Hi all,

Thinking of building a box bellows for some shows ive got coming up this summer. I'll be demonstrating and wont have any electricity hookup for my normal blower fan. I also do not have the budget to find an old hand crank bellows.

I've been watching some videos and I get the gist of how they work (they look really quite cool). Is there any reason that they cannot be done vertically? I would prefer to run a bellows by pulling down on a handle rather than a hosizontal push/pull motion (just what I find comfortable). In theory I cant see why this wouldnt be effective allowing gravity to handle the downward stroke and just pulling it up. Also by transferring it to an up/down motion, I'm opening the option of controlling with a foot pedal.

Am I missing some reason as to why it wouldnt work well?

For context, my solid fuel forge is a bottom blast with about a 200mm round firepot (with a flat bottom). I use steam coal, but I'm not adverse to using charcoal if I can't get enough airflow for green coal. Also, I will be forging mainly small stock (6mm-12mm) with the occasional bit of 25*5 flat bar. Although I would like to be able to forge upto 25mm square with this forge and get a welding heat on the smaller stuff without issue.

I've attached a sketch of what I'm thinking.

 

I would appreciate the thoughts and opinions of you wonderful peeps.

Sure, horizontal bellows have been around for a long time and can be very simple. My personal favorite is an open top barrel of water with a smaller one that telescopes into the larger, a lift mechanism and a couple 1 way valves. When you lift the "piston" barrel a flap valve opens allowing the space at the top to fill with air, (inhale). When you release it the barrel sinks into the water forcing air out through the other valve to your forge. Control the rate of air flow with a simple gate valve. A foot pedal makes a fine on off valve actuator.

You can do the same thing with round or square boxes but you'll need a way to seal between the pump box and body box. It's pretty straight forward.

There are leather vertical bellows that simply collapse and produce blast. The lifting and valving is basically the same on all of them.

Adding weight to the top increases pressure, flow is controlled with a gate valve.

It's all pretty easy once you get the picture.

What I REALLY like about vertical bellows is only having to pump them half as much. 

If you make a very large vertical bellows you'll want to use a smaller bellows to pump the main bellows up, same as a double acting or great bellows.

Questions?

Frosty The Lucky.

The barrel of water bellows sounds ingenious. I orriginally started to think of the option as there was an article in Artist Blacksmith about a lady designing one out of a stainless duct pipe. (Artist Blacksmith is a magazine here in the UK, you get it as a member of British Artist Blacksmith Association or BABA). I was aware of the vertical setup of like, leather bellows, i wasnt sure if there was a reason I'd never seen anyone do the same with wooden box bellows. The only issues I could think of is perhaps having less controll of the airflow pressure when the piston is on it's downstroke, as with a horizontal one you dont have to worry about any sort of flow adjusting valve as you just dont push the rod as hard.

I'm still looking into designs for optimum sizing, and in particular about the correct size of the air intake valves etc. But I'm having technical problems with the forum's search not working.

I'm not sure I understand what you mean by having a smaller bellows to pump the main bellows though?

 

Thanks for the feedback

Danny

I'm familiar with BABA and "Artist Blacksmith" both are available online. Well not BABA exactly but a person can keep up vicariously. 

The beauty of the vertical box bellows is you don't have to pump it constantly, lift the "piston" and it pumps air as it settles. A sliding gate valve or butterfly valve is pretty easy to make and you have control of the flow.

Make the intakes as big as reasonably possible, it's the output you need to control and there's no reason to have to fight drawing air in. 

The forum's search engine has been pretty bad since an OS change years ago. The best way to search the forum is to use your favorite search engine, say Google, I prefer Duck Duck Go myself. Anyway, enter your search terms and add Iforgeiron to the terms and It will search here first. Fore example, "vertical bellows, Iforgeiron".

About the same time the search engine went bad we lost most of our archived photos and articles in a server change or something. I don't recall. Anyway a lot of stuff was lost. (sigh)

Frosty The Lucky.

As you note above, letting gravity do the work on the plunger’s downstroke causes you to lose control over the blast in that half of the cycle (this is the same problem with the water bellows). You’ll also be lifting up whatever weight you’ve had to add to the plunger to force it down against the backpressure. It’s true that you’ll only be adding force to the system in one half of the cycle, but it will be twice what you would have otherwise.

My suggestion would be to ditch the idea of a bi-directional vertical box bellows. Instead, build something like what’s in your drawing, with the blast only going down the tuyere when you’re pulling down on the handle. The only work that gravity has to do then is to drop the plunger back down to the starting position (with one-way valves allowing the chamber to refill quickly), and you’ll retain control over the force of the blast.

Here’s a quick sketch of what I have in mind. The key elements are the valves: the outlet valve at A, the two plunger valves at B, and the two inlet valves at C. In the power stroke (on the left), the handle is pulled down, the plunger goes up, the plunger valves close, the outlet valve opens, and the blast is forced down the tuyere; meanwhile, the inlet valves open, allowing the bottom part of the chamber to fill. In the recovery stroke (on the right), the handle is released, the weight of the plunger pulls it downward, the outlet and inlet valves both close, and the plunger valves open, allowing the air to move from the bottom part of the chamber to the top.

16 hours ago, Frosty said:

I'm familiar with BABA and "Artist Blacksmith" both are available online. Well not BABA exactly but a person can keep up vicariously. 

Of course. Sorry. I am a member of ABANA, don't know why I'd assume an American smith wouldn't be aware of BABA

 

Having thought about it, I do have a 1.5m length of 200mm stainles spiral ducting (it used to be my chimney). That might be more uniformly shaped than what I can cobble from plywood. And a LOT lighter and easier to manage and move. Depending on if I can work out how to get a non-return valve into 2" black iron pipe, I can use the maluable pipe work as the secondary chamber on it's way into the fire inlet.

4 hours ago, JHCC said:

Instead, build something like what’s in your drawing, with the blast only going down the tuyere when you’re pulling down on the handle.

That a really interesting idea JHCC. I can definately see how that would work and be more controllable in terms of airflow. Would it be harder to maintain a good forging (welding) heat with a much longer wait between blasts?

Boy that didn't come out like I intended, sorry Danny. I was the newsletter editor for our local club and still get copies from all over the world as part of an exchange program. I tend to forget everybody isn't getting copies of everybody's newsletters. I love reading the sales ads, you guys have some really nice stuff. 

You've drawn a double acting box, pipe, etc. bellows which should work fine if you don't mind pumping it anytime you want air. If you place the outlet check valve hinges at the top where they connect to the box, cylinder, etc. gravity will keep them closed until positive pressure from that side of the piston pushes them open, I've read about plenty of guys having problems with valves mounted horizontally as show in your drawing.

You might want to watch some youtube blacksmith videos from the 3rd world to get a handle on how simple these things really are. A meter length of 15cm +/- dia. bamboo and a couple smaller dia. pieces to duct to the fire and a stick with feathers tied to it makes a surprisingly effective bellows. Some places there are plants with seed heads like giant dandelions that serve. 

On a bet several years ago I made a vertical bellows with a plastic bucket, duct tape valves, garden hose and a pond. The toughest part was finding something to make a lift bail but more duct tape served. One of the guys had some para cord and we found a stick for the lift lever. We weren't forging anything it was just a campfire but it was a roaring campfire.

Have you ever used a length of pipe and a paper bag for a bellows? That's crazy easy and the traditional version uses a goat or sheep stomach and bamboo.

Frosty the Lucky.