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View Full Version : Thread necromancy needed - locking a dial



Tony Ennis
01-13-2013, 10:02 AM
Some time ago, a few years perhaps, someone posted a diagram of a mechanism to lock a dial. The dial rotates freely on a hub. A screw runs through the center of a hand wheel, along the axis of rotation. The end of this screw is a wedge, and this contacts a rod mounted in the hub that travels radially to the hand wheel's axis of rotation. When the screw is tightened, the rod is forced outward, where it contacts the underside of the dial, locking it into place with friction.

Anyone remember that diagram?

vpt
01-13-2013, 10:14 AM
Subscribing, I want new big dials too.

J Tiers
01-13-2013, 11:22 AM
I did show the parts from the Rivett.....

http://img.photobucket.com/albums/0803/jstanley/rivettdialbinder.jpg

Tony Ennis
01-13-2013, 11:23 AM
I thought it was you, I did not remember it was the Rivett. Thanks sir!

Not even a spring. Cool.

Mike Amick
01-13-2013, 03:08 PM
wait a minute ...

I thought thread necromancy ... was like talking to dead threads

vpt
01-13-2013, 03:50 PM
So your handwheel must have a set screw? My atlas uses a stud and nut at the end to keep the handwheel on but that can be changed for something cool like this! I knew I subscribed for a reason! Thanks for the pic!

Tony Ennis
01-13-2013, 04:50 PM
My Atlas' 1" diameter dials have a slot set screw. So to use them I have to keep a tiny slot screwdriver handy, and a loupe, too. In short, it isn't happening.

Optics Curmudgeon
01-13-2013, 07:31 PM
I replaced the screws on mine with ones that have a nylon tip, provides a controllable amount of friction.

Edit: Oops, that was on the shaper, the lathe dials are mounted in a way that discourages that solution.

TGTool
01-13-2013, 08:14 PM
My Atlas' 1" diameter dials have a slot set screw. So to use them I have to keep a tiny slot screwdriver handy, and a loupe, too. In short, it isn't happening.

You can contrive to put larger dials on that, you know, and it can then include a reasonable settable zero. It fixes both those problems.

Tony Ennis
01-13-2013, 08:33 PM
Hence the reason for this thread.

Scottike
01-13-2013, 08:39 PM
My Atlas' 1" diameter dials have a slot set screw. So to use them I have to keep a tiny slot screwdriver handy, and a loupe, too.

My 10" Rockwell needs the slotted screwdriver too, but I can pass on the loupe - my dials are about 1 1/2" in dia. and my eyes are still somewhat OK.

edit: but the Rivett meathod, I like!

John Stevenson
01-14-2013, 03:58 AM
Got a couple of machines here that just have on 'O' ring installed on one of the parts, some have it inside the dial, some on the shaft retained part.
Dial stays where it is by friction but still resettable when needed.

Seems a very elegant and simple system to me.

Paul Alciatore
01-14-2013, 03:10 PM
I am not a fan of the slotted screw locks on dials. Or any other kind of screw. But it does allow you to set the position of the dial without disturbing the position of the screw.

So, how well does the locking screw in the shaft work in this respect? I mean, you are turning the lock screw in the threaded hole in the (screw) shaft so wouldn't that action tend to turn that screw shaft? And hence, disturbing the position that you are trying to set the dial to. Or does this not happen in reality?

I like the o-ring/friction idea that Sir John posted. You can hold the screw still while setting the dial. I did some design work in this direction some time ago with dials that had other special features. Perhaps I should return to that project.