Press safety ?

[Swede]

How about modern materials like Kevlar mesh? I salvaged an old kevlar vest, took it apart, and ended up with many beautiful kevlar sections.

 

These could be epoxied using thin marine epoxy or similar, to some sort of backing, perhaps 2X 3/4" plywood sections. I'd sandwich the kevlar between the wood. Or perhaps it'd be better to have the kevlar on the human side of the shield. Need to think about that one.

 

I agree with dagabu's explanation. You WANT the shield to crumple and absorb energy. It's not something that is supposed to do its job more than once. A kevlar police vest, once shot, has to be rebuilt, which is where I got mine. It had been shot too many times to rebuild, and was thrown in the trash.

[dagabu]

How about modern materials like Kevlar mesh? I salvaged an old kevlar vest, took it apart, and ended up with many beautiful kevlar sections.

 

These could be epoxied using thin marine epoxy or similar, to some sort of backing, perhaps 2X 3/4" plywood sections. I'd sandwich the kevlar between the wood. Or perhaps it'd be better to have the kevlar on the human side of the shield. Need to think about that one.

 

I agree with dagabu's explanation. You WANT the shield to crumple and absorb energy. It's not something that is supposed to do its job more than once. A kevlar police vest, once shot, has to be rebuilt, which is where I got mine. It had been shot too many times to rebuild, and was thrown in the trash.

 

Great point, I too have a level 4 vest that I got after my buddy got winged at the range (dont ask). Same idea even with the vest, the mechanism should shear at some point allowing the shield to part from the press. I would think that 1/4" threaded rod would work well.

 

I like the idea of laminating the panels since you have a front and back and if you cut the binding thread, you should have a dozen (or more) individual sheets to work with.

 

You may have created a new product Swede!

 

Dave

[jukka]

You may have created a new product Swede!

Dave

 

Something like those Kevlar curtains? And those angled towards explosive source to direct the pressure wave away from you.

[dagabu]

Something like those Kevlar curtains? And those angled towards explosive source to direct the pressure wave away from you.

 

Exactly, a V would cause the blast to radiate away from the middle leaving the host of pressure to bypass you.

[KruseMissile]

Great point, I too have a level 4 vest that I got after my buddy got winged at the range (dont ask).

 

 

I gotta know now lol! My brother got a PASGT vest from the gun show for like $15.

[Swede]

If you open up the early model kevlar vests, they contain not one but dozens and dozens of individual kevlar sheets or panels that are sewn into cotton envelopes. The square footage of individual kevlar sheets is very high, but to get decent protection, I think you'd need several layers epoxied (via squeegee or roller) to whatever substrate you'd want to use.

 

I think the best place (in retrospect) is sandwiched between two sheets of ply, for example. Sheet one takes the brunt of the blast, and probably will gather shrapnel so it won't bounce about the shop. The pieces encounter the kevlar layer, and in an attempt to continue towards you, the helpless pink-fuzzy cowering on the other side, it would have to physically push the kevlar into a pocket, clear the second sheet, penetrate the kevlar, and continue onward. If there's enough kevlar and it's bonded properly, I don't think a typical hobby device will make it through.

 

The entire shield might be blown into you unless secured adequately, enough to keep it from becoming a projectile itself, but not so much that it stands tall and immovably stiff, which would limit its ability to absorb impact and shock.

[drtoivowillmann]

Whistles have to be pressed (NOT RAMMED) to consolidate...how else are they supposed to be made?

 

Dear Bonny:

 

Whistles are funny things, but do you love them so much that you are disposed to die for them ?

I prefer to live and not to make whistles at all !!! When I would have to make them, will be separatedly,

in an isolated press in an isolated builduing, with total separation between people (workers) and the material.

 

If you want to die, use a rope around your neck and a beautiful tree.

 

I beg your pardon, but I love my pyro-friends too much to want to see them die. All whistles, even with

perchlorate are murderers !

 

Greetings from Brazil:

 

Toivo

[Bonny]

Dear Bonny:

 

Whistles are funny things, but do you love them so much that you are disposed to die for them ?

I prefer to live and not to make whistles at all !!! When I would have to make them, will be separatedly,

in an isolated press in an isolated builduing, with total separation between people (workers) and the material.

 

If you want to die, use a rope around your neck and a beautiful tree.

 

I beg your pardon, but I love my pyro-friends too much to want to see them die. All whistles, even with

perchlorate are murderers !

 

Greetings from Brazil:

 

Toivo

 

I understand what you're saying. But for those that want to make whistles, they do need to be pressed. I think it should still be emphasized that ramming is not acceptable. When I first started out and didn't know better I was ramming 1/2" whistles. I was lucky nothing happened, and learned that they should never be rammed after.

[zenen1]

hey guys, sorry to bring back an old thread, but i read through this and now i have a couple questions, are their any dangers with ramming straight bp with wood rammers?

also are their danger with ramming bp with added metals like titanium magnesium or aluminim?

[guntoteninfadel]

So basically pressing metals around spindle is bad? Or is this just limited ti Ti? I really want to put some Al and MgAL in my motor (it's why I got the press in the first place) just have not gotten around to it yet. Let me know what you think.

[pyrokid]

So basically pressing metals around spindle is bad? Or is this just limited ti Ti? I really want to put some Al and MgAL in my motor (it's why I got the press in the first place) just have not gotten around to it yet. Let me know what you think.

 

Correct. You want to avoid having any metal around the spindle because it increases the possibility of an accidental ignition.

 

If you start pressing the metallic comp right above the spindle, it is visible essentially right away after take off.

[dagabu]

So basically pressing metals around spindle is bad? Or is this just limited ti Ti? I really want to put some Al and MgAL in my motor (it's why I got the press in the first place) just have not gotten around to it yet. Let me know what you think.

 

There are lots of comps that use MgAl or Al in them around the spindle. The red chuffers I make have 28% MgAl in the fuel and that is pressed on the spindle. I would use caution and make sure you are shielded, you follow a known comp and be careful pulling a jammed spindle out of the motor.

 

http://www.youtube.com/watch?v=BXGrpxZhz40

 

 

-dag

[Mumbles]

Titanium is definitely a no-no around the spindle. It would make me at the very least uneasy about removing it from the tooling. It will however also eat up your tooling sooner than later.

 

To touch on the post made by Zenen1. Ramming BP with wooden dowels should be fine. If you want to be comfortable in case of an accident, a welding or other thick glove, face shield, and heavy clothing should minimize the majority of things that could go wrong. Ramming BP with metals in them is a different case. I wont BS you and say I've never done it. All I will say is that if you choose to do it, be sure to take appropriate precautions. but it is probably not recommended. Out of curiosity, what type of effect are you trying to make with the BP + Metals? Rocket delay tails, fountains, etc?

[guntoteninfadel]

I have been using a comet of ralphs glitter for rising effects on my rockets using both Al and MgAl. Every body here loves the snap crackle and sparkle on the rise. My fusing is less than spectacular though as I use that grey fast fuse instead of BM. Sometimes my rising effect sits on the ground waiting on the motor, sometimes it starts late and makes a round trip. I was thinking just to mix the MgAl I'n with the bp and press it. This is kinda making me think to just use it in the delay. Like I said though I have not fooled with it yet.

[madmandotcom]

have you considered a hand press? you can still get large amounts of pressure but you wont have large amounts of force