# Contact Burnishing Tool



## Big John (May 23, 2010)

I need to be able to remove oxidation from electrical contacts in tight spots. I can't use a regular contact file because they're too abrasive and will create metal shavings.

I'm thinking of a long handle (maybe 8-12") tool that would grip a small piece of Scotchbrite or maybe a piece of fine emery cloth so I could get it into tight areas.

Anyone have any recommendations?

-John


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## Mouser (May 4, 2011)

Forcepts?


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## B4T (Feb 10, 2009)

I was told filing down the contacts was a bad idea because the very tip is a different metal alloy that the rest of the contact..

All I am doing is buying a little time before the assembly has to be changed.. 

Was I given bad information??


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## Big John (May 23, 2010)

B4T said:


> I was told filing down the contacts was a bad idea because the very tip is a different metal alloy that the rest of the contact..
> 
> All I am doing is buying a little time before the assembly has to be changed..
> 
> Was I given bad information??


 I guess it depends why you're cleaning the contacts. If you've got seriously pitted/corroded parts, yeah, cleaning them is only buying time because the surface dirt is only part of the reason the contact is poor.

But if the mating surfaces are in decent shape, then giving it a light buff can do a lot to improve the conductivity of the contact: I've seen ratings of a several hundred micro-ohms improve down to 40-50 micro-ohms after cleaning.

Just be careful of shiny parts: Often they are silver coated copper and the silver is a protective layer; if you expose the copper underneath the contacts can deteriorate more quickly.

-John


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## Bbsound (Dec 16, 2011)

B4T said:


> I was told filing down the contacts was a bad idea because the very tip is a different metal alloy that the rest of the contact..
> 
> All I am doing is buying a little time before the assembly has to be changed..
> 
> Was I given bad information??


All though filing and polishing are technicaly the same thing, they are different.


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## Big John (May 23, 2010)

Mouser said:


> Forcepts?


 That might actually work... in addition to creating countless hours of amusement where I pretend to be a surgeon.

-John


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## John (Jan 22, 2007)

I have had good luck with glass bead blasting. The process actually peens the contact surface and removes very little material. Motor starter replacement contacts are very expensive and by very carefully bead blasting the contacts saves having to replace them.

http://www.wisegeek.com/what-is-bead-blasting.htm


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## Jlarson (Jun 28, 2009)

I have some little diamond contact burnishing tools from Jonard industries, I think, that I use extremely sparingly for emergency repairs. Between those and a clean cotton rag and some contact cleaner I usually have good luck.


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## Dave L (Jul 6, 2011)

This is what I would suggest. I use mine to clean molex pins, They start out dark brown and after a few swipes they look like new. 

http://www.mcmelectronics.com/product/SABU10191


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## Zog (Apr 15, 2009)

John said:


> I have had good luck with glass bead blasting. The process actually peens the contact surface and removes very little material. Motor starter replacement contacts are very expensive and by very carefully bead blasting the contacts saves having to replace them.
> 
> http://www.wisegeek.com/what-is-bead-blasting.htm


It also removes the silver plating. Plus I am pretty sure John is not able to disassemble the contacts.


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## Big John (May 23, 2010)

Ayuh, this is in place PM, there ain't no way I'm gonna try and remove these contacts in the field. 

I'll grab one of those fiberglass pencils, and unless someone's got a better tool, 9" sponge-holding forceps for $7:








Thanks.

-John


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## John (Jan 22, 2007)

Zog said:


> It also removes the silver plating. Plus I am pretty sure John is not able to disassemble the contacts.





Big John said:


> Ayuh, this is in place PM, there ain't no way I'm gonna try and remove these contacts in the field.
> 
> I'll grab one of those fiberglass pencils, and unless someone's got a better tool, 9" sponge-holding forceps for $7:
> 
> ...


If you are just doing PM's, a good contact cleaner would be the best. I thought it was repair work.:whistling2:


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## Wirenuting (Sep 12, 2010)

John said:


> If you are just doing PM's, a good contact cleaner would be the best. I thought it was repair work.:whistling2:


x2 
I would clean them with contact cleaner for a PM and only dress them as a get thru while waiting for new contacts.


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## Big John (May 23, 2010)

John said:


> If you are just doing PM's, a good contact cleaner would be the best. I thought it was repair work.


 I should've been clear, for repair the contacts do get bead blasted and replated, but this is just in-place maintenance where a good cleaning can improve the ductor readings.

-John


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## Wirenuting (Sep 12, 2010)

Big John said:


> I should've been clear, for repair the contacts do get bead blasted and replated, but this is just in-place maintenance where a good cleaning can improve the ductor readings.
> 
> -John


I never heard if bead blasting. 
Is there a size to think about doing that?
ie: size 3 and up?


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## John (Jan 22, 2007)

Wirenuting said:


> I never heard if bead blasting.
> Is there a size to think about doing that?
> ie: size 3 and up?


I did a size 4 starter a while back and the contact kit was close to $800.00. Bead blasted the contacts and it worked out very well. The starter was over 25 years old and it will probably last maybe another 7-10 years before the contacts or motor starter needs to be replaced. An IEC starter would of been a cheap option if the contacts needed to be replaced. 

Bead blasting is not the the same a sand blasting, it's like taking a very, very small hammer and pounding the metal flat. very little if any material is removed.


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## Wirenuting (Sep 12, 2010)

John said:


> I did a size 4 starter a while back and the contact kit was close to $800.00. Bead blasted the contacts and it worked out very well. The starter was over 25 years old and it will probably last maybe another 7-10 years before the contacts or motor starter needs to be replaced. An IEC starter would of been a cheap option if the contacts needed to be replaced.
> 
> Bead blasting is not the the same a sand blasting, it's like taking a very, very small hammer and pounding the metal flat. very little if any material is removed.


Thanks. 
I'll call our local supply house and get a base price. 
We have a lot of 25+ year old starters size 3+. 
Most just get new contacts. But some coworkers are replacing the contactor with what ever they can find, same with the o/l blocks. They never fit but that don't stop them. I hate it as it lets people open the can and hit the reset. People seem to like watching it pull in.


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## KayJay (Jan 20, 2008)

I just use the flexible 320 grit burnishing files for polishing chiller contacts. They are about as abrasive as a sheet of writing paper. You need a bunch of them though because they don't last long. I get them from McMaster.
BTW, I was always told that both emery and crocus cloth are conductive, so I never them for cleaning contacts unless I can flush them after.


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## TTW (Sep 14, 2012)

When I was in the Coast Guard I happened to snag one of these, used it a few times, alas, lost it long ago. It seems they are still around.

http://www.amazon.com/Jonard-Burnisher-Contact-Pocket-007/dp/B0000YHVCQ


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