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Hybrid ThorJack

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: Petitlu » Sun Jun 24, 2012 5:23 am

Ok for the mold!
Why cut off your head?
it can be overtaken from the mold.
Note, this is often the head that stops the penetration of the nail ...
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Unread postAuthor: Goats spudz » Sun Jun 24, 2012 10:14 am

Petitlu wrote:Why cut off your head?
What? :D
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Unread postAuthor: Petitlu » Sun Jun 24, 2012 10:29 am

:D

Why cut the nail head?
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Unread postAuthor: ramses » Sun Jun 24, 2012 11:10 am

How long are those fins!? It looks like you would need a very long, thin endmill to do that.

I think you might need to cut off the head to have access to put the nail into the mold.

If he counter-bored the fin end a little, (and the fins are large enough) you, the epoxy could completely surround the head.

I would suggest leaving the head on and making the fins big enough that you could use the head to index the nail into the mold, so it does not fall out during curing. Although, you could just make the mold the right length and use the tip for that. The fins (and head) might impede penetration.
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Unread postAuthor: Petitlu » Sun Jun 24, 2012 11:20 am

nails I shot like this in:

Image

Stope head penetration :

Image
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Unread postAuthor: jackssmirkingrevenge » Sun Jun 24, 2012 11:38 am

Petitlu wrote:Why cut the nail head?


... because it stops full penetration ;) also, it shifts the centre of gravity forward meaning the fins don't have to be so long.

How long are those fins!? It looks like you would need a very long, thin endmill to do that.


I calculate 1cm or so, which should be easy to achieve with a 1/8" end mill.
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Unread postAuthor: Petitlu » Sun Jun 24, 2012 11:58 am

I hope the demoulding will not be too difficult
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Unread postAuthor: ramses » Mon Jun 25, 2012 4:48 pm

jackssmirkingrevenge wrote:
Petitlu wrote:Why cut the nail head?


... because it stops full penetration ;) also, it shifts the centre of gravity forward meaning the fins don't have to be so long.

How long are those fins!? It looks like you would need a very long, thin endmill to do that.


I calculate 1cm or so, which should be easy to achieve with a 1/8" end mill.


my 1/8" end mills are much shorter, but have a 3/8" shank. I also didn't quite appreciate the scale of the mold.

If he will be removing the heads, I would encourage you to make the whole mold just long enough that the nail will bottom out flush with the far end so the fins are consistent. Maybe plan on leaving part of the nail back a little, so the pusher plate pushes on it, rather than the fins so as not to stress them too much.
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