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Designing a spreadsheet to calculate forge volume


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Hi All,

In planning for a forge my friend and I want to construct I started to build a spreadsheet that would calculate things like internal volume of a forge cavity in various shapes, amount of ceramic blanket needed, BTU per inch to reach forge welding temperatures etc.

It's a bit rough right now, but I'd like to polish it and consider releasing it for public consumption.  I've included a screenshot of most of what I have right now - ignore the numbers, they're for a forge that will never exist - we have already re-worked our plans since this was made.  Some of the calculations also aren't correct because of incorrect assumptions on my part. (Like that hard firebrick would make a good floor because it's wear and flame-face resistant, I hadn't considered that it's a huge heat-sink too.)

I'd like input from the community as to what could/would make this useful to you or someone you know.  Right now it only calculates two shapes, rectangular prism and oblong semi-circle.  I think it would need at least: Rectangular Prism, Oblong Semi-Circle (this is an arch with legs taller than the radius), semi-circle, circle and in the Forges101 thread I believe I read about D-shaped forges.  Would that be a half-dome with a flat front or back shaped like the letter D, and the opening on the flat side of the D?

If I can calculate volume, I can also include somewhere to specify the approx. thickness of the insulation, then I can figure out length of ceramic blankets, volume of castable refractory insulation and some other things.  Of course, this would all be approximate, and garbage in, garbage out.

Perhaps the greatest part of it for me, and the reason it might appeal to those of you who haunt this forum and answer the same questions all the time, is that by changing things like the length, height, width etc of the forge, you can directly see how much cubic inch difference it makes to your plan.  And when you're multiplying that cubic inch difference by say, 540BTU (which is from one of the threads the higher of the two BTU amounts req'd to reach satisfactory forge welding temperature) you can see how much changing size changes heating requirements.

In fact, in the same thread where that 450/540 BTU numbers are discussed, Frosty did some calculations and put some info about what size/how many burners to cubic inch for a reasonably square space you should plan on, so this could go on to include that info as well.

Would anyone use such a thing if it existed?  And if you would, what would you want it to spit out at you?



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The "D" shape is on its side. with the flat part as its floor. Box forges are rectangular. There are no triangular forges. Clam-shell forges have upper and lower changes that close and separate. Tunnel forges are cylindrical shaped, and normally about one and a half times as long as their diameters, with flat floors that are much narrower than "D"  forges.

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So, "D" shape forges are what I was calling oblong semi-circle. Box forges are easy to calculate and so are easy to add.

"There are no triangular forges." - that made me chuckle for some reason.

Clam-shell forges seem like they would be tough to calculate, but I'm sure I can figure it out with enough thinking.  Tunnel forges will be very complicated to calculate because of the challenge of calculating the volume of the cylinder, then removing the odd shape taken up to make the floor.  I'll have to spend some time with google to figure out the best way to make that work.

Thanks for the input Mikey - it's very appreciated!

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/clam shell forges are only calculated in the close position, because, if brick layers are added for the occasional odd job, they become similar to brick pile forges; variable. Most of the time, their movable upper half is just a convienient way to move large parts in and out of the forge.

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