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  #1  
Old 05-25-2022, 04:49 PM
Ducatichica Ducatichica is offline
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Default Hemisphere shaping

Hello folxs. I am trying to make hemisphere out of .063 3003 aluminum.
I am aiming for 10-12 diameter. The tools at my disposal are English wheel, shot back and hand tools. I can not seem to get a tighter arc than 4 “ with a depth of 3.5”. I can get it tucked down with a fork however when I try to smooth it out I get back to 4 “ arc.

I will try to get some pictures , I do not want a dome which seems relatively easy to achieve the sphere part is the harder part. Is this a matter of doing this is strips and welding and sanding back?

Your experience and guidance would be appreciated. I do not have any local gurus In seattle so gonna hope you can help an learning artist

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Last edited by galooph; 05-26-2022 at 02:21 AM.
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  #2  
Old 05-25-2022, 05:15 PM
Jaroslav Jaroslav is offline
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Use the steel ball and hockey puck. I think you're using "American Tooth" as a tool. No wonder you can't.
You will destroy the fibers of the material with your tooth and there is a problem with smoothing the surface. Start shaping carefully from the edge or your center will crack. I don't know what device you have, but it also works in a hand press. Slowly and gradually push the ball into the puck.
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Old 05-25-2022, 05:15 PM
fciron fciron is offline
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How are you flattening the tucks?

Tucking is the preparation for shrinking, so you need to hammer them down with a bit of technique. If you are flattening the tucks with the English Wheel I’m not sure you can get any shrinking, the EW is almost exclusively stretching machine.

My background is art metals so I usually shrink silversmith style, which they call “raising”. I smash the tucks down over a curved stake. For a dome like yours with the available tools I’d probably make a stake out of a piece of hardwood.

I’ll try to find some pictures.
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Last edited by fciron; 05-25-2022 at 05:18 PM.
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Old 05-25-2022, 05:35 PM
Ducatichica Ducatichica is offline
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Jaroslav I am not sure what you mean by “American Tooth” however I think I understand that I am damaging the fiber of the material. I have stretched the inner of one of my tests so severe that it got very thin and would flex with just finger strength. Pardon my interpretation as shrink the edges before stretching the center.

Fciron I think you might be on to something in my process I was tucking the edges then closing the from the inside with the English wheel. I tried Closing the tuck on the outside yet I think I was experiencing merely stretching them back to a radial curve and not getting the shrink. I will trying to picture what you are saying.

Thank you both I have lurked on your posts before and you folxs make me jealous appreciate your feedback and help
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Old 05-25-2022, 05:38 PM
Ducatichica Ducatichica is offline
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Default Ball and hockey puck

Jaroslav I think I understand by “American Tooth” you mean the tucking fork. I think you are talking about the low crown dish and ball at the edge to form the tuck. My brain take some time to figure out things as I contemplated your reply.
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Old 05-25-2022, 06:14 PM
fciron fciron is offline
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Try searching for “tuck shrinking” here. I think you’ll find some folks hammering the tucks down into hollow blocks to shrink then, which is easier to get one’s head around. I just don’t have a big enough block of wood to commit to it.
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Old 05-25-2022, 08:02 PM
blue62 blue62 is offline
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When Jaroslav is talking about the "American tooth" he means a "thumbnail shrinking die" used in something like a power hammer.


For tuck shrinking go to you tube and search for tuck shrinking by Peter Tommasini. It is a quick demo of tuck shrinking.
When you view it pay attention to how he starts out ....the inward end of the tuck forms a small "Y" shape you need to change that to an "I" shape then hammer the tuck down. Watch it several times you will see what I am getting at.


I would do that shape with the blocking hammer, shot-bag, and stump.
A mushroom shaped bench head would be helpful.


I would only use the wheel for the final smoothing.
When you put your piece in the wheel use the least amount of pressure as possible and stay away from the edge.
If you wheel out to the edge you will just drain the shape out of it.
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Last edited by blue62; 05-25-2022 at 09:02 PM.
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Old 05-25-2022, 08:53 PM
steve.murphy steve.murphy is offline
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Are you trying to make this solely from stretching and shrinking or multiple pieces welded together?
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Old 05-25-2022, 09:08 PM
Ducatichica Ducatichica is offline
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I am trying to do it just by stretching and shrinking. I think I need to up by shrinking game and will update after I get a bit better at that.
Most of my shapes and art has been thru stretching. The hemisphere is not getting a full shrink to match the depth and I have exhausted my skill at stretching the dome. Evidence by the finger push at the center of the dome
I believe I need to get it tucked down just a bit more
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Old 05-26-2022, 02:17 AM
Jaroslav Jaroslav is offline
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Do not use the tooth. There's one of the tools on my thread. You need a ball with a larger diameter, but even with the little one you can lift it where you need it. Clean work. You need a press, but it can be of any type. And EW for surface smoothing. If you need to lift the surface somewhere in the EW. Use the narrow bottom wheel. I use 0.5Kg gym weights. After refilling the bearing, it is a great tool. Good luck.

https://www.allmetalshaping.com/showthread.php?t=16457
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