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PM 4-Jaw Chuck
- Thread starter MWCurl
- Start date
- Joined
- Jul 29, 2014
- Messages
- 2,840
Thanks y‘all for the comments on 4 jaw chucks! I honestly have no experience with poor quality chucks, and will avoid taking chances in the future.
- Joined
- Jan 20, 2016
- Messages
- 602
I have one of their 4 jaw chucks for my 1236T. So far I am mostly pleased with it.
The mounting taper isn't quite perfect, so I have to install it in a specific way to get it to spin concentrically. If I just put it on and tighten each cam randomly, it gets pulled off to one side and I can't get work spinning right.
The jaws are pretty darn tight, but I suspect that will improve the more it is used. There was a little bit of grinding dust on the back side, but not too bad. Parts of it are pretty sharp so you need to be careful when handling. It had a few weights in the back so I assume they took the time to balance it.
Here is a picture of the contact of the rear face to the spindle face. I drew around the contact areas with sharpie so you can see. You can see some of the dust inside and the orange paint. Taper contact looks ok though.
A few more pictures if you are interested.
The mounting taper isn't quite perfect, so I have to install it in a specific way to get it to spin concentrically. If I just put it on and tighten each cam randomly, it gets pulled off to one side and I can't get work spinning right.
The jaws are pretty darn tight, but I suspect that will improve the more it is used. There was a little bit of grinding dust on the back side, but not too bad. Parts of it are pretty sharp so you need to be careful when handling. It had a few weights in the back so I assume they took the time to balance it.
Here is a picture of the contact of the rear face to the spindle face. I drew around the contact areas with sharpie so you can see. You can see some of the dust inside and the orange paint. Taper contact looks ok though.
A few more pictures if you are interested.
- Joined
- Mar 21, 2013
- Messages
- 4,118
Clocking or indexing a chuck on a lathe spindle is pretty normal in my experience. But then I'm just a amateur.
When I get a new chuck I go through the process of finding the orientation that works the best, and then mark the chuck so I can repeat when I am switching chucks back and forth.
When I get a new chuck I go through the process of finding the orientation that works the best, and then mark the chuck so I can repeat when I am switching chucks back and forth.
- Joined
- Jan 20, 2016
- Messages
- 602
It isn't so much that the chuck needs to be in a specific orientation relative to the spindle, it is that it there is a specific way it has to be tightened to get it to work right. There is one side of the chuck that needs to be tightened last, or the entire thing is pulled to one side and it doesn't spin true. This happens regardless of the position on the spindle or the position of the cams in the chuck.
It is sort of hard to describe and I am not exactly sure what is going on. But using arbitrary numbers, if I tighten down Cam 1, then 2, then 3, you feel Cam 1 go way farther and cam 2 and 3 don't tighten right. But if I tighten 2 then 3 then 1, 2 and 3 hold it in place correctly and Cam 1 can't pull it out of position anymore.
- Joined
- Mar 21, 2013
- Messages
- 4,118
Like I said, I'm no expert, but that doesn't sound right. My chucks sit flush on the spindle and all three cams tighten to about the same spot (depending on how much torque I give 'em) every time. To me, it sounds like you chuck is not sitting flush?
- Joined
- Jan 20, 2016
- Messages
- 602
It definitely isn't right, but I don't know what cause that to happen so I am not sure how to even begin trying to fix it. The 3 jaw and face plate that came with the machine don't have the same issue. Based on the blue transfer, I am thinking it isn't sitting quite flush.
- Joined
- Dec 3, 2013
- Messages
- 1,849
By not spinning true do you meant off center or not parallel(tilted) with the spindle axis?
When you remove the chuck does it loosen by itself or require a tap or a good whack?
If it loosens under it own weight I would pull the cam-loc pins, hold the chuck against the spindle nose and see if there is side to side play. If so I would be suspect the taper on the chuck is over size.
If the taper fit feels proper and/or loosens with a tap then I would try adjusting the seating depth of the cam-loc pins or even shuffling the pins to different positions.
If it requires a good whack to loosen then the spindle taper fit may be too tight not allowing all the mating surfaces to seat properly.
The internal D1-4 taper on my 4 jaw is good but on the tight side. The chuck must be drawn up evenly to the spindle or it will not seat to full contact. When installing it, on the first go around, I turn each cam ONLY to the first V mark. Then continue to tighten gradually in 2-3 more revolutions before final torque.
It takes a few taps with a dead blow hammer to pop it loose.
No amount of switching studs or cams will compensate for a tightish fitting taper. It is all in how gradually and evenly the cams are worked.
If you suspect that yours is not fully seating then maybe check it with some 'plastigage'.
It takes a few taps with a dead blow hammer to pop it loose.
No amount of switching studs or cams will compensate for a tightish fitting taper. It is all in how gradually and evenly the cams are worked.
If you suspect that yours is not fully seating then maybe check it with some 'plastigage'.
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