Atlas 3986 tuneup question

[someidiot]

Lots going on with the impending inevitable cold crunch (I just test fired the radiant heater I got for the garage last year and it seems to be running - better vent it, though!), but I took a little break tonight to pull the apron off of my lathe. The symptom is an inordinate amount of slop/lash in the carriage handwheel. Now that I can see the gears, they're obviously not meshing tightly and I don't know what I can do about it. Is this likely to be the normal wear these things exhibit after 70 (?) years? Are there replacement gears to be found?

 

[Mega arc 5040dd]

Lots going on with the impending inevitable cold crunch (I just test fired the radiant heater I got for the garage last year and it seems to be running - better vent it, though!), but I took a little break tonight to pull the apron off of my lathe. The symptom is an inordinate amount of slop/lash in the carriage handwheel. Now that I can see the gears, they're obviously not meshing tightly and I don't know what I can do about it. Is this likely to be the normal wear these things exhibit after 70 (?) years? Are there replacement gears to be found?

I'm not familiar with that Atlas model is it a 12"? I have a similar issue with my 10F that I hope to address in the next few months. Can you post pictures so we can see what is going on with the gears. Not sure on your model but on the 10F this can often be wear in the apron where the hand wheel shaft goes through and can be fixed buy boring it out and inserting a bushing.

 

[someidiot]

Yes, it's a 12". Here's a shot of the traverse gear case behind the apron (upside down for visibility). The small upper gear is the one behind the crank. Most of the slop is between it and the big gear below. There's a little play in the shafts, but even when I apply pressure to them it's not enough to close the gap in the teeth (clearly seen in this photo), so that's where the problem seems to be. There could also be some play between the smaller gear in the bottom of the photo (that's the pinion that engages the rack) and the rack, but that's harder to see.

So is the problem simply wear on the tooth faces? I took a look on ebay and quickly found https://bmpartstech.com/ - a guy in Michigan who makes replacement parts. He has the housing, shaft, and gears (together or separately), but not specifically the crank gear. I've dropped him a note.

 

[someidiot]

Oh - have I just spotted the obvious? That loosening those two mounting nuts will allow the case to be slid left a little to close the gap? If moved laterally rather than vertically it wouldn't just move the gap up to the rack+pinion.

 

[Mega arc 5040dd]

In the photo is honestly doesn't look like much slop between the gears. I would try like you suggested and see if you can adjust it slightly.

 

[someidiot]

Believe me, that's a lot when you're turning it (or want the carriage to stay still).

 

[Mega arc 5040dd]

It would be neat to see a side by side comparison of the old gears and some new ones.

 

[someidiot]

Hey - might not be the gears after all. As I was poking at it I found that two of the three bolts/nuts holding the case to the skirt were loose. That looks like it might tighten it up enough, but first I have to clean the whole assembly up - it's really cruddy. Will advise tomorrow.

 

[Mega arc 5040dd]

I can't tell from the photo but I am curious, the gear and shaft that go to the hand wheel on yours is there a bushing or does it just a hole in the cast of the apron? My hand wheel had a lot of up and down play and I could tell the hole the shaft goes though was wallered out. I decided it was time to take on the task of putting in a bushing but once I got it all apart I found that it already had one. I'm just not sure if they came with a bushing or if someone had installed one at some point in its 90 year life. It sure made the job easier than I had expected since I could just press it out make a new one the same size and press it in. I know that isn't quite the same problem as yours but figured since you had taken your apart I would ask.

 

[someidiot]

No, I wound up not going that far. I tightened down the case with as much "engaging bias" as I could apply to it. Still a bit sloppy, but I could live with it. But when I bolted the skirt back up I found that all of that lash is between the top pinion and the rack, and I'm not sure what can be done about that. I'd love it to be tight, but how important is it? I first noticed the problem when doing some facing, but now that I know to lock the carriage during that operation, the carriage crank drive slop is no longer a problem. Nor, it seems to me, does it really create a problem if one is cutting in one direction or the other.

But perhaps I'm being too forgiving in thinking of it that way and people who actually know what the hell they're talking about will correct me.