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Relay Repair

rbdjr59

Cast Iron
Joined
Jan 28, 2014
Location
Houston, USA
I have an old (mid 50's) Devlieg 3B-48 that has been more or less sitting for the last decade. I now am trying to put it back into service but am having troubles with the machine tool relays not functioning properly. One day everything works fine all day long but when I come in the next day my table feeds and rapids won't work or it won't switch between the table and head. Is it possible and/or advisable to try and rebuild these MTR's?FMCTechnip 147.jpgFMCTechnip 148.jpg
 
I have been cycling them for a long while. When the machine is running fine all is well with the world. When it stops my stress and frustration levels go off the charts. I don't have the money in this to pay an expert so I am looking for solutions that I can perform. I've been told that these relays can be rebuilt and that seems like something I may be able to do. I need a fix for this if anyone has any ideas.
FMCTechnip 151.jpg
 
You should get hold of an old pensioned off geezer who has grown up with relays and who could be tempted to find the fault(s). It may take a while but would not cost much, a few beers maybe and some boring talk of the good old days.
Sounds like a quite banal fault. Take out the main fuses and see if the proper relays switch on when supposed to. Clean all contacts involved.
Yes, it can take some time but the advantage with relays is you can actually see and hear when they function - or not.
I would be tempted but Houston is more than I can manage these days.
Good luck! fusker
 
Been down this road before; Sit down with a libation of choice and think about it.

I worked a Large American Pacemaker with a very similar configuration, Those relays, contacts, coils, springs and enamel are old. Even if you were to find a person with skill you still need parts...they are old.
With the new tech on the market it would not be a difficult task to eliminate/replace them completely.
I might go with a micro controller (yhea little over the top). Just do some research on the gargler here and see what options are out there, searching is free all it costs is your personal info!!
Call some relay/contactor places they are there to help you.
I have done 2 of these type conversions so if you have any questions just PM me happy to help.
 
It looks like there's some mechanical interlocking. I would look very carefully at that - something gets a little bent, and suddenly neither relay closes.

Failing that... find a circuit diagram, and you might be able to like-for-like it with new gear.
 
I need a fix for this if anyone has any ideas.

Ten years is a long time and a lot of opportunity for corrosion to work its way in. Clean the contacts and whatever you see.
Unscrew every connection one at a time and brush the surface with a wire brush. You can't lose.

(Don't screw up the slotted heads with the wrong size screw driver. Work on it with kid gloves and make it look like nobody ever messed with it. Make it sanitary again)
 
Well, I guess I'll try the old "take it apart and put it back together" plan and see what I can find. I've thought about trying to modernize but several people who would know have told me that these relays are great for the task and rebuildable, rugged as well.
 
Before you dig into tearing apart stuff, tell us was happens. Runs fine, then reverses but it will not go. Runs fine but shuts off while the machine is running, Will not start when cold, will not start when hot...you get the picture? When it fails are contactors closed or open. The problem may be and probably is somewhere else.

Tom
 
The most likely issue you are having is not electrical at all. DeVlieg used a lot of limit switches to sense things such as the way locks on and off, transmission lever location etc. Usually when a machine sets like yours and has weird symptoms, the issue is one or several of the limit switches are stuck. DeVleig liked to use a lot of plunger type switches and the plungers stick, usually in an intermediate position. DeVlieg also likes to use both normally open and normally closed position senses so a sticky switch effects more than just the one thing you would think it senses.

If you have your wiring schematic, hunt down every limit switch and verify that it is functioning correctly in both positions. Some WD40 or PB Blaster also will help immensely.
 
I would not use something like WD-40. Junk will just stick to it and cause problems down the road. A gallon can has a picture/drawing of a open electrical
switch box with a spray can nozzle pointing into the box. What a joke.
 
The relay pair on the right is probably an 'excluding' type interlock... which means it's either Y-D start, or a direction-reversing circuit. The mechanical interlock prevents one side from being closed while the other is closed.

Check the plunger switches per Zig's comment (make sure you don't have an errant signal holding one relay high). A giveaway, if it's stuck in one mode, is to check-see if the interlock bar is toggled in one direction, but the coil is not energized... if you see that circumstance, it means the mechanicals are simply stuck. IF the coil is energized, it means you've got a control elsewhere that is still energized when it shouldn't be.

Gut feeling is that the limit switches are 'snap action'... they have an overcenter spring type mechanism, and if they're glopped up inside, they're not returning after being actuated... opening, cleaning, and reassembling will fix that.

If it really IS the interlock mechanism, then disassembly will reveal dirt, crud, and worn spots. Dressing the worn spots on pivots and fulcrums, cleaning burrs from the sides of wear surfaces, or making new bushings for worn holes will do well after cleaning corrosion. A brief visit from a wire wheel frequently works wonders... a dremel with one, and another with a white stone will resolve many ails.

The only other thing that comes to mind, and it doesn't happen often, but can...

