G4003G Headstock Alignment

Check it again with another indicator. Yours may need servicing.
 
Disappointing as it is a brand new Teclock.
 
You can get some movement in the indicator reading by just turning the chuck by hand, I use my VFD jog which is 6Hz, this is slow enough and I run the indicator along the bar while turning. Also try to put the gearbox in neutral as opposed to in gear if turning by hand. The dial indicator head I use has a flat convex head, so more contact area, if your dial indicator is off from vertical then you can easily see a variance of 0.001". At 10-12" on a test bar I will usually see a swing of under +/-0.001", you are getting quite a bit more. The problem with most 4J independent chucks are the jaws have very course serrations so it may not clamp evenly, my 4J jaws are 0.200" at the tips with no serrations. You might try to repeat the test with a 3J, you are not concerned about the TIR, just the swing around "0" remains the same magnitude in either direction. This tells you if the head is aligned relative to the carriage position. Beyond that the two ring test can be used to further fine tune/check the alignment while cutting, this is also true of the tailstock once the head is aligned. Many of the newer dial indicator use the name of some well known prior manufacturer, but the internals are often lacking. My go to dial indicators are the Starrett 25-511 or 25-611, they will read 0.0001" and have a range of 0.200". NOS are lightly used ones come up at auction in the $60-100 range, super nice to work with and very accurate.
 
I used my Teclock, an old Starret, a cheap Shars DTI and my Compac DTI. Every rotation on every one was different. I ran it in back gear also. I could really tell at that point because the dial was vibrating so badly. That turned me on to the fact of vibration. Is it normal to have a lot of vibration in a work piece?
Then I tried the 3J. It seemed more accurate as far as holding the same readings per rev, still was a little different though.
FYI my 3J showed +.025" & -.025" @ 10" length.
 
OK. We got a little more done...kinda. We checked his 3-jaw and it looked clean. We didn't clock it...should have. My buddy slightly tightened up (3/16-1/4 turn) the back mounting bolt at the tailstock (TS) end of the ways in thinking this would bring the cutting tool closer to the work at the TS end. He did the test and no change in collar diameters. Still a 0.002" difference over 10". I'm thinking he should shorten the 2" diameter 6061 rod he's using to about 8"...giving him roughly 6" stickout and switch to the 4-jaw. If not that, then add a 0.001" shim under the operator side TS-end mounting bolt. The problem is he put silicon under the lathe where it meets the chip pan. :rolleyes: I'm glad it ain't my lathe but I feel for the guy. I still remember how it was being a lathe newbie! :confused 2:
 
Finally had time to help my buddy out some more. We put 0.002" shim under the tail stock on the operator side. Tightened up all the bolts again and let it sit for couple of days for the helluvit. Did another 2-collars test cut. For the record, the stock was 6061 2" diameter with 10.375" stick out from the chuck jaws. I measured the collars using my new Mitutoyo 101-118 0.0001" micrometer. Figured it was a good reason to get a ten-thou mic now. :grin big: We got 0.0003" difference between collars roughly 9.75" apart, the larger diameter at the TS end. Ya think more tweaking or leave it? I'm for leaving it. IMO that's pretty darn good for 2" stock with that much stickout.
 
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Did you stop the lathe, return to the TS end and make a spring pass? Bet that would have taken out the three tenths.
 
Yep. Spring passes done until no marks are made on the collars when running the tool back to the TS end.
 
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