Ribbon Forge Burner

[david hyde]

People don't seem to discuss the HP of the motor often when discussing blowers. Is the relationship between pressure and cfm related to the horspower of the motor .... kinda in the same way electrical power = volts (electrical pressure) multiplied by current (flow of electricity). In other words for given cfm, the more powerful the motor, the bigger the pressure (or visa versa) ???

[Robert Suter]

Great Info Dave, knowledgeable people with experience will lead us in the right direction, thanks. Pine Ridge has two burner types LP and natural gas. John uses natural gas, from what I remember he said, that the difference between LP and NG was that you need a longer mixing tube for NG, 9 times the width of the tube for NG and could be a little shorter for LP(is that right John?). I don’t remember him saying that there is any difference in the burners themselves. Pine Ridge has LP and NG burners, the difference may be subtle or just hype, we need somebody with the facts or experience with both gases to solve this mystery. David, I believe you’re looking for magic, fans work by pixie dust, the manufactures don’t want to fill our heads with a lot of silly nonsense about performance, just some unrelated numbers and pixie dust (hype).

Bob

[Lee Cordochorea]

Is the relationship between pressure and cfm related to the horspower of the motor .... ???

There is indeed a relationship. But there are a LOT of variables in addition to horsepower.

[Robert Suter]

Lee is right, and I shouldn’t be so flippant with my answers, sorry David. Fluid dynamics are hard for me to relate mechanical systems with, but as I understand it increasing horsepower after reaching the power necessary to move the fluid is useless and can be detrimental to the possess if it increases the velocity of the blades in an open system (non pumping) beyond the capacity of its exhaust, it breaks the fluids bond with itself (clips)and you are left with edge drag as your moving force. Fans built with a partially closed fan structure are poorly build, leaking air pumps with a very limited pressure, however, for our purpose they usually have their limitation in how poorly they are built and the intake capacity.

Bob

[Dave Hammer]

Performance.... Don't forget about the magic smoke that is put in the motors when they are made... Don't ever let it escape. If you turn on the blower and see the magic smoke rising (escaping) from the motor, it is not a good thing. If only a little smoke escapes, the fan may run, but not perform as well. If it all escapes, your fan will probably never work again (without surgical intervention anyway).

[Robert Suter]

Dave,
I meant to ask you about how hot the body of the burner gets in operation. Does it heat up at all? With all that air moving through I wouldn’t think it could get very hot, but what about after it is shut down, does the heat back up into the burner frame? The reason I ask is I’m wondering about what possible burner frame materials could be used. John, or anybody else with experience know?
Bob

[Dave Hammer]

Robert... My burner never got hot on the outside. It was significantly cooler than the outside of the forge body. Pine Ridge states that the burner needs to be mounted in a hole with "space" between the burner and the forge frame. This removes problems caused by conducted heat from the forge frame and potiential expansion of the burner (or forge). They further state that this space needs to be packed with thermal material (like kaowool) so there is no blowback by the sides of the burner.

In addition, they recommend the blower be run for a while after the propane has been shut off. The best case would be to run the blower till the forge has mostly cooled down. If you do all this, I don't expect the burner will get hot on the backside at all.

Pine Ridge has a depth of 5 inches of refractory, 3 of which are on the outside of the metal frame. This, basically, keeps all the metal back out of the forge.

I sound like a salesman for them, but I'm not. I do, however, have a great respect for the way their burners are made (and work).

[Bill Cottrell]

OK reading this thread has got the juices flowing. I made a ribbon burner several years ago and never got around to building a forge to put it into. I got it out today and looked it over and it is still in good shape after me moving it around to different shelves and dropping it once. I have one of the large 164 CFM blowers that Grant imports and sells thru blacksmiths depot that was sitting on a shelf too. The forge I had the blower in was donated to someone else but I kept the blower!
So I did some sketching today and am going to build a forge using Kaowool, Kaowool ridgid board, some of the lightweight insulating bricks, and a ceramic kiln shelf for the floor. It will be 12Wx12HX18"L and have a light gauge steel enclosure.. Still have to figure out a good door design front and back for it. Tom Ferry and I saw a ribbon burner in a glass makers glory hole (forge) and it REALLY impressed both of us with how HOT it got and how quietly it ran. I will put up a thread about the build and keep it updated until it either works or I manage to blow up or burn down the shop.

[Robert Suter]

Dave,
Thanks for the info. I was wondering about that, you spoke of gas leaking out of a poorly welded frame I’m lucky enough to have a mig and many years of welding experience, but not everybody is. What I was contemplating is those who have a torch can braise the parts together. I don’t think an emergency power shut down would get the frame hot enough to melt the brass. If you’re not experienced with braising you will find it easier with coated rods, but flux works fine. A little reading and practice will give you the results you want. It’s much like very hot soldering, the flux will clean the surface fairly well, but for the best results the steel needs to be clean and free of oxides (freshly ground is best) keep it smooth and don’t get it too hot. Grind the brass on the outside of the frame and check for holes, pits or cracks re-braise any defects and it should be air tight. Now if anybody can see a reason not to use brass please speak up, I don’t want anybody getting hurt from my ignorance. If you have more money than time, I think Pine Ridge has had nothing but good reviews, both you and John seem to think highly of them, and they have a very informative web page.
Bill,
This is great, maybe more people will join in and build a forge, and we can have a forge off! And if I fuddle it up you’ll show everybody how the forge works. I’m hoping Dave and John will post their forges in operation, both of them make excellent videos. You posted your plans in the other thread, why not post it here too so it doesn’t get lost in the shuffle. I was going to just start throwing my forge together, but thought if I was going to show everybody the build it should at least have a plan to start with. And I was thinking I would like to have features I have read others think important in a gas forge. Not having experience with a gas forge makes it hard to know if they are important enough to merit the effort. First I would like to have a reasonably large forge, but I want to be able to use only one burner for smaller stock. This I believe will require a removable wall. I would also like to have a three door system with no frame or insulation obstruction when the doors are open for odd shapes and such. I know these are not new ideas and I should be able to design it from others examples. Would anybody care to show me how they have accomplished this? I have a few ideas and I am going to get to drawing them up, then I’ll make changes when and if the wise members of the forum favor me with their knowledge.
Bob

[david hyde]

Fluid dynamics are hard for me to relate mechanical systems with, but as I understand it increasing horsepower after reaching the power necessary to move the fluid is useless and can be detrimental to the possess if it increases the velocity of the blades in an open system (non pumping) beyond the capacity of its exhaust, it breaks the fluids bond with itself (clips)and you are left with edge drag as your moving force. Fans built with a partially closed fan structure are poorly build, leaking air pumps with a very limited pressure, however, for our purpose they usually have their limitation in how poorly they are built and the intake capacity.

Bob

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