I have a Jet lathe (model JWL-1236; floor stand model) that I would like to use to turn a 30″ diameter table top. For those who know this lathe (or equivalent models), can you recommend a method of supporting the tool rest that would allow me reach in 15″ (to the center) around the outside of the plate? The extension arm that comes with this product appears to reach far less than 10″.
Please assume that I would rotate the head 90 degrees (the only way to mount the plate), that the slowest speed (500 rpm) is not too fast for this size plate, and that I would make an appropriate cross support that I would mount on the face plate that comes with the product. (Some will probably warn me about the high rotational speed for this size of plate.)
I do appreciate all of your recommendations. (If this subject was thoroughly covered in the forum, I apologize for not finding it and ask for the reference.)
Bert
Replies
about the speed. the outside rim of that table top will be taveling at about 4000 feet per minute which is extremely fast. if that tabletop is off balance which it will most likely be, your asking for a lot of trouble. these are more like the speeds you would expect a high production CNC lathe to run at, where the operator is at a safe distance away from the machine should something go wrong.
the first thing i would look into is slowing the speed down, then you can make a tool rest by welding a peice of angle iron on to a steel rod of the appropriate diameter. if you insist on trying to turn a piece this large on your lathe, mount it, wear the proper protective gear and fire up your lathe. now approach the peice as if you were going to work on it. if this doesn't get rid of the "balls of steel" syndrome then you are either extremely brave or extremely dumb.
Thanks, Andrew. Between your advice and one other, I'm convinced. I'll find another way to shape the top.
Bert,
The Jet catalog I have (a new one) does not list a JWL-1236 model, only a 708352 and a much smaller 708351. Thus I am not sure if the lathe pictured in my catalog is the same as yours. If your Jet lathe is similar my advice would be: DON"T TRY IT!! The catalog picture I see reveals a lathe that is woefully inadequate for spinning such a large diameter piece with or without an outboard tool rest.
Let me explain lest I come across as too pendantic. Large diameter lathe work is my specialty. I have a 1930's vintage lathe about nine feet long weighing in at about 1500 lbs with a shaft diameter of 1 3/4 inches. The lathe is built out of 4 x 12 doug fir beams with beds of 3/4 laminated steel. I used to bolt the lathe to the floor but now use a couple 100 pound bags of sand to dampen vibration. The head and tailstocks are solid cast iron and shaft speeds are variable from about 50 to 3000 rpm. This is my dream tool of course and I am lucky to have it. Between centers I can spin 8 foot columns 26 inches in diameter and outboard I can spin 7 foot tops. I have turned such large pieces on many occasions but even with this massive tool I often breeak out in a cold sweat of fear when all that wood starts spinning around. My warning advice to you is: Don't underestimate the amazing amount of kinetic force of revolving material. The kind of personal and property damge possible if the piece comes off the lathe is profound. One time I was spinning a large table top and three of ten thick faceplate screws broke and the top went right through a metal industrial type garage door. And this occurred with the lathe at slowest speed. It seems possible that your Jet lathe may not be sufficient to spin this 30 inch table top. A high degree of probability exists that your shaft may bend and/or bearings get damaged not to mention your motor burning out from the load. Consider maybe cutting the top circular on a bandsaw and sanding, routing, or shaping the edge for the profile desired. Even if you have to get a shaper cutter specially made that would be cheaper than a new lathe or a trip to the emergency room.
Just my two cents, take it or leave it.
sawick
Thanks for the very good advice. I'm convinced!
I helped a neighbor turn 2 20" maximum diameter columns (in three pieces each) on a really cheap craftsman lathe. We put two rails with the right taper above the column and ran a plunger router up and down the rails while we hand rotated the column. It worked well. We took turns spinning the routed column to sand it (whew!!)
I haven't given up finding a solution to turning the table top. If I understand your suggestion, I could try turing it by hand (simply use the lathe to support the work piece. Another way might be to set up another spindle for the table top that I drive with the lathe. Of course, I would have to reduce the rotational speed significantly, perhaps by using different pulley sizes. A 30" diameter plate spinning at 167 RPM would be the same centrifugal speed as a 10" diameter bowl at 500 RPM. If I can reduce the speed to less than 100 RPM while holding the plate securely, it should be safe (at least much safer!). The motor might not take this load, however.
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