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iron quake

Swage Blocks Concave Forms

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Is there any inexpensive way to make concave shapes (forms) to use in making cupped shapes? I know you can purchase swage blocks but the shapes are too small. Sizes are on the order of 3-10” diameters with radius 4-20”. I’ve not gotten any prices but I’m guessing having them CNC machined in steel would be very expensive.

I’m not interested in having a pattern made to have them cast, I don’t think. We have a very good foundry here and they could cast anything I could dream up but I’m trying to be cheap…as usual.

Any ideas folks?

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I've a got section of tree stump that I'm thinking of putting a depression in for dishing. Got the stump from one of the neighbors when they dropped a tree in their backyard. My guess is that it will work pretty well for sheetmetal-ee type stuff. Not sure how it will do for heavier material.

If it doesn't work, I'll use it for anvil stand or cut it up for firewood, or for tool handles. I'll make good use of it either way. :)

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You could do something like this depending on how deep you want the forms to be? Large diameter pipe offcuts can work too, make sure you grind/file the edges round. I have seen someone use the cut off end of a propane gas bottle as a large dish former.

Tree stump idea is great too!

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Heat a piece of 3/16 plate or thicker if needed sink to the shape needed then weld stiffiner around outside edge and other places if needed.

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Find out where the local welding supplier has their tanks hydro tested and see if you can buy failed tank *bottoms* as dishing forms---what the medieval recreation Armourers do.

Also start looking for toroids---lifting eyes, ring and pintal tow rings.

Also take a piece of round stock and heat it and bend it into a ring and arc weld the ends together

(ring/toroid ones are called "bottomless dishing forms" and are quite handy for working sheet metal where you don't want to overly thin it by hitting hammer against sheet against form)


I get tanks on a semi regular basis at the local scrap yard and cut them with my big angle grinder. ALWAYS BE SURE THE TANK IS EMPTY BEFORE CUTTING. and remember ACETYLENE TANKS CAN NOT BE MADE SAFE FOR CUTTING ONLY USE OXYGEN, ARGON, NITROGEN, CO2, HELIUM, ETC TANKS!

The companion to dishing forms is dishing hammers there is a description on how to grind the face of a regular 3# crosspeen into a dishing hammer over at armourarchive.org as well as discussions on forms, hammers, methods, etc

Ah yes almost forgot to mention that *old* CO2 extinguishers often have nice dimples and were thick steel---unlike modern ones. A local Fire Safety business may be changing out old ones for new ones and scraping the old ones. *Talk* with them and avoid any of them that used a dry powder as some of them were toxic.

Talk with your local SCA armourer's and see what they are using and where they got it too.

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Thomas's mention of tanks reminded me of something. I used to work for a company that hydrotested SCUBA tanks. The ones that failed we'd sometimes cut up and use for display/demo pieces for inspection training classes. Others we'd destroy the threads on and sell them for scrap.

Check with your local dive shop and see if they have any. The only thing to watch out for is that some tanks were/are made out of aluminum and probably won't hold up to any kind of bashing. Cutting the cylinders shouldn't be a problem with a metal cutting band saw.

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the bottom of oxygen cylinder's are concave cut off the bottom and use it. for planishing I use a ball stake to make the surface smooth. not hard hits bouncing hits like holding a drum stick holding the handle with your thumb and index finger as a pivot point. the remaining fingers as springs.

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