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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Lead screw mods.
- Thread starter toolman
- Start date
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
- Joined
- Sep 20, 2012
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- 560
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
If not you need a shear pin or summat like that.
Bernard
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
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
- Joined
- Sep 20, 2012
- Messages
- 560
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:
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:
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.
- Joined
- Sep 20, 2012
- Messages
- 560
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