Atlas 10f - Wobbly Countershaft

[Birt]

Hi All,
I am a neophyte, so bear with me: I have an Atlas 10F, purchased about a year ago, that has developed a significant wobble in its vertical countershaft, causing it to constantly fall. When I purchased the machine I tested it out and had no problems, and even when I first set it up at home things seemed fine, although I use it fairly infrequently. But it developed this problem very suddenly, to the point that I can't even run the machine now. I fire it up and within 30-60 seconds the rocker lever will work itself forward enough that the countershaft drops. It happens even with the spindle belt removed so there's no downward tension on the countershaft. I am flummoxed. There is a significant wobble visible if you look at the pulleys while it's running, which I suspect is causing the problem. There's also a significant amount of play in the roller bearing closest to the drive pulley (if that's the right term). Is there anything I can hope to do about this?
To compound the issue, the model number on the plate is TH-42 and a quick Google search seems to indicate that these machines only came with horizontal countershafts. When I purchased it, the previous owner had mentioned that the countershaft had likely been swapped out at some point (by an owner prior to him) but it seems not to have caused him any trouble.
I suspect there may be some other issues to deal with on this machine, but I can't even run the spindle long enough to warm it up and measure the runout.
Help?
John

 

[wa5cab]

Yes, a PO apparently changed out the original horizontal countershaft on your TH42 machine for the vertical one. That wouldn't normally be any problem other than that the machine becomes a TV42. Not having the machine in front of me, I can't guess what the problem is. But it will probably turn out to be from wear on some or all of the bushings and bearings.

 

[Birt]

Right, so is there anything I can hope to do about it? I don't imagine there's anyone making new bearings, do I take my chances buying a used replacement or two on eBay, or if I took it to a machine shop is there anything they might be able to do?

 

[wa5cab]

Birt,

The 10" Vertical and Horizontal Countershaft assembly both used the same Countershaft Spindle Assembly and Hanger assembly. So it is possible that Clausing may still have some parts. You may also be able to buy the bearings and races commercially. But if Clausing doesn't have it, you will have to make the spindle itself. You could also check for used Horizontal Countershaft assemblies on eBay.

 

[Birt]

Thanks for that. I contacted Clausing this morning, so we'll see what happens. According to this post I found on a random blog from just last month, they still stock a lot of parts for these machines: http://cholla.mmto.org/machining/lathe/clausing.html.

 

[cdhknives]

My countershaft was badly scored under the roller bearings and worsening rapidly, so I built carriers (and bought a D shaft...shaft rod with a full length flat for set screws) for sealed ball bearings. In my search I found open roller bearings identical in measurement to the factory units. If you want to rebuild in kind, a section of hardened shafting and replacement bearings is a viable alternative. You would still need to drill the grease ports and thread the ends for the grease caps. A search of this forum back a few months will reveal mine and another member's bearing replacement project. I have a CAD file posted with dims for the bearing carriers. It was a fun project...even if rushed by need of working with the failing bearing!

 

[cdhknives]

Found it:

http://www.hobby-machinist.com/threads/hot-hot-is-too-hot.34121/page-2

 

[Birt]

Found it:

http://www.hobby-machinist.com/threads/hot-hot-is-too-hot.34121/page-2

Thanks for sharing that - it is extremely helpful. Seems like a project I might even have a chance at doing, though I've not done any boring before (as I said, I am a neophyte). I was able to capture your drawings, though, so maybe with some guidance I can get it done. Did you find the bearings at bearingsdirect.com, as Wierd Harold did?

 

[cdhknives]

I bought mine at McMaster but only because I could also get the shaft material there and it didn't make sense to pay shipping from 2 places...

 

[Birt]

Another thought occurs to me that may be contributing to the countershaft constantly wanting to fall. The rocker bar that raises the countershaft has two flats ground in it (I thought it was supposed to have three for "idle" "drive" and "heavy duty" but I don't see a third position). Between those two flats is, of course, a corner. As you move the rocker arm and the countershaft rises, shouldn't it be at its highest point when resting on the apex of that corner? Then it would drop down - however slightly - to come to rest in the "drive" position. It would be kept from falling by the fact that it would first have to jump up over that corner, before dropping into "idle." Otherwise, couldn't any amount of vibration shake it out of drive (as mine is doing)? Measuring the motion of my countershaft with a dial indicator, it doesn't reach its highest point until it's fully in drive. Is it possible that corner has become worn down and that's causing me problems? I realize I may be completely mistaken.