Jump to content
I Forge Iron

New gas forge; learning to heat


Recommended Posts

I set up my Diamondback two-burner blacksmith model today, and boy she puts out the heat compared to my old washtub charcoal forge -- heats up the wall, too. I will have to fiddle with the location to keep the heat off the sheet rock.
One big difference between the two forges is the charcoal forge's ability to heat small areas of a piece of steel, while the gas forge tends to want to heat a lot more of it. Also learned that it is best to draw out points, etc. , toward the end of the work rather than at the beginning, as they heat up first and you have to quench them to keep them from burning.
Are there any tips out there for selectively heating stock with a propane forge, or strategies for working out a piece in these forges?

Link to post
Share on other sites

"Regulating" heat by adjusting individual burners sounds great on paper, but in the real world is complete nonsense. The refractories used in the forge will not allow and real temperature "zones" to exist within a forge chamber, period. The refractories job is to radiate that heat evenly into the forging chamber. If one burner is running lower pressure, then the side of the forge that burner is on will draw more heat from the opposite side in an effort to regulate the heat distribution. This is the magic of modern refractories. There must be rather significant differences in pressure to get any measurable effect, but this is counter productive and reduces the forges efficiency. I've been there, done that, and measured the results with modern digital equipment, it just don't work in the real world...

Link to post
Share on other sites

The several hundred smiths I know of that use propane forges regulate heat not usually by individual burner but at the regulator for both burners (or they turn one burner all the way off).

Even for an aspirated forge you can change the temperature quite a bit by turning down the pressure before it gets too low to aspirate with a properly build burner.

With blown burners it's trivial to adjust as you don't need to sustain the aspiration process.

I have one of each type of propane forges for about 10 years now

Link to post
Share on other sites

I'm not familiar with the layout of the Diamond back forge. There are two things you can do in the direction of selective heating using a propane forge.
One you can learn to make "convience bends". That is making bends so that the section you are working on is in the forge and the remainer is out of direct heating.
The second is to get some insulating fire brick and place it, or a piece of it, so sections requiring less heat are less exposed.
Once you get several bends in a piece it gets hard to manuver a the section that needs to be worked on into the forge with out getting whole thing hotter than it needs tobe.
Planning your work gets to be key for completing a project.

Link to post
Share on other sites

The point I was trying to make is, you cannot get separate distinctive "heat zones" in a forge by running burner #1 at Xpsi and burner #2 at Ypsi. The overall temperature is regulated by fuel pressure to all burners. More PSI=more BTUs which yields a greater interior temperature in the forging chamber.
Another option is to simply heat your workpiece and then lightly quench the area you do not want heated. This works great for upsetting a specific section in the center of a long bar for example.
If burning the end of a thin taper is a concern, the forge can be adjusted by lowering the pressure. You can effectively turn down the heat so that burning your work won't be a concern. It will take a little longer for the workpiece to "soak" in the chamber, but like everything else, it's a slight trade-off.

Edited by looper567
Link to post
Share on other sites

Looper, I think we understand your point.
My point is that propane forges are not the solution to all problem.

I and several others are tinkering with the Idea or ribbon burners to build a side draft chip forge. to adderss some of these difficulties.

I build my own propane and coal forges and my own burner designs for personal use so I have no professional interest in any of these discussions.

Link to post
Share on other sites
Looper, I think we understand your point.
My point is that propane forges are not the solution to all problem.

I and several others are tinkering with the Idea or ribbon burners to build a side draft chip forge. to adderss some of these difficulties.

I build my own propane and coal forges and my own burner designs for personal use so I have no professional interest in any of these discussions.


I agree, no forge will do everything. The ribbon burners sound like a great option for some applications, I would love to see a set in action. Planning out your work is critical, you can do an amazing amount of work in a regular old gas forge if you think ahead. In the meantime, a cheap and easy solution being employed by Artists and Blacksmiths all over the country is to use a simple LP "weed burner" torch. Available for under $40 at Northern Tool, they run on propane, heat large areas quickly, and won't drain those expensive oxy/ac tanks! These are used by many people to fill that gap in versatility, and they do it on the cheap. It's not a perfect solution, but for many shops, it an outstanding option.
Link to post
Share on other sites
  • 4 months later...

I have been running one gas forge or another for about 15 years now (in many different configurations ) and they do have there limitations as to what can be shoved into them .I tend to work multiple pieces of steel at a time and set the gas forge so that it is below burning temp .that way you can just pull the piece out and go .I never really noticed the even large heat zone being a disadvantage
I started with and still use a coke forge but in all honesty I reckon I use the gas 90%+ and the coke for the trixy remainder with big pieces or high temp welding of wrought .
the only way I have found to maker a smaller heat zone is to make a smaller Gas forge .
Gas forges have taken quite a while to take off in the UK with blacksmiths I am never sure why .

Link to post
Share on other sites

Hi, as I have never used a propane forge and have only used a coal forge once, yo may understand where my ignorance comes from. My understanding (maybe faulty) was that it is fairly easy to "burn" mild steel, especially thinner stock (like the point on a taper) if you are not careful. This was one of my experiences in my one day at a coal forge. I thought (again, may mistakenly) that one of the benefits of a gas forge was that the mild steel wouldn't burn, especially if it is properly tuned. Thus the idea of having several irons in the fire without the fear of burning them. Could somebody please address this? Thanks.~Eric

Link to post
Share on other sites

I've never burnt steel in a propane forge, but I wouldn't go so far as to say it's impossible. I'm sure it can be done. OTOH, coal/coke does it quite easily. This isn't usually considered an explicit reason to use propane, AFAIK, but it can be a nice side effect. That said, I really like the very high temperature potential of coal forges.

Overheating is actually more of a concern with higher carbon steel, as opposed to lower carbon.

Link to post
Share on other sites

I dont think you can burn steel in a gas forge if the gas pressure is set to somthing sensible, sure, the thinner sections will heat up faster but the whole piece will equalise to the interior temp of the forge soon enough.

You might get excess scaling on thinner sections if there is to much unburnt oxygen in the forge, but that is a different subject!

Link to post
Share on other sites

Gas forges can and do make steel into sparklers. Well at least my gas forge can. Due to the ability to control the atmosphere a good bit there is some proof against this from happening after burners are adjusted, pressure set, etc. It is also possible to outright melt the steel, something I haven't done yet.

Phil

Link to post
Share on other sites
Gas forges can and do make steel into sparklers. Well at least my gas forge can. Due to the ability to control the atmosphere a good bit there is some proof against this from happening after burners are adjusted, pressure set, etc. It is also possible to outright melt the steel, something I haven't done yet.

Phil



Yup, I agree fully, Ive melted (not burnt) steel before in my gasser, but like I said if the gas is set to something sensible its very rarely a problem.
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...