Controlling airflow on a forced air ribbon burner

[Chaz7795]

First time poster, long time follower. I’m building a ribbon burner forge and wondering is there a consensus on the best way to control the airflow? I’ve seen everything from ball valves to sliding gate valves downstream of the blower to different ways of diverting part of the airflow before the gas is introduced. I’m using a centrifugal type blower and I’m wondering should I be controlling it on the input or output side of the blower. Any suggestions much appreciated.

[swedefiddle]

Good Morning Chaz,

Welcome to the whatever this is, Loads of Fun and Interest!!  If you put your area of where you are making a Shadow, there probably is someone fairly close to you. If you enter it in your Avatar, it shows up every posting. Nothing to be ashamed of and nobody will harass you.

There is a rotating restrictor on the blower intake, of the blower you have. Fans work better of you put the restrictor on the output. Some people make a sliding sheet metal gate, or you can purchase one. There are different sizes for the different size ducting. I have used a big old gate valve, water shut-off, before with very good results. You can get a reostat to control motor speed as well. If you restrict the air input, the motor speed will increase because there is less load on the motor. this may also cause the motor to heat up a bit.

Ribbon Burners seem to work easier with a blower. I have a couple that I use with Atmospheric Burners, no fan. There is more options for control, with a fan.

Enjoy the Journey!!

Neil

[Frosty]

Welcome aboard Chaz, glad to have you. Ditto putting your general location in the header, you'll have a much better chance of meeting up with members living within visiting distance. 

Your blower already has a valve so air control isn't an issue. 

Neil and I differ on one point. It doesn't matter if you block the intake or output, not moving air reduces the load on the motor letting it speed up closer to the unladen RPM and run cooler. This is easy to check with a draw meter (whatever the electronic doohicky used to tell how much power is being used is called) You can feel it if you block the output with your hand, you'll feel air pressure until your hand blocks it and the pressure will drop considerably.

So, do NOT worry about hurting the motor by blocking the air flow in or out.

If you've been following the forum very long you know who I am. My ribbon burners are naturally aspirated, no blower means a trickier build to make a ribbon or other multiple outlet burner work properly. Once tuned to the job it's stable from stop to stop on my regulator settings. 

Once you get your burner set up it'll be easy to tune it with propane psi and air flow.

Frosty The Lucky.

[Chaz7795]

Thank you both for your responses. The flow control that’s on the side of the blower barely makes a difference shut all the way off I would say just by feel is still putting out around 60-70%. 
I may try the sliding sheet metal gate approach. It’s probably going to be a little trial and error. It’s going to be a little slow going for a while, but I’ll try to keep you updated on my progress as this is a spare time project. Again think you both.

By the way I live in Wilkes County in N.W. North Carolina. I’m not sure how to get that on my avatar yet but I’ll figure it out.

[Frosty]

Hmmm, taking a closer look I can see there's quite a bit of gap between the blower body and gate thingy. I wonder if you could put another thin aluminum one on top of the blower body and connect it to the handle of the existing one. Thinish sheet aluminum or maybe printer's tin, would move with the existing one but being thin the draw from the blower would suck it against the body for a tigher seal.

Maybe, hmmm?

Frosty The Lucky.

[Chaz7795]

Sorry about the misleading picture Frosty it was just meant to show the type of blower I have. My forge is still in the early phases of the build. Kinda building it as I go and trying to use the material I have on hand. This is we’re I’m at now, and figured the burner would be my next move. I have a ways to go yet so don’t be too harsh in your critique. I have a small shop and have to build something I can roll out of my way when not in use. I’m just getting started in my blacksmithing endeavor,  I have a cheap 110 pound vevor anvil that will just have to do for now.                                                                                                                                        

I’m a maintenance tech at a local distribution center, but I done machine work full time for 15 years before that. My dad was showing me how to thread and make things on the lathe when I was 13 or 14 years old, and he’s also the one who peaked my interest in blacksmithing. He’s been doing it as a hobby for about twenty years I guess. He has a nice coal forge, and a 275 pound Refflinghaus anvil ( talk about anvil envy ), and he’s also building a gas forge, slightly different style but the body is the same that he can use for those things that it’s not worth getting the coal forge going for.

