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Blaf

Nozzle forming tool

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Since I've recently purchased a nice small Lathe machine, I turned it on the other day and dared to make a nozzle forming spindle and corresponding aluminium base. And it wasn't hard to do it at all! On the contrary, it was pure pleasure to work with this precise piece of machinery. Material used for spindle was Brass rod of 6mm dia while round base is made of Aluminium cylinder of 55mm dia. Center (base) hole is drilled with 4mm dril and tapped with M5 tap die. Of course, the same thread was made on spindle bottom so that it could be screwed on the base. As you can see, spindle has a slight tapper so that nozzles come out conically shaped and (what's the most important) in the very center of the tube.

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You can see the wooden dowel with center hole corresponding to the spindle dia on the left and two blank BP motors on the right...one made by Bentonite and other by ground Kitty-liter. Both look pretty handsome, don't they? Haven't tested this perfected versions yet, though....

Blaf

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This is enlarged version of the same nozzle forming tool, but for 20mm inner dia motor. Note that both of those spindles are relatively short, which means they do not form long core. It is beacuse I discovered that my motors (using given tube dia & nozzle dia ratio) don't need long cores for fair thrust. Finished nozzle on the right is just about perfect, with shiny finish, eventhough it's not clearly seen on photo.

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The spindle is made of steel car engine valve, polished and screwed onto round aluminium base. Test launch is yet to come....

Blaf

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That looks nice Blaf :wink:
And are you having fun with your Lathe machine ?
I always liked to work with it when I was still at school.

And are the rockets wich you make with the rocket tools excellent (I guess) or are there still perfections to be made?

Pirate

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The spindle is made of steel car engine valve, polished and screwed onto round aluminium base


What engine did you get it from ? ( ie. Nissan Skyline R34 GTR :P )
( my dad has a " spareparts" engine block in the garage :twisted: time to disect it )

Thank you Blaf for this very good tip.


Greets Sickman

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Don't really know Pirate...but general rule of thumb suggests nothing is perfect. And yes, I'm having a Hell of a time with this little machine. I didn't know you played with it in school, lucky you...I'm completely self-taught in this field but so far I'm doing well using common sense and caliper.
As for the valve, I don't know what kind of engine it was but it should have been taken from 4-stroke 1100-1300ccm engine...that's derived from its size. The valve "hat" dia was originally 25mm which I turned down to 20mm and shortened its "leg" down to 40mm. Some facing and polishing was done then and here it is. But the truth is; this steel valve can be used as it is, just with shortened spindle...I made all this polishing to impress girls that might read this post...

Blaf

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As for the valve, I don't know what kind of engine it was but it should have been taken from 4-stroke 1100-1300ccm engine


Just checked with my dad and its a 1300ccm engine.
So size is OK, I only have to take it apart for the valve.
As for the base, I was thinking of staying in the car parts and use the piston (head).
With some modification of course. :P


thnx for the idea
Greets Sickman

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Well, these plastic tubes used to make BP rocket motors seem to have been too weak to withstand heavy ramming...a few of them cracked while ramming. And here is solution – plastic sleeve with a cut along its lenght which tightly fits over the tube and additional metal hose clamps which furtherly reinforce the whole setup.

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Now I can ram my small motors without being cautious...

Asembled setup with clamps tightened (not too much), plastic tube in place and ready to be rammed.

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Looks like some horrifying torture gadget, doesn't it?

Blaf

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Wow that looks ver nice again blaf :wink: you've found a good solution.
But are those plastic tubes that weak then? They look very strong to me. Were did you get those actually?

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Hi Yellowcard!

See the blue plastic tube sticked into green one? - that's the weak one. Its walls are less than 1,5mm thick and when I ram my BP with rubber mallet (as I always do with those small ones), it tends to crack. It happened several times to me so far. And so, I took this 6cm long piece of green plastic tubing...its intended purpose is water pipeline (side walls are almost 5mm thick to withstand water pressure)...made a cut alongside with steel saw and there you are!
My former motors were made of very similar plastic tubes but with thicker walls and they never cracked, but this batch of blue ones gave me little headache...and by the way, they come from POS terminals, you know those small machines with slots for credit cards?

Blaf

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No I don't know them....but I think I have a good address in my mind were I can try to get some of those plastic tubes... :( Thanks for the water-pipe tip Blaf ! :wink:

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