Z Axis Calibration Issue

[ycroosh]

iGaging scales were the best deal for the money. 10 years ago glass scales were selling for $400/piece and more. iGaging scales at that point were 1/4 as good for 1/10 of the price. The main problem I run into (as a "business") is the support head ache from various timing changes they introduce, etc. When these scales work, they are fine. The problem is that they work about 95% of the time, and I get to deal with unhappy customers the other 5% of the time, which is VERY expensive in the long run.

 

[ChazzC]

Solved..
While wait for a potential substitute, I decided to disassemble the Z scale & encoder from it's mounts on the column. While I had it on the bench, I compared the scale to the a few others I had (6" units). I noticed that there is a pattern imprinted/molded into the black center portion of the scale. When I looked at the 6" units I noted the orientation was 180 deg different. I figured that it can't hurt, so I slid the scale out of the encoder and flipped it 180 and slid it back in. I ran a test and it did not flicker and I was able to run the calibration option. I did not get any error messages re: the encoder steps. I carefully reinstalled it and run a full calibration on it. Everything worked perfectly. Not sure how or why this happened, but it seems like the orientation of how the scale in inserted into the encoder box is important. I have been checking it now for almost 2 days off and on - running the knee up / down, checking / comparing the dial readings to the DRO #'s - all good.
Who knew?! lol

Very interesting: iGaging specifically says not to do this & it will void the warranty; it may be that the orientation does matter (I figured it was because not everyone would be careful about how they reinserted the scale, particularly after cutting it to length). I flipped the entire assembly on Y- and Z- for my Mini-Mill install so I could get the correct orientation for + and - while having the cable exit where I wanted it (then saw the light and "Yuriy-ized" them so could invert the output via the App).

 

[opsoff1]

Re: cost - That's exactly the decision process that lead me to the igaging stuff. If anything goes kaput - I'll will definitely move to glass. Hopefully what I have now will outlive me.
For now everything is running great - couldn't be happier.
Ordering a Drewtronics Edgefinder next week.

 

[opsoff1]

Do Shahe scales work with Digimag encoders?

 

[ycroosh]

Do Shahe scales work with Digimag encoders?

No, Shahe are completely different scales. They use the standard "BIN6" format, and are generally more resilient to noise and glitches, but slower (about 10Hz refresh rate).

 

[ycroosh]

Very interesting: iGaging specifically says not to do this & it will void the warranty; it may be that the orientation does matter (I figured it was because not everyone would be careful about how they reinserted the scale, particularly after cutting it to length). I flipped the entire assembly on Y- and Z- for my Mini-Mill install so I could get the correct orientation for + and - while having the cable exit where I wanted it (then saw the light and "Yuriy-ized" them so could invert the output via the App).

There is really nothing you can damage by flipping the head, unless you "man-handle" the frame and break something mechanically. These scales are basically a variable capacitor (well, a few capacitors). As the area overlap between the pads on the PCB and the pattern in the frame changes, the scale can do some shenanigans to interpolate the position.
I'm surprised that this has any effect in the first place, since one would think that the pattern in the frame is symmetrical, but obviously there is something different enough that the orientation matters.

 

[ChazzC]

There is really nothing you can damage by flipping the head, unless you "man-handle" the frame and break something mechanically. These scales are basically a variable capacitor (well, a few capacitors). As the area overlap between the pads on the PCB and the pattern in the frame changes, the scale can do some shenanigans to interpolate the position.
I'm surprised that this has any effect in the first place, since one would think that the pattern in the frame is symmetrical, but obviously there is something different enough that the orientation matters.

While I have opened up an iGaging read head, I have only done so to evaluate shorter micro USB cables (to avoid the rat’s nest you saw a while ago), and didn’t delve into read pickups. Is it possible that the PCB pads aren’t (or weren’t, in @opsoff1 ’s case) symmetrical? I have a failed scale that I used for developing mounting details for the Mini-Lathe, so maybe it’s time to explore: who knows, maybe I can get it working?

 

[opsoff1]

While I have opened up an iGaging read head, I have only done so to evaluate shorter micro USB cables (to avoid the rat’s nest you saw a while ago), and didn’t delve into read pickups. Is it possible that the PCB pads aren’t (or weren’t, in @opsoff1 ’s case) symmetrical? I have a failed scale that I used for developing mounting details for the Mini-Lathe, so maybe it’s time to explore: who knows, maybe I can get it working?

I was kind of shocked that it worked. I initially took the encoder / read head apart to see how to flip the scale around. Slides right out and in. The only thing to be careful of are the small wipers. Flipped it and put the cover back on with the 4 tiny screws.
My only guess is that the actual reader / pick up isn’t exactly centered and flipping the scale 180 puts it into the correct position to reliably read position. Just a guess.