Traverse Gear Removal

Hey guys I got a new traverse gear case and I need to remove the gear from the old broken case. I'm assuming that the spindle is just mushroomed out over the larger of the 2 gears. But since my assumptions have left me with even more broken parts in the past I wanted to make sure that I was correct in this. What is my best method of removal? Thanks Richard

Hello Richard.
I am in the process of replacing the traverse gearcase on my Atlas 10F and I have just dismantled this assembly. I destroyed the mazac gearcase in the process.

Both the larger gear (part 341-057) and smaller gear (9-102-125) are pressed onto the shaft (9-68) up against a shoulder. The gears each have a square broached hole in them and each end of the shaft has a square end. The ends of the shaft are lightly peened over the gear bosses. After the gears and shaft have been removed from the case (10F-11), the gears can be easily removed using a brass drift and small hammer. You will need a tube to pass over the smaller gear to support the larger gear. Once the larger gear is off the shaft repeat the operation with a smaller tube to remove the smaller gear.

Before you dismantle the gears from the shaft you will notice that the shaft is asymmetric. The relief in the middle of the shaft for the leadscrew is not central. The shorter length of full diameter shaft is adjacent to the larger gear. When re-assembling in a new case make sure the shaft is the correct way round. Do not hit or load the new case when assembling the gears to the shaft as I reckon you will damage the mazac case.

One final point. After carefully inspecting the apron and saddle I noticed bright witness marks on the top edge of the 10F-11 gearcase and a matching mark on the saddle bearing plate (10F-54). Yes they were interfering. I do wonder if the mazac case on my lathe was cracked when the apron and the case bolts were tightened up. This would be worth checking before damaging your new 10F-11 case.

Good luck,
Ian

The zinc alloy that Atlas used for many cast parts was Zamak, not mazac

Mazak was a British version of Zamak.

OK. According to Wikipedia, that was at least partially correct in the early 1930's. It's possible that that is what Sphere and a couple of other British companies used when they license built copies of the Atlas lathes under their names. However, Mazak did not use ezactly the same zinc base as Zamak, it not being available in Britain at the time. So unless referring to British built lathes, Zamak is the correct term to use here in reference to Atlas built machines.

Gents you are right of course, zamak it is. Here in the UK we are used to referring this zinc aluminium-magnesium-copper alloy as mazac. It is the same rubbish material; hit it and it breaks.

Apparently, the difference between Zamak and Mazac is the purity spec for the zinc used (99.99% versus 99.95%). What difference that makes I couldn't determine. In any case, calling it a "rubbish material" is incorrect. It isn't suitable for all parts in a lathe or mill, as Atlas quickly found out in the 1930's. But aside from a few bouts of Zinc Pest in the early years, the parts that they continued to make out of Zamak over the next half a century performed quite satisfactorily until Clausing stupidly repeated the early 1930's mistake and killed the 6" MK2.

As a practical matter, it is also quite probable that had Atlas not used Zamak for many parts in their lathes, they and repair parts for them would not still be quite plentiful and relatively inexpensive today.