Acu-Rite Scale Repair?

One of the scales on my Acu-Rite 200S DRO does not work. I swapped the cables and confirmed that it is not the monitor. Any suggestion on troubleshooting the problem? Does anyone do repairs on these? The part number is 558111-08.

beeser said:

One of the scales on my Acu-Rite 200S DRO does not work. I swapped the cables and confirmed that it is not the monitor. Any suggestion on troubleshooting the problem? Does anyone do repairs on these? The part number is 558111-08.

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The read head slides out the end of the scale once the end cap is removed. That, at least, will give you a chance to look it over for mechanical problems.

I have had a couple issues in the past, with the head coming adrift from the spring arm that holds it against the scale. In one case the supplier of the lathe had put one on that was too small by about half an inch, and it banged into the end when the slide was at full travel. AcuRite took the old one back and sent us a new one.

My experience with dicking around with this sort of stuff has been that the majority of the problems with electronic stuff seem to be mechanical. Broken wires, bad solder joints, etc. Worth having a peek, anyway. Based on my experiences, you pretty much gotta be one of those that thinks the solution is a bigger hammer, to easily make anything worse.
Once the end cap is off, you can slide out the lip seals and see if the glass scale itself is intact. Get thee some lint free wipes and some alcohol to clean the scale. A pair of plastic tweezers would be of use there.

Failing that, post the travel length and the resolution you require, and like as not, someone has one around, for not too dear. Looks like 8 inch and 1 micron, from the part number. Correct?

Cheers
Trev

trevj said:

The read head slides out the end of the scale once the end cap is removed. That, at least, will give you a chance to look it over for mechanical problems.

I have had a couple issues in the past, with the head coming adrift from the spring arm that holds it against the scale. In one case the supplier of the lathe had put one on that was too small by about half an inch, and it banged into the end when the slide was at full travel. AcuRite took the old one back and sent us a new one.

My experience with dicking around with this sort of stuff has been that the majority of the problems with electronic stuff seem to be mechanical. Broken wires, bad solder joints, etc. Worth having a peek, anyway. Based on my experiences, you pretty much gotta be one of those that thinks the solution is a bigger hammer, to easily make anything worse.
Once the end cap is off, you can slide out the lip seals and see if the glass scale itself is intact. Get thee some lint free wipes and some alcohol to clean the scale. A pair of plastic tweezers would be of use there.

Failing that, post the travel length and the resolution you require, and like as not, someone has one around, for not too dear. Looks like 8 inch and 1 micron, from the part number. Correct?

Cheers
Trev

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Yes, 8 inch and 1 micron. I'll take a look inside and see if anything obvious is amiss and report back

If it doesn't work at all, it is almost certainly the read-head. If it is erratic, it could be anything from dirty to damaged.

I slid the read head out of the scale. The glass looks fine and I can't see any loose connections. The read head also seems to fit well in the scale. I get no response at all at the monitor. Is there anything else to check? Is it possible to just replace the read head?

Edit: I found replacement read heads online. Wow, are they expensive. Almost the price of a complete scale.

Have you checked the plug end of the lead to that reader head? Equally have you blown the head out with clean compressed air? Only takes one small spec of dust in the beam path to make em totally dead.

adama said:

Have you checked the plug end of the lead to that reader head? Equally have you blown the head out with clean compressed air? Only takes one small spec of dust in the beam path to make em totally dead.

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I swapped the cables at the monitor and the problem followed the X axis lead but I didn't check the plug end. I also didn't blow out the head with compressed air, just wiped it down from accumulated coolant gunk. I'll do both and check back again.

DROs have cables in motion. Before you spend a lot of money, you ought to try to check the cable itself. It's probably hard-wired at the read-head, but if you can gain access to the wire ends it would pay to check continuity for each wire back to the pins at the display end. If necessary, you could puncture the insulation with a needle probe to make that check.

Gordon Heaton said:

DROs have cables in motion. Before you spend a lot of money, you ought to try to check the cable itself. It's probably hard-wired at the read-head, but if you can gain access to the wire ends it would pay to check continuity for each wire back to the pins at the display end. If necessary, you could puncture the insulation with a needle probe to make that check.

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Good idea about checking wire continuity. I dove a little deeper into the head and found a lot of coolant inside where the wires are connected. That can't be good. Apparently the coolant entered around the metal sheathing and I'm sure some of it found itself under the thin plastic covering the wire connections. I'll try to dry/clean it out and also check for continuity to see if that helps.

Beeser,
A member here to contact would be HWElecRepair
he can probably help you.
spaeth

Beeser: Do yourself a favor and chuck the whole Acu-Rite system. Don't throw good money after bad. I purchased a new mill about twenty years ago with Acu-Rite readouts on it. After two years, I started having problems just like yours.I finally bit the bullet and purchased a new Sony system. Best thing I could have done, love them.

JH

spaeth said:

Beeser,
A member here to contact would be HWElecRepair
he can probably help you.
spaeth

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I'm in communication with Jon now. Thanks for the heads up.

At this point I see no reason to abandon the Acu-Rite system already on the lathe although the cost of a new replacement scale is expensive. Are there other scales from a different manufacturer compatible with the Acu-Rite 200S?

