Author Topic: iGaging DRO problem.  (Read 5150 times)

Offline websterz

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iGaging DRO problem.
« on: May 09, 2011, 06:56:00 PM »
I just finished (after several months of them collecting dust) installing iGaging DRO's on all 3 axes on my x2 mini mill. Z and Y work great, X...not so much. It is in full speed runaway mode apparently. It behaves as if the table is in constant motion. I switched out to one of the other displays and it still does it. Apparently it is an issue in the X axis encoder itself. Has anyone else experienced this?
"In the 60's, people took acid to make the world weird.  Now the world is weird and people take Prozac to make it normal."
 :med:

Offline narrowgauger

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Re: iGaging DRO problem.
« Reply #1 on: May 10, 2011, 01:28:27 AM »
Hi there

there is absolutely no difference in the individual iGaging DRO's with remote readout.  All readers and remote control read-out's are identical, with the only difference being the length of the scale bar.

therefore irrespective of the DRO being installed to the X-axis the problem could be one of several issues, including the installation.  To resolve check the following:

- has the face of the bar (black face) been scratched or damaged in any way.  if so this is the likely problem:
- is there swarf or other rubbish caught between the reader head (sliding element on the bar) and the bar.  if so remove the interfering material
- are the batteries fresh. Noting that the installation has taken place a long time after the unit was bought it is highly likely that the batteries are out of date.  this will cause the   reader to malfunction.  remove BOTH batteries and replace with new; do not use the spares that came with the unit since these are also likely to be out of date.
- is the reader bar set absolutely parallel with the bed.  If not this will cause the sliding head to bind along the scale bar and cause misreads.
- have you used the correct srews to attach the reader head to the table attachment.  It is possible to penetrate the back of the reader head if the srews are too long.  loosen scews and try again.  Use the originally supplied screws.

If none of these return the unit to the seller or iGaging USA direct for a replacement.

Hope this assists
Bernard Snoodyk
iGaging Australia

Offline websterz

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Re: iGaging DRO problem.
« Reply #2 on: May 15, 2011, 02:43:16 PM »
I changed the batteries and it made no difference. None of the other mentioned possible problems applied. A little backstory will help here. I had previously bought 2 6" units, one for X and one for Y. I found that to be too little travel in X so I waited until longer units came available and ordered a 36". I cut the scale down, using the supplied electronics to make a Z axis DRO. I removed the read head from the original 6" unit and installed it on the remaining portion of the 36" scale to be used for my X axis. Come to find out the orientation of the read head on the scale does matter and I had to turn the scale around. Once I made that change the unit works as it should, no more runaways or random .200" jumps in the display. Now I am noticing that there is a bit of backlash in all 3 units. With a dial indicator mounted on the table and zeroed against the spindle or the back of the mill I am able to move the table and register as much as .030" travel before the DRO display picks up and starts registering movement. Any ideas? Everything is mounted solidly so the head is not moving with the scale. I am baffled...  :scratch:
"In the 60's, people took acid to make the world weird.  Now the world is weird and people take Prozac to make it normal."
 :med:

Online PekkaNF

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Re: iGaging DRO problem.
« Reply #3 on: May 16, 2011, 04:42:05 AM »
Now I am noticing that there is a bit of backlash in all 3 units. With a dial indicator mounted on the table and zeroed against the spindle or the back of the mill I am able to move the table and register as much as .030" travel before the DRO display picks up and starts registering movement. Any ideas? Everything is mounted solidly so the head is not moving with the scale. I am baffled...  :scratch:

Could it have something to do with Quadruple mode? This is used to generate pulses from each edge of 2 signals (A/B) which are phase-shifted in relation to each other. This will apparently quadruple signal resolution, but only if you keep on moovin to one direction (direction is generated also from the phase shift, but then you need allready two edeges!). Or you could filter it. All will add up to that everything is not well....unless some serious math and logic is being done.

There is one note that come ot first on my search: http://emergent.unpy.net/projects/01149094674

I'm not saying this is this, but it jumped to my mind imediately!

Pekka

Offline Jonny

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Re: iGaging DRO problem.
« Reply #4 on: May 16, 2011, 05:12:54 PM »
.030" travel before the DRO display picks up and starts registering movement. Any ideas? Everything is mounted solidly so the head is not moving with the scale.

There has to be movement on something. Have seen a few installations where the owner thought he did a good job until shown the error, most common is using the depth stop screw as an easy means of fixing.
Have you manually tried fractional movements unattached?
Post a piccy of the mounting, it should help a lot.

Regarding the other matter i did have it using some scales (caliper type) with a remote 3 axis readout from Warco around ten years ago. Battery life was a week on all three as well LR/SR44.


Offline websterz

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Re: iGaging DRO problem.
« Reply #5 on: May 18, 2011, 12:10:02 AM »
There has to be movement on something. Have seen a few installations where the owner thought he did a good job until shown the error, most common is using the depth stop screw as an easy means of fixing.
Have you manually tried fractional movements unattached?
Post a piccy of the mounting, it should help a lot.

Not quite sure what you mean about the "depth stop screw". I have tried moving the units while unmounted and get instantaneous response from them when I move the sensor.

I can get pics of the mounts for you tomorrow, but they are secure, no doubt there. For the X axis I drilled and tapped holes in the back side of the table end plates (securely tightened BTW) for attaching the scale and attached the sensor using one of the chip guard screws already in place on the back of the table. Everything is torqued down half a good breath from stripping the threads. The Y axis is mounted exactly as shown here:


And the Z axis is basically the same as the X and Y but mounted vertically of course.

The two horizontal DRO's are covered by sheets of nitrile rubber to deflect coolant and swarf. I have not made any chips with the units attached so it cannot be foreign matter intrusion causing the problem. I really can detect no movement in the mounts. It is frustrating.
"In the 60's, people took acid to make the world weird.  Now the world is weird and people take Prozac to make it normal."
 :med:

Offline Jasonb

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Re: iGaging DRO problem.
« Reply #6 on: May 18, 2011, 02:36:24 AM »
Put a DTI onto the heads and bar in turn and then turn teh handwheels to see if there is any movement that can't be felt by hand. Looking at the pic I would say two fixings for the read head would make a more rigid job.

J