Atlas Is Tapering?

1.499 beautiful, so I think we can assume it's deflection in the head, other places include the cross and compound as well as the tool post, but because of a consistent taper at the chuck, I would rule those areas out, does your machine have timkens?
 
chevydyl said:
1.499 beautiful, so I think we can assume it's deflection in the head, other places include the cross and compound as well as the tool post, but because of a consistent taper at the chuck, I would rule those areas out, does your machine have timkens?
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Yup, timken bearings.

They are adjusted IAW the atlas lathe manual, but I'm going to drop and indicator on the chuck today and check for play/deflection.

I'm pretty sure the tool post isn't the problem, I've got a wedge AXA on there. The cross and compound might be a diff story. I've been chasing chatter on parting operations, so it kind of fits with where I've been looking for that also.

I get you guys' comments on chasing the last couple thou is sometimes a futile effort, but I haven't even tried yet.

I'm just looking to get the most I can out of the setup I have. If I try and get nothing better then at least I've learned a few things along the way.

Besides: it's a hobby for me, not a profession. I make things for myself and no one else (well, sometimes a couple friends or if someone flashes too much cash under my nose for something simple the local shop can't be bothered with). If I waste and afternoon checking and messing with things, it still all falls under just a relaxing Saturday of putting around for me.

:)
 
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Something to note is the tiny cross slide size, there is actually pretty small surface area for bearing, and some of the forces put on it by parting are tremendous. One mod for that is to make a new cross slide and full length gib, personally I already have the iron for the project, in addition to much greater bearing area would be the addition of t slots. Drawback is the compound protractor.... as well as having to add the dovetail for the compound mount, I'm not fully decided on the route yet, but I think I will have a block bolted down for the quick change, and if I need to use a compound I can either cnc a protractor into it or swap out the slide for the stock one.
I have heard great things about this mod
 
chevydyl said:
Something to note is the tiny cross slide size, there is actually pretty small surface area for bearing, and some of the forces put on it by parting are tremendous. One mod for that is to make a new cross slide and full length gib, personally I already have the iron for the project, in addition to much greater bearing area would be the addition of t slots. Drawback is the compound protractor.... as well as having to add the dovetail for the compound mount, I'm not fully decided on the route yet, but I think I will have a block bolted down for the quick change, and if I need to use a compound I can either cnc a protractor into it or swap out the slide for the stock one.
I have heard great things about this mod
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would you happen to have a link to this project? Or pictures perhaps?

Sounds like something along these lines:

marty-nissen-cross-slide-1.jpg

I've suspected the tiny compound (relatively) as being the source of some of my issues for a while....

marty-nissen-cross-slide-1.jpg

marty-nissen-cross-slide-1.jpg

marty-nissen-cross-slide-1.jpg

marty-nissen-cross-slide-1.jpg

marty-nissen-cross-slide-1.jpg
 
I made a T slot cross slide for my 12" Craftsman. It made a world of difference in chatter and stability. It did raise the compound higher than I liked and I did lose the degree marks for the compound. To solve that problem I used a compound off a 10" lathe. I then made a button that was raised and I was able to mark the degrees on it.

IMG_0885-1.jpg IMG_0883-1.jpg
 
Steve Shannon said:
My understanding was that the diameter got smaller as he got closer to the headstock, not larger. Was I wrong?


Steve Shannon, P.E.
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That's what I was getting too. Sounding like maybe there's some slop in the headstock as has been mentioned or just as likely the, to be expected, runout in the chuck. It's possible he's getting it as close to perfect as is possible with that particular machine. Live with it!
 
Google atlas lathe cross slide, there's some college link that sells castings iirc, I'm going to machine from a solid, with my own thoughts and design for form and function.
 
chevydyl said:
Google atlas lathe cross slide, there's some college link that sells castings iirc, I'm going to machine from a solid, with my own thoughts and design for form and function.
Click to expand...

If you start a new thread on this I will add some insight on when I made mine. That is the place that I got mine from but knowing what I know now I would do a couple of things different.
 
Rob, I actually got the idea from seeing some posts about the ugrade, but personally I'd rather machine it from a solid so I can do with it what I want ya know, I'm in the process of making the tooling for scraping it in. I put my small angle straight edge in the clean cycle the other night, hopefully it will stop moving now, I had cycled it through 500deg and freezing it but it didn't stop moving. After the higher heat cycle it looks different than the 500deg, and also seems to feel different on the outside, idk maybe it worked. The 500 degree cycle turned it brownish, and it was cleaned before baking. The clean cycle left it a dull gray, and seems rather smooth to the touch, almost slick
 
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