Call DROPROS. They can help you.

DRO PROS Digital Readout beats Heidenhain Newall Acurite Sargon Fagor

There are many scales that will work. There are two basic forms of quadrature scales - those with index (homing) marks and those without. Not sure what the 200 uses. Size will be an issue (and may limit your choices) if you are replacing the cross slide scale - sounds like you are.

Genuine Acu-rite scales will cost more, but they are good quality. If you chose another brand you may need to remount it; that can be time consuming to get "right" and you may need to make mounts for the head/scale. I just installed a 68 inch (yep, a bit longer than yours) scale with three mount points on rough castings. Took the best part of 2 days to make the mounts and get it dialed in.

beeser said:

I'm in communication with Jon now. Thanks for the heads up.

At this point I see no reason to abandon the Acu-Rite system already on the lathe although the cost of a new replacement scale is expensive. Are there other scales from a different manufacturer compatible with the Acu-Rite 200S?

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+1 for H&W, good guy.
Back in the dark ages when Acu Rite used incandescent bulbs in the reader heads I sent the reader heads to Dengel Associates in NJ to get the bulbs replaced when they burned out. Since LEDs have been installed I haven't had a failure.

There is a seller on ebay who sells scales compatible with just about every DRO. He's been mentioned here but I don't have a link. Newall sells scales that work with Acu Rite Newall Electronics, Inc

I have a very strong opinion on glass scales. The feedback already provided by others is quite solid.

If I were troubleshooting, I would get the pinout and use an oscilloscope to check for proper voltage and pulses. This would give you a pretty good idea where the problem lies. As stated, if a mechanical problem with wires its easy to fix. I have attempted to fix glass scales twice. Both were failing due to contamination. I had 50% success rate but even the repaired one only worked for another year or two.

Now for my opinion. Glass scale technology is old technology. It filled a nice void for many years where you got good resolution for a fairly good price. But the reliability is not good. They are subject to contamination and vibration - causes erratic and or total failure.

Today in the general encoder world magnetoresistive scales have taken over. The big advantage is the reliability and fairly low cost. They are sealed and don't suffer from vibration or contamination issues. I work with a couple vendors that produce magnetoresistive scales both rotary and linear.

I am at a loss why the DRO and CNC industry has not embraced magnetoresistive scales.

With that said, DRO Pros does offer magnetoresistive scales. They are made in India but I have used a set for many years and found the product to be solid. I retrofitted my Bridgeport with these scales last year when my x axis glass scale failed and and am quite pleased with the result. They are quite affordable. About to buy a set for my lathe.

Not saying you should abandon what you have. But look at what accuracy you need and see if it makes financial sense to replace with new or fix what you have. One Newall scale can cost nearly as much as a complete new system from DRO Pros.

Lakeside53 said:

Call DROPROS. They can help you.

DRO PROS Digital Readout beats Heidenhain Newall Acurite Sargon Fagor

There are many scales that will work. There are two basic forms of quadrature scales - those with index (homing) marks and those without. Not sure what the 200 uses. Size will be an issue (and may limit your choices) if you are replacing the cross slide scale - sounds like you are.

Genuine Acu-rite scales will cost more, but they are good quality. If you chose another brand you may need to remount it; that can be time consuming to get "right" and you may need to make mounts for the head/scale. I just installed a 68 inch (yep, a bit longer than yours) scale with three mount points on rough castings. Took the best part of 2 days to make the mounts and get it dialed in.

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Finding something that is a direct replacement to the Acu-Rite scale is a big plus regardless of whether it's a new complete system or just a replacement scale. I really don't want to tackle mounting something from scratch.

markz528 said:

Today in the general encoder world magnetoresistive scales have taken over. The big advantage is the reliability and fairly low cost. They are sealed and don't suffer from vibration or contamination issues. I work with a couple vendors that produce magnetoresistive scales both rotary and linear.

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Can you explain how they work in a paragraph? I googled and got lost immediately.

Mud said:

Can you explain how they work in a paragraph? I googled and got lost immediately.

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Essentially like a cassette tape. I believe they use a mylar type of material (I will find out exactly) and it looks like a long tape. Then they print a magnetic image on the tape. The reader reads the magnetic imaage.

There is a minuscule chance that the tape can be demagnetized - just like a cassette tape. In reality never heard of it happening.

markz528 said:

I am at a loss why the DRO and CNC industry has not embraced magnetoresistive scales.

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??? I don't know where you've been or what your talking about, but my lathe and mill both use magnetoresistive technology. Both 1um . Cheaper(not by much) and as reliable or more, than glass. Both of my DRO's are from M-DRO from UK.
The nice thing about them is simplicity in mounting, are impervious to most coolant types and can be cut to any length. For me, that's the biggest plus.

Just my two cents.

Rigor said:

??? I don't know where you've been or what your talking about, but my lathe and mill both use magnetoresistive technology. Both 1um .

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It's still Sunday in Canada. Are you half buzzed? Have a read of it again. I think you are in violent agreement. Then try not to punch yourself in the nose.

markz528 said:

I am at a loss why the DRO and CNC industry has not embraced magnetoresistive scales.

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