Charge well closures.

[rocketcharlie]

Hi all,
Does anyone use anything besides masking tape to close the top of a charge well? I can't think of anything else that would work. Maybe if I did 3-D printing I could make something, but I dont.

 

[tim cubbedge]

I’ve used electrical tape on a few occasions.

 

[jmmome]

Masking tape, with electrical tape around the circumference of the charge well to hold it in place.

 

[jimzcatz]

I use centrifuge tubes, they have a locking or screw on cap

 

[rocketcharlie]

Because I have tried to put 2 small charge wells and a 1/4" eye bolt on each end of a 38 mm ebay (coupler tube) it is really difficult to get tape of any type around the charge well. I was hoping someone had an idea about capping the charge well, but as I have said, I cant think of anything.

 

[rocketcharlie]

Jimz-
Do you secure the tubes or just place them in the airframe?

 

[FredA]

Try Hot Glue - carefully!

 

[H. Craig Miller]

Caps are very tight fit...

 

[rocketcharlie]

Fred, I did think about hot glue and might try it. Do you use this? Seems like it would cause the charge to be more energetic than tape.

 

[dhbarr]

I've seen folks use an earplug if the charge well is skinny enough.

 

[rharshberger]

I just use masking tape and dog barf to close the top of the charge well or centrifuge vial, then I don't have to worry about finding or leaving loose bits of plastic in the environment which don't degrade vs paper like dog barf and masking tape which quickly break down.

 

[Banzai88]

I use centrifuge tubes and a foamy ear plug or dog barf to take up the extra space, then when I'm prepping for flight, I put one wrap of masking tape around it and put it upside down in a plastic pipe cap.

 

[caveduck]

For now I just pack pretty tightly with masking tape over dogbarf like many people do. But I'm looking for a faster way to prep and itching to experiment with plastic "caplugs" - they're available in many sizes, and since I machine my own charge wells I ought to be able to get a good fit. A kevlar cord tether will keep 'em from dispersing over the range. They would get a small hole drilled in the face to pass the e-match leads and also provide a bit of pressure relief to stop them from getting popped off at altitude. McMaster no. 4491K141 might be about right for most rockets, I'd probably want to make the ID of the well about 0.475".

 

[Rocketjunkie]

I just roll a little tube of masking tape. Insert the ematch into one end and pinch it closed. Add BP and pinch the other end closed. Leave hanging on the end of the ematch wires. I place the charges at the closed end of the parachute bay or just above the motor in the booster section. The ematch leads go through holes in the bulkheads directly to the altimeter. This ensures new wires every flight. For small rockets you need to make sure the holes in the bulkhead are covered. A piece of tape will do.

 

[o1d_dude]

Masking tape and dog barf has not failed me yet.

 

[dshmel]

I use centrifuge tubes and a foamy ear plug or dog barf to take up the extra space, then when I'm prepping for flight, I put one wrap of masking tape around it and put it upside down in a plastic pipe cap.

I have used foam ear plugs as well. Not sure if they melt when the charge goes off, but they disintegrate.

 

[heada]

I've used vials with snapon caps, urethane wells from PML and home-made wells from pipe caps(pvc and copper). All work well and I use a combo of foam ear plugs, Estes wadding or dog barf to take up empty space and then topped with masking tape or rubber caps from PML to seal it. When using 4Fg black powder then anything is fine as long as you're not at extreme altitude. 3F, 2F or pyrodex gets extra tight wraps from the tape.

 

[jimzcatz]

Jimz-
Do you secure the tubes or just place them in the airframe?

I tape them to the bottom inside wall

 

[rocketcharlie]

This is good stuff! I had never heard of caplugs and I had never thought of foam ear plugs. Obviously the ear plugs would be for charge wells that are on the smaller side.

 

[FredA]

I tried hot glue on one rocket that had the same problem as you.
Worked fine but a bit scary to try the first time.
Just put a scrap of paper towel to cover the BP, then spread a thin layer over top to seal.

More energetic, maybe, but worked OK and just a small trace of the glue remained.
Easy enough to do your own ground testing.

 

[OverTheTop]

I normally use Kapton tape and then an o-ring around the outside to keep it in place in case the adhesive doesn't stick.

I have also been know to use, on large wells, soft-drink (soda) bottle caps. The thread is machined onto the top of the canister.

 

[JoePfeiffer]

For smallish rockets my charge wells are .38spl casings with the primer hole drilled out so I can screw it to the bulkhead.

I 3D print PETG plugs with holes to fit the e-matches, and shove them down the well. I typically put wadding above them and tape over the wadding, but that's insurance I'm pretty sure isn't actually necessary.

After I started doing this I heard the claim pointing the charge at the parachute could cause me to shoot holes in it; I had never experienced that issue so I kept doing it, and have still not experienced it.

 

[Rob702Martinez]

I use beehive tubes. Hot glue the ignitor in batches to the bottom and roughly cut them to length to keep in your tool box. When ready to use , fill with bp, stuff dog barf tight, either heavy masking tape it up or hot glue and masking tape. You can fill with bp see where you need to trim it, dump it out back into the can, trim the tube and continue on.

 

[David Schwantz]

What in the world is a "beehive tube"?

 

[Banzai88]

What in the world is a "beehive tube"?

Click here for beehive tubes

 

[Rob702Martinez]

These are the ones I ordered. https://www.amazon.com/dp/B01AM7Y9N4/ref=cm_sw_r_cp_apa_i_8cZEFbEA18K5A

 

[Crazyrocket]

I've done a bit of everything that other have stated above. For really tight areas, I will take a piece of duct tape, stick the ematch to the tape, pour BP on top and then fold the duct tape in on itself. This makes a nice small charge package.

 

[FredA]

Beehive tubes are a cool idea.
Just remember that "best practices" has the E-Match on the EXIT side of the BP.
You light the exit surface and all the BP must pass the plasma-ball instead of some getting [potentially] ejected before ignition.

 

[Handeman]

I use two piece of masking tape over the well at 90 deg. After the flight, there is usually a round piece of tape hanging from the top of the well. All the tape attached to the sides of the well, I have to peel off.

 

[David Schwantz]

Did not know about those. I assume that you cut to length and then seal both ends? When you prep a rocket, take some pics if you would and post how you do it. Might just have to try them. Thanks.