View Full Version : Mechanical Position Readout

Spin Doctor
01-17-2009, 04:27 PM
This is a back burner project. Anybody have any ideas on how you could build a Trav-a-Dial type readout for a lathe. I really have never liked watching a DRO for position when coming to the end of a cut. Probably because I watch* the pointer sweeping up to the "zero". Guess I must really be from the Jurassic. I've thought about gear driven off of the rack but you are dependent on just how good the rack is. Also a cable driven device with the cable fixed heastock with a weight on the other end being wrapped around a drum.

*I also have an intense dislike of digital watches. But I love DROs on mills and CNC :-?

01-17-2009, 04:46 PM
If you have a small lathe- you could use a dial caliper. Some very large calipers exist. You could also use a short dial caliper such as 12 inches that can be moved about .

Do you basically just mean "analog position readout"?

You could use a very coarse worm thread. Done with a mill and gear train dividing head. That is how Starrett Last Word indicators work.

Verniers might be possible.

For a Rack- Other Option

Do you know how accurate your lathe lead screw is?

Then make a worm with, say, 20 TPI and hob a worm wheel with it. Use the worm as a rack.

Spin Doctor
01-17-2009, 04:48 PM
I thought of a DC. Worried about chips

01-17-2009, 04:53 PM
I used a Starrett long-travel dial indicator for years as a Poor Man's carriage Trav-A-Dial until I got a DRO. Didn't seem to mind the chips :)

01-17-2009, 05:02 PM
Likewise, I used a 1" and 2" on my Rockwell. There was no other way to measure longitudinal travel in a cut...

01-17-2009, 05:09 PM
Baddog and I talked about this before when he was at the shop, and I don't like watching the readout either, much easier watching the dial. One of you smart electronic guys needs to make a display that we can attach to the dro that is an electronic dial that sweeps around:cool:

01-17-2009, 05:10 PM
Just use a Trav A Dial .They work great. Plenty on E - bay for good prices.

01-17-2009, 05:21 PM
Yep, you almost have to count cadence or something when watching the DRO. Analog is much better in some situtations...

01-17-2009, 06:08 PM
Similarly I find digital dial and test indicators- or rather dial, never seen a digital test indicator-- completely inexplicable aside from SPC.