truing up faceplate on metal lathe

I mounted the 12" faceplate that came with my import metal lathe and noticed that it is not even close to running true. My first thought
was to take a facing cut on the face and true it up, but upon further inspection, I noticed that the flat surface at the back of the mounting plate (where the cams come out) doesn't sit flat against the head stock. I pulled the faceplate to ensure it was clean and free of metal chips and other debri. It still won't sit flat at all. I flipped the faceplate around and mounted it to a 3 jaw chuck and was able to determine that this surface is flat and true. What else might be preventing the cams from pulling the faceplate flat/tight against the headstock? Is there anything I can do to correct this, or is it easier to leave it and go ahead and face the front of the plate?
thanks in advance, Nick
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Make sure your cams locking dowels are adjusted right. I would make sure the cams are in deed fully open, and recheck the dowels and it should fit snug up against the back of the faceplate to the spindle nose. Its possible the tapered bore that fits on the spindle nose is out of wack. Snug up each cam a little at a time and go from one to the other until they are all snugged up. If its still got a gap call your machines dealer for a new faceplate..........

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Thanks Roy. I have tried turning each cam lock a tiny bit, working my way around, but the same side always ends up with a gap. I put either of my chucks on and they line right up and run flat each time. I think it is definately the faceplate. Is it possible that one of the cams sticks out further than the others? I removed all three cams and cleaned everything up and put them back in and still have the same problem. If it is not something with the cams needing adjusting, my only other guess is what you suggested - the taper is not true.
Nick
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I would return it. When I get a new plate I will true to the lathe, I have an "A" stamped on my spindle in 1 spot when I true a backing plate or what ever I stamp "A" on it to line up with the spindle "A". this way when ever I remount the plate its in the same spot on the spindle. but the amount you are talking about is not correct with a cam mount.

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Done deal - I will take the faceplate back and ask for a new one. Putting a straight edge on the front and back, I can see that they appear to be flat, so my suspicion is that the taper is the issue.
Thanks for all of the replies.
Nick
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Don't feel bad. When I bought my Jet GBH1340 a few yewars back Jet sent me a total of three faceplates until I got one that I considered within reason to true up. They all fit the spindle of the lathe fine, but the runout on them was considerable, and I wuold have had to remove quite a bit of meat off the face to get them true. One had as much as .139" of an inch runout.........the one I finally managed to get that I accepted was almost dead true as received and only required light facing.
I also stamped an area adjacent to the locking cams with a number stamp, on the spindle nose and the chucks/faceplate which I used to iindicate that as being the reference point so they could be installed in the same position each time.
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==================enitirely possible, but before sending the faceplate back try turning the odd retaining screw in a full turn and remounting the faceplate. Most D style chucks/faceplates have the mounting studs retained with a small screw which you may have to remove and replace to adjust the mounting stud. You misht also try swapping the retaining studs between their holes to see if you can get them to pull in evenly.
GmcD
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It seems to me that the hardest part of making a camlock plate would be the stud alignment. You might have a problem with the stud location or parallelism. It should be possible to verify this by removing the studs one at a time and checking the fit, possibly installing a bolt through the spindle to pull the plate on. Just a thought. Don Young
wrote:

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Nick, if it is an accurate faceplate it shouldn't require any 'cams' to run true to run truer than +/- 5 mils on your lathe.
If wose than that II'd suggest that you return it as defective to the seller.
Harry C.
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I played around with it for a while last night - moving studs, trying to tighten different ways, etc. At one point I got the faceplate pulled fairly tight against the mounting plate, but it still wouldn't run true. I finally clamped the faceplate to my mill table and ran a dial indicator across the different surfaces. While all of the surfaces are flat, they don't appear to be parallel to each other. The bottom line is that this faceplate is a piece of junk and will need to be replaced.
Thanks to everyone for your input.
Nick
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