Need Help!- Steep servo motor (encoder) repair bill? advice please!

[aaronmk]

Hey everyone. I have a 1994 Light Machines VMC that i picked up for $5k in working order. the other day, i powered it on and the X servo instantly went full speed sending the table slamming to the left and breaking the drive belt. i removed the servo (a Litton - Clifton Precision servo) and noticed something loose and rattling in the encoder housing. I sent the servo off to ACS Industrial Services, Inc. for a quote to repair it. I didnt have much luck finding any other companies that sell or repair this servo. the quote came back at over $1600 to repair the encoder. this is substantially more than i guessed it would be but i have no baseline other than it would represent about a third of the cost of the whole unit. my questions are:

Is this price reasonable?
what are my other options?
know of any other repair companies?
what are the odds that the other 2 will do the same thing sometime soon?
would updating the entire system (computer and all) be worthwhile and cost effective?
what could have caused this so that i dont repete the same mistake?
is flood coolant interaction with the servo a possible reason for failure?
could i directly replace the encoder with a new model?

thanks in advance for any advice. I really appreciate all you active forum users!

-Aaron

[mike_Kilroy]

Originally Posted by aaronmk ....servo (a Litton - Clifton Precision servo).......repair this servo. the quote came back at over $1600......my questions are:

Is this price reasonable?
---$ 1600 is not unusual rpr cost for a servo motor if it is in bad shape....

what are my other options?
--- find another source to try? repairing yourself is probably not good choice as u wont have the right kind of parts.....

know of any other repair companies?
--- I know one: us. pm or email me (email in my name listing)

what are the odds that the other 2 will do the same thing sometime soon?
--- who knows? if this one has lots of coolant running on it and the other 2 do not prob not real likely....

would updating the entire system (computer and all) be worthwhile and cost effective?
--- depends on size of present motors and drives and how they talk to the control. we size and sell retrofit packages but no way to tell price w/o details on present stuff....

what could have caused this so that i dont repete the same mistake?
is flood coolant interaction with the servo a possible reason for failure?
--- if you are asking, I am assuming the motor was wet... yes, this is a a-number 1 cause of motor failure and possible run aways.

could i directly replace the encoder with a new model?
--- maybe. r u getting the motor back unrepaired? hopefully they will return no charge (other than shipping costs) to you like we do. if so,m take pictures and post and list encoder part no if you can find it and maybe we (collective cncforum - we are encoder distributor too) might be able to recomend a replacement.

Aaron, Clifton usually made either real small motors (1-2" dia max) or full blown military servos. tell us what physical size that motor is... if only 1-2" dia it may be worth looking at a low cost instrument motor/enc replacement or seems like the rpr charge should be 1/2 or less than 1600....

[Iron-Man]

Originally Posted by aaronmk Hey everyone. I have a 1994 Light Machines VMC that i picked up for $5k in working order. the other day, i powered it on and the X servo instantly went full speed sending the table slamming to the left and breaking the drive belt. i removed the servo (a Litton - Clifton Precision servo) and noticed something loose and rattling in the encoder housing. I sent the servo off to ACS Industrial Services, Inc. for a quote to repair it. I didnt have much luck finding any other companies that sell or repair this servo. the quote came back at over $1600 to repair the encoder. this is substantially more than i guessed it would be but i have no baseline other than it would represent about a third of the cost of the whole unit. my questions are: Is this price reasonable? what are my other options? know of any other repair companies? what are the odds that the other 2 will do the same thing sometime soon? would updating the entire system (computer and all) be worthwhile and cost effective? what could have caused this so that i dont repete the same mistake? is flood coolant interaction with the servo a possible reason for failure? could i directly replace the encoder with a new model? thanks in advance for any advice. I really appreciate all you active forum users! -Aaron

This seems very high. I have designed a system from scratch. I ended up using Litton Clifton Motors. They were purchased brand new on ebay for 34.00. I only had to change out the encoders. Total cost per servo motor was approx 45.00 including 500 cpr encoders. In my original search for new servo motors, I was quoted ~ 1200.00 for a new motor. This was way more than I wanted to spend. You can still find these motors on ebay. I believe seller 80servo still has some left. You will have to add encoders. Depending on what you need, these can be found new at great discounts.
You can see my work here: http://www.cnczone.com/forums/bencht...d_candy-4.html

80servo: 80servo | eBay

I just checked and it seems that he is out.

Things to check. If you have an oscilloscope, you can check the encoders. The rattling sound could be a broken encoder disk. Check all the cabling, especially the encoder wires. A servo running out of control could just be a bad encoder or wiring. Make sure that no initial settings were changed by accident in delivery. Try to find the specs on the motor and encoder. Look for these on ebay and if possible do the repairs yourself.

Hope this helps,

Iron-Man

[Al_The_Man]

Originally Posted by aaronmk Is this price reasonable?

Seems really on the high side to me, especially as mentioned, Litton are usually small motor manuf.?
As an example, a typical replacement high end Mitsubishi motor and encoder is usually less than you were quoted for a encoder repair.

Originally Posted by aaronmk what are my other options?

