86980zamac and [atlas_craftsman] Re: Atlas Mill limitations??
- Apr 9, 2014Well, it isn't all Atlas bashers....I have several pieces of atlas equipment (although not an Atlas lathe). A big drill press, a bandsaw, and two shapers. I like them, so obviously I am not an Atlas basher, should that come to anybody's mind....All have some zamak. Some is still good, and should continue to be good unless damaged a different way. Some was lead contaminated (zinc pest, or the like).And some was not appropriately used, as you say. I would suggest that certain uses were ridiculous.... dumb bunny engineers, or bean counters.I have a 1952 Atlas 1800 drill press. It's an 18" drill press with a big column, and a lift system that uses a lead screw to move the table or the head, depending on which you loosen. It was moved to the Clausing brand after a year or so. It's a BIG DP, close to 7 feet tall, intended for industrial applications.The little slider on the depth stop had zinc pest, and I had to make a steel replacement. The spring housing is zamak, and seems to be OK. The spoke hub on the downfeed is zamak, again no problems.Some maniac specified zamak for two other applications that should have raised red flags...... They used the hybrid zamac/steel crossfeed pickoff bevel gear from the 10" lathe for the raise/lower leadscrew driving gear. It has NO zinc pest, but the gear teeth were so mashed up that I had to make a new bevel gear. You can call it abuse if you like, but it's inherently a rough application, and the problem should have been no surprise. The gears are inside a cast iron enclosure, so that wasn't an issue of external grit damageThe other stupid application was for the split cotters. There are five 1.25" diameter two piece split cotters on the machine, which you loosen to move the head or table. While they had no particularly bad zinc pest, they were all frozen solid when I got the machine. It took a couple weeks of penetrating oil, work with screws set up to press them out, and finally the old reliable BFH to remove them. Actually, it took that time to LOOSEN them... once loose they came out easily, although I was not foolish enough to re-use them.... I put in CRS replacements, and those have been perfectly reliable. The zamak simply "flowed" and locked into the bores, with possibly a trace of pest corrosion to liven things up.Both cost-cutting measures should never have been tried.... not for an industrial machine where the adjustments might be used many times a day.The bandsaw has wheels which are Zamak, or similar, and work fine..... We all know what's zamak on a shaper. The ahapers have given no problems either.It is indeed probable that any bad zamak has already gone bad.... but that is not a guarantee. It depends on environment.... Bad zamak could last many decades in Arizona, but fail in a few months if moved to a humid environment.Jerry----- Original Message -----From: wa5cab@...Sent: Wednesday, April 09, 2014 5:08 PMSubject: Re: [atlas_craftsman] Re: Atlas Mill limitations??
That's about what I was going to say. Except that period sources that I've read only said that the zinc was either impure, not of sufficient purity, or contaminated. The contamination referred to may well have been lead. In any case, at this distance in time if anyone acquires a mill, lathe or shaper with all good Zamak parts, they will still be good parts when we all go to our rewards. Unless of course the operator crashes the machine in which case any parts failure is his or her fault, not the part's. :-)
Now it is true that even as late as about 1972 Atlas designers used Zamak in places that it wasn't suited for. Apparently the company memory didn't quite last from the mid 1930's until 1972. But other than that, the Zamak issue is just something that Atlas bashers like to trot out and tell to people who don't know any better. Like the bad batches of parts from the 1940's, the information is contaminated.
Robert Downs - Houston
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