Hot Bluing and Nearing Completion of Project

Yesterday, I finished the machining on the toolholder bodies. I need to make 5 adjustment nuts to complete the project. This means there are four toolholders that are good to go, as is.

Comedy of Errors

I do not think there is a single toolholder that is 100% right. There is the one where the tool in the collet grabbed it and chewed on the edges.

There are the three where I cut the dovetail 0.100 too deep.

There is the fact that the adjustment stud is too close to the dove tail. There are the edges where I missed the chamfer and have a ridge where there should be none.

Which takes us to

Hot Bluing

This was so much fun, not.

The formula that I used was 13 cups of water to 4 lbs of sodium hydroxide to 2 lbs of sodium nitrate. Bring to a boil, cook each piece of metal for 30 minutes. Rinse in hot tap water and then coat with WD40 or other oil.

First, I purchased a 5 qt stainless-steel pot to do this in. The stainless-steel handles were attached to the body of the pot with aluminum rivets. This formula will eat aluminum in short order.

Which it did. The pot sprung a leak and the boiling, caustic bluing mixture went everywhere.

I have more cleanup tomorrow to recover from that mess. That stuff started eating my hot plate.

As prep for each piece going in, I first deburred them all, used air to clean them, washed them in the parts washer, used air to dry them. Then Hagar cleaned them with acetone.

I don't think we got them clean enough. We should have used more acetone and got them 100% oil free.

After they were cleaned, they were hung from spring wire in the pot for 30 minutes. Then rinsed under hot tap water for 2 or 3 minutes.

Finally, they were sprayed down with WD40. I then used a Scotch Bright(gray) to lightly rub the flash rust from them. The results are what you see.

I think they are beautiful. They are not that deep black I was looking for. They have a sort of case-hardened look to them.

Yes, one of them is still in the white. I forgot I had three machined, so it wasn't processed into the pot.

Next time, I will clean each part better. I believe that the aluminum might have reduced the quality of the bluing solution.

We've put it all in a jug for use next time. I might have to remake it, making sure not to get any aluminum in the solution.

It is amazing watching aluminum bubbling away...