Thanks for the reply, and I try to keep you updated with my progress.

[Frosty]

I'm not being harsh Chaz, I'm being direct. If I think you made a mistake I'll say so and explain why, if that's too harsh for you let me know I'll leave you to your own devices. Okay? 

For example why the HUGE openings in your forge shell? How large is the work you're planning on doing in it? Have you looked through the propane forge section of Iforge? There are a number of proven designs with plans for a propane tank forges. If you pick one and follow just the one plan it will go well. Mixing and matching design features without knowing what you're doing is a good way to build failure.

Aren't you going to use a blower like the one in the picture you posted? If you are then at least think about my suggestion instead of arguing or restating what you want to do and telling me an unrelated story. For example, what does your anvil have to do with building a ribbon burner or do you plan on hammering on it? 

Stick to the subject, at LEAST think about suggestions, better yet give them a try and compose good questions. Can you do that? If you don't have a piece of sheet al in your resource pile try construction paper and see if it'll improve air control. Just glue it to the screw in the center of the existing gate valve and GIVE IT A TRY.

To be honest, I think you're making a mistake trying to make a ribbon burner, you're having more trouble than it sounds like you can handle just figuring out a basic a blower. Perhaps just make two single nozzle burners to get you up and forging?

Frosty The Lucky.

[Chaz7795]

Apparently I completely misunderstood your statement. I thought you were talking about something you saw in the photo other than the factory input damper, because the photo was from and odd position and probably confusing. That’s why I backed the picture out to show the entire build. The background info about myself was because I’m new to the forum, and I had seen similar info in one of your post, about how your father was a metal spinner and machinist. I’m not the least thin skinned, but I didn’t realize I was arguing anything. People’s mannerisms In different regions of the country obviously vary greatly. The ends can be closed back up if need be, I can even put the ends back in I’ve cut out, right now there’s no insulating material in the forge at all. I apologize for the rambling post, seems I had several things to address. I have a lot more I wish to say, but I’m obviously not as proficient at typing as you are. You must find it much easier to type than read. It seems odd that’s it’s so burdensome to read a paragraph of background information, but you don’t mind writing a book to address things I’ve not even asked about yet. If I chose to post again I’ll stick to the subject at hand.

[Frosty]

Uh HUH, sorry to bother you with requests to stick to a subject. I won't do it again.

[Chaz7795]

You are very unlikely to be bothering me with anything.

[BsnNFrnt]

Here is my rig for the airflow on my ribbon burner. This one is a plain 1&1/2” ball valve plumbed in approximately 2’ ahead of the mixing tube. I have had excellent luck with is set up for the last two years. I believe we even have the exact same blower. Hope that helps. 

[Chaz7795]

Thanks for the pic BsnNFrnt. I’ll take that PVC ball valve into consideration. Your blowers just like mine, I guess the input damper on the blower wasn’t enough? Just out of curiosity do you have any pics of the face of your burner? Just curious really about hole size and number of holes.

[BsnNFrnt]

Yes sir, the rotating damper on the side was not enough for me. I use a valve on the air flow of my coal forge set up too. My burner is 12”x4”, there are 32 individual crayon sized holes. As you can see from the pictures. I run a .030 mig tip for the propane supply and mixing tube has a blender vein inserted nearly the full length. I can attain welding heat around 4-5# of propane tank pressure. 
My forge opening is roughly 11” by 7”. I use various arrangements of doors depending on what I am working on. 
I went ahead and dropped in a picture of my crayon mold for reference. I got all the ideas and information from the ribbon burner threads on this site. 

[Chaz7795]

Thank you very much for taking the time to answer my questions, just what I was looking for.