Powder die and Corning machine

[bmarley5780]

I am thinkin that the top part can be cut off and just use the bottom part of 10 1/4 dia.

Ah! Now I see where your coming from. I would just use the bottom part!

[BPinthemorning]

Where should I get polyester resin for my pistons?

[Mumbles]

Bondo, sold for repairing boat and car bodies is generally a fairly good source I do believe. It might be called "fiberglass resin", but it is actually a polyester resin, that is then used to bind the fiberglass fibers.

[bmarley5780]

Corning drum ....

 

http://cgi.ebay.com/15-Gallon-Plastic-Barr...1QQcmdZViewItem

[Draco_Americanus]

that would be a big ass drum! would the less stiff sides cause the pucks to bounce rather then break?

[FrankRizzo]

Where should I get polyester resin for my pistons?

PM Tentacles about the possibility of him turning a custom diameter powder die for you from PVC. He's got a nice little lathe and about the perfect size rod stock to fit up to a 3" ID sleeve. I'd guess that he could do it for less than what you'd pay for Bondo and materials to cast your own.

[BPinthemorning]

Ok, every time I try to push my pucks out of the die I have, they break apart! How can I get them out without them crumbling???

[Arthur]

Slightly moist powder will compact rock hard under sufficient pressure. If you cannot raise this pressure then look at a smaller die to make a smaller dia puck.

 

The pucks then need drying and corning (rebreaking)

 

The pressing consolidates the mixture and increases the density of the solid, making the mixture as intimate as it can be. However a puck is a slow(ish!) burning solid and has to be broken to better sizes for use in pyro. This is called corning, it is basically hitting the puck till it breaks into small grains, and sorting the grains by mesh size for fast or slow purposes in pyro. Tenney L Davis describes corning as the most dangerous part of the manufacture and best done by remote control at a distance.

[BPinthemorning]

I know what corning is... And I am using a 12 ton jack, its just not staying in puck form...

[Mumbles]

Actually lighting a pressed puck will have it flying around like a flying saucer from accounts I've heard.

 

Would you mind better describing your setup, and how you are currently attempting to get them out? Without this information we can't help you.

 

In any case, it might not be that bad. I know several people who crumble the pucks into large pieces right after pressing them to make the corning process more manageable.

[tentacles]

Are you compressing the puck slowly, and letting it rest when it doesn't want to compress any more? It took me about 10-20 minutes per puck last time I made some. Otherwise you will compress it some, and it will stick, and you'll think that's all the farther it will go. But the powder needs to rest and compress, let it sit a few minutes and then give it a couple cranks on your jack, I think you will find it will compress more. It's not like pressing a rocket, where you have the mechanical advantage of small surface area. Most BP die sets I've seen are 2, 3, 4" and you just don't have the brute force with that much surface area.

 

You can compress dry BP into pucks also, I have done this - you're just forming a grain similar to making a BP rocket. But 1% water will help you out. If you use too much water it will squeeze out when you compress the puck.

[Bonny]

As Tentacles said, compress, then wait, then compress again. I used to use 12% water but now use about 10% water.There is some water that is squeezed out, but my BP once corned performs quite well. I found using less water pucks did not dry as hard and were more crumbly. Passfire states to use 10% water with about 5% alcohol added to it and had the same result when using less water as I did.

[GalFisk]

what would happen if you tried to light the puck on fire? Just wondering.

The only report I have ever heard of lighting a whole puck is from Lloyd S. on rec.pyro. He said they have taken off like frisbee's, jetting around at random. Not something I want to be near, actually.

Idea for a new firework: spin stabilized BP puck

[psyco_1322]

Flammable hockey pucks, yay.

 

Yah it shouldnt matter if they fall apart after pressing, you still got it to the density it needs to be. Its just in smaller pieces now.

[BPinthemorning]

Mumbles, earlier you told me that bondo would work for my pistons, but even after plenty of dry time, they just crumble in my press. Do you happen to have any experience with bondo? If so, what am I doing wrong?

[JCrewPyros]

Bondo as in Paint and body for vehicles bondo? I used to paint and repair cars and I don't see in any way "bondo" could be used for pressing pucks. Even if you used a whole tube of hardener it would become to brittle. If someone has used it then please explain on that alittle more.

 

If Mumbles says it works then it must actually. He is a very good source of information. I would just like to know what the process is that creates a material out of Bondo that could withstand that type for pressure.

[justanotherpyro]

It was used by dan williams for a comet pump which may be the most common place this technique comes from. http://www.pyrotechs.org/dwilliams/comet/comet.html

For the powder die though he uses cast resin

http://www.pyrotechs.org/dwilliams/powderdie/powderdie.html

[Mumbles]

Yes, having never made it myself, I was simply going off of Dan Williams' results, if I did indeed recommend it. My brief experience with bondo in the terms of automotive repair would make me think you got a bad batch or you mixed it wrong. Globs left on tools and newspaper were essentially small rocks when fully cured that took significant force to fracture, and even then they didn't crumble.

[FrankRizzo]

If anything, the recommended product would've been Bondo polyester resin, *NOT* the body filler.

[TheSidewinder]

If you make APCP, you probably already have PBAN or HTPB (R-45) and the curatives. I'm pretty sure either of them will do the job, as well.

[BPinthemorning]

Mumbles, you said it would work on the last page of this thread. I'm not blaming you, and I'm not at all mad, the bondo does indeed say it is polyester resin, so I would think it would work. this doesn't seem to be the case. Does anyone know if I should just add extra hardening mix? Or is this just a lost cause?

[FrankRizzo]

You used the *clear* resin mixed with sand, right?

[justanotherpyro]

One of the reasons why Bondo is amazing is because of its versatility. It can be set and cured differently for more of a rubbery type final product or for a rock hard final product. It should work you just have to find the right method of using it. I suspect that you are right in that you might not have used enough hardener.

[BPinthemorning]

I'm going on spring break, skiing in Colorado. (stupid 6 am flight, now I have to get up at 3am tomorrow). I'm gonna make some pistons with a load of hardener. They get a whole week to dry, and then we'll see what happens.

[Poindexter]

Holy thread bump.

 

Briefly I have gotten into making my own BP because I am an avid recreational pistol shooter, and my wife loves fireworks. So a win win. I am working on coming up with a base mix that I can corn directly into pistol powder. Once that is set I can can then add a bit of carbon and a bit of sulfur to "my" base mix mill dust to come up with all of the standard BP pyrotechnic compositions.

 

I have my pucks up to 1.7grams / cc and have scoured the internet looking for a better way to break up my pucks into usable sizes. i am getting about 35% 20-60 mesh and 65% fines using a mallet. I have found a couple references that my mallet technique is poor, but no references about hwo to use a mallet more effectively. Still playing with that.

 

There are, that I know, two extant methods for making a corning (puck breaking) machine. One, the passfire developed billiard ball mill already alluded to in this thread, and two, the machine developed by William Congreve in the early 1800s.

 

The other decent thread on the internet about corning BP pucks is here:

 

http://www.muzzleloa...id/203267/tp/1/

 

With the Congreve mill illustrated on page three like this:

 

 

As a retired homebrewer of my own beer, I immediately thought of (very common if you know to google "malt mill") machines like this just as an example:

 

http://beersmith.com/barley-crusher/

 

So for my next challenge I will talk to a couple local to me machine shops about replacing the steel rollers on the prefab unit with brass rollers, while simultaneously working on my malleting technique and trying to figure out if there is a catch or subtlety to the passfire design.