Charlie's Shed - Chemical Blacking

 Way back in the dim and distant, when I was rebuilding my SQ4 in fact, I had an incomplete set of engine bolts so the SQ4, like the FH years later, wears stainless steel fasteners everywhere. That incomplete set was chemically blacked, a process which was almost universal for protecting fasteners from corrosion until the 1940's, when Cadmium plating became popular.

Cadmium is pretty toxic, and by the mid 1980's most fasteners were zinc plated - a process very much in use today.

However! Our Model A is not going to be wearing shiny fasteners, which raises a little machining challenge! The issue is, when we are missing fasteners, the ones that are commercially available are either stainless or zinc plated - and will probably not be the right pattern - we don't want nuts with both sides chamfered or bolts with stamped text on the heads! Secondly I don't want to spend hours removing zinc plating, so we will make the missing fasteners on the lathe.

Here's a batch of 1/2" CEI nuts I made earlier:

So here goes. This is the GP Cool Black Metal Blackening Kit from Gateros Plating, and if I recall correctly this is the 1 litre kit.

Here are the instructions:

For the first try I followed Process 2 in the instructions, with 3 minutes in Cool Black solution and drying the Rogard Supreme Seal with the hot air gun. A bit patchy but an online video for another manufacturer's kit suggests that 5 minutes in the alkaline cleaner is required, not the quick dip & wiggle that it got from me.

For the second job, I used Process 1 with two minutes in the Cool Black solution:

Third job: a wash with carb cleaner, 2 minutes in the alkaline cleaner, 2 minutes in the activator, 2 minutes in the cool black, 2 minutes in the oil. Much better:

The ambient temperature here is about 5°C, and I am doing this in an unheated workshop!

I think I'm getting the hang of this now. This is a spacer for the frame stud near the top of the gearbox, and after a dose of carb cleaner and a rub over with a rag and a brush dipped in alkaline cleaner it was unable to pass a water break test. I dipped it in the alkaline cleaner again for 5 minutes after which it successfully passed the test. This was followed by 1 minute in the activator and 2 minutes the cool black - this picture was taken after the first 30 second dip in Rogard: 

This is the finished spacer - which ironically I'm not going to use - it's now had three dips in Rogard and one dip in dewatering oil.

I'm calling that a success.

More Plating...It's been every evening this week...

Well I am persisting with the zinc plating while waiting for my Bantam engine to come back. I've reworked all of the engine fasteners now, not brilliant but usable, along with parts like the clutch adjuster. I've also plated a few spacers, chain adjusters & the brake adjuster:

Quite passable I think!

Plating

So, I've started plating some Bantam parts using a 4 Amp 6V/12V battery charger and Gateros Bright Zinc kit - £59. for enough to make two 4.5 litre tanks. I wanted to clean up the rusty fasteners & clutch adjuster on the outside of the engine.

I started by running a die along all of the fasteners to clean the red Hermetite out of the threads. Then they went in a caustic soda electrolytic bath, followed by a rinse.

Then it's a minute in a 30% hydrochloric acid solution (brick cleaner from B & Q), and straight into the plating tank. It's a struggle to get the voltage right with a rudimentary controller in the form of a coil of resistance wire, but the results are passable - especially as I was really looking for a cadmium plate look-alike, not shiny zinc.

Here are a batch of parts in the plating tank:

And here they are again after about 20 minutes:

A 'before & after' shot:

So having tested that out, onto some more valuable (read scarce) parts. These are the steel parts from Amelia's Solex 26 AHD in the tank. Same process as before:

And here they are after plating. They are still attached to their handling wires here, but they have been  in the clear passivating solution for about 60 seconds.

And here is the carburetter assembled. All the brass has been cleaned with Farecla G3 compound, a toothbrush and a brass wire brush in the Dremel. It all looks to be in nice condition though it will need a new set of seals and some parts from David Jones, including the air bell, the Bi-Starter knob and it's bracket.

The other thing I need is to find out what the cable bracket looks like, if there was an adjuster, and where the throttle return spring goes... anyone got one I can copy?

A pleasing distance from the 'before' shot from last week!

Carburetter

Well, while waiting for the Bantam engine rebuild to get moving (I'm waiting for the crankshaft to come back from Rex Caunt) I've been plating fasteners using a kit from Gateros.

While I had the tank out, I thought I would get the Ariel carburetter ready and plate the steel parts. I've been experimenting with aluminium cleaning with an electrolytic soda bath, along with various household products.

Here is a household product with which I have become acquainted:

I started with a spare Zenith mower carburetter I had knocking around:

I attacked one of these with Cillit Bang descaler and got this in a few minutes:

The electrolytic bath didn't help much. I started with the Solex 26 AHD from the Ariel, which looked quite horrible to start with. These carburetters appear on several small french cars - they were specified by Ariel because the constant vacuum from the four cylinder engine can prevent a spring return slide from closing:

But after a couple of hours with a small brush & Cillit Bang:

This is what it is supposed to look like:

The next step is to make some decision on how to plate the steel parts. I fancy a nice yellow chromate passivate...

Parcels still wrapped - more electrics

Well, the eBay parcels are still under wraps. Christmas is coming and sometimes it isn't wise to buy too many present for other women, however much shiny paint & chrome they will have when they are finished!

So in the meantime, let's get on with the headlamp. We've got a nice original SSU700, no repro bits here!

The instrument panel looks like it is off a WD bike; it's in great nick but the ammeter is wrong - it's not the white face one with the ignition light that should grace a Square Four headlamp.

Also, there are some flaky bits. The edges of the pilot light aperture are rather ragged - it's an aluminium casting and I'm not sure how to repair it yet. Then there is the rim:

The picture is not too hot but it's bent and it looks like it has been thrown down the road. I'm going to see if I can straighten it before I give up and buy a new one.

Here's the inside of the switch panel from the inside. All right & proper, apart from the ammeter I mentioned before. A new one will have to wait though - the proper ones will be like hens teeth!

Lighting switch, cleaned up nicely.

Here's the pilot light mounting plate. It was missing, but I made this one from some photos & dimensions provided from the fantastic people on the AOMCC forum. It's designed to hold one of these in the underslung pilot lamp:

And here is the ammeter, with the steering damper knob lurking in the background. I'm going to tackle the rim and the headlamp fasteners with a Plug 'n' Plate chrome plating kit, and see how much of the original stuff I can save.

More later.