Replies

1. 
   saschafer | Jun 14, 2008 03:44am | #1

   Something is not right. Even with a bent shaft or lots of misalignment, you can still turn a piece so that it's round. The only way to get out-of-roundness is if the alignment changes during the turning process. So, I would have to think that not only is something out of alignment, but it's loose, too. (And it could be that the looseness is what's causing the misalignment.)

   -Steve

    

1. 
   fishwood | Jun 14, 2008 08:52am | #2

   So Steve, you think perhaps it is I that could be out of alignment. HA Ha. So what else could be the problem? I am racking the brain, the only thing I come up with is bearings or bent shaft. Any body Help.

2. 
   fishwood | Jun 14, 2008 09:12am | #3

   Steve, I have tightened every nut & bolt so to speak. I've been working with the Jet people, there just doesn't seem to be a logical answer. I just can't except that I have used a lathe for the last 2 years and now I don't know how to make this one work.(It's been a week now). It catches at slow speed after I turn my wood to what should be round and it still will thump, thump and at higher speed it gets violant. I am hoping it's not a shaft or bearings. It is what it is. What is the best why to find out what is what?

1. 
   saschafer | Jun 16, 2008 06:18pm | #11

   "It catches at slow speed after I turn my wood to what should be round..."

   What does that mean? Is it round or not? (It should be easy to measure.) If it really is round, but now it's only catching at one point (easy enough to verify when turning the lathe by hand), the only possibility is that the wood has shifted since being turned round. A bent or misaligned shaft, or any sort of problem with the pulleys, cannot explain this. For the wood to have shifted, there has to be looseness somewhere in either the headstock or the tailstock.

   -Steve

    

   Edited 6/16/2008 12:34 pm ET by saschafer

1. 
   oldusty | Jun 16, 2008 07:23pm | #12

     Good point Steve ,      maybe the centers when spread out are not the same anymore , but did he say even with face plate he gets the same ?

                  dusty

1. 
   fishwood | Jun 16, 2008 08:33pm | #13

   Yes, I,v been around lathes enough to know to check all the obvious. The same thong happens with face plates, spur centers & chucks. I wanted to blame a small blemish scared out on the inside of the forward shaft, but that wouldn't explain the chuck & plate.

2. 
   philip | Jun 14, 2008 09:17am | #4

   If I read you correctly it seems that the lathe is vibrating, rather than having a bent shaft/spindle.
   It is easy to check for spindle run out but this is rare.
   So I suspect that something is out of balance-the usual culprit is a pulley, which could be bent, loose on the shaft, not true on the shaft or especially in the case of heavy cast iron pulleys it is not balanced due to internal casting voids.
   Another cause of vibration is the state of the drive belt and or the tension of this thing. If the belt is tatty fit a new one and try different tensions.
   Then there is the motor and motor mountings. Check the motor when it runs-is it stable and smooth running?
   Then there is the stand on which the lathe is mounted - are the feet evenly on the floor? It may be useful to fit rubber foot pads to absorb vibration, and even add weights to increase the overall weight.
   The "tech guys" at Jet don't sound much use if that is all they can say.

   Philip Marcou
1. 
   fishwood | Jun 14, 2008 09:34am | #5

   You sound like you have some knowledge in this field. I have tried adjusting the belt tension as well as putting extra weight on , that didn't work. It doesn't make sense why it would shake out of line at most any speed. Should I take it to a Jet pro or any other suggestion? Thanks, Bill

1. 
   jako17 | Jun 14, 2008 10:37am | #6

   It may sound obvious but have you looked at the back register on the shaft.Is it clean no burrs etc 

1. 
   CarvinChris | Jun 14, 2008 05:42pm | #7

   I suggest running the thing without any attachments on, all the little access doors open and take the machine through it's operating ranges.  While doing this you may be able to observe and find the trouble through process of elimination.  Please be careful though.

   You may have done this already, but I didn't see it wrote in the posts.

   Good luck,

   Chris.

3. 
   SawdustSteve | Jun 15, 2008 06:19am | #8

   Make sure the tail stock is firmly locked in place. It is the only part that can move and make things go thump.....

   While you're at it, CAREFULLY check the internal Morse tapers in both the headstock and tailstock for a ding, burr or even some paint. If the centers are not seated properly, they too will give you the 'out-of-round' feeling
   SawdustSteve

1. 
   fishwood | Jun 15, 2008 08:10pm | #9

   Thanks, I did find a bit of tare out inside the headstock right at the leading edge and I put emery cloth to it. I hope the isn't the problem as I sure the is an expensive fix. The tail stock would not effect the trueness of the headstock because I'm not using it when turning lids or the like for small boxes. I thought I would give it one more shot at adjusting the feet on the stand before I strangle an old man. Poetic don't you think? Hardy har har. fThanks For your input, Fishwood.

1. 
   oldusty | Jun 16, 2008 05:41pm | #10

      fish,

                  If all the tapers are clean , is it possible your step pulley if yours has them , could be bent or have a chip or piece missing or an Allen nut / set screw  part way out that holds the pulley to the shaft ?

        are any and all pulleys lined up correctly ?

                 dusty

                

1. 
   fishwood | Jun 16, 2008 08:44pm | #14

   I think all the pulleys are lined up from looking at them, but I'm not really sure how you tell other than watching them. I have put a run out gauge on the shaft and I get .005 witch seems tolerable. This is got me going. I may have to take it to somebody who is in the know and spend bucks I shouldn't have to. Thanks, Fishwood

4. 
   Vwright | Nov 11, 2008 09:30am | #15

   My first lathe had the same problem from the sound of it. Mine started off barely noticeable and soon became unbearable. On my setup it was bearings. If I put a large piece on a face plate and tugged around at it, I couldn't feel anything. Get it spinning and it was a whole different story. If it is your bearings, they should be relatively easy to replace. Good luck.