Trying To Blue Mild Steel

[odyseus10]

Greeting to all
My first post on here !!

I've been building ths 'Dark Lady Clock' by Brian Hogger the last year or so as my first trip into metalworking

So I have had a long road including having to build a dividing head (this took 3 attempts!) and all the tools etc + having to learn using the lathe and milling machine pretty much from scratch.

I'm a fair way through and I've completed the first few chapters including the making of the main wheel assembly, main arbor, plates, second, hour wheel and escapement. I have also made the Depthing tool.

BUT I just cannot get a good even blue on the main plates ?? Every flippin' time I seem to over cook the heating process and one end of the plate turns from blue to grey?? I then have to sand down and start again

I just don't know how Brian got such an even finish - unless he used some form of Kiln?

I can easily blue the small component and once I have made the two pinions and bushes I'm ready to 'plant the train' - only If I have managed to blue the main plates.

Any advice from you learned members ??

All the best

John

 

[epanzella]

I do my rifle builds with rust bluing. The tank only holds boiling water. You can't miss.

 

[BRIAN]

Hi John
"Guess who" When I blued the plates for Dark lady I used a large propane torch and adjusted the flame so it was fluffy not roaring, suspend the plates on a wire so the contact area is free to heat up with the rest of the plate, rotate the plate with the wire and move the flame over the whole plate to get an even heat. start from the bottom and work up .
do this as near to the quench bucket as possible so no time is lost when quenching.
A slight variation in colour adds to the artistic appeal so don't worry, so far I have made three of these for the family and the the one with the most uneven bluing looks the best???
You can always send me a PM if you want help, and you are on the best site for advice.
Brian.

 

[Andre]

Remove it from heat sooner, or quench in oil when the ideal dark blue color appears.

 

[owl]

get a much larger, fairly thick metal plate, put your parts on that and heat from the underside, you will get more even heat that way. You still need to quench immediately on getting the color you want.

 

[atlas ten]

I seen youtube video torch blue clock parts using brass tray filled with brass cuttings then put parts in heating from underside.
Jack

Sent from my SGH-I337M using Tapatalk

 

[odyseus10]

Well some experiments over the weekend using my IR thermometer seemed to show promise..
I used my electric top oven and the thermometer was showing 280degC tantilisingly close to the correct temperature (I'd settle for purple). I put two plates in the oven. One went dark brown the other didn't change at all?? I later realised i'd bought stainless steel, two plates made of mild steel and two of stainless steel - doh.
I then used a soft flame on the 'browned' steel and got a reasonably even blue(ish) colour. So onr plate done another to go

 

[chips&more]

One of those IR non-contact thermometers is only accurate for comparing a known temperature source with the same emissivity as to an unknown. Otherwise, when just looking at a temp in question your reading could be in error because you do not know its emissivity. Those IR guns are good for repeat measurements and iffy for actual temperature. And you must maintain/fill the field of view.

 

[george wilson]

Kitchen ovens just do not heat evenly enough to make a good,ever spring temper blue. I have a Paragon knife maker's oven that WILL do a very even color. But,of course,mine cost nearly $1000.00 years ago. I have the 22" deep one.

If you do have to resort to heating and progressively quenching clock plates,I would not use oil. The oil will of course get on the plates and screw up further attempts to get the blue color. Use water.

IF you are very patient,and practice enough,you could learn to delicately apply the torch enough to blue the whole plate. Observe where the color is coming up and apply no more heat there for a while,as the color will keep rising. Overheat,and it will go past blue and turn gray.