Dro $#@&^%*&^$#$

[Sshire]

I was marking a part's centerline for drilling. Dykem. Clean surface plate. Set Starret Digital Height gauge to .250. Scribe line.
Move the part to the mill. Haimer ZeroMaster in a collet. Find center. Locate hole position. My usual procedure is to press the center drill as a check. The mark was not perfectly on the scribe line. Close but not as it usually is.
Four hours later.
Dial indicator set up to measure table travel compared to the Haimer. They agree but DRO reads 0.0045" short.
Next I put a 1" Jo block in the vise and used the Haimer to measure it. The DRO says .9935"

Switched DRO scale cables to the lathe DRO. Same result.

Took the scale apart and cleaned the glass with lens cleaner. Reassembled. Same result.

I think I've eliminated all variables except the scale itself. I have an extra that's a few inches shorter and will have to re-drill the mounting plate.

If anyone has a suggestion or something I've missed. PLEASE let me know.

 

[gbritnell]

Hi Stan,
I've used converted digital scales for readouts. I've used dedicated scales with remote readouts and my latest readout is a glass scale setup on my mill. The converted scale setup I would say worked within a couple of thousands (acceptable) The dedicated scales with remote were a bit more accurate and repeatable but the glass scales as far as I can tell are dead on all the time. Periodically I will make a setup with 1-2-3 blocks and gauge blocks just to check everything.
The only readouts I have trouble with are the I-Gauging scale I have mounted on my big lathe. I'll touch the tool, set the -0- and make my cuts. Occasionally when I get ready to make another cut the scale is way out of the park. Why it changes like that I can't say.
As far as your question goes I can't give you a direct answer. I would think that there is some fault in the reader head as the glass scale can't change. I got my unit from DRO Pros. Good warranty and good backup.
gbritnell

 

[Sshire]

Thanks, George
My glass scales are DRO PROS. Have had them on both the mill and the lathe with no prroblems. When the West Coast woke up, few hours ago, I called DRO PROS. Although they were stumped, they said, "Send the scale to us. It wiill go on the bench the same day we receive it. If our tech can't repair it, we'll send you a new one under warrenty."
Try that with an EBay special!

 

[Swifty]

Maybe the reader head is a bit loose?

Paul.