Slightly OT: Drum Switch Lubricant

Hi,

I know this is slightly off-topic, but I figured that one of you guys would know something about it. I'm in the process of rebuilding one of those rotary drum reversing switches for a machine tool. The contacts are dirty and slightly corroded, but in pretty good shape overall. They seem to have the remainder of some kind of lubricant on them, and I'm wondering if they should be relubricated after cleaning. They are a "wiping" style of contact, and operate a fractional HP single-phase motor. If so, what is a good lubricant to use?

Thanks,

Paula

DO NOT use spray style contact cleaner to clean the contacts. If you do it may solve problems only temporary but the dirt and dust will attract to the cleaner residue and cause intermittent contact problems later.

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This is probably the reason they appear oily now, someone used WD40 or some form of spray lubricant/cleaner. These switches may build up carbon residue depending on enviromental conditions and also appear oily.

I would thoroughly clean and dry the contacts.

TECHNICALLY I would throw out the drum and use a micro plc like the DL05....alot cheaper and less maintenance.

You should contact a lubricant manufacturer to determine the correct "grease". I know that some large disconnect switches use lubricants from Mobile while others use ones from Dow Corning.

As for cleaning the existing grease there are specific products available from CRC Chemical and LPS designed not to leave residues on electrical contacts and also not destroy insulating components.

Ron, it sounds like her drum switch controls the motors directly through horsepower rated contacts.

Paula,
White Lithium grease on the shaft only, the contacts should be DRY. The contacts are usually silver flashed copper/nickel (Those I've seen anyway)

I use 1500 grit to refurb contacts and a thick business card for final polish

WD40 or any oil type spray will definitely cause the contacts to weld/stick
I do use a non-flammable brake cleaner to hose down contactors
(I'm betting other's will weigh in on this)

But then again, I use a mix of Slick50 and ATF to free up bearings while the new ones are on order.

Rod (The CNC Dude)

Rod said:

Paula,
I do use a non-flammable brake cleaner to hose down contactors
(I'm betting other's will weigh in on this)

But then again, I use a mix of Slick50 and ATF to free up bearings while the new ones are on order.

Rod (The CNC Dude)

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LOL I love brake cleaner!!..Its also usefull on the hands to get rid of the grease..a little chilly going on and stings a tad on the cuts..but it cleans the hands!!!..also leaves them a little white afterward..but there clean!!

As for the drum switch. I myself have never come across one thats needs servicing..(unless it sat for years without being used)..And all the ones i ever worked with were in feeding rooms in farms, They controlled the silo winch, across the line forward and reverse.

The only "service" we ever had to do was take the cover off and get the silo dust out them. Most of the time it took a screwdriver to get the worst of it out (Once that stuff packed in there and damp its like cement!!) Then blow the switch out with an air gun..good to go for another 10-15 years!!

Quite a few had pit marks on the contacts but nothing so bad that i would consider sanding and cleaning..

In short i would say the drum switches are one reliable piece of equiptment, I would not use any kind of grease on the contact points, As others have said all its going to do it attract dust..

Just my 2c

D

PS just talking about drum switches brings back memories of trade school!! any else remember hooking up 11 or was it 12 point drum switches for 3 phase motors?? LOL

D

Paula, take a picture of the drum and post it. Then everybody's who's thinking along the lines of relay contacts will see that you may actually be refering to a sliding contact, and not just a little wipe as the contacts lift open or closed.

The lubercant your looking for may be something like this: http://www.echeloninc.com/contactlubricants.htm

http://www.syn-techlube.com/Electrical%20Greases.htm

Dont use a "run of the mill" lubercant as the arching will cause it to burn and eventually gum up the works.

Wow, thanks for all the replies!

Didn't want to make too much of this, since it's just a little fwd-stop-rev switch on an old bench lathe. In fact, it still seems to work fine, but since I'm going through and fixing up the rest of the machine, I might as well do the switch.

Don't laugh, but since I've been in my new house, I've been putting together a little workshop, and I picked up this old South Bend at a good price:



It's actually in very good shape, mechanically, but I decided to give it a bit of a facelift. You can see the little drum switch on the top left side. I would take a picture of the inside of the switch, but it's in pieces right now. The contacts are blackened, and there's some kind of residue on the edges of the contacts that looks like coagulated lubricant. From what you guys are saying, it sounds like cleaning and running them dry is the way to go. They won't really see that much wear.

