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| mini-lathe leadscrew clutch? |
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| MetalMuncher:
--- Quote from: Brass_Machine on April 27, 2014, 08:49:05 AM ---I can't find the link I was looking for... I hope I didn't imagine it. :Doh: --- End quote --- No problem. We've got some good ideas flying here. :) |
| MetalMuncher:
--- Quote from: drmico60 on April 27, 2014, 05:49:20 AM --- --- Quote from: MetalMuncher on April 26, 2014, 06:52:58 PM --- --- Quote from: drmico60 on April 26, 2014, 10:39:34 AM ---.weebly.com/new-threading-banjo.html --- End quote --- Very nice! Now I understand the "banjo" nickname for this device. Your autostop mod looks interesting too. But why do you have it made so you have to choose between auto stop and using the DRO? Is there no way to use them concurrently? A later post by Tomrux poses a valid concern about things moving out of mesh at the least desirable moment. But I am thinking there must be a way to fit a control lever to the banjo which would have some sort of positive detent arrangement, like the reverse lever on the back of a mini-lathe, so the banjo position would be safely constrained. Maybe even similar to some of the pro lathe controls which protrude from a curved surface, and have a spring loaded knob that is more flat than the shaft used for reversal on thep lathe. --- End quote --- I cannot see how you can effectively use the dro whilst using the autostop. You use the DRO to set the autostop but once the cut is being made the dro serves no purpose. With my banjo it is clamped very securely to the lefthand pillow block extension and I have had no problems with the gears disengaging during use. Mike --- End quote --- I think the concern with your setup, at least for me anyway, is that if it is easy to swing the banjo to adjust it when you want to, could it possibly move on its own when you don't want it to? What holds it in the position you set? If it is the clamping action on the pillow block that holds it from moving, well, that seems just as much work to adjust as manually removing a gear from the stock setup. And still requires removing the gear cover. I had thought the clamp was a means of mounting it to something that is allowed to turn, so it could be effortlessly engaged/disengaged. That's why I envisioned a means of moving a control lever/knob attached to it, with a detent system. What I am after is something that can be adjusted as easily as moving a knob or lever, with no tools required. |
| MetalMuncher:
My current thinking is to cut the leadscrew shaft (this would reside behind the lower portion of the control box) and bore a 1/4" hole in the cut end of each segment. Ream the holes to end up with a nice slip fit for a piece of 1/4" drill rod. In the short piece of leadscrew shaft, toward the gears, hold the rod in place with a roll pin, extending out from the surface on each side of the leadscrew shaft enough to provide a dog for engagement. On the longer section of leadscrew, toward the carriage, another roll pin through it, but past the depth of the inserted drill rod, which now acts as a pilot shaft to hold the rods aligned as they rotate freely from one another. Because the length of the leadscrew needs to remain a constant, the material sawn out of the cut will need to be replaced, so a bushing washer will need to be made to fill that gap, turning freely on the pilot shaft. Next, make a sleeve that is reamed to a slip fit over the surfaces of the adjoining shaft segments. In that sleeve, mill a slot from one end on opposing sides that will fit to span the two roll pins as it slides toward the gears, providing the dog clutch engagement. It will need to be long enough to have abundant material toward the right end of it, unslotted, so it will be strong enough to keep the sleeve slots from trying to widen under the load of engagement. Round the inside corners of the open end of the slot to assist engagement as the sleeve is moved. I need to do some measuring, but I am hoping to have enough clearance on the unthreaded section of the leadscrew to park the sleeve when disengaged, and have some way to slide it (lever, knob, etc.) protruding out the right end of the control box, yet not get into where I have my carriage stop clamped to keep things from hitting the chuck jaws. I use an aftermarket 4" chuck, which is rather large, so there is a lot of leadscrew below it that never sees use. If necessary, I may have to allow the back end of this sleeve to cover some of the unused leadscrew threads when it is disengaged. Depending on how these dimensions work out, I may have room to put a yoke lever on the RH end of the sleeve to move it. (Like a clutch yoke on a manual transmisson car.) Otherwise I am thinking a sort of top hat shaped knob on the end of the sleeve, to pull it right or push it left. I wonder if such an arrangement would stay where it is set while using the lathe, or if a detent system would be needed to hold it in each engaged/disengaged position? |
| drmico60:
--- Quote from: MetalMuncher on April 27, 2014, 10:56:20 AM --- --- Quote from: drmico60 on April 27, 2014, 05:49:20 AM --- --- Quote from: MetalMuncher on April 26, 2014, 06:52:58 PM --- --- Quote from: drmico60 on April 26, 2014, 10:39:34 AM ---.weebly.com/new-threading-banjo.html --- End quote --- --- End quote --- --- End quote --- I think the concern with your setup, at least for me anyway, is that if it is easy to swing the banjo to adjust it when you want to, could it possibly move on its own when you don't want it to? What holds it in the position you set? If it is the clamping action on the pillow block that holds it from moving, well, that seems just as much work to adjust as manually removing a gear from the stock setup. And still requires removing the gear cover. I had thought the clamp was a means of mounting it to something that is allowed to turn, so it could be effortlessly engaged/disengaged. That's why I envisioned a means of moving a control lever/knob attached to it, with a detent system. What I am after is something that can be adjusted as easily as moving a knob or lever, with no tools required. --- End quote --- Hi Metal Muncher, The banjo clamps to the pillow block extension with a screw. A quarter of a turn will lock the banjo securely to the pillow block. If you replaced the screw by a rod threaded at one end and cut a small piece of the gear cover away then all the operations to swing and lock the banjo can take place from outside the gear box cover. No tools would be required. Mike |
| guminase:
This Gentleman has made a nice, detailed Desciption of a Dog-Clutch for a Mini-Lathe: http://www.gadgetbuilder.com/Dog_Clutch.html |
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