View Full Version : Hopping turnings
05-05-2002, 01:59 PM
We have been trying to turn baseball bats on our craftsman lathe. Its an older lathe, with the tubular bed. We know that the lathe isnt a wonderful piece of machinery but it seems like we should at least be able to turn something round on it. The problem is that when we start getting the bat turned down a vibration starts so bad that you can see the blank moving 1/4" or more in the middle. Even the lightest of touches gives this same reaction. If someone with a leather glove on dampens the vibration things work very nicely, the wood flies off the blank in large chunks. Otherwise little divits come out and when you turn the lathe off the "round" looks like a golf ball with oval holes.
The lathe is bolted down to a very heavy table, even with someone standing on the table the vibration will move things off the table.
Am I wrong in thinking that you should be able to turn a 34" blank without something to dampen vibration? This same problem with both ash and maple bat blanks.
We think we have the tools sharp, when the wood first gets round large pieces fly off nicely.
05-05-2002, 02:53 PM
For what its worth, i have exactly the same problem with my jet 1236 lathe. it has a true cast bed and a good stand.
i have attributed it (rightly or wrongly) to dull tools. and since i am not good at sharpening my gouges, the problem gets a little better and then worse again very quickly.
but i think that the biggest problem is the overall length of the blank. when i turn other shorter things (like little minibats- souvenirs), it doesnt happen, or at least very minimally.
what i have tried, and it helps some, is to put the handle end of the bat at the drive spur and the barrel down on the tailstock. that keeps the lightest part of the bat near the headstock so that it doesnt have quite the chance for vibration.
and the dimples... i have just learned to deal as best i can and then clean them up with the 1" skew chisel.
also, i dont mean to insult your turning abilities, but make sure the bevel is always in contact, that was a problem when i started turning.
good luck with it, hope it helps.
05-05-2002, 05:32 PM
Leave the dimples and hit golf balls hahahahah....don't you just hate a smart ass??
Sounds like mapleman is on the right track to solving this situation but I can't for the life of me equate dull tools to hopping unless you are speaking of an equal and opposite force to the tool bouncing away because it is dull. Try holding it in position ,knowing full well that when it makes contact with the wood it is going to try to jump away.
05-05-2002, 06:11 PM
the reason i think it is partly due to dull tools, at least in my case, is because if the tools were sharp it would sheer a shaving right off, "without the piece knowing it" so to speak. but with dull tools, it is more of a nick or a chip, where the piece gives off the woodchip because it has to. i think this is really a problem when you have a long blank on the lathe.
i dont know if i made any sense with that, but i tried. :P
Dick, do you do much spindle turning? or do you focus on bowls, and short stuff? just curious about your observations. and, do you have a mini or a regular lathe? WAIT, dont take offense anyone :+
05-05-2002, 06:28 PM
I don't have a speciality ,I'm just getting started. I have a 39" capability and can swing 15"..The big craftsman,had to get Paul Bunyan to help me set it up..... LOL..... I am in the midst of gettig some tools,and accessories and have joined a turning club to get some first hand advice.
05-05-2002, 10:05 PM
now i am envious - ummmm, a turning club. ummmmmmm.
i wish i could find one in NY.
john the mapleman
05-06-2002, 07:00 AM
Not sure how close these are too you, but they seemed to be the closest, but I think it would be the first one.
Serving: Albany area; Western MA; Southern VT
Meeting Date: 1st Wednesday except Jan & July
Chapter Web Site: http://home.nycap.RR.com/awa2/
2062 New York Rt 67
Valley Falls, NY 12185
Central New York Woodturners
Serving: Central New York
Meeting Date: 2nd Tuesday
Chapter Web Site: http://www.home.twcny.rr.com/cnyturners/
11309 Calkins Rd
Cato, NY 13033
Finger Lakes Woodturners
Serving: Greater Rochester and Finger Lakes Area
Meeting Date: 3rd Thursday
19 Willowview Dr
Penfield, NY 14526
Hudson Valley Woodturners
Serving: Bergen, Passaic, Rockland & Orange Cty
Meeting Date: 2nd Thursday
8 Copeland Dr
Suffern, NY 10901
Hope one is close.
"If it is worth doing, it's worth overdoing"
05-06-2002, 02:32 PM
i think you have answered my prayers!!!!!!! :P
one is even the same area code as me! thanks again Bill, i have to give those people a call.
john the mapleman
05-06-2002, 11:11 PM
Getting back on the subject !!
Something else may be causing this phenomenon,
Grab hold of something with a large diameter attached to the Headstock ...like a face plate and try and rock it. Even if the movement is minimal it will indicate play in the headstock bearings.
I had a lathe very similar to this in the UK...with the single tubular bed and found that it vibrated and was difficult to get a good surface...as I was teaching myself at the time I thought this normal. Someone suggested I change the bearings...from memory I think there were three and it took all of twenty minutes to get them out.
They matched up in size to UK washing machine bearings so were easy to get hold of and I could get HD (heavy Duty) ...not Home Depot..
Bearings which made a big difference.
The other thing with longer spindles is that you might need to build a work steady. ....check out the woodturning links....as it maybe that you are getting natural whip as the spindle decreases in size...Not helped if the bearings are worn.
Last but not least the tail stock might be set tighter than it needs to be. If the work runs out of true through "whip" and sets up vibration, the tendency in homo sapiens generally is to tighten the tail stock up, this then distorts any thin spindle even more.
Dull tools alone will give you all the defects you describe but shouldn't cause the other symptoms.
Hope this helps,
05-07-2002, 01:23 AM
Thanks everyone, you have given me some good ideas to investigate. Hope I can figure this out, turning things will get pretty frustrating and not worth the effort otherwise.
05-07-2002, 06:34 AM
Let us know how it goes, if you get a chance to go.
"If it is worth doing, it's worth overdoing"