Even heat w/ramp master question.

R

ricky_arthur

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Jan 4, 2013
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Is this normal? So I got the new furnace set up today. Heat treated a 154cm kitchen knife and everything went good. Did cryo and then first temper in my shop oven while furnace cooled down. By then the furnace was down to 350ish. So I decided to do the second temper in the evenheat. Put the knife in and set for 400 for 2 hours and watched it go up to 400. I heard the relay shut off at 400 but the temp rose to 425. Then dropped slowly down to 399 and turned back on. Went up to 400 then shut off. This time it went all the way up to 430 before starting back down. Is this normal for the furnace to over shoot by 25-30 degrees? I can't imagine that's any more accurate than my kitchen oven in the shop I've been using. I never see my thermometer rise more than about 5-10 over before settling in. Thanks
 
I'v had that happen too, I think it's caused by excess heat retained in the fire brick, if you let it cool right down and then fire your temper cycle, it will then come up to temp and hold to within 5 deg. I know it's hard to wait just leave your blades in the cryo longer it wont hurt them.
 
Yep, it takes a while for the oven to level out and hold a low temperature like 400ºF - give it a while and it "finally" settle down.

Ken H>
 
what did you set your ramp speed to? if you set the ramp speed at to high a level it is normal to over shoot the set temp until the heat stabilizes. I normally set my ramp speed to the same temp as I wish to see ie... if I wan to temper a blade at 450 I set the ramp temp to 450 per hour.
 
Bill. Thanks for the tip. Does that add another hour to the time it takes to temper? Or do you ramp it up to temp. Then change the ramp time once it is already to temp?
 
ricky_arthur said:
Bill. Thanks for the tip. Does that add another hour to the time it takes to temper? Or do you ramp it up to temp. Then change the ramp time once it is already to temp?
Click to expand...

it doesn't add a full hour but it does add time. I guess you could program two steps. the first being to ramp full power to 350 with a five minute hold then ramp at 400 and hold the desired time.
 
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