Forge...venturi vs blown

silver_pilate

silver_pilate

Joined
Oct 30, 2002
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Now that I have my anvil, I am finally getting around to collecting the equipment necessary to add forging to my skill set. I have considered building my own, but I am strongly leaning towards buying Darren Ellis' 8-HT horizontal forge.

Regardless of whether I build my own or purchase one, I am going to build a PID controlled setup based on the plans posted by Stacy a while back and the setup JT completed recently. I know either type of blower can be set up for PID control, but I'm not sure which is best for my purpose which will be general forging for a while and occasional welding later on.

My question is about the +/- of forced air (blown) vs. venturi burners. Darren's forge comes with your choice of venturi or blown burner, so what's the skinny on each setup? I believe forced air burners can reach higher temperatures than venturis, but if a properly set up venturi can reach welding temps, is there really any need for the blower? Is there a significant savings in gas usage in one vs. the other at forging/welding temps?

Thanks in advance for any advice you can throw my way.

--nathan
 
Nathan,

honestly i've not even completed a knife yet. but i've built a forge and a blower. i started out thinking that a venturi would be the easiest to build and ended up buildding a blown burner because it ended up easier to build in the long run.

from what i understand from talking with various guy is that it is easier to get to welding temps for blown burners than for venturi burners. now i'm not saying that there arent guys out there welding with venturi burners, just saying alot of guys i've talked to with venturi's wish they had a blown burner instead and that the heat isnt there for them.

the blower in Indian Georges web site really works and is as easy to make as it looks. the simplicity of it still amazes me. course now i understand enough to know that most are simple.

good luck buddy

jake
 
If using a PID, a blown forge is far better.

While you can use a venturi to run a forge and turn it on and off with the solenoid, it will not be even and will reignite with a woof every time it cycles. A blown forge can be operated with a two-stage controller as per my plans.

besides that, it is far easier to make and operate a blown burner.
Stacy
 
Years ago I built a mini forge and EZ Bruner (venturi style) as designed by Ron Reil and still it use at home. I thought it would be simpler and liked that I didn’t need to have electricity close by. This spring we got one of Darren Ellis' 8-HT horizontal forge with the blown burner at work. I haven’t used it a lot, but I think I like it better then my venturi, enough that I probably make a blown burner for use at home. We have natural gas in the studio at work, so I don’t thinks it truly apples to apples, but the control/adjustability seems better and its definitely quieter.

Todd
 
I have a brand name venturi forge, it is easy to use, it is nowhere near hot enough to weld despite what the manufacturer claims. I have been building blown forges for the last 5 years, I leave my venturi forge at one of my student's house unless I am teaching somewhere

-Page
 
Should be any reasonably sound design venturi burner will produce welding temperatures if the forge volume and burner output are matched. Generally given, 350cu.in. for a 3/4" venturi burner. That is a thing a person finds at both ends of the venturi burner spectrum... Larry Zoeller's 3/4" "modified side-arm" and Rex Price's 3/4" T-Rex.

Mike
 
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Thanks for the information, everyone. It looks like I will build a blown setup for whatever forge I come up with for the versatility, assured high temps, and ease of construction. Thanks everyone!

--nathan
 
The other end of the blown burner spectrum is the low temperature end. Many venturi burners won't run without sputtering and back-flame below 1500-1600F. With a blown burner, you can throttle it down to as low as you want. So, no worry about overshooting a 1200F sub-critical anneal, etc.
Stacy
 
I think to get an equal performance from a venturi (which IS possible) you need to really have it dialed in. You can put a blown forge together with baling wire and duct tape and have it reach hi temps. ;) :)

I've had both (a few times over for each) in my shop, and feel a blown forge is easier to dial in with temperature, and JUST AS importantly...with atmosphere.

Keep us posted Nathan :)
 
I have both up and running now. For general purpose forging (around 1800 degrees + or -) the venturi runs on about 10 PSI, my blown forge runs on about 3 psi.
 
I agree with Nick. I have both types that I have built. Both will reach welding temperatures, both require the same amount of gas to build that heat. The difference is, on a forced air setup the orifice size and placement is almost immaterial, you just adjust volume of gas and air. On a venturi burner the orifice size and placement has to be correct for the venturi size and shape. The pressure has to be higher because this is what carries the air into the burner. Tuning requires experimentation.
If you buy a functional unit of either type the hard work has been done and only adjustments for your conditions need to be done. If you like to build things and understand how they work either type can be built from scratch, but forced air is easier. Noise level on either type can range greatly with design and component choice.
Have fun.
Alden
 
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