# Lead screw mods.



## toolman (Oct 28, 2013)

Hey guys, my "new" lathe is missing all of the support pieces at the end of the bed except for a cone washer and a two bolt plate that attaches to the side of the bed. I can get all of the parts, but the end of the LS threads are pretty dinged up as well, where, I assume, the cone washer rides. I'm thinking ofturning the shank down just a hair to true it up, them building a new adjustable mounting bracket with a roller bearing in it. Has anyone else here done anything like this or is an actual roller bearing even needed for the lead screw?


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## Privateer (Oct 28, 2013)

There is a step that the washer nearest the headstock rides on, and the other has a pin that rides in the keyway, not much else to worry about. As long as the area between those two washers remains unchanged, you shouldn't have any issues if you want to turn down the thread to a smaller diameter. 

Terry


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## Dranreb (Oct 28, 2013)

Not sure that a roller bearing is needed at all, I would think a bush would be fine, perhaps you already know that if you make your own support bracket for the tail stock end it has to act as a fail safe, meaning it is weak enough to break off before any major damage happens, if for instance the compound hits the chuck under power. 

If not you need a shear pin or summat like that.

Bernard


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## aforsman (Oct 28, 2013)

Bernard,

I'm kind of an Atlas newbie.  Could you elaborate a little more on the "failsafe" action of the leadscrew bracket and how it works?  I am also curious about the backside washer/spacer that is pinned into the keyway - I have never understood the purpose of it.  Is it related to the failsafe?

Allen


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## Dranreb (Oct 28, 2013)

Hi Allen, the bracket is lightly made but strong enough to take the normal side thrust from the lead screw under load. If something goes wrong that increases the thrust above normal then the bracket breaks off below the mounting screws.

As the screw is still being turned by the change gears but is no longer captive at the other end, with the half nuts engaged and the carriage not moving it just winds itself out of engagement with the gearbox, so the carriage stops before any gears strip or something worse happens.

seems to me that the backside pinned washer is to prevent the jammed nut from being wound off  by the screw turning. 

Bernard

Just edited to hopefully  improve clarity :nuts:


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## aforsman (Oct 29, 2013)

That makes sense.  Thanks for the info.

Allen


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## iron man (Oct 29, 2013)

I really wonder if that was intentionally designed that way or if the light weight part just ended up working that way you really dont see that on any other lathe?


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## toolman (Oct 29, 2013)

iron man said:


> I really wonder if that was intentionally designed that way or if the light weight part just ended up working that way you really dont see that on any other lathe?



That's what I'm wondering. I've also seen two different setups on these. One is a solid (aluminum?) bracket, and the other (like mine) uses what looks externally, like a larger version of the brass compound screw and a steel bracket to support it. I've also seen references to roller thrust bearings at the tailstock end. Since mine is missing everything but the steel bracket, I'm not sure what mine is supposed to have.


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## iron man (Oct 29, 2013)

Mine was busted when I got it so I made a new one out of steel with a brass bushing it has worked fine for about 20 yrs it looks stock.  I just made a new lead screw for mine and it is working just fine.


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## Dranreb (Oct 29, 2013)

iron man said:


> I really wonder if that was intentionally designed that way or if the light weight part just ended up working that way you really dont see that on any other lathe?



Just had a look in the Atlas lathe operation book and it's function is described in there, there are folk on here that will know the history of this feature, hopefully we will be enlightened soon!

Bernard


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## Privateer (Oct 29, 2013)

> I really wonder if that was intentionally designed that way or if the light weight part just ended up working that way you really dont see that on any other lathe?



The following is an excerpt from the Manual of Lathe Operation circa 1937:

_ The lead screw bearing on the tail end of the lathe serves as a "safety valve" protecting the lead screw. One of the most common accidents on the lathe is letting the power feed drive the carriage into the headstock or tailstock. Serious and expensive results from such an accident are prevented by the light construction of this bearing. The lead screw simply forces itself out and breaks the bearing casting. In this way the light bearing prevents what would otherwise be an expensive breakdown.
_
It would appear to me that the engineers in the early 90's intentionally designed it that way. I suspect that many of those shops turning out those 'improved' or 'stronger' bearings, are not aware of the intended design feature.

Terry


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## iron man (Oct 29, 2013)

It is amazing they come up with that I dont believe I have seen that on any other lathe. I guess if you watch what your doing and not hit the chuck or headstock you should be fine.


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## Privateer (Oct 29, 2013)

I can only speculate that perhaps they had the hobbyist in mind when they designed it. Thinking, how can we spare the guy will very little money a big headache after he buys our product. Whereas in larger production lathes, I would guess the mindset is, the operators should be properly trained before using the equipment.

Terry


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## pdentrem (Oct 29, 2013)

You can modify your leadscrew so that you can use a shear pin. In Projects In Metal Vol 1 there is an article on how to cut the leadscrew, slip a coupler ie pipe, pin one side of the coupler and shear pin on the other half. I did this years ago so that I did not have to replace the support bracket. I used an alum siding nail as the shear pin. I never had to replace the pin but luckily I did not have a crash either.
Pierre


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## kd4gij (Oct 29, 2013)

That lead screw bearing was used to cut cost verses a clutch as most outher lathes have. The later model craftsman commercial and atlas had a clutch.


