The Home Machinist!

Just picked one up but I can't budge (loosen) the inside knob that locks the eccentric worm engagement (worm is currently engaged). I used large channel locks, turning clockwise, but it won't budge and I am afraid to put a large pipe wrench on it in case I break something. Does anyone have any expereice with this issue or know what might cause it to jam (besides just getting stuck over the years). Overall it seems in good shape.

I'm not familiar with that particular device, but turning most threads clockwise, as you suggested, tightens (right hand thread), not loosens. Might be a good idea to ascertain the hand of the thread in question.

H

Sometimes one long knob is actually two separate rings. Can't remember if B&S or Cincinnati but if there are four knurls with space between, one locks the other. Its best to see the actual patent illustration.

Not familiar with the model you have, but here are some videos of restoring B&S dividing heads.

Both of these guys are pretty competent.

Maybe one of these is yours, or is similar enough:

B&S dividing head restorartion (3 parts)
Brad Jacobs
https://www.youtube.com/watch?v=dSzy1dbZKPw

Disassenbly and Assembly of a Brown & Sharpe Dividing Head
Kieth Rucker
https://www.youtube.com/watch?v=DXef8SfT8fw

Steve

Thanks SteveM, that second video really showed the inside well. The stuck knob turns a spur gear which turns a nut on the eccentric shaft that locks said shaft from turning (the gear pair explains why clockwise turning loosens it). No doubt about the unusual direction as the knob has a direction arrow labeled "tighten" pointing ccw. I'm now glad I didn't break gear teeth by applying too much torque. I guess I'll have tyo dis-assemble and soak offending parts in liquid wrench or some-such. Though, from the views in the video, it looks like there might not be a better way to apply torque to the locking nut except through its gear train.

Jamesframes wrote: ↑Tue Nov 05, 2019 7:50 am... soak offending parts in liquid wrench or some-such.

Use a 50/50 mix of acetone and automatic transmission fluid for your soak. It can un-stick just about anything.

Steve

To end this post, in case someone has the same issue and searches for it, here is what worked. First I found a video titled "Disassenbly and Assembly of a Brown & Sharpe Dividing Head" which had great views of all the working inside parts. This was invaluable. Now to summarize my problem - No matter how hard I tried (with a pipe wrench no less) I couldn't loosen the knurled locking knob with the gear that turns the eccentric lock nut. The eccentric was full engaged (worm up) and wouldn't budge of course. Seeing theviews of the inside, I was glad I didn't strip the gear teeth and knew I couldn't just apply more torque. I ended up making a special sleeve-tool that had a protruding tang on the end to engage the eccentric shaft (where it normally is prevented from rotating too far). With a large wrench on this tool, and a pipe wrench on the knurled locking knob providing torque in the same direction, I was able to force the eccentric around to get the worm away from the spindle worm gear. This allowed me to take the spindle out and thus access the insides. I then got a piece of steel to block the gear teeth on the actual locking nut and, with a pipe wrench again also adding to the blocking torque, applied torque on my tool in the opposite direction (on the direction that would cause the nut to loosen). It took a pretty big effort but it did come loose (before any gear teeth got stripped thank goodness) and so it was a success!

Now you have it pretty well knocked but something may be escaping.. Pin Spanner. It is like a Hook spanner but is a forged handle with a hardened pin. That would be perfect to hold the inside ring of the knob. That is what those holes were for.