23 replies to this topic

[Arthur Brown]

That Aluminium is not cheap really isn't a good answer. You are trying to make a safety critical item, you need it to be safe, so please allow for the cost of doing best practise well.

If you want to play plastics, I have heard of someone making a sand loaded polyester resin mould inside a length of 3 or 4 inch HDPE pipe.

[parabolic]

You are trying to make a safety critical item, you need it to be safe, so please allow for the cost of doing best practise well.

Arthur, i'm sorry but I don't agree with you.

Are you suggesting that an aluminium clam shell is there for my safety?

the only protection items possible is lexan sheild and or a remote way of pressing the motors in a closed room.

in my opinion clamp shell design is only to stop case spliting so regardless of cost it does not matter what it is made from so long as it can withstand the pressure.

and when I work in this hobby I don't class it as 'playing' I take a very serious approach.

Edited by parabolic, 05 August 2011 - 09:25 AM.

[parabolic]

Parabolic, what sort of rocket motors are you thinking of pressing?

I think you could have problems extracting BP motors with a solid sleeve and especially with motors in the 3lb range and nigh impossible with the loading pressures of whistle mix.
You may prove me wrong though!

Vic, it was whistle type project. it may have to be two piece we will see.

I don't plan on doing anything soon, I'm way to busy at the moment anyway.

Edited by parabolic, 05 August 2011 - 09:24 AM.

[digger]

Parabolic, what sort of rocket motors are you thinking of pressing?

I think you could have problems extracting BP motors with a solid sleeve and especially with motors in the 3lb range and nigh impossible with the loading pressures of whistle mix.
You may prove me wrong though!

It is surprisingly easy to press em out of a solid sleeve. The only requirement is that the bore is smooth and parallel. I had no idea if it would be an issue until I tried it and it worked fine.

[whoof]

helix, one of the main reasons I want to get away from machining a hole is because I don't have tooling to bore a 1.5mm 10" long hole..

Do you have a lathe, a boring bar for that diameter is fairly easy to make.

I have been experimenting with rocket body design winding carbon fibre around a centreless ground bar as a mandrel, they are incredibly strong.
Math says 1.5mm thickness will resist in excess of 10000 PSI.

Edit

http://www.carbonolo...m-od-p-131.html
Is off the shelf

Edited by snert, 05 August 2011 - 12:46 PM.

[dr thrust]

spotted this on pyrobin, most impressive

[Vic]

Nice, looks like 4oz whistle tooling.

[barra69]

I have quite a bit of experience using epoxy resin in boatbuilding. Resin with filler will can be used as engine mounts for large caterpillar engine units with no problem. If you have a look on West epoxy site you will get info on how to make the mix. Fine sand works well as a filler, however you may wish to put some glass cloth into the shell after pouring the initial 'skin' of straight epoxy. Just gives a little extra insurance as far as strength is concerned.
A point to note. Make sure you use epoxy and not a polyester resin. There is almost no shrinkage in epoxy.

[parabolic]

nice advice barra69; thank you.

I have gone back onto homebrewing beer/wine again as it's coming up for the festive period by the time its ready to consume , so this one is on the back burner now.