IF the polepiece of a contactor winds up in the path of a strong DC discharge, it can become magnetic, which can cause the contactor armature to 'hold' when it shouln't. Typically, AS will de-gauss the circumstance, but not always. Not likely, but a non-magnetic screwdriver touched to the polepiece with no power will tell you... if it sticks, it's been magnetized. Don't think it happens on machine tools much, but I've seen it happen on trains when an axle grounding shoe went bad... traction current took a different path...
 
You should get hold of an old pensioned off geezer who has grown up with relays and who could be tempted to find the fault(s). It may take a while but would not cost much, a few beers maybe and some boring talk of the good old days.
Surely. If the BS and War stories is ALL yah want.

Where WORK is involved? Still $2,500 Euro/day, portal to portal, First class air, four & five star meals and lodging, and 30% of the estimated time - 3 day minimum, unless yer on a hefty retainer already - and paid up-front.

Might be cheaper yah buy a contact burnisher,


Contact Burnishers

...clean any varnish, rocks, gummy seminal fluids, rodent turd and dog hair outta the housing, armature, & rocker, springs, or hinging, check spring tension, conductivity of rivited leads, hidden corrosion or faulting at crimps in general.

...tell whatisface to go run HIS contacts all raggedly-ass when he starts with the "leave the contacts ugly, they are smarter than humans, rougher the better." BS.
 
I wondered when Thermite would show up, no substitute for his style! Thanks to all for their input and I will try to cover all the comments with my reply. The major malfunction is that the machine has a switch that changes the feed/rapid function from the spindle head (up/down) to the table (left/right). The problem occurs when I switch from the table to the head and then back to the table. The machine stays stuck in the head mode. I know just enough about electronics to make me dangerous but it seems to me that one of these relays is sticking and not letting the machine switch. I'm thinking I need to go in there and clean up/refurbish as able these two relays and see if it will stay working. FYI, the machine works fine for a couple of days and then locks up. A couple of days later it magically begins to work again! The switch in question is on the top row, 4th. switch. FMCTechnip 149.jpg I am aware of the complexity of this machine as to the interlocks and limit switches but am praying that the problem is these relays. I have cleaned and exercised all of the easy stuff all ready so we will see. thanks again for the help.
 
Relay cleaning cleaning is an art...

Do not use abrasive or sprays yet.

A voltmeter to measure across contacts at terminals will show if connected so you can troubleshoot.

If you want to just do all of them then you can do one at a time.

Take photos then remove it to get clearance if needed.

Cut plain printer paper into long strips same width as the contacts and place between contacts and with gentle pressure pull paper through.

This cleans them.

Paper is about 6000 grit and will not remove much metal but will polish well

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
I would check for a voltage on the coils of these relays if working properly and in fault mode
If voltage is the same in fault mode the relays are malfunctioning
If you have no voltage on a coil that should be getting any the problem is not the relay

Peter
 
I wondered when Thermite would show up, no substitute for his style! Thanks to all for their input and I will try to cover all the comments with my reply. The major malfunction is that the machine has a switch that changes the feed/rapid function from the spindle head (up/down) to the table (left/right). The problem occurs when I switch from the table to the head and then back to the table. The machine stays stuck in the head mode. I know just enough about electronics to make me dangerous but it seems to me that one of these relays is sticking and not letting the machine switch. I'm thinking I need to go in there and clean up/refurbish as able these two relays and see if it will stay working. FYI, the machine works fine for a couple of days and then locks up. A couple of days later it magically begins to work again! The switch in question is on the top row, 4th. switch. View attachment 287553 I am aware of the complexity of this machine as to the interlocks and limit switches but am praying that the problem is these relays. I have cleaned and exercised all of the easy stuff all ready so we will see. thanks again for the help.

There should be a limit switch that senses which way the the drive power is connected, Head/Table. That is where your problem is. It is very unlikely to be in the relays. Usually these are a plunger actuated limit switch.
 
Electromechanical relays have two “lifespans”, an electrical lifespan of the contacts and a mechanical lifespan of the moving parts. Typical values to which devices like MTRs were made would be 1 million electrical operations (at full load) and 10 million mechanical operations. Contacts can be changed or repaired so you can “respawn” from an electrical standpoint, but the mechanical lifespan takes into account ALL of the components, some of which never move but begin to fall out of tolerance.

10 million operations sounds like a lot, but considering that Square D stopped making that line of relays 40+ years ago, and hasn’t supported them for the last 30 years in terms of replacement parts, I would not waste time and energy trying to repair them. You can replace contacts, but from the sounds of it, your problems are more mechanical in nature and although you might be able to find and custom make one Bad part, it’s just going to move the strain and stress to the next weak link in that chain, to where you will be spending more and more time than it is worth to keep It running. Just replace them with more modern components. Those mechanically interlocked relays actually look like a reversing contactor, so a small IEC reversing contactor would likely take its place.
 
"the machine has a switch that changes the feed/rapid function from the spindle head (up/down) to the table (left/right). The problem occurs when I switch from the table to the head and then back to the table. The machine stays stuck in the head mode."

Then the problem is the switch, not the relays!!
 








 
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