52:10

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Tony Pratt 1 on 08/11/2020 11:29:52:

Machine tools are or should be made to a properly dimensioned & toleranced drawing so interchangeability of parts & accessories will not be a problem.

Tony

.

You may very well think that, Tony … and yet we are informed that

”Two of the angles were Warco WM250's and the other a US machine that bears a cunning resemblance to the WM250V.”

… so perhaps the point is lost upon Weiss

MichaelG.

[Henry BrownParticipant @henrybrown95529]

My Warco GH1322 came with one, I've yet to find a use for it…

[BazyleParticipant @bazyle]

There seem to be a few people who miss-understand why manufacturers make lathes. It is to maximise the profit fo the shareholders and directors relative to their other options of making manhole covers. No other reason. Getting prissy about a bed angle doesn't increase profit unless the marketing director says it can be used to increase sales.

[Tony Pratt 1Participant @tonypratt1]

Posted by Bazyle on 08/11/2020 12:38:09:

There seem to be a few people who miss-understand why manufacturers make lathes. It is to maximise the profit fo the shareholders and directors relative to their other options of making manhole covers. No other reason. Getting prissy about a bed angle doesn't increase profit unless the marketing director says it can be used to increase sales.

It will be of paramount importance that the lathe bed mating angular faces match to a high degree of accuracy so being 'prissy' about said angles is mandatory in decent machine tools.

Tony

[Clive FosterParticipant @clivefoster55965]

Henry

When it comes to saddle stops it seems that folk either never use them or use them pretty much all the time.

I rarely set up without either the multi stop or a micrometer stop. Usually only on quick and dirty jobs where there is already a flange to work to.

The effective and accurate saddle travel dial on the 1024 hand wheel converted me from an occasional, only when I had to user, to enthusiast. Made setting easy enough that the advantages were obvious. A DRO would be the modern way. The P&W has neither travel dial or DRO but I quickly twigged that a gash, no longe wring to gether, gauge block set and internal micrometer set easily filled the gab.

So nice to be able to power feed up to just short of the stop, drop the feed and seamlessly pick up a hand feed for the last fer thou. No worries about over feeding into a step or not quiet going the same distance each cut leaving a flange with ugly looking lines. The micrometer breed make is dead easy to trim off a few thou or tenths of a mm when a ocating step or lfange isn't quite far enough along.

Yep I know that setting the topslide parallel to the bed and reading the dial gets you to the same place. But you can't power feed a topslide and when parallel to the bed the thing gets in the way. Quite apart from the issues of setting dead parallel. Life is too short for running a dial gauge up and down a test bar between tweaks as you try to get the last half degree out.

Clive

[Henry BrownParticipant @henrybrown95529]

So true with most things Clive. The Warco does have a travel dial on the saddle that I use when boring blind holes. For precision measurements I tend to use a DTI onto the topslide once checked for parallel to the bedways. The stop that came with the Warco is a micrometer type but is s a bit of a fiddle to set up. When I was on the handles the only lathes I used that had stops were the capstans for repetition work of course.

As for Bazyle's comment, there are a couple of things that could have been done much better as a trade off for the "fancy" things like the awful metal handles (changed) and the stop without affecting the bottom line. For the money though I'm happy enough with the machine.

[Clive FosterParticipant @clivefoster55965]

Henry

I'm intrigued, how do you make a micrometer stop a bit of a fiddle to set up when you have a saddle travel dial.

The micrometer ones I've used on the SouthBend Heavy 10 and S&B 1024 seem to be the standard configuration. I can't see how eithre could be fiddly. At least not after you have twigged that the funny "what the heck is that for" bracket is needed to reposition the stop on the Heavy 10 to use with collets.

Clive

[Chris Evans 6Participant @chrisevans6]

Posted by Henry Brown on 08/11/2020 12:21:49:

My Warco GH1322 came with one, I've yet to find a use for it…

Different type of work requirement to me. I use my bed stop on nearly every job I do, but then I do seem to make more bolts for motorcycles than is healthy for a chap…..

[not done it yetParticipant @notdoneityet]

To answer your question:

1) Cheapness on the part of the manufacturer.

2) The likelihood of someone crashing the carriage into a fixed, immovable object causing damage (and complaints?).

My near 70 year old lathe has one – its an auto-stop, too for the long travel.🙂. Supplied as standard equipment by the manufacturer. I use it on a regularly.

[Howard LewisParticipant @howardlewis46836]

My lathe bed appeared to be 90 degrees, so I made a Saddle Stop with a micrometer barrel.

It clamps to the bed with just a plain piece if steel, just like the Saddle lock built into the saddle. Clamping force is applied by a M8 setscrew.

When the clamp is pulled down to lock, if the clamp and bed angles differ by a degree or so there will still be two point contact against which the clamping screw can react . The clamp will behave in the same manner as the Saddle Clamp, and prevent movement.

The forces likely to act on a Saddle Stop are very likely to be less than those exerted on a Saddle Lock (Since it has to withstand forces resulting from cutting action ) It is unlikely that we would want to subject a Saddle Stop to forces as great as those.

This could raise the question of whether the angle of the Saddle will exactly match that of the prism on the Lathe bed. Given the angles already quoted by the O P, that might not be guaranteed!.

After all, we are using it as a Stop rather than a Lock.

Howard

..

[old martParticipant @oldmart]

I made two for the Smart & Brown model A and the wear at the left end of the prismatic bed measured 89 degrees, the unworn right end was 90 degrees.

[Howard LewisParticipant @howardlewis46836]

Since my Saddle travel indicator is on the Handwheel that ultimately drives the pinion engaging with a rack, I do not expect absolute accuracy. Indeed, I am surprised by the accuracy that it does provide, but do not regard it as a high accuracy measuring instrument.

In contrast, my stop, clamped to the bed and with a micrometer barrel is regarded as being more accurate, and is used where closely controlled lengths are required..

No doubt, if the power feed were not disengaged, or hand feed was were pressed home with vigour, the clamp might be displaced, or inaccuracy creep in because of the changes in clearances or deflections brought about by greater forces.

Maybe I am wrong in power feeding to just short of the stop and then hand feeding to bring the Saddle to rest gently against the stop. But that seems to work for me.

Howard

[Henry BrownParticipant @henrybrown95529]

Posted by Clive Foster on 08/11/2020 14:47:18:

I'm intrigued, how do you make a micrometer stop a bit of a fiddle to set up when you have a saddle travel dial.

Clive,

The issue is that the clamp is a right fiddle to get the stop onto the bedway due to the proximity of the covered leadscrew to a couple of fiddly cap screws that act on the clamp plate. I had another look at it this morning and it occurred to me that I could probably modify it a little to either replace the cap screws with hex head screws or drill a hole through from the top and have the clamping action made from the top rather than underneath. Another job for the roundtuit…

Henry.

[derek hall 1Participant @derekhall1]

I have a spare micrometer head that I was thinking of using in much the same was on my Myford. However what is stopping me is protection against swarf and coolant…

Regards to all

Derek

[Henry BrownParticipant @henrybrown95529]

Derek, I took my stop apart this morning and the thread is pretty crude (12mm fine pitch) so I'm not expecting it to be very accurate on its own.

Maybe you could fashion a cover to keep the worst off?

[Author]

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