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| Mini Lathe Speed Reduction....... |
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| andyf:
That's the one, David. Andy |
| Lew_Merrick_PE:
This pending project is relatively far down the priorities list, but I will be moving the motor on my MiniLathe out from under the base casting so it can have multiple pulley ratios going into a (to be added) jackshaft that will sit in the (to be vacated) volume. The advantage of this (from my knothole) is that I can get better torque at lower speed ratios and free up the area occluded by the motor cover today (which I will need for my taper turning attachment). My plan at this point (and subject to change without notice) is to mount the motor on a 2- or 3-position lateral slide that mounts to a (belt-tension-wise) second slide that will use a cam to maintain belt tension. That way I can loosen the cam, move the motor to the proper belt alignment position, and re-tighten the belt (fairly) quickly. There will need to be some tin-bashing to make a cover that keeps the swarf out of the drive, but a pivot/hinge and pivot-hook snap latch should take care of that... |
| loply:
--- Quote from: Lew_Merrick_PE on January 11, 2012, 12:08:24 PM ---This pending project is relatively far down the priorities list, but I will be moving the motor on my MiniLathe out from under the base casting so it can have multiple pulley ratios going into a (to be added) jackshaft that will sit in the (to be vacated) volume. The advantage of this (from my knothole) is that I can get better torque at lower speed ratios and free up the area occluded by the motor cover today (which I will need for my taper turning attachment). My plan at this point (and subject to change without notice) is to mount the motor on a 2- or 3-position lateral slide that mounts to a (belt-tension-wise) second slide that will use a cam to maintain belt tension. That way I can loosen the cam, move the motor to the proper belt alignment position, and re-tighten the belt (fairly) quickly. There will need to be some tin-bashing to make a cover that keeps the swarf out of the drive, but a pivot/hinge and pivot-hook snap latch should take care of that... --- End quote --- Lew, not only can moving the motor accomplish this, but here's an experiment for you to try. Take off the head of the lathe and remove the motor. Observe that the head is bolted to a piece of the lathe bed which is supported at the front of the lathe, but that the corner of the bed furthest from the operator at the left end of the lathe is just floating with nothing supporting it. Pop a dial indicator stand on the bed and put the needle in this corner and push down with your thumb. It will deflect by a very surprising amount. 10/15mm thick floating cast iron sheet is not very rigid when it's not supported at all. Moving the motor will allow you to put a "support" in there and will stop the entire flippin' head from rocking and rolling when under pressure. |
| Stilldrillin:
I had a gentle tweak at the control board, the other day. A very small movement on MAX, reduced the revs to "correct". But, this then caused very slight creep when control pot was turned to zero. A slight movement on MIN solved the creep, but the top revs increased slightly. As I often use a 5" chuck, I turned the ACCEL to give 3secs acceleration time. This then disturbed the other two settings..... Again! Finally, (after 5 mins), all was balanced satisfactorily. Today, I made the two motor mounting washers, to work with the cradle. Hopefully this will give a more rigid motor location. Also, I started on turning the pulleys to fit....... After the speed/ acceleration alterations, the lathe performed perfectly. :thumbup: David D |
| andyf:
Hi David, Glad the tweaks to the pots have got the speed to behave properly. There's a plan of a jackshaft speed reducer here, though it is single speed: http://www.toolsandmods.com/library/ralph_patterson_speed_reducer_2.pdf I think you are in the Yahoo 7x12 minilathe group; at least, a couple of messages from a Stilldrillin (but with a surname which doesn't begin with D) recently popped up for moderation, because you/he's a new member. In the Photos section, there's an album called "Belt Drive" showing a multi-speed reducer, though it seems to involve two jackshafts. Andy |
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