Mini thumbnail dies

[Dema]

Hi,
I've just buy this mini "harbor" press at a flea-market for about 3 $, and I like to play a bit around it.
so I spend 1/2 an hour to build a pair of thumbnail dies, just to test wich thickness of aluminium their can tucking.
It can easy tuck a 19 gauge Al sheet. :o
Maybe some of you can suggest a better ideal shape for the dies?

Dema

[John Kelly]

Hi Dema,

Can you post a picture of a tuck formed with the tool?

John www.ghiaspecialties.com

[Richard K]

For Shrink die plans Go to:

http://www.metalmeet.com/photopost/data/3086/medium/43Shrink_Die1.jpg

[Joe Andrews]

:shock: Richard you could have given me that! We Start Machining the Shrinking Dies Tomorrow. I'm going to start a thread showing the processes from start to Finish. Richard sent me a set of his Dies and we laid them out on our CMM. Richard said the set he sent worked very well. Once he has a chance to try them out and make any necessary adjustments we can go into production. I machined a fixture today to hold 8 dies at once, the initial dies will have 1 Inch round Shanks that are an Inch long. We have to put a flat on the Dies Shank in order to Orient the Dies to each other. In the new thread I will be open to suggestions for different Shanks.

[tdoty]

I made a pretty darn decent set of thumbnail dies from Richard's plans. Dutch says they're good, who am I to argue with him?

Tim D.

[Dema]

Hi Dema,

Can you post a picture of a tuck formed with the tool?

John www.ghiaspecialties.com

Hi John,
here is a picture of the tuck with the actual tool.

Dema

[John Kelly]

Hi Dema,

Those look pretty good! Perhaps a little too close together to hit accurately with a hammer. Do they flatten out when you hammer on them, or do they shrink? What type of hammer are you using to shrink them with? What technique are you using?

John www.ghiaspecialties.com

[Dema]

Hi Dema,

Those look pretty good! Perhaps a little too close together to hit accurately with a hammer. Do they flatten out when you hammer on them, or do they shrink? What type of hammer are you using to shrink them with? What technique are you using?

John www.ghiaspecialties.com

I'm just lerning about this technique, 8-) till now I was use the "Italian technique"
I have to practice to flatten by hammer :?:
Dema

[Joe Andrews]

HI Dema,

I would suggest you change the die to a Taper, The idea when Shrinking a panels edge is to gather it up gradually. Try between 10 to 15 degrees, maybe a bit less. The further into the panel you go it should be gathering less material, or to the outside you should be gathering more. To really get a good shrink to a panels edge it needs to be done this way, also try putting in less tucks at a time and giving more space between them.

[John Kelly]

Hi Joe,

In my opinion... depending slightly on the hammering technique chosen, it does not matter much what the inboard form of the tuck is. The outboard portion of the tuck is more important. The inboard part can be anything from a big bubble to a nice tapered tent like shape without making much difference to the final outcome.

John www.ghiaspecialties.com

[firstgenbird]

My notion of how tuck shrinking works is that you position the sheet such that hammer blows drive the metal into itself, making the sheet shorter. So the more vertical the sheet is, the more effective the hammer blows will be. I think the tucks may produce more shrink for each tuck/crush cycle if the vertical edges are made as steep as possible without introducing stretch. A limitation will be a tendency for the tuck to fold over during crushing. Too steep will cause fold over. Too shallow would give you less shrink per crush. I would try making the edges steeper and see what happens.