I’ve had my iGaging DROs on my Taig mill for a little over 18 months, and they have worked beautifully!
However, a few weeks ago, I started seeing this sometimes when I’d move the Z-axis:
It would give accurate readings a lot of the time, but randomly, I’d get this ‘Err’.
At first, I thought it might be an in intermittent short or open in the wire. So, I went for a while wiggling the wires when I’d see it. Sometimes it helped, but mostly, it didn’t.
If I moved the mill head up or down a bit, I’d usually get an OK reading. But it made the Z-axis DRO unreliable enough that I had to go back to using the dial markings a lot.
Today, I decide to see if I could get to the bottom of it.
So, I took the Z-axis unit down, and played with it off the mill. Same thing of course, as you slide it along the bar, you’d get ‘Err’ sometimes.
I tried cleaning the bar, and cleaning out the read head of all the little chips and dust as best I could. It seemed a little better, but I still got the ‘Err’ as I moved the read head up and down.
So, I decided to take the unit apart. Worst case, I’d have to replace my Z-axis unit. And if it remained as it was, I was going to have to do that anyway. So, what did I have to loose?
It comes apart easily enough. There are four little screws in the corners that open it right up.
And there’s not much to it inside. There’s a little cable that connects in to the read head, the circuit board, and a chunk of steel that slides along the encoding bar.
I unplugged the cable, and took out the 4 screws that held the circuit board to the steel guide, and here’s what was on the backside. The code reader. Pretty interesting…
And looking up close, you can see lots of little bits of metal on the reader. “THIS is the culprit”, thinks I. I’m hot on the trail!
I clean the board carefully, reassemble it, and lo-and-behold…. It still happens… ‘Err’…
OK, not as simple as I’d hoped.
So I play around with the unit more. Sometimes, it seems really good, and then, sometimes, I get ‘Err’ all over the place… What gives?!...
Till I start to realize there is a LOT of play in one end of the encoder bar. It will wiggle up and down by 1/16” or more. Here it is at one extreme:
And here’s the other:
A little more fiddling, and is clear that when the bar is held consistently ‘down’ toward the bottom of the read head, I get good readings, all the time!
So, I start to look into how to keep the bar down. And when I look inside, I see this cavity where it looks like there was probably a gib of some type, and it’s not there anymore. So, I decided to make one. I decided on using a strip of brass ship that I have, and building up the back side with several layers of double sticky tape. Like this:
That worked a charm. Consistently good readings all the time for the usable length of the DRO. Yipee!
After declaring victory, I reattached the DRO back onto the mill and all is good with the world
Just wanted to share this with you all since I know there are several people out there who have the iGaging DROs, and might find my (mis)adventure useful someday.
Kim
