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Arbor pressing 4 oz bp rockets

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#1 royster


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Posted 20 January 2021 - 11:55 AM

I was searching for information about this but i didnt find much for 4 oz bp rockets, i did find a lot of useful information. I spent 3 hours last night reading ancient posts it was very entertaining. 😆

So im trying to move from the mullet to an arbor press, i never had much problems hand ramming, the rockets were consistently good its just that after 2-3 my whacking gets a little sloppy, also after a while the the rammers start digging into the mullet.

So i set up a 1 ton arbor press following ned gorski instructions for extending the working height. I pressed a bunch with different results, seems like theres a sweet spot i havnt found. A little too much force and theres a lip on the outside of the tube, too little force and it doesnt hold well. In short, many catos.

Im going to set up a force gauge, i was wondering if anyone has already found that sweet spot of force with a similar set up and dont mind sharing?

Also i would appreciate any other suggestions, so far i was making 4 oz nozzless on universal tooling from Woodys, waxed nept tubes, as far as fuel i granulate with a fine mesh and press it dry. Should i wet it before pressing?

Waiting on nozzless tooling im very excited about.

#2 Mumbles



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Posted 20 January 2021 - 03:21 PM

You really should keep your rammer away from a sweet mullet.  Gotta protect that Tennessee Waterfall.


What you're probably finding is that the tubes are not quite up to the task of handling the pressure.  A few more experienced builders can chime in, but you're probably going to want a tube support to allow optimal pressing.  To start with, I'd suggest looking into mylar sheets.  It's cheap and remarkably effective.  It's just a coiled sleeve of plastic film.  There are sleeves made from slit PVC pipe as well, but they've largely fallen out of fashion.  There are of course also very nice machined ones you can purchase if you'd prefer. 


In terms of pressure, the traditional pressure is probably about 6000-6600psi.  Some have found more recently that this is probably overkill.  I'd personally start at maybe half of that and see how it goes.  There is something to be said about over-pressing rockets as well and getting cracks or defects from the tube springing back.  There's a good deal of information on pressing damp from JustVisiting on the forum.  With this, you can absolutely get away with a lower pressure. 

Just so you guys quit asking, here is the link to the old forum. http://www.xsorbit2....forum/index.cgi

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#3 Bigmark



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Posted 26 January 2021 - 08:47 PM

Yep had the same problems when i first started with the arbor press. I ended up getting a tube support and started using 2% water in my fuel. These where 1/2" motors nozzles 75 15 10 fuel. Haven't had any problems since.
I did give it a few seconds of dwell time on each fuel increment. At the time I didn't have a ptf gage.

#4 shockie


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Posted 27 January 2021 - 04:03 PM

I concur.....if you are going to use an arbor press you're going to have to have a tube support of some kind. 

this helped me out alot:




I also agree with the 2% water in the mix. 


also you might want to consider waxing the inside of the casing, now that you are pressing:


http://pyrobin.com/f... rockets-V2.pdf

#5 royster


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Posted 05 February 2021 - 07:28 PM

After messing around with pvc i had laying around and achieving unsatisfying results i ended up 3d printing tube support. With 3 hose clamps and %2 water it seems to do the trick.

Tested 3 rockets with the nozzleless tooling and they ripped, one of them was packed with extra force and it went snoop dog high.

Going to test with a dummy load and see if it could possibly lift a "3 ball shell.

Thanks for the help

#6 EastTxPyro


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Posted Yesterday, 10:25 AM

I bought a arbor press for my small rockets and love it. I use 65/25/10 BP for my 4oz and my 8oz rockets. But have added 2% moisture to my standard BP and works great too.

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