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WoW!

As i stated a while back I've picked up a new 36'' jet lathe a few weeks ago. It was covered with some kind of rust inhibitor and i washed the bed down with varasol and fine steel wool. The speed control was a bit strange but none the less it was pretty quick. This morning I decided to make SWMBO a vase,chucked up a piece of wood and turned it on. The speed was rather slow so I proceeded to turn it up,then it just stopped all together.I then took out the four screws that held the cover plate on,everything looked fine but the clutch wheel on the motor was sticky(more rust inhibitor). I cleaned off the shaft,re-installed the belt added a lttle grease,then it happened . I reached down and turned on the lathe it started up and scared the shit out of me. It had a mind of it's own and danced across the basement floor,I took cover under the bench as a piece of oak came flying out of the bed doing 5oo miles an hour and struck everything in the basement twice and coming to rest only after it took out several cans of wood stain on a shelf. Holy Jeezes! I have a new found respect for the lathe. I've decided that i'm going to get some good advice before attempting to turn another piece. Since the machine doesn't have a speedometer and I haven't a clue about lathes,how do I determine how fast I want the lathe to spin ? What is the rule of thumb (speed) for starting off with a square chunk of wood ? The third nipple on my chest is starting to disappear from last weeks adventure.I need help before everything in the house is dented tks Dan

Reply to
Dan Parrell
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Rules of thumb include:

1) Start (and restart) at the slowest possible speed keeping your hand on the switch in case that is too fast. (Solution is to balance better with bandsaw, chain saw, Boy Scout knife, whatever...) 2) Increase the speed until it just begins to vibrate and then back off one notch. (You will have to identify your own 'pucker factor' for incipient vibration on your own.) 3) Max speed is determined by multiplying the diameter in inches by the RPM and never exceeding 9000 (or is it 9600?). Example, 6" dia maxes at 1500 RPM. Now this doesn't mean you should go that fast, just that you should not exceed that RPM with good quality wood. Crappy checked wood will have a lower maximum speed.

Almost all of us have a similar story. Learn from it well; you may not be so lucky next time. Someone said that most woodworking tools can maim you but a lathe can kill you if you are not careful.

Best of luck, David

Reply to
David Wade

Dan Parrell wrote: (clip) What is the rule of thumb (speed) for starting off with a square chunk of wood ? (clip) ^^^^^^^^^^^^^ The rule is, when you don't know what is going on, start at the lowest speed. The excitement you had must have been due to a couple of possible causes: 1.) The piece of oak could have been way out of balance. 2. The piece of oak may not have been firmly held on center in the lathe. How did you have it mounted? If it was on a faceplate, it might have not have been tightly screwed down. If it was between centers, you may not have had firm pressure from the tailstock. Maybe the tailstock wasn't locked down.

Go back and set the lathe for its lowest speed. Do not mount any wood. Turn it on, and see how it behaves. Then advance the speed a step at a time to the maximum, and then down again. Maybe do it a couple of times. Turn it off at the lowest speed. Always bring the speed down when you are turning the lathe off for the day. It's so easy to forget to check when you come back a few days later to turn it on again.

After you are sure that everything is working right, it is time to mount a piece of wood. After what you have been through, I would start out with a piece that is balanced and centered. Turn the lathe by hand to make sure everything clears. Make sure the toolrest and tailstock are tight. Then, stand aside (out of the "line of fire,") and turn it on. If the piece does not come off the lathe and chase you under the bench again, you can turn up the speed to a reasonable value, and start turning something for SWMBO.

Good luck.

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Leo Lichtman

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Grandpa

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