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## toolman (Oct 30, 2013)

Just got off the phone with the nice folks at Clausing and the two washers and the bearing will be in the neighborhood of $100. I think I can do better for less, I guess we'll see...


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## Privateer (Oct 30, 2013)

They are very proud of their spare parts, and most of them are priced accordingly. I was surprised, however, to find that the half-nuts were only 34.63. Those are on my list of must haves in the near future. The brass nuts for the compound and cross feed were not quite as inexpensive, 10F-19 was 76.96, and the 9-306 was 44.72. I've seen some for sale on fleabay that claim to be new, one seller in particular has a set for 58. 

Terry


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## wa5cab (Oct 30, 2013)

Clausing doesn't (unfortunately for us) use new equipment sales to subsidize old equipment parts prices.  Parts cost what they cost.  My guess is that the old equipment parts department operates close to income neutral.  When the day comes that they can't do that, they'll disappear.  

Robert D.


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## pdentrem (Oct 30, 2013)

I'm with Robert on this one. We are lucky that Clausings still supports these lathes. Many companies dump their inventory of spares into the secondary market or worst recycles the metal into something else. The list of parts is getting smaller every few years as the old stock is used up. Eventually there will a sale out of Clausings for the remaining parts and they will be gone.

Remington purchased the Parker shotgun maker a long time ago. Later they had lost interest in servicing these old guns and sold the entire parts inventory, there were no takers at first. Ending up going to one of their employees. Fortunately said employee and his son who is still repairing these guns, can make a living at it. It is a labor of love and dedication, and one does not always get that in the service and repair field.
Pierre


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## toolman (Oct 31, 2013)

I was actually pretty impressed with the prices, especially compared to buying them from Sears (the washers were over $30 ea.). I priced about a dozen parts and they had every single part in stock, which is pretty freaking amazing in my book, but I'm a cheapskate who likes "improving" things. My vision for this project is either a roller bearing or graphite-impregnated bushing in a steel or aluminum mount, attached with breakaway bolts, OR, I could just pay attention and not crash the carriage into anything solid! :lmao: I also thought about using a detent type system, where the lead screw would just pop out of the mount in case of a crash.


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## Privateer (Oct 31, 2013)

What about some sort of magnet arrangement holding the end of the leadscrew to the bed, and in the event of a crash, it just slides away, and nothing breaks.

Terry


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## toolman (Oct 31, 2013)

Privateer said:


> What about some sort of magnet arrangement holding the end of the leadscrew to the bed, and in the event of a crash, it just slides away, and nothing breaks.
> 
> Terry



That should work as well with a stout enough magnet to keep it in place.


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## Dranreb (Oct 31, 2013)

Just remembered I found a strange thing when rebuilding my 10f, I now wonder if this is a plate let in to repair damage after a non original LS bearing had broken loose.

I look a pic at the time meaning to ask about it but never did, I may now be forced to take it off to have a looksee behind it....watch this space  :biggrin:




Bernard


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## pdentrem (Oct 31, 2013)

Dranreb said:


> Just remembered I found a strange thing when rebuilding my 10f, I now wonder if this is a plate let in to repair damage after a non original LS bearing had broken loose.
> 
> I look a pic at the time meaning to ask about it but never did, I may now be forced to take it off to have a looksee behind it....watch this space
> 
> Bernard



Well I have never seen that before! Has to be a repair. No reason for it to be there.
Pierre


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## aforsman (Oct 31, 2013)

> What about some sort of magnet arrangement holding the end of the  leadscrew to the bed, and in the event of a crash, it just slides away,  and nothing breaks.



Not a bad idea if you were going to build a bearing from scratch.  Modern rare earth magnets can generate a tremendous amount of force.  A couple of 1/2" diameter ones face-to-face could probably form a 100+lb bond.  Several sets could be used to make a breakaway coupling.  Not sure what amount of force would keep you "safe" without causing a breakaway during normal operations.  I would think 300lb would be plenty, but that's just a wild guess.


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## HarryG (Dec 11, 2013)

pdentrem said:


> You can modify your leadscrew so that you can use a shear pin. In Projects In Metal Vol 1 there is an article on how to cut the leadscrew, slip a coupler ie pipe, pin one side of the coupler and shear pin on the other half. I did this years ago so...Pierre



Pierre,
Are you talking about PIM books?  I've looked at all my PIM Vol. 1 magazines with no luck finding this article. I'm another
"visual learner", i.e, could use some help here...
Thanks!
Harry


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## pdentrem (Dec 11, 2013)

It is actually in the "Metalworking Book One The best of Projects in Metal" Pg 20 called Lathe Shear Pin Modification by Richard Torgerson. It is from the year 1988 to 89 of Projects in Metal magazine.
Pierre


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