Look for a compatible encoder, whether through shaft or shaft coupled, the cost would be WELL below that, there are several manufacturers out there.

Originally Posted by aaronmk know of any other repair companies?

There are many a search with google will turn up, get quotes from more than one first.
Usually the replacement is often cheaper than the companies that offer encoder repair.
It is ofen a fairly straight forward task to replace an encoder, the exception is if it has commutation tracks, but even this can be done with the help of a dual trace 'scope.

Originally Posted by aaronmk what are the odds that the other 2 will do the same thing sometime soon? would updating the entire system (computer and all) be worthwhile and cost effective?

It is impossible to predict, but encoders are built fairly rugged, most are glass disc and are used in some very harsh environments.
Al.

[pimpbike]

Did you try contacting www.lightmachines.com?
I doubt they will charge you $1600 for a replacement encoder that's just highway robbery!
Find the encoder part# and look up the specs. You may be able to get a replacement at low cost from Usdigital.com

I would definitely check your encoder wire for any bad connections as this can cause a runaway. Check your limit switch also as it should have stopped the drive from breaking your belt. If the y axis servo is the same as the x, I'd try disconnecting it and bench testing the x axis making sure your x axis servo drive is not on the fritz.

Goodluck!

Dan

[aaronmk]

Thanks for all the advice guys. I tried switching the servos to test the driver but it is too smart and knows right away that there is a missing servo and wont send power. I am having such trouble finding a supplier or repair person online that will even contact me back. very frustrating! mike_Kilroy, I sent you an email; are you (or anyone else) still interested in taking this on? I would be happy with either a replacement or a repair, I just need to get the machine running again. attached is a photo of the servo moter.

Here is the information on the servo/encoder:

CP 550-1000-LD 1396
P/N 32-0000-0027
(invoice says it is part number: 31-1200-0043)

again, thank you all so much for your quick replies!

-Aaron

[Al_The_Man]

If you get stuck I may be able to help.
It is a DC brushed motor so it should be straight forward, what is the diameter of the rear shaft? 1/4" ?
BTW, quite a while ago I picked up a raft of those motor from our local surplus store, $24.00 each complete with pulley!!
I don't think I have any left.
Al.

[pimpbike]

Is there any numbers on the encoder? What did intelitek say when you contacted them? I'm curious...
Here's an idea. Swap X and Y motors and leave them both plugged in and bench test it. If the y axis motor plugged in x axis drive still takes off I would look at the encoder wire and test it

[awerby]

But I'm cheap...

Is this price reasonable?

[It may take micro-surgery to put that old encoder back together again. But that doesn't mean it's really worth doing.]

what are my other options?

[Replace the encoder, replace the motor/encoder assembly, replace the whole servo system. ]

know of any other repair companies?

[They'd probably want the same amount. This is why people in this country don't bother trying to repair things...]

what are the odds that the other 2 will do the same thing sometime soon?

[It's hard to say; they could last for years more, or go out right away.]

would updating the entire system (computer and all) be worthwhile and cost effective?

[You could probably do it for $1600 and still have money left over. If it's all running on a 1994 computer, it's definitely worth considering. But getting the ATC to work without having the software might be a challenge. Ask Light machines what they advise; they might have an upgrade path, or at least new software that you can install.]

what could have caused this so that i dont repete the same mistake?
is flood coolant interaction with the servo a possible reason for failure?

[It wouldn't have done it any good. But this was probably damaged in shipment.]

could i directly replace the encoder with a new model?

[Maybe. Is it an encoder or a resolver? Resolvers are trickier to deal with. There's a Clifton motor on Ebay that looks similar: Item # 380119597437 ]

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[Al_The_Man]

I checked on my stock, I have one motor but does not have the encoder, do you know what resolution it is? I have a few 1/4" Renco that may work.
There is probably a parameter where you can set the resolution which would not make it so critical to replace with the same Counts/rev if you knew it.
The thing to watch with the ebay types, is if it is the same voltage, there were a few variations made for OEM's.
Al.

[mike_Kilroy]

Aaron, sent you an email too; we recvd ur motor today. the encoder disk is off the shaft hub. Here are choices:

We can do one of 9 things for you:

1. Charge you $1600.00 and repair it (joke)
2. Return no changes, no charge (u pay shipping)
3. epoxy glass disk back on shaft hub & return untested ($ 50 plus shipping)
4. same as 2 but also test encoder outputs ($ 150 plus shipping)
5. same as 3 but also test motor ($ 175.00 plus shipping)
6. replace encoder with new 1000PPR one (u said u thought it was 1000ppr) $ 300 & 2 weeks
7. try to test enc PPR and then replace with same value $ 450 & 2 weeks
8. replace with stock 1024ppr 5v differential output encoder here $ 100.
9. send you this enc with same hub size as spare encoder $ 50.

[aaronmk]

As an update, Im making parts again! I sent my servo to Mike Kilroy to get it repaired and they ended up needing to replace the encoder. This was done at a much more reasonable price than the origional company's quote. Thanks Mike for the great service and great price. If anyone out there needs machine repair, give Mike a call. He's a pleasure to work with.

-Aaron