Thanks again,

Paula

I NEVER use sandpaper or emery cloth to clean contacts. These do nothing but make the problem worse. Sandpaper embeds in the contact making a higher resistive connection and causing more arcing and pitting. The right way is to use a contact burnishing tool (or crocus cloth in an emergency) to lightly dress the contacts. If these are sliding contacts, then a conductive grease should be very sparingly used. I would use Cool-amp (I think that is what it was) and after putting on a small amount, then I would wipe it off with a clean lint-free rag. There would still be a small coating on the contacts, but there should be nothing visible. Note that conductive greases have silver in them and are expensive and very conductive so you can cause tracking if you get it place you don't want.

With all that said, since this is a small lathe, I would probably not worry with all this and clean them with some contact cleaner and be done. Worse case would be to replace it with another drum switch which can be bought for about $20. Most of what I stated I've used in power equipment and critical relays.

Paula,

If you find a tool stock/post for your SB Workmate, Please let me know where you got it. I have the exact same lathe; (It was my Grandfather's)Some how the post went missing during the last move.

I was thinking Drum Sequencer not REVERSING Drum Switch, the details are important.

In the old days we use to, as a joke, send helpers looking for a left handed monkey wrench or light bulb grease, these days they actually have light bulb grease.

In 30 years of working with these types of Drum Switches I have never used or heard of using a lubricant on the contacts. The literature for these devices is hard to find but I find no reference to using any lubricant. I can provide wiring literature.

In general I have always thought clean and dry was how electrical connections should be, any grease, oil etc would change the dielectric constant of the material used for the contacts, just as pitting will do over time. The rotating device may be lubricated. In most case, if not all, you never want to use a petroleum based lubricant, they are usually have a low flash point. Lithium stearate is a high temperature grease that also resists water/moisture.

One of the first places I looked was the McMaster-Carr catalog, and they had the conductive grease that Bruce mentioned above. It's expensive due to the silver content, and probably overkill for this application. Sounds like I just need to clean the contacts (non-abrasively) and let it go at that. I don't want to replace the switch, as it's the original South Bend switch that came with the lathe in 1947.

Mike,

Is this the part you're talking about?:



If so, you can usually find one on eBay. Unfortunately, South Bend stuff is hot right now, and these things usually go for thirty or forty bucks.

Thanks for the help, guys!

Paula

I can fix it! A AD06DR and...

I'm guessing the blackening and pitting is from using the reversing switch to 'brake' the motor (all guilty raise your right arm - NO the OTHER right arm)

I'd just flush the parts, polish the contacts and check for severe pitting. Ignore the pitting, re-assemble with a dab of Lithium (not on the contacts), as Ron said, and run the little guy. You wont run it that much. A quick-change tool post and a 4-jaw chuck and you're good to go.

Mike,
I'll look for the tool post, I deal with machine tool parts - will PM if I find one.

Rod (The CNC Dude)

Paula & Rod,

I've had a hard time finding the post for that tool stock. We've three other lathes, and talked to a few local MT suppliers, but no luck.... Actually I wasnt the one looking. I delegated it (the search) about a year ago.. and I'm still just left with a rotary pole sander... About once a month I mention it to our shop and I get Yea Yea Yea, we cant find it... But I just found a website for South Bend so I'll give them a call Monday myself.

My SB is older then yours, as there's no gearbox to the right of the drivescrew. I've just got a selection of gears and a chart to indicate which gears for what speeds or threads etc...

Be sure to keep your workshop heated enough so that you dont get condensation on your lathe. Otherwise you'll just break into tears when the lays etc.. are covered with rust. If you keep it nice and toasty then dont worry about the contact grease. But if it's in a barn or garage, I'd grease em' up.

A few years ago I helped a friend with a couple of davits. We bought new drum switches (AB I think), and they came with a little tube of lube for the contacts. He didnt think it was right to dirty the contacts with grease, (ha ha) so the next spring we were back at Mac & Mac for new switches. They got the grease the second time around....

Edit: Whooa! Paula thanks for the ebay links!!!

I Googled and found my favorite Quick Change Tool Post made by TS Engineering

for a $100 you get the post and 4 tool holders:

http://www.littlemachineshop.com/products/product_view.php?ProductID=1785

I HAD a used Hardinge CNC that I stuck a 4-jaw on - real sweet

Make them blue chips

Rod