Thread: Chucks & Camlocks

Hi Bryan,
Another job well done, and I am glad the holes worked out so you didn't need a back plate.
As for the setup, you used what you had, and with careful setup you pulled it off just fine.

As for the camlock pins, I would carefully grind the slot on one side until they line up, then put a tack of weld on the other side to build it up. You don't need to build it all up, just a bit where the head of the socket screw is to stop it turning back around. I would make the tack a bit higher and then grind or file it to size.
With only giving it a tack it shouldn't bother the hardened pins either.

As for the grinder, I would use a 4 inch angle grinder with a cutting disk as this will be more precise than a grinding wheel. It shouldn't need much so just use the outer edge of the disk to nibble away at it and to keep the shape. Doing it this way it wont take to much off in a hurry and muck it up.

Dave

Stuart, if I'd known you would modify it I would have provided a better drawing. I can see why the big cutout needs to align with the cams, but there's no reason the screw notch has to be aligned with that. Must be easier to make that way. I thought about reducing the screw heads but I think I will run out of head. Easy to try though.

Dave, thanks for the advice. Widening the grooves was the next thing on my list. I wouldn't have thought of the dab of weld though. Must admit it worries me a bit, despite your reassurance. It would have to soften a small area wouldn't it? Are you saying that would not affect the strength of the pin? Or just not enough to matter? It's not something you want to be taking chances with. I could try it with the extra play and see if it becomes bothersome. In fact I might just try using it without the screws fitted. If it annoys me I'll fix it.

Hi Bryan,
If you want to do it that way, wrap some thread tape around them then screw it in until it's in the right spot. Try not to screw them down to far, so you don't have to back it out.

Dave

Two things to throw into the mix -
Firstly, I suspect that one of the reasons there is no set torque for tightening these things is lubrication - the torque to get to yield on a bolt is almost halved if the bolt is greased vs. dry. As manufacturers can't guarantee the state of the spindle camlocks (that is, how well lubricated it is) you could be under or over tightening badly.
In response to an earlier question, the cams hang on due to friction - think morse taper. The angle of engagement (tangent to the cam surface) would be enough to be self locking so the cams would not come loose. A D1-3 drawing I have talks about a rise of 0.063" in 210 degrees. The diameter is approximately 0.75", so this is an angle of 2.62 degrees. In contrast, a tapered mill spindle (say a ISO40) is at the critical angle where it is not meant to be self locking and has an angle of 8.13 degrees per side - note that the critical angle is worked out as a dry joint.

Michael

Thanks Michael, that's very interesting. So will lubricant make it release easier?

Also does your drawing include any tolerances?

PS: Dave, good suggestion, thanks.

Lubrication will work both ways - easier to do up but easier to undo too.

Tolerances vary but are typically a couple of thou. There are a few in tenths and a positional tolerance of 0.002R

Michael