New Chainplates

[galleywench]

I ordered some .25" 316 flat bar from online metals to make up my new chainplates and I'm going to have holes punched/drilled at a local machine shop, but I've been reading online about passivating and/or polishing them to help prevent corrosion. I understand polishing and I'll get a quote from the local machine shop to see how much it will cost, but will ultimately probably do the polishing myself. What I don't know is whether or not passivating the chainplates is neccesary in addition to polishing and if so, is it done after polishing?

Does anyone have any ideas/knowledge about this process?

[Zach]

I don't know if passivating comes before or after polishing, as I've never had it done.

Ease over the corners with 120 grit, and sand up through 220, 320, skip to 600 on a power sander. I use an 8 inch pad sander. I'd carpet tape them to the workbench fairly close together, and work one side of all of them at a time.

You need a couple pieces of 120, 220, 320... but more than a few of 600 as it doesn't stay sharp very long on stainless, it will also get hot enough that you have to watch the temperature of the glue if you are using stick on pads.

A soft jaw vice, or clamping device that won't scar them is handy for the next part.

If you have a mini-grinder, you can get a spiral stitched flannel buffing wheel that will fit on it. Get two. One for Red Rouge and the other for emory rouge. Wear a respirator and goggles. Also, consider doing this part outside as there will be a fine coating of waxy mist with strings and all. There is a right side, and a wrong side of the grinder for corners, one that tries to run toward you, and the other that tries to run away. Be mindful of the edges, and go along them where the buff is parallel to them not perpendicular and it'll be easier on you...

Start the grinder, and load the wheel by holding it up against the emory compound until it will take no more, the spinning buff will pick up the compound off the stick. You'll have to do this periodically, the last of it will come off the wheel and you'll start throwing threads all over the place... Add more. Basically you'll leave a stripe of compound everywhere you pass over the part, and keep polishing until it is gone. Then add more to the wheel if you still see scratches, and keep going. The emory will leave a little bit of a "haze" if you will, even after it is clean, but should have no discernible scratches.

When you are consistently hazy... Change buffing pads, and wipe everything down with acetone until clean. You are changing from coarse to fine grit, if you will, and any leftovers on the part will continue to persist leaving scratches... Don't mix the red rouge and emory on the same buffing wheel, as it will always remember the coarsest thing you've used on it...

The red rouge, will take off the haze and make them mirrors.

Zach

[rescuesailor]

Passivating or electropolishing simple removes rough surfaces from the stainless. It basically chemically sands and polishes the surface like sandpaper. Search Youtube for some interesting video on the subject. I am having this done to my chainplates at the machine shop. I will post pictures afterward. To me saving the labor with a brighter finish is worth the cost.

[galleywench]

Thanks for the responses. The local machine shop where I am having them drilled had no interest in polishing them mechanically and does not do passivation. He told me that unless I wanted that mechanically polishing them is not worth it for them because of the time involved. In any event, I just got a call that they have been drilled and shaped, so I will pick them up today and polish them myself.
The old ones were never polished and were very raw looking. I don't think they are original (51 years old), but probably from the mid 80's. They held up pretty well but pitting was evident on all of them.
I did take one of the old ones and run through 120, 220, 320, 400, 600, 800, 1000 grit paper and they looked beautiful. Pretty close to mirror like. I'll probably do the same with the new ones and add in the jewelers rouge as a last step.

[Skipper599]

I can see I'm a little late in responding to this query, but my suggestion would be to find a local "Metal Polishing" company to do it. I went to one who specializes in polishing parts for Harley's and show cars.

[earlylight]

How costly is it to have stainless steel polished by a shop that specializes in it?

[JoeC]

this info may be helpful or harmful.....just found out recently that SS may corrode as quickly as bare steel in an environment that lacks oxygen....it seems that oxygen causes a surface film of corrosion(for want of a better word) on the SS which prevents it from corroding any further....I certianly would use SS for chainplates but I would hesitate to polish them for the reason mentioned above as it would remove this surface film and then any area of the installed chainplate that may be isolated from oxygen may be compromised....

[Carl-A259]

The real problem with SS chainplates is where they pass through the deck, this is where corrosion sets in. They work well for external chainplates though. I would stick with Silicone Bronze when replacing. HEY!! What do I know???I'm just a kid!!!

[earlylight]

SS chain-plates have served many of us very well for many years. It is just one more item that should be checked from time to-time. I pulled my 31 year old SS chain-plates .last year. There was absolutely NO sign of crevice corrosion. I do take care to re-bed them about every 3 years.