PM DRO display fickering?

COMachinist

COMachinist

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My DRO display is flickering last 3 digits? It is grounded good, and the hash marks in the right orientation both on the same end of the scales. Any reason why this is happening? Y Axis seems the worst, it is impossible read the last 3 digits. All scales are tight, dialed in flat and level. Read heads to .020 with white shim. No florescent lights in the shop. No 3 phase drives running. Shop power is120/240 200 amp service, grounded with 8 ft Cooper ground rod??????.
CH
 
Is your shop power a separate service, or fed from another local panel that is also grounded? It may be possible that you have a ground loop issue (I only know enough about multiple grounds on services causing issues to have an opinion, but I do recall that building grounding systems need to be carefully designed).
 
Grab a small flat screwdriver, wiggle the serial port cables up and down while tightening them further into the display unit. I saw this on a brand new DRO X axis then remembered I thought the serial port cables fit very loose on the pins. It's been rock solid since.
 
markba633csi said:
Is this a new symptom or has it always done this?
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Just finished the DRO install. Which came with my PM935v. The power in to the shop comes in from the same pole and Trans former that the house is onI have n o t been in any hurry to install it until now. Been Just using the mill with the axis dials. need for a DRO until now. I have an EL-400 from DRO Pros 0n my lathe form day one several years ago. It is rock solid, it is only 10 feet away from my mill on the same shop power as my mill.
CH
 
coolidge said:
Grab a small flat screwdriver, wiggle the serial port cables up and down while tightening them further into the display unit. I saw this on a brand new DRO X axis then remembered I thought the serial port cables fit very loose on the pins. It's been rock solid since.
Click to expand...
I did this all ready, they are tight and solid.
 
Sure it could be noise at the inputs or the cable or even a bad sensor, but it might also be an internal cable going to the display that is loose .... or that the contacts re getting corroded or dirty. If it is not under warranty then I would gently remove the cover and look for loose wires. If the cables going to the display are flex (flexible circuit board) cables I would not take them apart. They are commonly used in small display devices and are sometimes difficult to get re-installed so that they work.

If by the last three digits you mean the most sensitive positions (small distance measurements), then this might indicate that the sensor is not sending a repeatable signal. However, since you said it is happening on both sensors then it is most likely that the sensors are not getting power/ground correctly (noisy) or that the internal signal converter(s) are failing.
 
COMachinist said:
I did this all ready, they are tight and solid.
Click to expand...
Is it a MagXact? If so read on...I purchased an EL400 earlier this year from DroPros. The same company makes those and the MagXact's. I have installed several DroPros over the years.

This one however was completely wigging out. Not only were the numbers flickering but it started losing position, it even ran backwards even though I was still moving the table in the same direction. I was on the phone with them for quite a while trouble shooting. Yeah all the hocus pocus bad power, poor install nonsense excuses. They decided to send me a new power supply board thinking the power supply was bad and undervoltage. An hour later I had fixed it myself.

I noticed when I installed this one the serial ports are big time SLOPPY loose. I grew up in the ear of serial/parallel ports. They are supposed to be tight on the pins. Back then you didn't even need to screw them on. This felt like the pins weren't even there. I had already tightened them with the thumb screws pretty good but for X even that wasn't enough to get contact with the pins. I had to crank it in with a screw driver.

SO if your unit is wigging out like this, my money is on the sloppy port/cable fit. It could be yours are just a bit sloppier and you can't get it tight enough to make contact reliably.

Hope you get it sorted.
 
Fixed it. The hash marks have to be on the same side, not the same ends. Flipped the scales and they are rock solid. They just as acurate as my DROPros with the 123 block calibration method. The reading is less than .5 thou by my mitoyo indicators. Very happy to have the mill done and set up. Now on to the solid tool post for the PM12x36 ultra Precision lathe.;-)
 
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