how to setup a digital straight edge

I got one in a shop auction, 8", never out of the box. It is marked STM and made in China. It seems fairly well built. I got it to put on my mill/drill X-axis, but the setup eludes me. The end brackets have holes and are pretty straight forward, but the back of the travelling digital readout head has 2 small tapped holes. I'm not sure of the connection here. I guess it must be attached to a bracket on the mill/drill and the ends on the table, but it as only an 8" travel.If the table travel is longer, I assume I must design the brackets to be movable to encompass that extra travel. Can some kind person here give me a few ideas on this subject or point me in the right direction, a websight perhaps?

Dang! I was going to post a drawing of the setup but the batteries in my electric pencil went dead.

I guess everyone is waiting to see what a digital straight edge looks like. Got any pics?

"I guess it must be attached to a bracket on the mill/drill and the ends on the table, but it as only an 8" travel.If the table travel is longer, I assume I must design the brackets to be movable to encompass that extra travel."

Actually, it would be better to have a scale that matches your table travel. To "rig" something up, you might try using magnet mounts for the scale (to the table) and a fixed mount for the reader. This would allow you to position the DRO scale as needed. I'm not sure if the reader would take kindly to a magnetic mount. In any case, one part needs to move and the other is fixed.

I think what he has is a cheap LCD read out for a quill. Like you mount to the front of a Bridgeport head. Probably reads in 0.0005 increaments. To put this on a X axis? Maybe have the thing able to slide around and be relocked. Still limits your travel. Sounds like a lot of trouble to me. If the parts are small, it could work. Good luck
Bill

[This message has been edited by Mr Bridgeport (edited 07-06-2004).]

http://www.littlemachineshop.com/products/product_view.php?ProductID=2013

I found this pic after some searching. To explain briefly, I setup my mill/drill with movable 1" dial indicators on all the axis of travel. Its OK for the little stuff I make, but now I need to make a jig mold, the two halves will be end to end and the overall length will be 6". I thought the chances of moving the dial indicators several times without error was too much to ask for. The digital scale presented itself and here we are. Now, I can set it up to do just that area on the mill as I don't think I will need that much accuracy over the entire lenght of the mill, but jf I can place the scale anywhere on the table travel, then I can work around obstructions such as a mill vise without having to remove it , then have to set it up and dial it in again. Get the idea. It didn't cost much so why not use it?

several years ago, i adapted a unimat vertical milling head to my atlas horizontal bench mill...however it was a pain for me to use the factory longitudinal table travel indicator dial..besides being small and difficult to read, the table screw and feed nut had lottsa wear, requiring notation for accurate movement in both directions...what i did was to mount a $30 chinese (enco) dial caliper to my machine....this entailed grinding off both inside and outside ears, then attaching the rack porion to the table front (i mounted it at 30 degrees off of vertical to clear any material to be clamped to the table top ) the dial portion is attached to the knee part of the mill,by means of the little screw knob on the bottom of the dial that allows clamping it to the rack.by attaching a small "ell shaped bracket" to the knee ,this bracket just touches the bottom of the dial portion, allowing it to be fastened to the mill....so i now have a "travel rack"

Having a scale shorter than the table travel does limit you.
You can just center it on the X travel and live with that. Or you might possibly mount some De-Sta-Co clamps that will clamp the end of the scale onto pads. The pads could be made so the scale ends fit nice and tight. Several pads and clamps could allow you to re-locate the scale.

I would just get something longer. Trying to relocate the scale to accommodate longer table travel would be a pain. I don't know what kind of repeatability you are after. And it seems like plenty of room for error to stop, re-locate the scale, re-zero, add in previous travel, and continue on.

Good luck.

Les

Hmm, if it is on a mill-drill, mounted to the backside, the already minimal y travel will be reduced by whatever the thickness of the scale/readr/mounting set up is.

Might you mount it in the front T or dovetails slots (for the original hard stops)? Then it can be slid along and easily repositioned or removed by loosening 2 screws. Mount the reader on the verticla post, or make a new support for it to screw on where the center post locates.

smt

"Might you mount it in the front T or dovetails slots (for the original hard stops)? "

My original thoughts! This is how I hooked up the dial indicators on the X-axis.Just wasn't sure of the connection on the back of the digital head. I'll have to rig a bracket to fit. Thanks all for your ideas.