Bluing steel part.

[Pigi_102]

Hi all.
Before starting my first engine build I needed a boring head, and decided to make one as per http://www.deansphotographica.com/machining/projects/mill/boring/boring.html

After finishing, to protect her from rusting I decided to hot blue her. Here the procedure that I hope may help someone.
I took a chunk of brass to get some swarf, mounted on the lathe and faced it "heavy" to get sligthly big swarf.
After getting enough swarf I took a metal cup and filled with parts to blue and brass swarf.
I put the cup on kitches fires until got the blu I want.
When reaching the blue I have quenched in unused motor oil.

The result is really nice, at least in my opinion.

The brass swarf are needed to get an even heating to the parts. Is mandatory to very good clean the parts as also a little point of oil or grease could end in a parte not blued ( don't ask me how I know it  )

Hope this help someone.

Pigi

 

[petertha]

Neat. What is your temperature & soak time recipe? And what alloy is the steel head itself?

 

[Pigi_102]

I haven't a way to measure the temperature, but according to this image attached it should be somewhere around 285/310° C

I kept the part in the cup until I've seen the blue I was looking for on the exposed side of the part.

It took something around 15/20 minutes to get there.

The material is leaded-steel alloy ( I think you call it free cutting steel ).

Pigi

 

[Cogsy]

Great job. I'm going to file that away for future use for sure. Thanks.

 

[Wizard69]

Are you using some sort of glueing solution? I guess I'm not sure how you lock in the blue.

 

[Longboy]

I have been flame coloring my rocker arms on a couple of engines with a propane torch. A little tricky on small parts as the hue can change rapidly as the temps go up in a mater of a few seconds.

 

[Pigi_102]

Are you using some sort of glueing solution? I guess I'm not sure how you lock in the blue.

No glueing solution, only what I told.
Take the pieces, put in brass, heat on fire till the blue, quench in oil, clean with towel or paper.

Pigi

 

[mcostello]

Check out "Clickspring" on Youtube He does clocks and parts.

 

[Pigi_102]

That's exactly my ispiration !

Pay attention to clickspring channel, BTW, it give dependency

Pigi

 

[Wizard69]

No glueing solution, only what I told.

Take the pieces, put in brass, heat on fire till the blue, quench in oil, clean with towel or paper.



Pigi

Sorry, that was suppose to be blueing solution. Auto correct did me in - again.

This has me wondering if this is true bluing because normally you think of caustic baths to blue things.

 

[10K Pete]

This is called....... Heat Blue.!!

Used in watches, clocks and guns for a long time. Works especially well
with polished parts.

Not traditionally used for large parts. Small parts and screws.

Pete

 

[ruzzie]

I tried out a blackening kit from www.janekits.com.au

 

[Pigi_102]

I tried out a blackening kit from www.janekits.com.au

That looks nice !
In any case is a chemical solution, while my way ( well, the way I used, not my way ) does not need anymore than heat.


Pigi

 

[Swifty]

I've been using a chemical blacking kit for years, works very well and the chemicals last for years.

Paul.

 

[Scribealine]

A very old method indeed!
Used mainly in watch making in the late 1700's, to blue watch hands and screw heads,
the finish can be enhanced with a fine polish prior to heating, the brass swarf method is always used in horology.
Good to see it.
Cheers

 

[bmac2]

Scribealine. You got me. I had to go look that one up.
ho·rol·o·gy
Noun
The study and measurement of time.
The art of making clocks and watches.

 

[petertha]

What is the significance of the brass chips/shavings when torch/heat bluing steel? ie. is there something special about that particular alloy over other choices? Or is brass just what's usually found in a watchmakers chip tray under the lathe?

 

[Buchanan]

The brass serves to conduct and spread the heat in a uniform way, you can spoon or move the brass around on the part to heat one part more than the other to obtain an even color. Clean sand also works. The emphasis is on clean. Any oil or grease will give color variations. A very fine sand paper finish(2500) grit gives a better blue than a mop polish. The type of steel also affects the color Chrome or nickel does not help things and stainless steel is usually hopeless. It is simple to try and if you are not happy with the results it is not to difficult the remove the blue and try again. Every time this happens the polish also improves! The trick is to keep every thing clean and heat slowly. The atmosphere seems to have some effect on the color as well. The old folk always said to use a charcoal fire for the best results. A hot air gun also works as a heat source but I have not found the results to be quite a good as a flame.
An electric muffle also works, you can take the temperature up a few degrees at a time to get the color you like, especially when the part has thick and thin sections.

Buchanan

 

[petertha]

Thanks Buchanan. That's kind of why I was asking the question. The blueing temp looks to be just outside the range of my little re-purposed engine bearing removal oven (formerly known as our kitchen mini toaster oven). But assuming you could dial in a specific temp & let it soak there (maybe a conventional heat treating oven in low temp mode) presumably this would be more consistent vs. a torch... would underlying shavings or sand or whatever make any difference if for example you could jut suspend the part on a wire so it was hanging with the exact same atmosphere all around it & no 'bed' contact of any kind?

ps - I've been lurking on your website just fascinated with the clock constructions. Incredible work.

 

[Buchanan]

Pertha. yes, I mostly do just that, hang parts (clock) on a thin wire in an oven, The temperatures are obtainable in most cooking devises. Pigi's color chart back a few posts is correct. Screws , I use a block of brass with clearance holes for the thread and heat from below with a small butane torch. Thank you for the compliments . You can see more at www.buchananclocks.com.

Buchanan