Hot Rods Part clearance for triple chrome plating

I drilled my I beam axle and am going to send it out to be chrome plated. My spindles and my wishbones slide onto the bosses tightly right now in bare metal.

I understand the chrome doesn't add thickness to be concerned with, but the base metals will.

How much should I machine off the 4 bosses so this will all go back together nicely?

.010"?

 

I'd tape off the areas of concern, as triple-plate chrome will chip.

 

That's kind of a "how long is a piece of string" question, since you are dealing with thousandths of an inch tolerance and various chrome shops and plating thickness.
Call your shop and ask if they have a typical dimension or can mask, as mentioned. Also what they suggest to machine the surface if needed and if this affects any warranty. Get all the info straight from the source.

 

I would have the plater mask off all the surfaces that need to fit together. We didn't do that at work on a firetruck, and I spent 3 days with a 3 cornered file getting the plating off of the splines of the rear drive axle caps.

 

two rubber stoppers with a thru bolt might work.

Or a few of these.
https://shop.advanceautoparts.com/w...age/2214/large/5701252_rnb_02600_pri_larg.jpg

I'm guessing A hunk of hose epoxied into each axle hole would probably be easier to remove than unwanted plating.

 

Call the plater.
Remove what they say off the part.

 

At the chrome shop I used to work at, we had some orange goop we could paint onto machined surfaces so the plating wouldn't go onto them.

Keep in mind that in something like a kingpin hole, the plating won't throw all the way down to the center evenly, there will be a thickness of plating at each open end that will taper off into nothing as you go down. So that will have to get coated regardless, or you'd have to re-ream them out.

I'd consider doing the same thing with the bosses. The amount of copper it takes to chrome plate something can vary quite a bit, I don't know if they could calculate that exactly beforehand.

 

I would probably also be concerned about hydrogen embrittlement which is a byproduct of the chrome plating process and can weaken the metal and cause cracks in the parent metal. Usually after chrome plating the part if structural is subjected to a process called p***ivation. Here is some more information:
https://en.wikipedia.org/wiki/Hydrogen_embrittlement
P***ivation:
https://www.electroplatingmachines....ly to improve the,used method in recent years.

 

Thanks for the input. Before posting here I already talked with the shop that is going to chrome it, and they didn't have an answer. Mind you, they do excellent work and I have used them in the past for parts. At least I don't have to worry about metal buildup on the through bores with the way they do things.

Of course different shops, different people running things, different voltage, and a slew of other variables could affect the thickness of the built up metal.

I can't be the first guy who has thought of this before having parts chromed instead of after when they don't fit together. I was hopeful that someone or a few people would have been through this so I could get a somewhat educated guess, or at least a range to take a stab at.

My best guess on range is between .01 and .045" at this point.

 

We had similar. Had to chrome some mechanical pieces that pressed in. Our machinist removed material off parts before plating. How much?
Don’t know.
Whatever the chrome shop told us.
I guess they measured a before and after on a chrome part and come up with something close enough that worked.

 

Decorative Chrome Plating is typically less than 0.001 inch actually closer to 0.0006 inch give or take 0.0001. It’s extremely thin and will not cover any blemishes or defects.

 

Take your measuring tools to the shop and measure the under plating before it goes into the chrome vat. If it's to big, filling it off before chrome is added shouldn't take very long.

 

I had a friend who had a small machine shop, making specialty parts for the aerospace industry. One part had to be hard chromed to a specific diameter. He relocated from one coast to the other, looked for a new supplier, sent some parts to be done based on their ***urance they could hold the tolerance needed. He has to throw away 7000 dollars in parts when they came back to large.

 

Galvanic plating will always build up the most at sharp edges. So when you plate a flat plate with a bore, the edges of that bore will be tightening up - therefor it is useless to remove material from the bolt that goes into that bore, if it fits the edges, it is lose below them... You can hone that bore back to proper dimensions, reaming will not work as the chrome is too hard. Or you cover up the bore with a rubber bung and can ***emble the stuff after chroming as before.

 

I bought a five speed conversion for an OT transaxle some years ago. They lengthened the main and pinion shafts, ground it .001" undersized, then had them hard chromed .001" oversize so they could finish grind them to the correct dimension.

 

I drilled speed holes in my clutch and brake pedal in the roadster and had them plated. I didn't think about the mil thickness of the chrome, and I couldn't get my bushings to fit. I had to use a small cylinder hone until the bushings fit. In hindsight I wouldn't change a thing. I don't know how chrome would hold up in my pedals or in your kingpin holes. I would rather grind it away and have a steel, uniform surface.