Igageing digital machine scales - first glance

[Holescreek]

The ancient Sony DRO on one of my Bridgeports (42") died quietly sometime after Christmas. It had lived a long life. It was so old that it used glowing wires for the numbers.

I started looking around at DRO prices on Ebay and various sites but am a little hesitant to dump another $500 + into the mill right now, especially since I haven't been making anything for sale for a long time. My smaller Bridgeport has a nice Chinese DRO with glass scales and is my go-to machine for everything that will fit so the larger machine usually has the table loaded with a vice, rotary table and dividing head for small projects so I don't have to set them up special for a project.
I've been wanting to see if the Igageing scales were any good so I got on Ebay and ordered a 35" and two 12" scales for roughly $120. I mounted the 35" on the X axis (table) which actually only uses 21" of the scale but it fits nice. Today I mounted a 12" to the Y axis, and soon will be mounting the other 12" to the knee (Z axis). I already have a 6" caliper style readout on the quill.

I have two concerns already with the scales I mounted, my first concern is batteries. The batteries in the 12" scale were dead already after having spent 48 hours in the readout with the power off. My other concern is accuracy.

With the Sony DRO mounted the readout numbers matched the dials on the handles whenever I took the time to set them. I verified the calibration of the scales with gauge blocks when I initially set the machine up and was confident that everything was right. Today before I closed up I checked the Igageing scales against the handwheels and was not impressed.

I checked the 12" scale first, "as delivered" with a brand new set of batteries (second set in two days). The chart on the top is as delivered. First I checked every inch starting from one end of the scale to the other, then I set zero roughly in the middle of the scale and went 4" each way, always taking the backlash out of the leadscrew and approaching the number on the handwheel turning clockwise. I didn't like what I saw so for S&G's I swapped the readouts from the 35" & 12" scale and tested it again (bottom chart):

I was running short of time but I managed to do the same test on the X axis (still had the readout from the 12" on it):

So far I'm not impressed. I considered putting a set on my lathe but frankly I get better accuracy out of it's 62 year old dials than I could expect from these scales. At best, they will keep track of the inches traveled and I'll have to go back to using the handwheels for anything important.

 

[davidh]

do you remember what the specs on the igaging said you could expect ? ok, i just looked. . . 0-36" = .013 error

i do have the specs posted on my Facebook page for Absolute models . . 0-38"= .003 much better. . .
if your curious, "birch industrial tool service inc" is the Facebook page. i have made a little gadget to replace the battery in them and connected a pair of readouts using two of these gadgets, to a pair of AA batteries. if you figure out the usage of power, it computes to a few years of continuous "on" before the AA batteries would go dead. the dual battery pack came with an on / off switch and i wired in a tiny led to remind me to shut it off. . .

I'm sorry your not happy with your purchase decision. perhaps you could sell them and get the better ones ?

i will again be selling both models next week when my shipment arrives. very well discounted as before.

 

[Bamban]

DavidH,

What is the difference between the absolute models and the older ones? Do the newer ones have better precision and repeatability, not talking about readout resolution?

Thank you.

 

[atunguyd]

Consider the touch DRO project from yuri for your igageing scales. Yuris software has the ability to calibrate to the error of the scales and also gives you a full DRO solution.

Sent from my SM-P605 using Tapatalk

 

[Bamban]

Consider the touch DRO project from yuri for your igageing scales. Yuris software has the ability to calibrate to the error of the scales and also gives you a full DRO solution.

Sent from my SM-P605 using Tapatalk

The limitations of the system the OP experienced is with the read out and not the scales, is that correct?

How does calibrating the error of the scales work? Do you have to find out the error and input it into the program? How many points do you have to establish so the error is zeroed out or it just takes one input and the system assumes the error is constant across the measured range?

I am about to purchase iGaging scales, the reason I am curious. Just want to learn as much as I could.

 

[Holescreek]

I would be lying if I said I wasn't a little disappointed, I think it's human nature to want things to work out better. As is, at least it'll count the inches for me!

As someone who repairs gauges regularly I was surprised that swapping the readers had such a noticeable effect on the accuracy of the scale. At the very least it shows where a sizeable amount of error stems from. Someone smarter than I might be able to figure out how to pair the sending unit and the reader?

Consider the touch DRO project from yuri for your igageing scales. Yuris software has the ability to calibrate to the error of the scales and also gives you a full DRO solution.

Sent from my SM-P605 using Tapatalk

That is the route I'd planned on taking when I decided to go this route, I'm just having trouble wrapping my head around the steps it takes to get there. I posted the question you just answered on another forum tonight, it's great to hear that scale comp is doable. No doubt Yuri has the system figured out, I either need a step by step instruction to follow or just have to quit all other activity and delve into it to figure it out myself. If I get to the touch DRO stage, I'll certainly install one on the lathe. Thanks for the info!

 

[Holescreek]

The limitations of the system the OP experienced is with the read out and not the scales, is that correct?

How does calibrating the error of the scales work? Do you have to find out the error and input it into the program? How many points do you have to establish so the error is zeroed out or it just takes one input and the system assumes the error is constant across the measured range?

I am about to purchase iGaging scales, the reason I am curious. Just want to learn as much as I could.

My experience with that portion used to be called "scale mapping". Depending on the control requirements the scale installer would use a laser to measure at intervals and input the "actuals" into the control. The control would determine a compensation formula to adjust the readout to fall within parameters. That's a real vague answer I know, it's been a really long time since I was involved (as an observer mostly) in that. In setting up my CNC I did something similar but it was called leadscrew compensation.

 

[atunguyd]

Holescreek and Bamban,

On the touch DRO system the calibration is for the endpoints only, you basically move the table/carriage a fixed number of inches (using your handwheels) and then use the number on the display to apply a correction, obviously it is better to try to keep this movement as large as possible. It is pretty much explained by Yuri here:
http://www.yuriystoys.com/2014/02/dro-scale-calibration.html

On some DRO displays there is an option to do a similar end to end calibration and some have the option to segment the scale and calibrate each segment, my Chinese branded Sino display on my Lathe has this option but the manual in Chinglish si such that I am clueless on how to program this feature

 

[ycroosh]

Scale mapping isn't thad difficult to implement. I had it in TouchDRO in one of the "internal" builds. I took it out mostly because the calibration process is pretty annoying and with non-absolute scales this wouldn't work very well. I.e. every time the scale resets it would need to be re-calibrated. Moreover, iGaging scales aren't really a good choice for high accuracy setups. When I had them on my mill I used the DRO to get "close enough" and then used dials for the last thou.
If it becomes a "missing feature", I can re-add it later...
Regards
Yuriy