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| mini-lathe leadscrew clutch? |
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| MetalMuncher:
--- Quote from: drmico60 on April 27, 2014, 12:05:22 PM --- --- 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 --- Thanks 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. --- 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 --- End quote --- |
| MetalMuncher:
--- Quote from: guminase on April 27, 2014, 12:45:24 PM ---This Gentleman has made a nice, detailed Desciption of a Dog-Clutch for a Mini-Lathe: http://www.gadgetbuilder.com/Dog_Clutch.html --- End quote --- Thanks guminase! And welcome to the forum! :) |
| DennisS:
Hi MetalMuncher, and everyone else. I'm a newbie to this forum but have been a reader for a while and learned a lot from folk who are very obviously more skilled than I can ever hope to be. But I just had to join to post a reply to your plea for a leadscrew clutch for a minilathe. This is my third attempt to post, others seem to have become lost somewhere in the aether, probably because I had some large photos attached. I faced exactly this problem a while ago and built an electro-mechanical dog-clutch for my minilathe that seems to work very well and also acts as a very accurate and flexible saddle-stop when turning under power. I am not posting any photos this time in the hope that this post makes it through, if someone can tell me what I'm doing wrong with the photos (attaching jpg's from my desktop) I'll get some photos on. I should also have some hand-drawn dimensioned sketches somewhere if those might be of interest. Best regards Dennis |
| MetalMuncher:
Hi Dennis, and welcome to the forum! I am sorry you are having trouble with the pictures. I have problems posting pictures here too, so I usually just post a link to the picture stored somewhere, like in a Dropbox account. I believe in the introductory sections there is mention of another type of online photo storage you can also use. Electromechanical sounds intriguing, and fancier than the design I am currently making. So I'd love to learn more about it. If this type I am making works out I'll post it on here with some photo reference. Basically it is rather simple. I intend to cut the unthreaded part of the leadscrew (hidden behind the control box) and remove enough to leave a 1/8" gap in the shaft after facing the cut ends. I'll then make a custom washer to fit this gap and set its thickness to assure there is no leadscrew endplay. In between the cut ends, and through that washer, will be inserted a piece of 5/16 drill rod, to keep the two halves aligned. Two 1/8" dia. by 1" long spring steel roll pins will be inserted crossways through the leadscrew shaft, so their ends stick out. One will pass through the short piece of the leadscrew AND through the 5/16 "pilot shaft" between the leadscrew cut ends. The other will pass through the leadscrew shaft just off the opposite end of the 5/16 shaft, so the long piece of leadscrew will be free spinning on the pilot shaft as long as the clutch is not engaged. As a clutch, I am making a sleeve that will slide over the leadscrew. The LH end of it will be slotted through both sides, with the slots running parallel to the shaft, and long enough to allow the sleeve to slide past the exposed ends of both roll pins in the engaged position, sliding the sleeve toward the gears. To disengage, the sleeve will be slid back toward the chuck, so that the first roll pin is no longer in the slot. The RH end of the sleeve will stick out just enough beyond the RH end of the control box to grasp a raised ring I'll turn on the end of it, as a sort of knob. I'll have to enlarge the control box cutout for the leadscrew. I don't anticipate the sleeve moving on its own. But if it does, I have some ideas how to prevent that. |
| DennisS:
Hi MetalMuncher, Sounds similar in some ways. But I fitted additional leadscrew mounting blocks to keep the alignment of the two parts of the cut leadscrew (it is possible in the space available) and disposed of the problem of leadscrew endfloat that way. I then used cross-pins in the two parts of the leadscrew with a sliding sleeve to engage. The sleeve is moved manually into engagement against a spring and held in engagement by a latching mechanism. The latch is released by a low-voltage solenoid that is powered via a switch mounted on the lathe ways and operated by contact with the carriage. In fact because there is no mechanical linkage to the solenoid alternative methods of switching are possible and the switch could be mounted anywhere on the ways or even on the carriage itself. The only sensitive issue is finding a spring that is strong enough to disengage the mechanism while cutting under power, but not so strong that manual engagement is difficult. I'll have another go at posting a photo. Dennis |
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