Pressing Rocket Fuel - Possibly lower pressures needed with waxed tubes ?

[Maserface]

Interesting stuff, Ill be testing hotter propellants for sure.

thanks

[mabuse00]

Time to bring this very interesting tread back to the top.

 

I have a question:

This depends on the method of course, but I'd just like to hear some rough numbers:

How thick are your wax layers?

[DavidF]

I don't measure the thickness, but I have measured the weight. Ideally, a waxed 1lb NEPT rocket tube will gain about .4 gram. A 3lb tube will gain around .7 gram. The hotter the wax is when applied, the better. If you use pulpy tubes, they suck up a couple of grams in the 3lb size. If the tubes suck up more than that, they are probably no good for rockets.

 

I like the dauber method because it makes over-application of the wax less likely.

[Mumbles]

A quick calculation based on those masses comes out to 0.0015" coating on a 1lb and 0.0018" coating on the 3lb. Does that seem reasonable?

[DavidF]

Yes, that seems reasonable. If a regular piece of paper is about .005", a third of that seems about right.

[mabuse00]

In fact do not care how much the tube swallows, I was rather worried if a tight fitting rammer might become to tight.

Ill have to try it out anyway.

 

 

What melting point does your Paraffines have by the way?

My thought is something like "the lower the better" to prevent it to freeze to early, thus avoiding unnecessary layers.

[NeighborJ]

I've taken a rammer and put it in my oven then dropped it thru all my waxed tubes to remove the excess wax. Usually a swab waxed tube will have no excess buildup so it isn't necessary to size the wax with the hot rammer. The swab is the best method for applying wax and I'm grateful to DavidF for sharing it.

[OldMarine]

I heat my wax until it just begins to smoke a bit then back off just a tad. The hotter it is, the less buildup you'll get and you only need a very thin layer. Shotgun bore swabs are the cat's meow for this task!

[dynomike1]

4oz tubes i use a 50 cal. swab.

[FlaMtnBkr]

Does anyone know if this has been discussed more thoroughly somewhere else where there is more involvement and data?

 

I would also be curious about the tube winder that was mentioned on the first page. I imagine it's something probably from Ned's site? Also, anyone know how much activity there is over there now that it's a few years old? Passfire too if anyone knows.

[OldMarine]

Fireworking is a busy place and Dave has extensive info on all things rockets there.

[mabuse00]

Since I haven't found something to abuse for this - like shotgunn swabs or somehing - I wonder if anybody here has found some material that can be used.

Some kind of not to soft foam that must survive the hot wax while staying in shape.

[OldMarine]

I use shotgun bore swabs mostly but for my 5/8" tubes I use circles of Scotch-Brite mounted on a dowel to apply the wax. Works well once you get past the pain in the neck of making the little discs and punching a hole for the dowel in them.

[MrB]

I'm daft, for sure, but why would we bother with swabbing?

You need a pot to melt the wax in. Put a (metal) cone in it, something like this, ok, so this one i think is to expensive, and over engineered, but the craftsmanship is stellar, anyway... back on topic...

Put cone in pot, put tube to be waxed on cone, pour vax in with suitable tool, fill to desired level, (I'd leave a tiny bit unwaxed, just so i could get the tube on the tooling, possibly part of the clay nozzle) lift the tube, and drain the wax back in to the pot instantly, and you are done. Swabbing sounds like it would be more labor intensive, and possibly, more of a mess.

[DavidF]

This is part 1 of my tube support video.

http://pyrobin.com/files/Tube%20support%20for%203lb%20strobe%20rocket%2C%20made%20for%2020%20bucks_1.wmv

 

Here is Part 2 of the tube support video.

https://www.youtube.com/watch?v=hDY_yz-QpGA

 

 

Here is a link to an article about the tube-waxing.

http://pyrobin.com/files/Reducing%20Catos%20in%20Pyrotechnic%20rockets-V2_1.pdf

 

I hope these help. I'm usually around here, if anybody has a question.

[mabuse00]

 

I'm daft, for sure, but why would we bother with swabbing?

B, I just did exactly that. With most tubes you're fine that way. But there are others that simply wont suck up the wax. No matter how hot you process the stuff.

 

 

Scotch-Brite sounds interesting. But they have a variety of foamstuff... Some of them are very rough and large pored.

Can you name a particular product?

[OldMarine]

Here ya go:

https://www.amazon.com/dp/B001KYQBX0/ref=cm_sw_r_cp_dp_T1_Yl7FzbJYGGYKS

[DavidF]

I use the blue no scratch ones, lower down on the page.

[OldMarine]

I use the blue no scratch ones, lower down on the page.

Do they cut more easily? Those green ones are a booger to cut and punch.

[DavidF]

Yes they do. It's a different material than regular Scotchbrite.

[OldMarine]

I'll pick me some up on the next Wallyworld incursion. My current dauber is getting ragged.