What did I bend? Not paying attention

rx2man

Active User
Registered
Joined
Jun 24, 2013
Messages
26
OK so I screwed something up. I had a block of briar in my HF 7x12, Apprentice 4 way chuck. What I forgot to do was tighten up the jaws. Wood goes flying out and hits me in the shoulder. Go to drill the air way and notice there is a lot of wobble and the 5/32 in bit is bending back and forth. OK so I know I screwed something up. So I get out my dial indicator. The chuck has a .005 wooble. But I cant tell if the wobble is in the chuck, the spindle or if I screwed up the bearings. It seemed like there was a slight wobble in the spindle chuck adaptor and I tried to shim the high spot with a piece of post it note but it did not help at all. I am not a machinist and I take back meds that make you stupid, not the best combination I know. I am not sure what to replace, and it does not seem like you could distort/bend a chuck but briar is really hard wood and it was probably at 800 rpms when the block flew out, I am guessing it whacked the bed way first. I have a pipe that I need to get finished in the next couple weeks and this does not help at all. Just not sure where to start replacing parts.

*edit* just double checked and dont think the block could have hit the bed way and and bent the chuck. Wondering if turning the blocks of wood without using the tailstock could have caused it to get out of alignment??
 
Last edited:
Went back and removed the chuck and spindle adaptor. Looks like its the bearings as the wobble is in the spindle.
 
Hey man.. Just saw your post, people must have missed it today.

I have bent a spindle before, in a small Atlas lathe. Sucks. But no biggy if you can get the parts.

Maybe you can take this opportunity to upgrade the bearings while you are in there? Hah hah, take advantage of an unfortunate situation and come out better at the other end?

It is very likely that the wood hit the bed ways, bending the spindle before hitting you. It is possibly the bearings themselves. It depends on what type of wobble. If you look down the spindle and it looks like a hula dancer, with the middle of the bore wobbling differently than the end, it's your spindle.

Bernie
 
I would be surprised if you bent your spindle, that takes a pretty good wack. When you are measuring the runout, what are you measuring against? The problem with measuring runout is that you have to pick the right surface. Getting things "just so" is expensive, so there are only a few surfaces on your machine that will be true (which is fine). These are going to be the spindle taper, the spindle flange (the part the chuck sits back against) and the the reference shoulder (not sure if that is the "official" name). Measuring against the body of the chuck is not going to give you an accurate reading. I recommend checking against the spindle taper (the MT3 taper inside the spindle nose).

Odds are you just pushed the chuck around a little on the flange. If it is a 4 jaw independent chuck, you should be able to adjust that 5 though out.
 
Thanks for the help. There is a Arbor, Sherline/Taig 3MT in the spindle. Got to think that there is too much metal there to distort. I measured against the spindle flange. When I tightened up the bearings it helped but did not eliminate the wobble. And as was suggested time to upgrade to the tapered bearings. Its been a great lathe up til this point and especilly for the money. Without it I would not have been able to make the pipe below.

Custom Bamboo #1.jpg

Custom Bamboo #1.jpg
 
Hey man.. Just saw your post, people must have missed it today.

I have bent a spindle before, in a small Atlas lathe. Sucks. But no biggy if you can get the parts.

Maybe you can take this opportunity to upgrade the bearings while you are in there? Hah hah, take advantage of an unfortunate situation and come out better at the other end?

It is very likely that the wood hit the bed ways, bending the spindle before hitting you. It is possibly the bearings themselves. It depends on what type of wobble. If you look down the spindle and it looks like a hula dancer, with the middle of the bore wobbling differently than the end, it's your spindle.

Bernie


So I get me new tapered bearings, I install them. YAY....NOT, its still wobbly. .005. REALLY PISSES ME OFF. So now I need to order the spindle and another set of bearings. No way I am getting them off without screwing them up. OR maybe I can but dont want to put it all together and find out the bearings got hammered removing them. Its a PIA to pull it all apart although it should not take as long next time since I now know what I am doing.
 
Did you put the dial indicator on the inside of the spindle taper? Is that where you are seeing runout?

Maybe time to upgrade to a little larger lathe.
 
OK, more importantly - how is the shoulder? To hades with the spindle and bearings. (but I hope you didn't dent the briar wood...)

And --- that is one beautifully crafted piece BTW.

_Dan
 
Back
Top