mini-lathe leadscrew clutch?

Gallery, Projects and General > How do I??

<< < (8/9) > >>

MetalMuncher:
DennisS, what did you find out to make posting attached pictures work? I still can't do it. I set up the settings to upload some jpg pictures but they never get posted. In fact my whole post in which they were supposed to BE never gets posted.

So, they can be viewed here.

https://www.dropbox.com/sc/tq50rm3a85ca6tv/OzIQB1jIpy

MetalMuncher:
OK, it seems trying to add multiple attachments to an original post won't work. But I was able to attach ONE photo to a post. Then using the Modify option on that post, I was able to add 3 more attachments, one at a time, saving after each one, and re-clicking "Modify". Klunky, but it worked. :)

So here you can see the sleeve and modified leadscrew. A 5/16" pilot pin of drill rod is inserted between the 2 pieces of leadscrew, and then I made a custom washer to remove all endplay when the leadscrew is installed. The washer is visible between the two roll pins. The left roll pin holds the drill rod pilot pin in place. The right roll pin passes through the leadscrew shaft away from the pilot pin, so that end of the leadscrew can rotate freely on the pilot pin when the sleeve is disengaged from locking the 2 pins together.

I'll have to enlarge the shaft hole in the right side of the control box. The ring on the sleeve will extend a little to the right of the box when engaged, and extend a little more when disengaged. The sleeve moves about 0.400" to operate the clutch. The sleeve is 1.1" in diameter (not counting the ring on the end for moving the sleeve) and the inside has 2 different diameters, as the threads on the leadscrew are approx. 5/8", but the un-threaded shaft is 0.593". The sleeve is just over 4" long, made from 12L14 leaded steel.

I had to shorten the top setscrew that helps align the motor housing, so it did not stick out so far, as it was in the way of the sleeve turning. I cut down a setscrew so that the locking washer is nearly flush with the socket head, and put that in place of the stock setscrew.

The plastic baffle that keeps the control wiring off the leadscrew may work with some modification, otherwise I may need to make something to replace it.

DennisS:
Hi Metal Muncher, an elegant solution and probably certainly more easily accommodated within the limited space available. I presume that you will be using a selector fork of some sort to engage/disengage.
I had to relocate the big electrical "choke" that normally occupies space in the bottom of the control box but did manage to fit that within the box and added a cooling fan to the power transistors as well - I was already running low volts to the relay and happened to have an old 12v computer fan sitting doing nothing, so ...
I snipped a little off the black plastic guard that keeps the electrics off the leadscrew and was able to refit that. See photo attached which is an earlier
As for photos, previously I had been posting very large jpg files that were not being accepted. Once I resized those to 640x480 there was no problem at all.

MetalMuncher:
There's a lot going on in there, DennisS! :)

I had thought I might use a fork to position the sleeve clutch, but with some careful tweaking and lithium grease I have it to where I can move it with a finger. The tendency to stick a little at either extreme of travel, beyond the amount needed to work, got annoying, so tonight I provided a solution. I constrained the "knob" ring's travel so that the sleeve can't dead end against either direction. So it is no longer sticky. Works very smoothly now. :)

I had to deal with that plastic "shelf" inside the box too, because it would have contacted the sleeve in my design. After kicking around some ideas, I settled on creating a wedged spacer to go under the mounting flange for the shelf. One side is flat against the lathe bed, and the other side is at a 15 degree angle. This causes the shelf to tip upward at 15 degrees, missing my clutch sleeve, but still doing its job of keeping the wires away from the leadscrew.

Here's a shot of my constraint bracket. The knob's raised end travels 5/8" between the ridge on either side of the bracket, but has to stay within it.

There must be some difference in the way models of this mini lathe are wired, because I don't have a choke in the bottom of my control box. I can't say I've ever noticed any problem electronically here while the lathe is in use.

DennisS:
Hi MetalMuncher,
you are right, there are a number of different circuit boards for these mini-lathes, and what will be inside the control box seems to vary from supplier to supplier.
This probably also affects what can be added within the control box, I guess you only find out what you've got when you open it up, and work from there. You are constraining the throw of the sleeve, have you given any thought to adding a detent that would hold the sleeve at either setting, against the possibility of the sleeve "wandering? Detent could easily be implemented on a selector fork.
Dennis

Navigation

 Message Index

Go to full version