Plastic vial (centrifuge tube) size

kjkcolorado · Nov 18, 2018

For those of you who use plastic vials (plastic centrifuge tubes) to make your deployment charges, what size do you use? Online I see a lot of 2ml for sale, but not sure they have enough capacity. Currently the largest charge for any of my rockets is 2.5g of 4f black powder. Thanks.

cwbullet · Nov 18, 2018

I used 1.5ml, 2.5 ml, 5 ml, and 10 ml tubes. I remove the caps with cardboard rockets and use tape to seal them. I have found that I can often use tape or rubber gloves tips also.

tfish · Nov 18, 2018

a good rule of thumb is..

1ml = 1gr of BP

Tony

kjkcolorado · Nov 18, 2018

tfish said:
a good rule of thumb is..

1ml = 1gr of BP

Tony

Thank you. I was wondering about that. Somewhere I have a bunch of ml measuring spoons and syringes for medicines from when our kids were young, but can’t find them right now. Was going to measure some BP and dump it in to check.

kjkcolorado · Nov 18, 2018

cwbullet said:
I used 1.5ml, 2.5 ml, 5 ml, and 10 ml tubes. I remove the caps with cardboard rockets and use tape to seal them. I have found that I can often use tape or rubber gloves tips also.

I’m assuming you remove the cap and use tape to hopefully avoid a relatively harder projectile inside a cardboard airframe...?

cwbullet · Nov 18, 2018

kjkcolorado said:
I’m assuming you remove the cap and use tape to hopefully avoid a relatively harder projectile inside a cardboard airframe...?

Bingo. With fibreglass, it does not matter.

Banzai88 · Nov 18, 2018

The largest rockets that I have so far are 4 inch, and the 1.5 does just about everything for me, but the 2.5s are a little easier to fiddle with. I drill a hole in the bottom, insert the ematch wire, and put a bead of hot melt glue just under the chip just as it goes in the vial. I pull it to the bottom, keeping it carefully centered. Pour in powder, pack with dog barf, and cap with your favorite method.

Lesson #1, do a continuity check of your ematches FIRST!!!!

Lesson #2, a little bit of hot melt glue goes a long way.

OverTheTop · Nov 18, 2018

tfish said:
a good rule of thumb is..

1ml = 1gr of BP

Is that 1 milliliter = 1 grain or 1 gram

? If you are aiming for a "gram" then a "g" is all you need (and indeed all you should use).

cwbullet · Nov 18, 2018

A little extra BP is ok, a lot, not so much.

ANair · Jan 17, 2019

Banzai88 said:
The largest rockets that I have so far are 4 inch, and the 1.5 does just about everything for me, but the 2.5s are a little easier to fiddle with. I drill a hole in the bottom, insert the ematch wire, and put a bead of hot melt glue just under the chip just as it goes in the vial. I pull it to the bottom, keeping it carefully centered. Pour in powder, pack with dog barf, and cap with your favorite method.

Lesson #1, do a continuity check of your ematches FIRST!!!!

Lesson #2, a little bit of hot melt glue goes a long way.

Why not use ampoules for this? I am just checking online and trying to make sense. I really do not have much idea about this but my brother has been onto it for his project work and I wanted to ask why not ampoules? I guess you can find really cheap ampoules suppliers for this. There are plastic ampoules available with 20 ml size and also they can be sealed close pretty well. I understand that this might not work but I just want to know the reason for it. Centrifuge tubes do have a pointy end that could work but vials? That doesn't make much sense.

cwbullet · Jan 17, 2019

Ampoules are purposely frangible and cause fragments. I really prefer with metal which is more durable and takes a lot more force to fracture or flexible tubes that will be less likely to fracture and damage the rocket or people around it.

Steve Shannon · Jan 17, 2019

ANair said:
Why not use ampoules for this? I am just checking online and trying to make sense. I really do not have much idea about this but my brother has been onto it for his project work and I wanted to ask why not ampoules? I guess you can find really cheap ampoules suppliers for this. There are plastic ampoules available with 20 ml size and also they can be sealed close pretty well. I understand that this might not work but I just want to know the reason for it. Centrifuge tubes do have a pointy end that could work but vials? That doesn't make much sense.

Ampoules are usually glass or a brittle plastic designed to break with a snap to hold medicine. Glass would absolutely not be useful because of the risk of shrapnel and I don’t think most brittle plastics would either. Any cheap, small, easily burst soft plastic container that holds sufficient BP and an ematch should work.

Sorry, cwbullet. I didn’t see your reply. Feel free to delete mine.

cwbullet · Jan 17, 2019

Steve Shannon said:
Ampoules are usually glass or a brittle plastic designed to break with a snap to hold medicine. Glass would absolutely not be useful because of the risk of shrapnel and I don’t think most brittle plastics would either. Any cheap, small, easily burst soft plastic container that holds sufficient BP and an ematch should work.

Sorry, cwbullet. I didn’t see your reply. Feel free to delete mine.

No. This topic is a good on to double tap. You used much better wording. Not sure everyone knows the word frangible.

Banzai88 · Jan 17, 2019

ANair said:
Why not use ampoules for this? I am just checking online and trying to make sense. I really do not have much idea about this but my brother has been onto it for his project work and I wanted to ask why not ampoules? I guess you can find really cheap ampoules suppliers for this. There are plastic ampoules available with 20 ml size and also they can be sealed close pretty well. I understand that this might not work but I just want to know the reason for it. Centrifuge tubes do have a pointy end that could work but vials? That doesn't make much sense.

I'll have to post a picture when I get home, but the way I drill a hole and thread the wire through and use a glob of hot melt glue to secure in place, the ematch head is secured into the vial and completey covered and exposed to the black powder. Works perfectly every time.

djs · Jan 17, 2019

Easier than hot glue- I just use sticky tack (poster material). Cheap and better to work with.

cwbullet · Jan 17, 2019

djs said:
Easier than hot glue- I just use sticky tack (poster material). Cheap and better to work with.

I seal my AB bay with this stuff - works every time.

Charles_McG · Jan 17, 2019

For 1.5"-2" rockets, I use the caps from Dentek dental brushes. Small. Cheap. A smidgen of dog barf in the bottom and the top to keep the powder from running out.

djs · Jan 17, 2019

cwbullet said:
I seal my AB bay with this stuff - works every time.

Same- I hate hot glue guns because it never goes where I want it to, and always leaves a mess. Poster tack is easy to mold into place.

What I do with the centrifuge tubes is feed the wire through a hole in the bottom. Then I wrap the poster tack around the top of the ematch, just a little below the ematch head. Then I pull it downwards into the centrifuge tube. At this point, the sticky tack becomes "self sealing" against the hole.

Rocketjunkie · Jan 17, 2019

Aerotech BP comes in a 2 ml tube. 15 ml tubes can be found here https://www.mcmaster.com/7979t33 I make a packet with masking tape in all sizes from .3 to 10 grams built on the ematch head. Must use real BP if using tape.

David Schwantz · Jan 19, 2019

I just got a really BIG bag of the 2ml ones. I can send you a couple if you'd like to test them out.

Plastic vial (centrifuge tube) size

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