Atlas Half Nuts OEM vs Brass

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If you two had your way, there would be no Atlas machines around for you to denigrate as the company would not have survived.

Making the half nuts and many other parts out of cast iron would be fine, but the price would be or have been 3x to 5x the cost of the Zamak V ones. That market was already sewn up by SB, with no room for another player. And we would not be having this repeat argument. So if you have nothing positive to add to the discussion, please take your comments elsewhere. They will not be tolerated here nor anywhere else on this site.
 
markba633csi said:
Would naval bronze be superior to regular bronze or zamak? I would think a leaded bronze like SAE 660 would be a good choice
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markba633csi said:
-Mark
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I wasn't able within a few minutes to find a reasonable definition of the term "naval bronze". So I don't know and will withdraw the comment. But I would suspect that your comment on SAE 660 is probably correct but that the parts cost would be increased again over brass as it will be for brass versus Zamak V. But for different reasons.
 
For the record, I have found Atlas lathes to be quite capable within their limitations- the gears have never been a significant problem other than being somewhat messy, so I run them nearly dry. They seem to be self-lubricating to a certain extent, I suspect due to the zinc and copper content
-Mark
 
Larry$ said:
Zamack was used because it is reasonably strong, easy to cast and cheap. A good choice for the intended market.
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Zamac or Zamak is an acronym for an alloy of zinc, magnesium, aluminum and copper; both spellings are commonly used, but I'd think Zamac is more proper, as it represents the correct spelling of the ingredients.
Brass is not a very good bearing metal, it can wear rapidly under pressure, naval bronze would be better, and sae 660 (bearing bronze) probably better yet, but cast iron , I think is better yet, as it is porous and can take up oil, and it works well against moving steel parts without galling, and is long wearing.
 
benmychree said:
Zamac or Zamak is an acronym for an alloy of zinc, magnesium, aluminum and copper; both spellings are commonly used, but I'd think Zamac is more proper, as it represents the correct spelling of the ingredients.
Brass is not a very good bearing metal, it can wear rapidly under pressure, naval bronze would be better, and sae 660 (bearing bronze) probably better yet, but cast iron , I think is better yet, as it is porous and can take up oil, and it works well against moving steel parts without galling, and is long wearing.
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The "K" in the word ZAMAK is from the German word for copper, being where the alloy was first used. That from a history from Atlas. . . I won't comment on brass being used for the half nuts. I have used it for other "screw followers" where it seems to last about as long as ZAMAK, give or take depending on how well it is maintained.

Iron has many advantages, as described above. But one of many(?) reasons it is not used for lead screw followers is to maintain the "purity" of the lead screw. I don't know the proper word for purity but lead screws are one of the central issues on a "screw cutting lathe". Their accuracy is central to the work, without which the machine is just a "lathe".

By making the half nuts softer than the lead screw, all (or most) wear is on the followers, the half nuts. The lead screw cannot be easily replaced, nor is it an inexpensive repair. The followers are a cheap and fairly easy to replace. When the machine goes "out of tolerance" on the followers, there is the option to relagate the machine to non-critical work until the repairs can be accomplished. When the lead screw wears out, cutting is also affected and takes much longer to correct. It has been protocol for many generations to protect the accuracy of the lead screw at whatever the cost. Using iron for lead screw followers, to me, would be a sign of poor design.

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Bi11Hudson said:
The "K" in the word ZAMAK is from the German word for copper, being where the alloy was first used. That from a history from Atlas. . . I won't comment on brass being used for the half nuts. I have used it for other "screw followers" where it seems to last about as long as ZAMAK, give or take depending on how well it is maintained.

Iron has many advantages, as described above. But one of many(?) reasons it is not used for lead screw followers is to maintain the "purity" of the lead screw. I don't know the proper word for purity but lead screws are one of the central issues on a "screw cutting lathe". Their accuracy is central to the work, without which the machine is just a "lathe".

By making the half nuts softer than the lead screw, all (or most) wear is on the followers, the half nuts. The lead screw cannot be easily replaced, nor is it an inexpensive repair. The followers are a cheap and fairly easy to replace. When the machine goes "out of tolerance" on the followers, there is the option to relagate the machine to non-critical work until the repairs can be accomplished. When the lead screw wears out, cutting is also affected and takes much longer to correct. It has been protocol for many generations to protect the accuracy of the lead screw at whatever the cost. Using iron for lead screw followers, to me, would be a sign of poor design.

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But, we must note that nearly every lathe made in relatively modern times , other than Atlas, has used cast iron half nuts, this is a fact. The only other material that I have ever heard of was from an old friend that had an ancient lathe that had babbit half nuts, poured in place, I saw it once, it was about 36" + swing, can't remember who made it. May have been a McCabe.
 
OK, benmy, that is more than enough Atlas bashing for the year. It may be a fact that every other brand of lathe except Atlas made between 1935 and 1955 used cast iron that had to be fully machined from bar and cost about 3X what the Atlas ones did and didn't work any better than the Zamak ones. It is also a fact that during that time frame, Atlas produced and sold about as many machines total as the sum of the production of the next three or four competitors. And it is also a fact that out of Atlas and the three or four competitors, Atlas is the only one that you can still pick up a phone and order most of the parts for if you want to restore one to factory new condition.

Otherwise, I think that this thread has outlived its usefulness.
 
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