new forge first burn

[mark.177]

a member from another forum sent me one of his experimental forges, a thermostat and probes a few days ago but with all the bad weather we've had have not had chance to use it till today. the hope was i could get it to hold a consistent temperature and thus allow me to soak the o1 steel blades i have for the correct soak time (20-30 minutes!)
after some initial tweeking of the air inlet and regulator i had it running at 9psi and it held 810-812c! i had two blades to heat treat, one 6mm and the other 5mm, both in o1 steel. both got a soak of 20 minutes with around 10 to get up to temp so 30 minutes each and i can tell you it was the longest 30 minutes! having to hold the blades there free hand for that time.
the blades were quenched in pre heated rapeseed oil at 75c and then tempered at 250-260c (255c with + and - 5 degrees error)
just waiting for the blades to temper before i can put an edge on them and see what difference the soak makes????

 

[dazcon]

Looks good but pretty big. I thought the gas jet should enter from the side so the flame would spiral around the cylinder giving a more even heat distribution.

 

[mark.177]

Looks good but pretty big. I thought the gas jet should enter from the side so the flame would spiral around the cylinder giving a more even heat distribution.

i thought that too and it does take a while to get it up to working temp but once there with some tweeking its incredibly stable, 30 minutes with only + or - 1 degree c. the temperature in the bottom "working half" is really even from about 2" in right to the back

 

[dazcon]

Control of the heat is what you want so it sounds good. You've got the option to do bigger blades as well. You'll have to come up with a rack or something to hold the blades. I wouldn't want to be standing there in front of the forge for half an hour holding a blade.

 

[dazcon]

How long are you doing your temper for and what Rockwell are you aiming for?

 

[sunndog]

Looks good kit mate, i'v gotta ask......why did you have to hold the knife?, half an hour must have felt like an eternity. Could you not have knocked something rough and ready up to hold it or was there some special reason?

 

[mark.177]

tempering im aiming for 255c for a hardness of 59, two lots of 2 hours plus pre heating/warmup.
the plan this morning was just to run the forge and see if it would hold temp but it went so well i grabbed a couple blades to heat treat... if ide planned a little better i could have/should have rigged something up to hold them... yes its seemed an age!

 

[sunndog]

Ah, you got carried away.....yeah I think most of us have been there more than once matey

 

[mark.177]

just put an edge on the first 5mm thick blade and wow! the whole time i was holding the blade in the forge (30 minutes!) i was thinking grain growth and all kinds of bad things going on with the steel but the temperature was holding steady at 812-813c. on the two blades i had already ground the bevel this time on these two leaving a 1mm edge but it didnt take long to put a working edge on, very little steel was removed. its the sharpest edge yet my only concerns now is will it hold up to heavy chopping without chipping or folding... will have to wait till tomorrow!

 

[Robson Valley]

This whole forge and knife thing is disgustingly attractive to me.

Theory here for heavy chopping is to have the wood actually split ahead of the edge rather than cut it.
Have enough steel behind the edge to support the service requirement. 30 degrees total included bevel should work.
My only experiences involve splitting both soft woods (cedars) and hard woods (mahogany & birch.)
Both my big axe and froe have approx 1/2mm wide edges.