this post was submitted on 02 Oct 2024
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So I'm not sure this would qualify, it may be too simple. I'd been thinking about trying to build a solar forge (I got to learn forging from a really good blacksmith who worked with coal for a couple years, though I am very much an amateur). I've seen videos of people using old fresnel lenses from rear projection TVs to burn through skillsaw blades and if you can melt steel, you can certainly forge it. It might just be slow, or too focused on one spot, requiring some movement to distribute the heat, something I'd have to mess with. It'd also be a bit of a safety hazard overall, but at least it'd be outside on a paved driveway instead of of inside a shed like my old coal forge.
I was picturing something similar to this smelter but with a reused TV lens, and a fire pot where his crucible is. The mechanical parts would be for rotating it to keep the sun shining through the lens, and possibly for adjusting the focus. Stability and safety would be a big consideration, don't want the wind blowing it around too much.
Again, not sure if it's what you're looking for, but I'd like you to get some usable answers here. Best of luck with your project, thank you for reaching out to involve the community!
Very cool stuff. I might have to look a bit more into this. There's a chap melting copper here with a 13 square foot lens - looks like a pretty small beam, not sure if usable for your purposes. But cool idea, have you got some lens dimensions in mind?
Also, definitely not guaranteeing any safety, but think i'll give it a shot.
That's great! I don't have specific dimensions in mind (only because I haven't sourced a lens yet). I'm not sure about the beam width. I think no matter what, it'll be a narrower heat than you normally get with a coal fire or propane forge, so the blacksmith would probably have to adjust beam and shift the position of the piece to distribute the heat. But people make all kinds of things using little coffee can forges so if it allows for even that scale of project it'd be very useful.
It might not be a drop-in replacement for a traditional forge, but it could be a really cool way to preserve a lot of the practice without burning coal or gas. Let me know if I can help at all!
Sure, I'll work off that copper coin lad's dimensions and try and make it adjustable like the smelter. Could you point me towards an example of the little coffee can forge?
Sure! Generally they're just an old coffee can with a thick layer of plaster of Paris and sand or firebox cement on the inside. They cement in some torch parts so they can attach a can from a burnzomatic torch and blow fire into the small, contained space from the side while having a hole on the front (usually with some loose firebrick for a door) to insert the work.
https://m.youtube.com/watch?v=xv9nnEhgfuY
I don't know that the design itself is actually applicable here, just that they're a good demonstration that even with a small forge, you can do some pretty cool blacksmithing.
In practice I think a solar forge would have to be open from the top, and couldn't really benefit from the tight space confining the heat, so it'd probably be closer to using a portable ferrier's anvil like you might see reenactors use at the fair, or something like this:
Though it'd look more like that artist's smelting rig with the big lens and all.
Thanks! I'm really excited to see what you come up with
Just to add, the way I pictured this working was to set up a basic smithee, probably a three sided shed so I'd have a dark place to work (helps to gauge the temp of the metal by color). I'd get some of those gas welder's goggles with the flip up flip down lens (or use my electronic welder's hood) so I could safely look at the work in the firepot (solarpot?) then take it inside to quickly work on it. I'd stow the forge inside the smithee (or in an attached lean-to) when not using it. One feature that might be good would be a way to cover the lens and unclip it from the forge so it can be stored in a box or wrapped up, to reduce the risks of it starting a fire.