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Hand Cranked Forge Blower Build

Here are the pictures of my Hand Cranked Forge Blower Build, made using a Mole Hand Grinder found on the internet (which has a 1 to 10 gear ratio), some old side pannels off a PC, a few small rivets, some protective steel corners that came with a kitchen worktop and some 12mm Aluminium angle iron. 

 

Here are the picture's of the grinder on its own. 

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The back piece with the right angled brackets. 

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Starting to rivet together the fan blade using 12mm aluminium angle iron. 

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Cutting the brackets to size and drilling the holes for the rivets. 

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After riveting the first part of the fan case together. 

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I then ran out of rivets but decided to continue using cardboard to check everything would work alright. 

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The rivets I needed arrived and so the rest of the fan surround went on as well as the bolts to hold the front panel on. 

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Here is the fan blades and mounting disk, its not perfectly balanced so does 'wobble' abit but it should be fine for the amount I will be using it. 

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And here is the 'almost' finished blower. I ran a line of bathroom chalk around the joins on the inside of the case to cover any small gaps and the bolts hold the front on tight. I don't own a hole saw large enough to make the 80cm dia hole in the front so lots of small holes with have to do for now. All that remains is to find a piece of tubing to connect the blower to the forge and then try it out. 

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The blower seems to be providing a reasonable amount of airflow although I think it isn't recieving enough airflow from the holes in the front. 


Ill try to take a video when its working and post a link to this thread. 

 

This blower has probably cost me between £40-£50 and around 30-40 hours of time, I'm a pretty slower worker but when your doing something you enjoy the time really doesn't matter. Buying a hand cranked blower in okay condition would have most likely cost £60+ but I wouldn't have learned anywhere near as much as I did by doing it myself. 

My original inspiration came from this thread here: http://www.iforgeiron.com/topic/22816-home-built-hand-blower/

If anyone has any suggestions or advice, or wants to ask any questions then by all means feel free. 


Thanks for reading and hopefully there isn't too many pictures, I know how much you guys enjoy them. 

Tom

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That'll work a treat once you open up the intake port. A chisel or sabre saw will open up the intake port easily enough and a lot faster than drilling a bunch of holes. Heck, use a larger bit and drill so they connect, clean up with a file and you're golden. Lots of ways to make holes in metal, especially aluminum.

Frosty The Lucky.

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Nice job building your own forge blower. Makes me want to build one even though I don't need one.

Let us know how well it works after you get it hooked to the forge.

 

Steve,

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looks great. I'll be interested to see how well it works :)    I've had the same thought with some hand grinders I've got, but the blowers I have are all more like 50:1 rather than 10:1 (I may have one grinder at closer to 20:1 thinking about it?)

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IIRC there have been pics posted here about 3rd. world blacksmiths that apply to this thread. The one that keeps coming to mind is a Viet Namees fellow who makes forge blowers as a support industry. He uses trashed bicycles for the gear train and crank, The blowers themselves as I recall were nothing more than a circle of thin steel, aluminum, whatever was handy on an axle with impeller vanes riveted, screwed. . . attached around it. There was only one shell piece covering the vanes the spinning disk formed the other half of the snail case.

Simple and effective devices. If someone here has a link I'm sure it'd fit right in here.

Frosty The Lucky.

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I just did dot to dot with a few different sized drill bits until the centre piece fell out, a few mins with a half round file and the hole was finished. Found a pipe to connect it to my forge, so will duct tape it all up and give it a try tomorrow. Ill try grab a video on my phone.

Also how much grease to the gears need? Is it possible to put too much on the gears, I do have some gear oil as well which my grandad gave me today. 

Tom

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Just a little drizzle of oil every couple sessions will do the trick nicely. The rectangular pieces cast proud on top of the shaft with the cover plates are seep oliers. (If that's the correct term.) A little oil on each felt or in the valley and it'll slowly seep down into the bearings and then on to be slung on the gears. Don't use extra heavy oil, plain old 30wt is what most of these things were designed to use and there is a LOT of tolerance, rendered bacon grease is just fine but it's hard to get in to the bearing. That requires a hot wire probe of the channel to melt and get the lard/tallow/etc. to flow. Not recommended but it'll do in a pinch.

To check, just touch the felt with the tip of your finger, if it comes away oily it's good, if dry give it a LITTLE squirt.

Frosty The Lucky.

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Just seen your post about Q max cutters ID, I can honestly say i have never heard of them before but they look really simple to use. I guess if i was cutting many holes this size I would invest in one of those or a hole saw. 

The weather looks good today so ill put a few drops of oil through the little oil channels and then see if it works,

Fingers crossed :)

Tom

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So I spent the afternoon trying it out, It was sort of working. However the pipe I used to connect it to the under side of my forge was well over a metre long, it was due to this that I think it failed at heating the 15mm square past a dull orange heat. (There could be other issues here, like using a brake disc thats too shallow, not building up enough coal/coke around the fire, etc etc). Im going to get another pipe and try again later this week. 

 

Thanks for the help guys, Tom

 

 

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So that's what they're called: mole hand grinder.

I just found a smaller version of these in my dad's barn and immediately recognized the presence of higher gear ratio as I went to crank it. He said I could have it so I'm going to see if I can build one of these myself. Albeit, probably with cardboard and a whole lot of hot glue instead :)

On second though, I just realized I have a bathroom fan I picked up for cheap. I just extracted its blower wheel (part no. 99110842) which I'm thinking of turning it into an attachment than can plug into this mole hand grinder somehow for manual crank, or a drill for powered crank :)

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