Nickel vs copper shim material for crush fit

Mud · Oct 15, 2020

Had an experienced rebuilder recommend I use pure nickel shim material to correct the fit of shell type plain bearings in a machine because that's how he does it. Another says brass or steel would be OK but he hasn't actually done it
.
Think of a situation similar in size to the main bearings or rod bearings in an auto engine, about 3" diameter and 2" wide. I need to change the fit by .014 on the diameter to get the correct crush, so I'm considering using .007 shim in the saddles. The alternative is a new iron casting, other methods of refit are not practical here because of tight clearances and the way the machine is constructed. Oversize bearing shells are not available.

This NOT an auto engine, don't lecture me on engine bearings please.
Nickle is hard to find and very costly in the amounts it is sold in. I'm wondering where nickel shim is commonly used or what it's intended to be used for, has anyone here used it for a specific purpose?

Copper shim is also soft and conformable and conducts heat well, since it's a lot more available and much cheaper (hundreds$) I'm looking at using it instead of the nickel.
Thoughts? Experiences?

thermite · Oct 15, 2020

Mud said:
Had an experienced rebuilder recommend I use pure nickel shim material to correct the fit of shell type plain bearings in a machine because that's how he does it. Another says brass or steel would be OK but he hasn't actually done it
.
Think of a situation similar in size to the main bearings or rod bearings in an auto engine, about 3" diameter and 2" wide. I need to change the fit by .014 on the diameter to get the correct crush, so I'm considering using .007 shim in the saddles. The alternative is a new iron casting, other methods of refit are not practical here because of tight clearances and the way the machine is constructed. Oversize bearing shells are not available.

This NOT an auto engine, don't lecture me on engine bearings please.
Nickle is hard to find and very costly in the amounts it is sold in. I'm wondering where nickel shim is commonly used or what it's intended to be used for, has anyone here used it for a specific purpose?

Copper shim is also soft and conformable and conducts heat well, since it's a lot more available and much cheaper (hundreds$) I'm looking at using it instead of the nickel.
Thoughts? Experiences?

Copper is malleable and ductile, Prolly roll yerself any custom thickness wanted. I'd expect it to walk under cyclic stresses over time. Brass & bronze are stiffer, but work-harden.

How about Stainless? It's a common shim stock material..

PS: I think if your source meant Stainless he would have said Stainless.

But scarce as un-alloyed Nickel is, I wonder if he actually had a Cupro-Nickel alloy or Monel?

Bill D · Oct 15, 2020

I would think copper is harder then the babbit in the bearings so the babbit would crush before deforming the copper fitup. Of course new improved babbit may be different then what I know as lead based babbit.
Bil lD

Mud · Oct 15, 2020

Bill D said:
I would think copper is harder then the babbit in the bearings so the babbit would crush before deforming the copper fitup. Of course new improved babbit may be different then what I know as lead based babbit.
Bil lD

The bearing shells have steel backs, just like an engine bearing. They form an interference fit in the saddles when the saddle size is correct. I need to restore that fit by shimming with the correct material between the iron housing and steel shells.
There's no room to install sleeves, too small to metal spray.
I've heard a legend of a man in Poland who builds his own bearing shells from Clevite77 material when standard bearings are not available, I know of no one who can do it that is accessible to me. So we want to use shims.

Limy Sami · Oct 15, 2020

I've always used steel or brass (often guided by what was on the shelf

)

I really can't see the point of nickel, ......but I'm willing to listen.

MattiJ · Oct 15, 2020

Copper is soft and galls easily if you need to press the bearing halves with any sort of force during installation.
Nickel probably not so much. No idea if this is any concern in your use case.

Online metals has 50 yard rolls for about 200 usd..any other source should be about 50% cheaper.

edit:
Shop-aid appears to be the brand and this was listed as their distributor Nickel Shim 6" x 50" Rolls | Tools & Supplies
Lot more reasonable sounding than onlinemetals.com

Mud · Oct 15, 2020

MattiJ said:
Copper is soft and galls easily if you need to press the bearing halves with any sort of force during installation.
Nickel probably not so much. No idea if this is any concern in your use case.

Online metals has 50 yard rolls for about 200 usd..any other source should be about 50% cheaper.

edit:
Shop-aid appears to be the brand and this was listed as their distributor Nickel Shim 6" x 50" Rolls | Tools & Supplies
Lot more reasonable sounding than onlinemetals.com

Thanks for that. I'm seeing prices of ~$380 per roll elsewhere and I'm considering trying a couple sizes.
Press fit is not a concern, the shells are clamped in place in a split housing.

Cole2534 · Oct 15, 2020

Are there thermal expansion considerations? It probably doesn't get hot enough to make a hill of beans, but may lead you toward the reasoning of one's suggestion?

Sent via CNC 88HS

Mud · Oct 15, 2020

No, typical machine parameters, Cast iron housing, steel shaft, maybe 180° F, pressure oil lubrication.

rbjscott · Oct 15, 2020

Mud said:
No, typical machine parameters, Cast iron housing, steel shaft, maybe 180° F, pressure oil lubrication.

I would use Brass shim stock And have many times.

JS · Oct 15, 2020

How about use a plating process to selectively add metal where needed?

Have had machines with spherical bearing housings were machined to accept a piece of mechanical tube.

After it was fastened to the housings, machining was preformed to re new the spherical seat......

Not the quickest and if not the machined correctly, it will not work the way it was intended.....

Had a few machines that we sent parts off to GE......

GE will make new bearing housings for spherical bearings ........for a price.......

Bill in PA · Oct 15, 2020

Mud said:
The alternative is a new iron casting, other methods of refit are not practical here because of tight clearances and the way the machine is constructed. Oversize bearing shells are not available."

I assume the typical method of resizing a connecting rod cannot be applied to this application?

I believe this company will do custom bearings or may be able to provide a lead or ideas:

Aftermarket - King Bearings - Engine Bearing specialist

Bill

dian · Oct 17, 2020

why would the shim need to be "conformable"? it replaces the steel backing so it shoud be steel. any compliance will alter the crush. how much excentricity does the bearings have?

Limy Sami · Oct 17, 2020

rbjscott said:
I would use Brass shim stock And have many times.

+ another on that, ..................... and start worrying about something else Mud

muckalee · Oct 18, 2020

You have to sneak up on this fitment. Use 316 SS shim stock, start with 0.003 inch in both halves and lead wire or plastagage to confirm the decrease in diametrical clearance. Place the wire around the shaft every 1/4 inch or so to identify straightness of shaft surface as well as diametrical. respond to results by changing the shim thickness to obtain the desired clearance.
Is the bearing flanged, pinned or grooved? I have a 50 yo Clevite catalog with buyers guide and will search for a suitable replacement, if you send the dimensions.

thermite · Oct 18, 2020

rbjscott said:
I would use Brass shim stock And have many times.

I happen to stash Bronze, not SS nor Brass, but yazz.. unless..

Mud would know about what sort of corrosives, if ANY, may or may not also exist.
Note that he DID say it wasn't yer expected IC engine.

Even so, that leaves reefer compressors in ammonia as well as less corrosive gases, steam, air-reduction, all manner of pumping or simple conversion of rotary motion to recip, in a gearbox for an Old Skewl up-and-down sawmill.

Not really a lot of "limits" to what it might be as needs a connecting rod.

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