Building A New Change Gear Quadrant For My 12x36 W Qcgb

Congrats.
Now you'll be back up and turning chips in no time.
Those Gear boxes are going for $250 - 300 so you should come out good on that deal.
 
Gunner said:
Some of the ones on eBay are made of brass, too. Which are easier to damage than the original Zamak ones.
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I do alot of casting, I also make a Zamak alloy that i use for alot of stuff, it is based on ZA27, its as hard as cast iron and almost as strong, its more brittle then cast iron by about 25%. its weak point is that it melts at about 925 so you would have to be carefull when up agains High temps. It makes really good gears as well as cast parts for a lot of things, one of the high points it that it acts as bearing surface due to the 2+%copper that is alloyed in, you can use it as a bearing against a shaft up to about 2500 rpm with oil.

Art B
 
That reminds me of a perennial question. Has anyone ever found believable written proof of which Zamak alloy Atlas actually used? I've seen it written that it was Zamak 5, but with no substantiation to back up the statement.
 
I'm not sure but while I've got mine down I'll either take a gear in and have it scanned or do specific gravity??? test, wiegh it in water.

I should be able to let you know what Zmak it is.
 
I'm having a new continuation of the old problem the the QCGB I made one good gear box out of my old one and the one i bought off of ebay, the ebay box bearings for the shaft that carries the selection handles were badly worn as if they had never been oiled. The gear box that was on the lathe didn't have some of the washers etc. so i merged the parts. the interesting thing is that it works just fine and then it binds up and stalls the DC motor, if it didn't stall the motor it would have broken the quadrant again. I'm finding that if there is no back pressure and it is just carrying the lead screw and the carriage it runs just fine, but if I'm even cutting a fairly light .020 cut it will bind up the gear box after about 20 to 25 inches of travel using an 8 threads per inch. at that point i can reverse it and back it up a few inches and then go forward and it will bind up at exactly the same place every time. I released the carriage feed and moved the carriage to a different location, the new bind up point was repetitive and in a different location on the shaft so I think that eliminated it being a carriage issue. The fact that it will go the 20 or so inches before it binds again once i go past the bind point seems to me that the problem would be in the thread gear tree right at the output gear, when i look at it i can't see anything wrong and i cant make it bind at all when hand turning the gear box. The 20 inches also shortness if I go to a higher thread per inch.

Any suggestions on where to go next.
 
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