My forge's going to take a while!

Joe, you did really good with that layout - looks like a real "tin knocker" at work. In the old days a person who worked construction with sheet metal, doubt that term is still used in these "modern times" {g}

Bro I'm old, but even I had to look up the term 'tin knocker'! ;)

Thanks Ken!
I was busy but it doesn't seem like a lot accomplished.

First I welded up the inside scroll and cleaned up the outer welds a bit. Then I cut the top and bottom of the scroll halves to final shape, leaving a 1" lip to bolt through. And then I drilled the bolt holes. Cut a few 3/8-16 pieces of all thread for bolting the halves together. Then I mocked it up again looking at the gap I need to fill for the sides. I think a decent working gap will be about 6.5" that leaves a 1/4" clearance top and bottom on the squirrel cage. I found this 6" wide roll of aluminum flashing that just might work without a lot of cutting, kinda thin, maybe I'll double it up? Once I'm happy with the sides I will need to build some kind of exit box for the rectangular opening.

Tomorrow I'll cut the top inlet opening and maybe try the flashing for the sides.
That's gonna suck some air out of shop. You might need an oxygen monitor to be sure there's enough air left to breath {grinning} Bet it's going to be noisy but you need to be wearing hearing protection anyway so the noise won't be an issue. Good work
Thanks Ken!

Fairly productive morning. Got the inlet hole cut and the rest of the 3/8" all thread supports. Then put it all back together for what could possibly be a final assembly. And then let it rip....

Then I messed with the aluminum flashing, it's woefully thin, like .020", 25 or 26 gauge. I was almost afraid to try it. but I did and it seems to work OK. A bit scary as there was only 4 small C clamps holding it down. I'd feel better with something like a 20 or 22 gauge.

It is a roaring beast! And the sides aren't even close to being sealed up. Kinda of worried about unclamping it from the table, it might go airborne. Be interesting to find exactly how much air it's moving. In the video you can see it looks like maybe the top half of the scroll is flexing, or it could just be the squirrel cage tolerances, I'm not sure. Maybe I should put in an internal support? Or maybe a strut of some sort across the top? Once it takes the weight of the inlet duct it may get worse?

I'm going to call IMS Monday and check the price of some 20 or 22 gauge sheet metal. I have to decide the final mounting of the sides as well. Pop rivets are quick and easy but if I have to take it apart they are a pain. I could drill and tap a bunch of small holes!? Maybe pop rivet the top and tap the bottom!?

Another issue I may or will need to deal with is the galvanized duct. I've cleaned the ends of zinc with vinegar but haven't come up with a way to strip the middle section. Zinc fumes become problematic at around 395° F, call it 350° F to err on the side of safety. I'm not sure how far away from the forge that kind of heat will still be acting on the duct. I could just give it a go while wearing my respirator and monitor the temps. Or maybe I just use an orbital sander and strip it manually.

Still need to build the exit box which will include the cut off which I believe increases performance.

So close and still so many questions!
That sucker is BLOWING!! I doubt the zinc will be a problem in the duct - remember they're blowing outside pretty hard and will disperse nicely in the large open outside air. Maybe wear respirator for first time. Can't be too careful these days.
Thanks Ken, sounds like good advice, I'll manually strip the OD and let the heat take care of the ID!

I didn't get much done today. Spent quite a lot of time coordinating my online food orders and delivery and then getting what we won't use immediately vacuum packed and into the freezer. Also spent quite a bit of time pondering my next steps.

Though I finally decided my next steps.

1, I would build a flange for the top inlet to stiffen the top of the scroll. The flexing has me worried especially when I add the weight of the exhaust tube on top of it.

2, I'm going to try to use the 16 gauge sheet metal I already have on hand to form the walls of the scroll. Not really sure I can bend it around that scroll but it costs me nothing but time to try. I know I would certainly feel more comfortable if it was 16 gauge. If I can get it bent around the scroll I'll probably pop rivet the bottom and tap holes for the top. Not much metal there (16 gauge) so I may have to deal with that.

3, then thinking about the exit/exhaust box with the cut off I think I can just fabricate that out of the same 16 gauge and just pop rivet it in. Maybe tap and screw the top.

So here is what little I actually accomplished today....

Basically I just cut out a 16 gauge flange and then rolled a 1" x 1/8" ring which will be welded to the flange. Though I might need to tighten that ring up some. Then this will be bolted or pop riveted down to the top half of the scroll. Not only should it stiffen the top substantially but positively lock down the air inlet.
Good work Joe. Isn't it amazing how much time it takes to do projects like that? Look so simple but VERY time consuming.
Two days and I still think I didn't get a lot accomplished but it is what it is!

