Replies

1. 
   jimmyk | Aug 01, 2003 04:50am | #1

   Is it off center left to right, or up and down? If it's up and down, then it's a pain to fix because you need to shim the low component. If it's off center left to right, then there should be adjusting screws on the tailstock and/or headstock to move it back on center. On my delta lathe, the screws are on the tailstock down at the bottom parallel with the ways. They are two set screws; one in front of the machine and one in the back. You need to loosen one to tighten the other because they are opposing screws. Your machine may be different, so if they're not on the tailstock, look around the base of the headstock. Good luck.

2. 
   SawdustSteve | Aug 01, 2003 06:19pm | #2

   Shel... Start with the basics.  Put the chuck on the lathe and place a large (1 inch diameter) piece of steel rod into the chuck, sticking out only an inch or two.  Turn the chuck by hand and use a dial indicator to check if everything is running true (concentric) with the headstock.  If it is, then the problem either lies with the tail stock, or, more likely the dowel you used is out of round  (very common occurance).   If the lathe has a morse taper in the headstock and tailstock, use a rag to clean both internal tapers, place NEW 'dead centers' in each end and carefully slide the tailstock / dead center combo up to the headstock / dead center assembly, lock the tailstock and CAREFULLY check that the two points meet.  If they don't then you have an allignment problem that should be corrected by (hopefully) adjusting the tailstock.     SawdustSteve

1. 
   Shel | Aug 01, 2003 06:37pm | #3

   Will try all suggestions and report back later. Shel

3. 
   Manchild | Aug 01, 2003 10:53pm | #4

   I have an old craftsman lathe that is very inaccurate but I can get pretty good results with it. Alignment is always off unless I move things around. The problem is I have to check every time I go to do a new operation because the results are not repeatable. Right now I have a torn piece of a magazine under the rear left corner of the tailstock. You just keep taking pages off until you get the results you want.

   I've been drilling out the center of titanium bolts recently. If I line up both ends and put a pilot dimple in the end I can get the drill bit(3/32") to bore a straight concentric hole. Once it is off it just gets worse.

4. 
   Steinmetz | Aug 01, 2003 11:35pm | #5

   Shel, If you can't correct the runout in your lathe by adjusting the tailstock''Set over' screws, you may have a twist in your bed. 

   ( Not your four poster)  Many times an old lathe is bolted down to a warped benchtop.  Try to Level the bed and check for 'Twist' .

   When located, the twist can be un-twisted by shimming the offending leg/legs. Stein.

   Then rebolt,  When it comes to beds, be gentle.

1. 
   Shel | Aug 02, 2003 03:36am | #6

   follow up: the tail stock appears (visually) to be high, maybe .0005; and when i chucked a piece of steel about 1.25" in diameter, an indicator showed a difference of 20 thousandths in each revolution. so i guess primary problem is either mis-alignment in the back plate or in the jaws. unless someone has a really simple fix for the chuck, i'll try living with it for a while. thanks for all the input. shel