The Home Machinist!

Hello all ,does any one know of a source for the Van Brocklin Machanical lubricator ratchet wheel? I am getting ready to build one for my 4-8-4 northern in 3/4 scale, I can build the other parts needed to make it, but I feel I can not do this part. I know very little about case hardening metal ,only it can be very dangerious to do. Any help would be great.

squandt wrote: ↑Tue Apr 20, 2021 2:44 pm ,only it can be very dangerious to do. Any help would be great.

Dangerous?

How so?

Pack hardening isn't dangerous unless prolonged heating in a closed environment is an issue.

The first hour of pack hardening provides the greatest depth of penetration. After that, roughly an additional depth of .010" per hour is achieved. For a ratchet wheel, I can't see why you'd have to soak the part any longer than an hour. It could be placed within a small metal box loaded with carbon and heated for the appropriate amount of time. Coked peach shells are often used. So long as you do this operation in a room with ventilation, I am struggling to see why you think it's dangerous.

H

how many do you want and of what dimensions? when i make them, i usually make 6 or so and cut them off like cookies...

as H says -> case hardening is not dangerous...any more so than silver soldering or huffing glue...

I worked at a plastic mold shop in California, we caseharded mold guide parts, had the CAOHSA fine us for not having the proper permits,training etc. So I am a little gun shy, we used a kiln and bone charcoal, plus the dip,don't recall what it was called.

I make them from drill rod, slice them off, heat them indirectly to avoid burning the tips of the teeth, and plop them (quench) into a can of oil. Temper in heated sand, and you're done. Easy Peasy. Once you've made a set you'll wonder what all the fuss and apprehension was about.

I can't recall how many teeth I put in the last set I made, what diameter and how many teeth does your design call for?

The dip may have been sodium cyanide. That is dangerous.

I believe that is what it was, I remember the skull and cross bones label, we wore rubber gloves and a face mask to put it in the steel box full of the bone charcoal and then cover it and close the kiln, cooked it for 4hours and let it cool over night. Next day we cleaned the parts and oiled them.

KenG wrote: ↑Tue Apr 20, 2021 6:17 pm The dip may have been sodium cyanide. That is dangerous.

you are probably thinking of potassium cyanide..

Bill Shields wrote: ↑Tue Apr 20, 2021 6:43 pm

KenG wrote: ↑Tue Apr 20, 2021 6:17 pm The dip may have been sodium cyanide. That is dangerous.

you are probably thinking of potassium cyanide..

Very little difference between the two, each lethal and each capable of doing the job. I am familiar with them, having used them for extracting gold.

The action of case hardening isn't dangerous --but cyanide is. Cyanide is not necessary for case hardening, nor is case hardening the only option at one's disposal. To that end, I heartily endorse the comment from gwrdriver. This item lends itself quite nicely to being fully hardened, because it is not subjected to shock. You might even explore the use of air hardening drill rod. Makes heat treat a little easier.

H

Drill rod as gwdriver suggests. W-1 or O-1 tool steels are relatively inexpensive, harden and then temper to light straw color. Make a few extras and try to find them in 15 or 20 years when you need one.
Denny

Cyanide comment was intended to get readers to actually look up the processes and make informed decisions about both.

You might consider purchasing one from AJ Reeves of London England. web-site ajreeves.com