Replies

1. 
   saschafer | Jun 10, 2009 04:44pm | #1

   If the mating surfaces on the taper are clean and rust-free, then it's probably a defect in the drive center itself, and the only remedy is a replacement. Do you have another center (a dead center, for example) that you can install in place of the live center, just for testing? If you install the other center, and it checks out okay, you've pretty much eliminated the female taper in the headstock as a problem.

   -Steve

    

2. 
   jako17 | Jun 10, 2009 04:44pm | #2

      Have a good look at the MT on the drive centre and see there are no burrs ,smutz etc. Then test with another centre like the one from the tailstock.you say that you have already cleaned the mandrel taper.These may only be general suggestions as none of my lathes are Jet

1. 
   dustymctevish | Jun 10, 2009 05:56pm | #3

   Sure enough, found a big ol bur on the drive center shaft, filed it down a little and got less wobble but will replace it anyway.   Just to make sure I put the live center in the head spindle and took some measurements, .0015 wobble.

   <!----><!----> <!---->

   Thanks, any suggestion on drive centers. 

1. 
   mike4244 | Jun 13, 2009 02:56am | #14

   I use just a simple 2 blade drive center. I have 4 blade drive center that so far had never been used. It is still wrapped in the oil paper it came in 10 yeras ago.

   mike

3. 
   MikeHennessy | Jun 10, 2009 06:33pm | #4

   Don't do much turning (and never did all that much), but is .007" really a problem from a practical standpoint? Just wonderin' is all.

   Mike Hennessy
   Pittsburgh, PA
   Everything fits, until you put glue on it.

1. 
   dustymctevish | Jun 10, 2009 06:45pm | #5

   I really don’t know but as bad a turner as I am every little bit helps.<!----><!----><!----> 

2. 
   Napie | Jun 11, 2009 08:01pm | #6

   Not really, take a look at a spring pole lathe...

1. 
   MikeHennessy | Jun 11, 2009 09:25pm | #7

   "Not really, take a look at a spring pole lathe..."

   Well, the reason I asked was, the first lathe I ever used was a beast of a thing made in the 1800's, wooden bed, hand-forged centers and crank, foot treadle, . . . . Slow, but it did the job and I made some pretty nice table columns on it. I'd be surprised if the thing was within 1/8" of true. LOL! But with the higher speeds on a modern lathe, . . . dunno. Maybe it makes a difference? (Since then, my turning experience probably totals less than 10 hours in 35 years, so I truly have no clue in this regard.)

   It seems to me that sometimes us WWers get our shorts in a bunch 'cause our tools aren't meeting the tolerances expected by a machinist. Aren't such tolerances for wood useless goals, tho'? What with significant digits, and all that.

   So, turners of the world -- does the OP need to worry that his center is off by about the thickness of two sheets of paper? Will that make a difference if, say, he is turning a spindle over about 1/8" in diameter? So the spindle will be a bit out of round -- it's wood. It'll be that much out of round anyway after about 10 minutes exposure to the air, no? Will it cause vibration problems? Something else? Am I missing something?

   Here's my dirty little secret -- I don't even own a dial guage. There! I said it! Is all that stuff I've made so far without one worthless? Have I been forever crippled by my hand tool background where a wooden folding ruler was the only measuring device I could resort to? (Still my favorite rule, BTW.)

   Only half kidding, but still, I wonder what's a reasonable range of tolerance for power woodworking tools. Are all those measurements posted in tool tests really meaningful? I understand that .007" might be an issue in a router bit spinning at 20K rpm, but that's a tad faster than a lathe would be expected to run, no? Do I really need to worry that I've never even measured the runout on my Cheapo TS, or checked blade parallelism with anything but a steel straightedge held against my miter guage?

   I used to attend a lot of guitar workshops where beginners in my age bracket (greying) would show up with $2K+ Martin guitars they couldn't play ('cause they never practiced). I'd show up with my $300 POS beater (backed up by 5 years of hard practice), and the newbies would be all amazed at how wonderful the *guitar* sounded. Is the lust for the last .001" the Martin guitar of woodworking -- something that WWers attempt to substitute magically for skill and experience? ("If only my TS was more accurate, I could make that Goddard breakfront.") I must admit that I often find myself lusting after some new miracle tool, gimick, or adjustment that'll make me into the next Tage Frid. As if! LOL!

   Not trying to dump on OP, or anyone else for that matter, I'm just curious if maybe we don't tend to overemphasize things that really don't matter all that much (tho' we'd like to pretend they do), just because we can. Kind of an excuse to avoid the dreaded need to put in the time and practice to develop the skills.Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.

1. 
   Napie | Jun 11, 2009 09:48pm | #8

   I have often had the same thoughts.  We are talking about a material that will move a lot more than those tolerances just based on the weather clouding up.  Most of what we call classics in the furniture world was built without such precision instruments.  Turning may be the least precise for of woodworking (ornamental work excepted but that is far more machinist like) and that is an attraction to me, the spontaneity of it.       <!----><!----><!---->

2. 
   dustymctevish | Jun 11, 2009 09:50pm | #9

   We do…I mean I do, based on the cost of the machine, the more it cost the higher the tolerance I expect.  But if you were to see some of the stuff that comers off my lathe you’d wonder why. 

1. 
   MikeHennessy | Jun 11, 2009 09:55pm | #10

   I hear that -- I just wonder if maybe the machine could be the best in the world based on other factors, like constant speed, weight, versitility, I dunno . . . and the runout don't mean bupkus.

   I'm not saying the runout isn't a practical problem - I just don't know.Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.

2. 
   Jimma | Jun 11, 2009 10:52pm | #11

   Nothing wrong with sloppy stuff that works, I guess, but there are some turning projects that require precision, like delicate ornaments and things that have to fit together. Even a pepper mill has a certain tolerance needed for the mechanism to work right. A table leg, on the other hand . . . well, who's going to check it?

3. 
   saschafer | Jun 12, 2009 02:45am | #12

   Any lateral offset in a drive center will not cause the piece to be out of round. All it will do is cause the little hole created by the point of the center to be offset from the true center of the turned piece.

   -Steve

    

4. 
   trackersoft | Jun 12, 2009 06:22pm | #13

   These are cheap and well made:

   http://www.pennstateind.com/store/headstock-drive-centers.html

   I have never had a drive center shipped with a lathe that was any good. Even my powermatic!

   Scott