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Some advice on sealing the end of a brass tube

C

caidenrichards

Plastic
Joined
Apr 5, 2020
Hi guys. I'm looking for some advice on how to seal the end of a brass tube. I'm wanting to mass produce this item so I'm looking to keep the price as low, while also remaining as durable as possible.

Currently, I'm using a cylinder with a slightly larger diameter than the inner diameter of the tube, and pressing it into the end of the tube. This is working well, however I'm worried of integrity over a long period of time, because the part that is pressed into the end of the tube is constantly being rammed into.

As of now, I believe I have two more options:

  • Threading the end of the tube
  • Drilling through a brass rod almost to the very end

The tube is 100mm long, which is concerning to me for the amount of material that would be lost in drilling it out.

I'm wondering if there are more options that I'm not seeing, and if there are any that stand out as the most durable, economical approach.

I'm also wondering how durable what I'm currently doing is--will it loosen over time? What if I use epoxy in conjunction with this method?


Thank you for your help :)

View attachment Tube - 6.5x8x100.PDFView attachment bottomCapRod.PDF
 
Drilling from solid would be very expensive from a material standpoint, let alone the machining.

Depending on the "ramming" going on, adding a shallow groove to the center of the small cylinder which is pressed into the tube, and then using a small round-edged steel wheel on a bearing to "roll" a section of the tube into the cylinder groove would give a good enough mechanical interface.

I would not thread or epoxy the cylinder in. Too costly or not secure enough.
 
eKretz said:
Solder it.
Click to expand...

I considered that and dismissed it. IMO, too much fussing with flux, solder and heat application, then cleanup of the flux and heat discoloration. I've done a fair amount of copper and brass solder work, and if I can avoid it I do.

Look at modern copper water and airline installations - cold crimped, not soldered.
 
Nah, quick and easy. Slap some tinning flux on the pieces, slide them together. Assemble a hundred plus at a time and put them in the oven for a few minutes. Way faster than just about anything else.
 
I agree soldering would be best. Hold it wait hear me out.....LOL
Do it the way a lot of elechickens do.

Obtain a crucible or something that will allow you melt solder in it
Dip the plugger end in appropriate flux
Place your plug, cap or what ever in tube
Then just submerge the plugged end in the solder pot, remove once you see the solder flow / wick into the joint (should be right quick) wipe the excess and Bobs your uncle.

I believe if you prep a load of them (flux and plug).
Your time at solder pot will be less than other methods.
Just make sure you have enough solder in the pot, cause dipping 50 one after another will lower the pot temp.
Also if you are not familiar with working molten metal do some reading, can be very dangerous; any moisture is going to flash to steam.

Best of luck, let us know what method you finally use.
 
Yup soldering

clean
flux
solder them like a bench full of plumbing fittings

make sure the clearance is enough for the solder to flow

Used to do a job where we coiled solder around a bar and slit it to make lots of little rings and a big soldering iron
 
I would suggest crimping.
Machine a recess into the plug..
Make e crimping tool which crimps the tube into the recess.

No additional material needed, no flux, no cleaning, no discoloration..

Or make the recess like a grip 'hook'..
If you can machine the plug oversize with some locking teeth and then press it in. I think this would prevent it, from ever comming out again..
 
I agree soldering would be the simplest, but if your hell bent against solder I would suggest cold welding. Look at something like a crystal can for example. Simple fast cheap and easy.
 
I would probably try a dab of solder paste on the end of the plug, then stand them upright on a hotplate (plug down... but then I would have to say downright and that makes me look illiterater). My guess is the solder would wick down into the joint and make a hermetic joint with minimal discoloration and cleanup. We used it by the ton in the electronics world. Once I proved it would work, I would make a couple fixtures that held 100 at a time. One's cooking while the other is cooling.
 
Can you turn a shoulder on the plug so it’s, say, 8mm large OD x 7mm small OD and press it in right up against the shoulder? If the ID of the tube is 6.5mm you could also turn the small OD to 6.5mm and slightly crimp the end of the tube so it is no longer round but oval. That way when you insert the plug the tube’s modulus of elasticity will help keep everything in place. Good luck!
 
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