What to do about cold spots?

D

Dana Hackney

Joined
Nov 1, 2005
Messages
174
Hi folks,

I just recently got my forge up and running and have noticed that I must have a cold spot someshere near the front of the forge. I find that that when heating a piece of steel the entire piece heats up nicely with the exception of a small area (1.5 -2"?) back from the mouth about 2". The area near the mouth heats up okay.

This forge was constructed from an old 9" O2(?) cylinder. It's about 12"x5" inside dimensions and I have the burner coming in near the top of the cavity, about half way down the forge. I've got in lined with inswool and ITC100 I bought from Darren - works very well with the exception on that one cold spot.

Also, off subject (sort of) - is there any health related problems when heating up a piece zinc plated rod in the forge? A friend of mine wants me to fabricate a spike (mushroomed head with a taper on the opposite end) and I was wondering if zinc fumes (?) are hazardous.

Many thanks,
Dana Hackney
Monument, CO
 
I can't help you with the cold spot but ZINC FUMES ARE VERY HAZARDOUS! It is best not to try to forge zinc plated or galvanized material. If you do decide to go ahead with that project:
1) Make sure there is a lot of ventilation around your forge, preferably some form of fume hood that sucks the vapours out.
2) Wear a good quality respirator.
 
Zinc fumes killed Paw Paw Wilson. Good man.

go buy some steel
try some firebricks around the mouth of the forge
 
Weird that the mouth is hot, but not back.....how is that heat getting to the mouth without heating that part of the forge? Id look into that....somehow that heat isnt evenly circulating. You have the back side of the forge closed off, right? That might help forcing the heat to escape out the mouth....perhaps try angling the burner slightly up or down to get the heat curculating more evenly?

Lastly, heat your blades inside a steel pipe....the pipe will aloow things to heat more evenly than being exposed to the flames directly, but it may take a bit longer to get the pipe up to temp.
 
I will forgo the zinc coated stuff and opt for the plain steel!

Thanks also, guys for the suggestions on the forge. I think I'll try angling the burner a bit, as well as using the pipe. Am I supposed to be using square pipe and how big (wide) should it be?

The back of the forge is closed off and I have been using the fire brick at the mouth. I've basically got a square hole equal to the width of the refractory brick that lies at the bottom of the forge.

Many thanks,
Dana
 
Could be running hotter at the mouth because more of oxygen its burning leaner and thus hotter there. Definately sounds like a circulation issue. If you can get away with a shorter inner dimension, I'd make a removeable wall inside it and adjust back and forth. I think your heat just isnt moving around well. Just my .02. Shawn
 
it may sound counter intuitive but my burners are angled slightly toward the mouth of the forge. I got that one from a post by Randall Graham. Search for Randall here, I've posted it a couple times. Good information from observations he saw in his shop
 
Thanks Shawn for your suggestions. I'll keep this under consideration if
Mike's idea of angling the burner towards the front a tad fails to work.

I've said this before but I'll say it again - this forum has got to be one of
the greatest sources of great information on the web! I've posted a lot of
questions, some dumb and some not too dumb, and I never leave without
receiving really helpful comments and ideas. I've got a binder full of
stuff I've printed out and keep close at hand.

Thanks again, guys!
Dana
 
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