First I welded up the top exhaust inlet ring and welded it to the flange. Then I pop riveted it to the top half of the scroll. It certainly stiffened up the top a lot, don't think I need worry about that flexing anymore. I may regret leaving that foam seal on that exhaust inlet...time will tell.....

Then I tried using an orbital sander (60 grit) to remove the galvanization from the outside of the 8" duct but that was taking like forever, what you see is about 10 minutes worth!!!...... might have to pursue a different tactic....

I bought some 20 gauge (.040") sheet metal from IMS, a 1'x4' piece was like $6! Interesting they are practicing social distancing there. They would only let so many people in at one time and only if you were wearing a mask. They would also sell you a mask for $3 if you didn't have one. Saw one guy leave fairly upset.

Got the 20 gauge cut into a 48" x 6.625" strip and proceeded to put the sides on the scroll. Kinda slow with all the drilling and pop riveting but it came out OK. It was a bit tight wrapping the 20 gauge sheet around the scroll form, I don't think I could have done it with 16 gauge with no place to clamp.

You can see where I miss-drilled the one hole in the side2 and inside2 picture. I was still on the flange so I'm not worrying about it.

Here's a short video of it running with the sides in place. I didn't even have the all-thread tight at this point. It certainly blows more (subjectively) than before. It actually sucks my hand down in the video.

Tomorrow I'll start working on the exit/exhaust outlet with the cutoff in it.
Here I am sitting 'n waiting to see how that works with the forge. I do think it's gonna really pull some hot air out.
Well I more or less finished up today! Still more to play with but I think without much doubt the exhaust blower is a success!

First I made a quick simple version of the exhaust exit box, really just consisting of the cutoff for the fan. Forgot to take a picture of the cutoff! Kinda interesting when turning on the blower (freestanding) without the cutoff installed it would just stand still on the workbench and start blowing. After installing the cutoff when you turned it on it would torque about an inch CCW. (The squirrel cage rotates CW) It would only do it on the steel bench top not on the concrete floor.

Here's a couple of quick videos at about 40 minutes after I fired up the forge. The first from the front and the second from the rear.

Hopefully you can see the IR thermometer readout clearly.

The ceiling never got over about 100° and it's 102° outside currently. Last time I fired the forge up I was measuring ceiling temps around/near 200° and it was much cooler outside.

The galvanized duct temps seem OK, might have to watch it near the hood during an extended forging session.

Not sure if the exhaust blower is affecting the forge burning negatively, don't really have any time on this forge.

For the future I might try mounting the blower to the forge cart, it's a bit fiddly to get the tubes all together and they will probably only get worse in the future as they get dinged up. Might try mounting the forge a bit lower.

Overall I'm pretty happy with it!
Sure looks like the forge is doing good and the vent is doing it's job keeping things cooler. You got it. The duct isn't all that hot even with flames from rear of forge being pulled up into vent. With a brick closing off rear of forge that duct isn't going to get near so hot. I doubt it will ever bother the galvanizing.

Now, are we ready to start forging something? What will be first project?
Sure looks like the forge is doing good and the vent is doing it's job keeping things cooler. You got it. The duct isn't all that hot even with flames from rear of forge being pulled up into vent. With a brick closing off rear of forge that duct isn't going to get near so hot. I doubt it will ever bother the galvanizing.

Now, are we ready to start forging something? What will be first project?

Thanks Ken!

I think you are definitely correct, I wasn't even thinking about the fire bricks! Also they will affect how the forge heats up as well! More testing there for sure. I wish I had thought of using the fire bricks before testing today. As they say live and learn, hopefully I live that long! ;)

Well as exciting as it sounds, I have some RR spikes hooks promised to friends and family. I really want to try my hand at a hammer and some canister Damascus. Remember I'm fairly new to this game and I'm just learning! I do think that this blower may extend my forging window a bit into the summer until maybe it gets real hot around here or maybe all summer IDK. Currently it's only 86° in the garage and it's 110° on the back porch. I really think the exhaust blower is going to be a big help, I learned a lot and it was a fun build. Thank you for coming along!
I've intentionally steered clear of posting on this thread, just because I didn't wanna muddy the waters. Been a while since I checked in......DANG! Looks like you've built an entire new industry!! :) Funny how one project always seems to lead to another! :)
Ed, we always appreciate your advice and please don't ever worry about "mudding the waters", if it is different than what we're thinking, most likely we NEED to change our thinking and need your guidance.