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Mounting D1-3 Three jaw chuck

rock_breaker

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I have an Enco 13 X 40 lathe that hasn't seen much service and I just discovered a problem with the 3 jaw chuck that came with the lathe. I am a newby when it comes to cam lock chucks, so I didn.t pay much attention when uncrating and getting it level; the 4 jaw seems to be OK. Will check that further when it cools off this evening. (Most of my work has been between centers or 4 jaw) but when using the 3 jaw to turn down some 1" mystery metal stock the chuck came loose in the cam lock mechanism. I got it shut down without any major mishap. I checked the clearance between the chuck back plate and the camlock assembly and found the chuck will pull tight to the cam lock assembly on one lock pin but leaves about a 0.010 gap on another lock pin, actually, I believe the taper is to deep in the chuck. It is a straight back chuck so the only place to get more clearance is by facing the cam lock assembly. I did check the cam lock face. the taper on the end of the spindle and the end of spindle with a dial indicator and got less than 0.001 run out on the three surfaces.
I would certainly appreciate comments from anyone that has overcome this problem. Ican;t at this time buy a new lathe.
Ray
 

ttabbal

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On mine, there is a cap screw next to the stud preventing it from rotating. On the ones that are loose, remove the screw, turn the stud in a turn or two, put it back and try to lock it. It takes a couple of tries for me to get them to the correct length. You should be able to get them to have zero play but still turn the cams pretty easily.
 

Bob Korves

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Benmychree is correct if the studs need adjusting. If you cannot get enough engagement for the mark on the cam to fall between the two marks on the spindle when tightening them down, try unscrewing any tight pins by one revolution. A set screw keeps the pins from rotating and must be removed to adjust the pin lengths. If a pin is too loose, the cam will go past both marks, which means the pin must be screwed in one revolution.

While you are at it, that sounds like it could also be the chuck hanging up on the spindle nose, which would keep the chuck from seating flush to the spindle face and could also keep the camlock studs from fully engaging. To be correct the chuck/back plate should be pulled down tightly to the spindle face all the way around the diameter. Check by holding a strong light behind the joint and look for light around the entire perimeter of the chuck/spindle interface. No light should be visible. All the marks on the cams must end up between the two marks on the s;indle for the chuck to be installed correctly. If you achieve all that, then the chuck is fully seating to the spindle face. Now, loosen the camlocks completely and try to remove the chuck. It should not fall free. It should take a bump from a wrist or dead blow hammer to free the chuck (or back plate) bore taper from the spindle nose taper. If the chuck does not seat when installing it, the seat is too tight and will need to be fitted to the spindle taper. If the chuck easily seats flat to the spindle face, but then falls off when the camlocks are released, then the chuck/back plate bore is too loose on the spindle nose. A loose fit will require new parts or machining the back plate or chuck. A tight fit, especially an almost good fit, can be repaired by using high spot blue, trial fitting the chuck to spindle nose, and removing metal from the high spots on the chuck or back plate, not off the spindle nose, until the fit is correct. Warning, it typically takes very little metal removal to make the fit correct, too much metal removal makes it too loose, which requires a new part or machining the chuck or back plate.

The chuck not seating against the spindle face also causes the chuck to exhibit a "wallow" runout when testing the chuck for runout. Sometimes it is even easily visible, and no good work can be done with that condition. My Kent 1340 exhibited that problem with one chuck, the other fit perfectly. The face plate also was too tight. I made them correct myself. That would probably be a warranty issue on a new lathe, but good luck with getting it reconciled easily with the seller or builder with a Chinese lathe. I can give you more help if you need it.
 
Last edited:

JimDawson

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You may be able to adjust the cam lock studs so that the cams will engage them properly.

What benmychree said. That is the first place to start. I would first remove all of the cam lock studs and make sure the chuck back will mate to the spindle nose. Then screw them back in to the line and try it again. The cams locks should turn to about the 4:00 o'clock position when properly tightened.

I don't know if your spindle nose is marked, but in the picture below the line on the cam socket should line up between the V and > when properly locked.

1534642073262.png

Here is a setup I did to work on the back of my junk 4 jaw on my 13x40. I had to recut the back plate mounting area. You could do something like this to your 3 jaw if needed. Fit the chuck to the spindle nose if needed, do not make any changes to the spindle.
1534642306604.png

1534642327940.png
 

aliva

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The pins should have an engraved line to indicate proper threaded depth. Remove the socket head bolt beside the pin, screw the pin into or out of the chuck till the marked line is flush with chuck surface.. reinstall the socket head bolt. You may have to turn the pin till the bolt will screw in, make sure you can still see the line, don't bury it. Do this will all of the pins.
 

Superburban

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Yes it's slanted, and no it shouldn't be. That is high quality work from the People's Chuck Factory #4 :grin: It was cheap.
That blows my mind, Can't even imagine how they could be so far off. The chuck was hand held in the T slot cutter machine?
 

rock_breaker

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ThANKS GUYS!
I now have some usable knowledge of how to adjust the cam locks. I have been all over the place from camming over to not holding at all, hopefully the indexing marks are there. I know the groove for pin depth is on all three pins. No doubt I will review these comments several times before I get it right. I will start again in the morning. The 4 jaw is doing the same thing only less clearance. I hear you about not cutting the spindle or taper. If necessary I could cut the back of the chuck but I will be back here before that happens. It is flat. The runout on the chuck is 0.020 which says a lot about the quality. That may change if I can get it mounted correctly. I am wondering if better quality chucks with three pins are available?
Thanks again and have a good day!
Ray
 
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