Thread: Riding The Wobbling Ghost

88 Have you cleaned the MT2 on the headstock. Could be some buildup in there. I'd have to go look but I think the headstock is bolted onto the ways with 4 bolts. Loosen them off & align it perfectly with the tailstock. Also clean out the MT2 hole on tailstock. Check & see if the centering pin on the live center will go down inside the mandrel. The pin is small & the hole in the mandrel may not be deep enough for it to center. I've drilled my mandrels out 1/8" deeper than they were & got rid of any wobble.

Originally Posted by Mobil Man

88 Have you cleaned the MT2 on the headstock. Could be some buildup in there. I'd have to go look but I think the headstock is bolted onto the ways with 4 bolts. Loosen them off & align it perfectly with the tailstock. Also clean out the MT2 hole on tailstock. Check & see if the centering pin on the live center will go down inside the mandrel. The pin is small & the hole in the mandrel may not be deep enough for it to center. I've drilled my mandrels out 1/8" deeper than they were & got rid of any wobble.

Thanks for the response.
I did clean out the MT2 hole with a fine file and sandpaper. There were some gouge marks I can only assume came from that handle you use to push out the mandrel or spur gear. I didn't take off much, just enough to clean it up a little. I removed the 4 bolts, but don't see any way to re-align it without putting stress on the bearings on the other side of the headstock. Seems like they either line up or they don't. FWIW, the tailstock doesn't SEEM to be the problem, the mandrel will wobble without the tailstock being engaged (gravity could do that) I replaced the live center with a 60 degree center and it made no difference in the wobble. (chewed up the new center a little..) I think the 60 degree center accomplishes the same thing as drilling out the mandrel .. the pin angle on the live center that comes with the lathe is too sharp for the inside of the mandrel.
But even without engaging the tailstock or live center, there seems to be a high spot to the revolution of the headstock.. only noticeable when I put a mandrel in it. The wobble gets more noticeable with length, and when snugged up to the tailstock, the wobble is most noticeable in the middle, since the tailstock holds the other end of the mandrel in place.

Frustrating...

88 Like you said "the pin angle is too sharp for the inside of the mandrel." Go ahead--Find a drill bit the same size as the hole & drill it 1/8 inch deep. I don't know MM [metric] but 1/8 is as deep as this "1". Reminds me about the blond. She was watching these 2 rednecks looking up at this long pole. She asked them what they were doing. "Aw we're just figgerin how to measure the height of that thar pole." So she goes over & gets a wrench. unbolts it & knocks it over on the ground. Measures it & says " it's 21 feet long." One redneck says to the other" just like a blond--try ta figger the heigth & she gives ya the lenght." My daughters like this one---they are both blond.

New London 88 you said the wobble is in the middle of your mandrel when the tail stock is brought up. It sounds like the mandrel itself is bent. If it can unscrew from the morse taper, just roll it across a flat surface. If it runs flat and true the only other causes could be, over tightening of the brass thumb nut or over tightening of the tail stock itself.

One way to over come this problem is use an adjustable mandrel or the method I have used for a while is the no mandrel method. You cant do slim lines or European style pen but all pens that the bushing slide into the tube can be done this way .

https://www.woodworkforums.com/f69/mandrel-set-53900

Hope this will help

Darren

Originally Posted by bdar

New London 88 you said the wobble is in the middle of your mandrel when the tail stock is brought up. It sounds like the mandrel itself is bent. If it can unscrew from the morse taper, just roll it across a flat surface. If it runs flat and true the only other causes could be, over tightening of the brass thumb nut or over tightening of the tail stock itself.

checked the mandrels and they seem ok.. at least the ones with the removeable shaft. But the wobble happens without the tailstock being used, too. The wobble moves to the middle when the tailstock is brought up. I can only assume that the tailstock is stopping the wobble from being twice as bad. ?? If I back the mandrel out of the headstock, the wobble goes away.

Originally Posted by bdar

One way to over come this problem is use an adjustable mandrel or the method I have used for a while is the no mandrel method. You cant do slim lines or European style pen but all pens that the bushing slide into the tube can be done this way .
https://www.woodworkforums.com/f69/mandrel-set-53900
Hope this will help
Darren

I have an adjustable mandrel, too.. it happens on all of them, including a new one that doesn't have a removeable shaft. But I do think that one is warped anyway. I can put it in the tailstock and rotate is slowly by hand and that wobbles. The others don't.
And I like the no mandrel method, I've used it. I just need to be careful not to flare the tubes with too much pressure.

Thanks for the ideas .. I'll still investigate more.

Sounds to me that the spindle on the lathe is the culprit, what lathe have you got? My Jet Mini had this problem and I had my spindle re-machined and sleeved as it was out. The thread on mine is now spot on but the MT is out. Point I am making here is that the MT and the thread were not concentric to each other or to the bearings.

When I had mine machined, they used my collet chuck to mount in in a metal lathe to machine the spindle where the bearing seats and sleeved it, so that means I can only use it to mount my Collet chuck or Scroll chuck.

I also know that my lathe is not the only one to have this problem too.

Originally Posted by DJ's Timber

Sounds to me that the spindle on the lathe is the culprit, what lathe have you got? My Jet Mini had this problem and I had my spindle re-machined and sleeved as it was out. The thread on mine is now spot on but the MT is out. Point I am making here is that the MT and the thread were not concentric to each other or to the bearings.

When I had mine machined, they used my collet chuck to mount in in a metal lathe to machine the spindle where the bearing seats and sleeved it, so that means I can only use it to mount my Collet chuck or Scroll chuck.

I also know that my lathe is not the only one to have this problem too.

Mine is a Jet Mini, too. I wonder if I should start looking for another rig..

This has to be the forth thread involving a dodgy Jet lathe

The "filing the MT" part sounds suspicious to me..

And what does "the live center and the spur gear pins sorta line up" mean? Anything less than perfectly aligned centres result in badness...

Shoulda bought the Leda instead...

I think that this problem is caused due to cheap production, it seems that a lot of the cheaper machines suffer from it regardless of the brand, I bought a new Carbatec Mini lathe which is pretty much identical to the Leda, once it was set up it has this wobble problem, initially thought it was a dodgy madrel, replaced this, same problem. I'm going to return my lathe and get a VL100, I've never seen one of these with any problems. There is some truth in the old saying "You get what you pay for".



Slyffer

Originally Posted by funkychicken

This has to be the forth thread involving a dodgy Jet lathe

The "filing the MT" part sounds suspicious to me..

And what does "the live center and the spur gear pins sorta line up" mean? Anything less than perfectly aligned centres result in badness...

I filed out the inside of the insert? where the MT slides in. It was a little chewed up, not smooth. I just cleaned it up a bit. I assume it is from that handle that pokes out the mandrel.. that's all I can think of.

and "sorta" lines up .. well, the pins touch, just not at the points. My eyes are bad, so I need a magnifier to see it, but looks like it's off by .5mm or so.
And yeah.. it's badness..

Originally Posted by Slyffer

I think that this problem is caused due to cheap production, it seems that a lot of the cheaper machines suffer from it regardless of the brand, I bought a new Carbatec Mini lathe which is pretty much identical to the Leda, once it was set up it has this wobble problem, initially thought it was a dodgy madrel, replaced this, same problem. I'm going to return my lathe and get a VL100, I've never seen one of these with any problems. There is some truth in the old saying "You get what you pay for".
Slyffer

Cheap production could be the culprit, but the machine wasn't cheap. (inexpensive) It was about $300US. To my mind, that's still a hefty chunk of change and I think it should at least do what it is designed to do..