Cadmium Plating

Once everything was stripped of zinc and blasted it was sent to Aeropropeller in Broomfield Colorado for cadmium plating. I wired things together so I could sort them upon their return as I understood this would work for the plating process. I was wrong and everything was returned in two Zip-lock bags. Fortunately I took a lot of pictures and sorting was not too difficult, although it took a lot of time.

The cad plating looked very good. One lesson learned is that I should have removed the old cad plating before re-plating parts. It is easy to tell which parts were not thoroughly cleaned.  Parts that were polished shiny had a shiny finish on them. Parts that were left with a frosted finish returned with one. The plater told me that cad would not stick to stainless steel. I mistakenly sent a couple of stainless Oddie studs for plating and he was correct. Although they took plating it is bunched up and can be removed with my finger nail. The bead blasted finish on stainless does not look significantly different than the cad plated finish in my view and will be the method to get the correct finish, although I have to admit I would prefer cad to blasted stainless.

I knew there would be parts I missed in this process and that I would need a “plan B” to cover for them. Cad platers have a minimum required batch size. In effect this means you cannot send out a few nuts and bolts for plating. I needed 16 pounds minimum and sent 25. I am planning to purchase a paint that is “frosted aluminum” to hit things I missed. I may also be able to send parts I missed with the batch for my next restoration.

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Update - March 2016:  Aeropropeller has changed its business name to Colorado Plating, LLC.

Stripping Zinc & Sandblasting Hardware

This is an area that chewed up a lot of time. Larger parts are easy to hold and clean up in a sand blaster but small parts were a challenge. All zinc must be removed before CAD plating parts or it will not stick. I have a small blasting cabined that has 50 micron glass beads in it. I tried to remove the zinc with this but it was slow going. I researched “zinc removal” on Google and found that pure lye mixed with water will dissolve zinc. The only local source of pure lye was a product sold at our Lowes hardware store called “Roebic Crystal Drain Opener”.  I purchase a small can of this and set about dissolving zinc.

When water is added to the lye the bolts will smoke under water. If this does not occur more lye must be added. They came out of the solution with a black oxide coating them. After the zinc was removed I bead blasted all parts to bare metal. The most difficult part about blasting was holding everything. I will need to come up with a better system next time. 

Caution: I assume fumes from zinc removal to be toxic. Do not breathe or do this process inside. I assume leftover solution is also toxic. I recommend disposing of it at a hazardous waste collection site. (common in the US). 

Making & Fixing Bits

A couple of pieces had to be made. The brake rod was cobbled up and the header tie bracket was missing. These pieces seemed easy enough to make so I fabricated them. The brake rod was threaded on both ends using my BSF die and I tapped out the pin end of the rod clevis to accept the threads. The header tie was sheared to size and the slots will be milled. I will send it out for chrome plating with my other bits. I also fixed parts with poor threads. Some of these seemed beyond repair but they cleaned up alright. I purchased some odd ball taps and dies for this task. I now own 5/8-18, 5/8-20 & 9/16-20 taps and dies. 

Some of the threaded bits made or fixed before plating.

I also decided to make a few of the valve cover studs as they are rather expensive. I started with long grade 5 UNC bolts and cut out the unthreaded portion to use as stock. I threaded them with my dies to the appropriate length. I did not know if my “India dies” were up to the challenge but they held up without issue.