Ribbon Forge Burner | Page 2 | Tutorials | Forum

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) ???

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... 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).

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,
Did I miss the question? I did a great deal of research on fans when I built my first coal forge. It was a while ago but I don’t think anything has changed. If your question is can you formulate an equation to predict output across all fans the answer is no, there are too many variables. Compensating for them would create individual equations. If you’re trying to increase output by increasing HP that should not work, it is because fan manufactures build the fans at very close to the maximum output for the size of the intake. That way they can rate the fan at its maximum. I’ll let you in on a little secret fans can be made a great deal quieter, most of the noise from these fans are at the intake, they are swallowing a lot of air for the inlet size. If you add a fan speed control in the mix (not a dimmer switch it will burn your motor up) and lower the RPM the noise drops dramatically. *edit* Also it will allow you to use variable CFM without restrictions that cause more noise. If this doesn’t answer your inquiry could you rephrase it? That way I’ll have another excuse to regurgitate my copious pap upon an unsuspecting world.
Bob
*(of course if you are using a fan that requires you to use it at its maximum you’ve got a problem, the fan must be overrated for the application.)

David,
OK I’ll try, the answer is no. As I understand it fluid dynamics do not relate to mechanical energy directly unless the fluid is contained within the system. Look at a wind tunnel, the turbine blowers use the speed and pressure of the preceding propeller to get enough intake to increase the pressure and speed of the air to allow the next to increase to its capacity. If you increase the power and speed of one in the middle of them past its available air supply it will not add anything to the system and may be detrimental to it. If you use a air compressor (a closed system) increasing the HP will help until you reach the intake capacity of the system or you suck up all the air in the world. As for the sales tactics used with fans, it’s hard for most people to figure out what they need and hype instead of facts probably sell many more fans. The thing you need to understand is the limit on the fans is not HP it is the intake capacity. They only have so big of an area to get air from when that is reached it cannot do any more. A fan with a greater CFM rating than you require used at a lower RPM will give you a longer lasting quieter blower for your application.
Bob

I'll chime in here. I really think it would be better if you have something needing welding but don't have the equipment or experience to just take it to someone that can do it for you. Cost would be minimal and you will have the comfort of knowing it was done correctly. If anyone in my area needs this done just bring it over - no cost.

Bill,
Offering the weld up anyone’s frame is very generous of you. And I agree, I would use brass as a last resort, but somebody may have that need. As for hijacking the tread I don’t think that’s possible I may be wrong but I think when discussing the tutorial system with Grant the idea was to let the thread develop as it will with comments from any who wish to contribute. As gems appear in the thread they are moved to the first post with the poster’s name and post number. People who are only interested in the outcome of the thread need only look at the first post. If they find a post that interests them they can navigate to it easily and see how it developed. The idea is to have fun and build a tutorial that has the best of the information in an easy to find way. When it’s done (I believe how that is to be decided is one of the things that Grant wants the members to do) it will be edited into an article and placed in the CMS with the contributors names. To stay on topic is to keep the posts about the design, building techniques, parts, use, maintenance, safety and anything else that pertains to a ribbon forge. Having a WIP in another thread is cool too. But post stuff here too as you see fit. The tutorial is for all the members to contribute to, a question from anybody can start an avalanche of information to pour out of some very informative people, look at how this thread got started. This thread may be Grants test of how well the system will work before committing all the time and effort into it that it will require. Hopefully it will be a success and many more tutorials will develop and flourish here. I’m sure Grant is receptive of any suggestions on how to make this work.
Bob

I guess one of the things I'm grasping at is trying to identify a sutable blower for a blown forge (with capacity to spare for upgrading) I'm mulling over replacing my 3 x 3/4 " atmospheric burner forge with a blown version for a variety of reasons. I like what I've read about ribbon burners

The blowers Grant sells don't seem available over here and the available ones can be a bit pricey for what is just an experiment for me at this stage ..... which leads to ebay and the hit and miss on offer, grain blowers, bouncy cancel blowers, carpet dryers etc etc etc. My initial thoughts where to get what looked a good "beefy" industrial one with a good sized motor which hopefully could deliver more than enough cfm at a suitable pressure ..... which leads to the question (which may or may not be appropriate) "what's a good sized motor in horses"