How Do I Lower My Forge Temperature?

Joined
Jul 8, 2002
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Yeah it is an odd question, but I need to lower my forge temperature.

The lowest temp I can currently get is about 1750 °F. That is with both "doors" open and the lowest possible setting on my propane regulator (less than 3 psi, my gauge does not read any lower).

I need to get down to about 1450 °F to make some sterling silver mokume. If I run it at the 1750 °F there is a really good chance at having a meltdown and turning 9 ounces of silver into a slag pile at the bottom of my forge.

The only thoughts I have are:

1) Using a low pressure regulator
2) Building a smaller burner

What ever I do O need to keep an oxygen free environment in the forge. Any other suggestions?

Thanks for your help.
 
Joined
Sep 14, 2002
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Sean, from looking at your website, seems you are running a venturi burner? Build a forced air burner (or have me build you one :D ) with a needle valve in-line with the gas circuit, and you can pretty much regulate it down to whatever temp you want to run...

:)

-Darren
 

Stacy E. Apelt - Bladesmith

ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
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Have Darren do it for you if you have to use gas,but it would be much better to buy an electric HT oven.It is far superior for mokume.Also,check the eutectic temperature of silver/copper to make sure you don't melt your mokume.At 1432 degrees it will become liquid.If you haven't read it,I highly recommend the book,"Mokume Gane" by Steve Midgett.
 
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Nov 24, 1999
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I'd say that darren has the best solution for long term, but for the time being, you may try to make a choke for your burner so that you don't get as much air flow. And then if your regulator doesn't get low enough, maybe partially close the ball valve :confused:
 
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I never tried this, but it may be worth a try. Put a needle valve between the regulator and burner. This will allow you to adjust the fuel mixture. :confused: :confused:
 
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Sean, I don't have a venturi type forge, mine is forced air. But on a venturi you still have to have an air supply that is sucked into the tube, Right? If this is so, can you make a cover over that supply area and reduce the amount of air available, then flood with a little more gas and this should cool the chamber. Also, if it has a tweco tip, would enlarging the tip, either by replaceing with a bigger holed tip or drill out a tip to allow for more gas? I know that with my forge, to cool the forge I can cut the air back and add a little more gas and it will cool it way down. Just talking out loud, I don't know if this will help or not, Good luck.

Bill
 
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Jun 25, 2001
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B . Buxton said:
Sean, I don't have a venturi type forge, mine is forced air. But on a venturi you still have to have an air supply that is sucked into the tube, Right? If this is so, can you make a cover over that supply area and reduce the amount of air available, then flood with a little more gas and this should cool the chamber. Also, if it has a tweco tip, would enlarging the tip, either by replaceing with a bigger holed tip or drill out a tip to allow for more gas? I know that with my forge, to cool the forge I can cut the air back and add a little more gas and it will cool it way down. Just talking out loud, I don't know if this will help or not, Good luck.

Bill
that is the same principle in tuning a two cycle engine Carburetor.
the cold inefficiently burnt gas does the cooling.

but of course,, you do not cut the air on the Carburetor. :eek: :)
 
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Thanks for your input guys, I appreciate it.

I am going to try to choke the air flow first and then progress thru the other Ideas. I am pretty tight on cash flow so buying anything new is my last resort.

bladsmth - I have the book and i was looking at page 60 near the bottom for sterling and palladium it says 1490 °F, but I also see where you are talking about too.

Dan - The stuff I made for the Colaboration Knife was copper/nickel silver and that seems to fuse around 1880 °F according to my pyrometer.

The stuff I want to make next is sterling silver and nickel silver mokume which will be a very subtle grey on white contrast.

Thanks again, and i will let you guys know how it works out. My silver should be here on thursday, so I have some time to do get it right.
 
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Well, I got her down to about 1400 °F. Kind of funny looking when she is burning at such a low temp. The way I got her there was to use Bill's idea and choke the air flow.

I built a little gizmo out of copper sheet that just clips onto the burner's venturi and allows me to stop almost all the air flow if I wanted to. I also had to buy some more kitty litter to put in the bottom of the forge to block some drafts that were letting air in and causing temps to go to high with the rich atmosphere.

At 5 psi and almost fully choked she hovers at 1400 °F but is a fuming, swirling, wicked looking fire breather.

Another intersting thing I noticed yesterday was that my copper and nickel silver mokume did not fuse until 1922 °F. The other day I had some start to fuse at 1888 °F but that bond did not end up being very good. Both showed the same signs of fusion. :confused:

I need to get my thermocouple in between my pressure plates to rule out any errors in my temperature ramping procedure and possible hot spots in my forge.

Tomorrow my silver arrives. I wish that i would have ordered an extra ounce to do some trials with, but you know how hind site is :rolleyes: . Anyway keep your fingers crossed and hopefully I will have a sucess story to tell in about 24 hours.

BTW, anybody know how to patina nickel silver or sterling silver?

Thanks again for all you help.
 
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