and the biggest downside to this is it is likely to end up on your belts
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12" Atlas Reverse Tumbler Gear Stud
- Thread starter paul s
- Start date
and the biggest downside to this is it is likely to end up on your belts
I've broken down most of the carriage/apron and found that the half nut guide has a hairline crack that runs from the hole where the spring and ball impinge, to the edge of the casting. Is this something I can live with? Can it be repaired? Or should I look for a replacement?
This lathe only has power on the crossfeed, not on the longitudinal (other than using the halfnuts) - do I have that right?
The last part left on the apron is the handle/gear/shaft for the power crossfeed - the pin came out easily, the handle not so much.
This lathe only has power on the crossfeed, not on the longitudinal (other than using the halfnuts) - do I have that right?
The last part left on the apron is the handle/gear/shaft for the power crossfeed - the pin came out easily, the handle not so much.
Last edited:
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- Dec 25, 2011
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No, there is no practical way to repair the halfnut guide. Yes, I would replace it.
Your 2nd paragraph is either incorrect and poorly worded or correct but poorly worded. It is incorrect in that it does have power feed capability for both longitudinal and transverse (cross-feed) drive. It is correct in that longitudinal drive for both turning and threading is provided by the Acme threaded leadscrew and the halfnuts. Much more expensive lathes have two methods of longitudinal drive. The lead screw and half nuts are only supposed to be used for threading because it maintains the thread accuracy for much longer. For turning, the carriage is driven by another drive shaft through a gear arrangement that is conceptually similar to the cross-feed drive. However, whether this is actually money well spent or not is subject to argument. My attitude toward the question (which would almost certainly be ignored or overridden by the sales department if I were running the engineering department of a lathe manufacturer) is that a lead screw, half nuts and the gears to drive them are almost certain to be cheaper, simpler and more reliable than the drive mechanism including drive shaft and second set of gears. So if the lead screw and half nuts need to be replaced in order to maintain threading accuracy, just replace them. You still save money. And the machine is automatically more reliable because it has fewer moving parts.
What's the problem with removing the cross feed knob?
Your 2nd paragraph is either incorrect and poorly worded or correct but poorly worded. It is incorrect in that it does have power feed capability for both longitudinal and transverse (cross-feed) drive. It is correct in that longitudinal drive for both turning and threading is provided by the Acme threaded leadscrew and the halfnuts. Much more expensive lathes have two methods of longitudinal drive. The lead screw and half nuts are only supposed to be used for threading because it maintains the thread accuracy for much longer. For turning, the carriage is driven by another drive shaft through a gear arrangement that is conceptually similar to the cross-feed drive. However, whether this is actually money well spent or not is subject to argument. My attitude toward the question (which would almost certainly be ignored or overridden by the sales department if I were running the engineering department of a lathe manufacturer) is that a lead screw, half nuts and the gears to drive them are almost certain to be cheaper, simpler and more reliable than the drive mechanism including drive shaft and second set of gears. So if the lead screw and half nuts need to be replaced in order to maintain threading accuracy, just replace them. You still save money. And the machine is automatically more reliable because it has fewer moving parts.
What's the problem with removing the cross feed knob?
I was thinking that the crack in the halfnut guide is constrained by virtue of a pin on one side, and a threaded fastener on the other. Initially, I thought replace it, but once bolted down, I'm not sure that crack can open up.
Don't know - I think the knob is just on there very tight. I may end up leaving it and cleaning around it.
Don't know - I think the knob is just on there very tight. I may end up leaving it and cleaning around it.
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OK. If the guide looks like it would remain in place even if the crack were to propagate across the part, and if the half nuts are not sloppy in the guide, then leave it.
If none of the parts that you would have to remove the shaft in order to change look like they need to be replaced, then put the pin back in and leave the knob and shaft in place. You might damage the knob or something else getting it off. Then you would have to find a replacement for that or those parts before you could put it back together.
If none of the parts that you would have to remove the shaft in order to change look like they need to be replaced, then put the pin back in and leave the knob and shaft in place. You might damage the knob or something else getting it off. Then you would have to find a replacement for that or those parts before you could put it back together.
I would think about replacing it. I think you are correct, the crack would be held together once reassembled, but I would be concerned about the corners being broken off of the hole
I would think this may allow the detent ball to wander out of position and cause problems.
I would think this may allow the detent ball to wander out of position and cause problems.
Here's a picture where I've circled the crack, it's very faint. The crack has already propagated across to the edge, and it's all the way through.
I saw a picture of another casting - the hole for the detent ball is drilled similarly. It's so close to the edge, that breakout is unavoidable, I suppose.
I saw a picture of another casting - the hole for the detent ball is drilled similarly. It's so close to the edge, that breakout is unavoidable, I suppose.
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Hi Paul- you're at the point now where the truly devoted Atlas owner whips out the milling machine and makes a whole new part from scratch, adding additional material where possible to strengthen the weaknesses in the factory design. Then he installs said part where no one but him will ever see it and appreciate the back-breaking and Herculean design effort he put forth.
If you are not quite so devoted and perhaps a little more sane, you go to Ebay and buy one.
Mark
If you are not quite so devoted and perhaps a little more sane, you go to Ebay and buy one.
Mark
Still working on the apron, now dealing with the thread dial. It's got a "rough" spot in its rotation, so I'm trying to take it apart for cleaning. I pressed the gear off, didn't expect a knurled shaft - it won't fit through the body. I'm assuming that the dial portion presses off?