Atlas V36 rebuild

[jwmay]

I'm not sure. I tried to remove the rack from the original once, but it was fighting me. I didn't have a good reason to take it off, and I was afraid I'd bend or damage it if I continued with prying on it. It's pinned and screwed in place. In this particular case, the rack from the other is not the same length, so it most likely won't be a direct fit. If the holes could be lined up, it's possible I could cut the other rack to fit. But I'm suspecting the issue is with the gear more than the rack. I don't have a good reason for that, other than I think the gear is a replacement made by someone in the last 10 years. And I have a stubborn presupposition that almost anything made that recently will not be as well made as something from 60 years ago. ha ha Is that "agesim"? I don't know. Anyways I know "intellectually" I'm wrong with that assumption, but I can't shake it.

 

[wa5cab]

Like you, I have always assumed that the 12T gears are Zamak. There are three gears plus the rack involved. When the carriage is off of the bed, do you feel any drag when you turn the hand wheel?

 

[jwmay]

No, it’s smooth turning when removed. There’s some play in the shaft with a gear on both ends. I put the carriage on the other bed, and couldn’t tell an appreciable difference. I do think I found one clue though. It’s rougher moving towards the headstock than moving away from the headstock. On the other bed, there was a rough area once for every full rotation of the hand wheel. I’m assuming that indicates an error in the gear, or a bent shaft. My two clues don’t seem consistent with each other. Perhaps the rack is worn more on one side of the teeth than the other? If that’s the case, I may actually have to break down and buy a new part, if available. It’s not visibly apparent if that’s the case. Maybe I could flip the rack end for end.

 

[wa5cab]

I don't think that I would try flipping the rack end for end. First, the racks are countersunk on the visible side, so you would have to countersink the holes on the present back side and the existing countersinks would leave the screws unsupported. Second, the pins are tapered and although I assume that the holes in the rack were drilled to print and the tapped holes in the bed were done to print, I would assume that the pin holes in the bed were match drilled and the holes reamed on assembly.

Secondly, there is a 2:1 reduction between the hand wheel shaft and gear and the rack shaft and gears. So a once-around rough spot on the hand wheel implies that the problem is related to the hand wheel shaft or gear, or that the rack 12T gear is oval or egg shaped.

 

[jwmay]

Maybe at this point, the best thing to do is nothing. It’s not a huge deal to take the apron apart later, if I discover I’m unsatisfied with something that I suspect is related to this.

But to be clear, on the machine being rebuilt, the action is rougher than I expected through the full rotation. I’m used to a much newer machine though, so it’s possible I should temper my expectations. I considered blueing all the gear teeth, to later inspect for uneven wear. I could do that now, and continue on. Once it’s in running condition, I may find it’s not an issue that needs addressed.

 

[wa5cab]

That sounds like a reasonable plan.

 

[jwmay]

Well this is a bit of a fast forward kind of thing. Here you can see it’s mostly assembled. I’m ordering some link belt, and have decided on leaving a few pieces unpainted/painted some other color for now.

My tee slotted cross slide is as yet unfinished. I’ve moved house since last I posted. So there’s my excuse.

I’ve got some electrical to sort out at the new place before I’ll be able to run either Grizzly mill or lathe. Which prompted a mad dash of assembly on this machine that’ll run on 120 volts.

 

[jwmay]

After much turning of handwheels, I decided I didn’t want to do the dovetails for the new cross slide. 11.5 inches of cranking was too much for me. I ended up asking a friend to finish them with his machine equipped with power feed. He milled the ends, finished the dovetails, and drilled and tapped for gib screws...oh and he surface ground the top and bottom . All that’s left is milling the gib to size, and drilling for the cross slide nut. Not out of the woods yet. I’ve screwed up simpler jobs.

 

[jwmay]

So... finally got around to that gib and crossfeed nut job. It's like I lost a whole year somehow. I don't think I'm alone though. Anyways, here's a picture of a set up that didn't work as expected. Luckily, for the first time ever I made a practice piece out of aluminum first, which showed me my error. I ended up using some jacks and round stock to hold the gib in the casting dovetail, and machined it that way. My set screws are too short, or I didn't machine enough off the sides of the casting. Not an insurmountable problem, but a short term problem nonetheless. So here it is done. Thanks for looking.

 

[jwmay]

Well the little Atlas is getting warmed up for another improvement. I've definitely abandoned any notion of being fiscally responsible with this machine. Hopefully I'll be threading 20tpi and turning at .0042 ipr by the end of the month. Wish me luck!
On a separate train of thought: I've noticed people are getting pretty picky about how the words "restore" and "rebuild" are used. So maybe I should have titled this thread Atlas V36 evolution? Or just Atlas lathe made useful?