Actually stole this idea from Adrian in another forum that he was posting on. Trying to give credit where it is due. 🙂
Bought these plugs like 2 years ago. Never did any thing with them.
To keep from having another seam in the tube, and exterior screws,
I was thinking of trying to glue a ring near the middle of this tube to sandwich the Ebay into place between the cap and the ebay sleeve (or body) I think it would really just make a huge mess inside, and I would have trouble getting the ebay into place because of stray epoxy.(and you know that would happen) 🙄 Plus super long leads to ejection charges from one end or the other! 😕
Then I thought about this. The plumbing compression plugs.
I could set up all the ejection charges on short leads and just slide the ebay to the center of the tube. 🙂
Making a long tube type spanner tool out of conduant to tighten the anchor eyes would be simple. You could actually adjust where the ebay goes down the road, as you shortened the tube to cut out those zippers. 😉
I know the plug will hold, because last year I used it with 3/8" lifting eye in the end of my 3" "Hair of the Dog" fin can, hanging on the engine hoist chain, from the ceiling, to pull out a case, where the tape had rolled over on me! Had to use all my weight! That was tuff! 😯 Thats why I had your case so long Joe!
My only concern, is will the thing deform my tube and mess up my arrow dynamics? 🙂 Any thoughts "BOYS".... Kinda new territory for me. 8)
...and I got the idea from Ed Wranowski, who made an av-bay with compressed o-rings on each end to hold it in place. When I saw these at Home Depot, I recognized them as using the same principle, and they work great, at least for 38mm. I have had some damage caused by over-expanding a 2" one to work in a 54mm (2 1/8") airframe. What size tube and pipe testers are you using?
...and I got the idea from Ed Wranowski, who made an av-bay with compressed o-rings on each end to hold it in place. When I saw these at Home Depot, I recognized them as using the same principle, and they work great, at least for 38mm. I have had some damage caused by over-expanding a 2" one to work in a 54mm (2 1/8") airframe. What size tube and pipe testers are you using?
Its 3"
I have a picture in my head, but I would'nt mind seeing the Ed Wranowski design.
Hey guys,
I too remember when Adrian posted this, I later asked a plumber that i work with from time to time, he said he has shot many of these off the end of pipes with 10 PSI. I think those caps are only rated for 3 to 5 PSI. Adrian did you ever have one give way? I love the Idea, just worry about it coming loose. I guess if you sand down the inside of the two disc, it would allow you to tighten it more, by compressing the rubber more?
On my 38mm rockets, the plastic does not bottom out, and I can tighten it up to at least the point where there is a visible bulge in the tube from the outside. That stopper is not coming out, and it works perfectly every time. No movement until you want it to.
When I used a 2" one on a 54mm tube, I had to expand it all the way in order to get it to stick, and the plastic did bottom out. Also, having all that unsupported rubber on the outside let it twist sideways, and it somewhat damaged the tube it was in. I don't recommend using the 2" one for 54mm. I haven't tried other combinations, so I'm interested in hearing about the 3" one used in a 3" rocket. I think that sounds promising.
Hey guys,
I too remember when Adrian posted this, I later asked a plumber that i work with from time to time, he said he has shot many of these off the end of pipes with 10 PSI. I think those caps are only rated for 3 to 5 PSI. Adrian did you ever have one give way? I love the Idea, just worry about it coming loose. I guess if you sand down the inside of the two disc, it would allow you to tighten it more, by compressing the rubber more?
Like I said above I had it in the end on one, to pull a case and was using all my wieght. 1.5 x 1.5 =2.25 x 3.14159 = 7.06 x 5psi = 35 pounds
Yep...Just checked the scale..I weigh more than that 😉 Im a fat guy.
Even in the end if it does slip, its teathered on both ends.
I think it does call for some ejection test though. The big question is, is it stonger than the shear pins I will use. I think so. 😕
Here is a .pdf of my design. I've crumpled a 3" tube using my car to pull against it and it didn't slip 🙂 Also - you can bulge fiberglass tube if you don't size the caps right and compress them too much.
Edward
Ordered an assortment of 3 inchish (actually slightly lessish) o-rings today from the McCaster place.
I think I like this better than the plumbing plugs, and it takes up less space. 🙂
Ordered an assortment of 3 inchish (actually slightly lessish) o-rings today from the McCaster place.
I think I like this better than the plumbing plugs, and it takes up less space. 🙂
WELL.....nun of those worked. bigest was 1/8"
Just ordered 3/16" and 1/4" (2-7/8 od) Im hopeful for the 3/16"
1/4" probably to big.
What are your tolerances on the other rings? 1/4" o-ring is very very big and is much harder to compress.
I have made a 3" version where the o-ring was a -232 (3.012 x .139 x 2.734) For that one I would make a plate or step on your bulkhead that the o-ring fits snugly over - you should not have to stretch it at all. 2.75" is probably about right, maybe just a bit smaller. I would make the step between .0625 and .075 tall. This allows the o-ring to compress and expand outward enough.
This type of retention takes much more finesse than others, but when you get it right you can't move it at all. I took my 3" version and put it into the middle of the tube, put a piece of PVC that fit the tube to press against the e-bay and used a post driver on the tube. I crumpled the tube and it didn't budge. It is very secure once you get the tolerances dialed in.
Edward
I was thinking about what you are doing. It came to mind that you could do the same with a large rubber bumper, or grommet. If you took two pieces of plexiglass or aircraft plywood, cut out discs that you could place on each side of the grommet, and then screw it down to compress it with an all-thread or bolt going through the middle, you could have thd same thing with a shorter length. If say you needed a 3" O.D. grommet, could you find one? I think you can at http://cableorganizer.com/grommet/rpd-grommets.htm. Check it out and see.
That is basically what the o-rings in my design are doing. I add about .25" total length to my e-bay for having two o-rings added on. I also chose o-rings because they are available in many sizes.
Edward
What are your tolerances on the other rings? 1/4" o-ring is very very big and is much harder to compress.
I have made a 3" version where the o-ring was a -232 (3.012 x .139 x 2.734) For that one I would make a plate or step on your bulkhead that the o-ring fits snugly over - you should not have to stretch it at all. 2.75" is probably about right, maybe just a bit smaller. I would make the step between .0625 and .075 tall. This allows the o-ring to compress and expand outward enough.
This type of retention takes much more finesse than others, but when you get it right you can't move it at all. I took my 3" version and put it into the middle of the tube, put a piece of PVC that fit the tube to press against the e-bay and used a post driver on the tube. I crumpled the tube and it didn't budge. It is very secure once you get the tolerances dialed in.
Edward
I was starting with 2-7/8 od, but your saying 3 inch ? Inside of the tube measures 2.90 or maybe thats the coupler.
Im gona have a lot of misc. orings orings before im done!
We gona have to have an oring tossing contest!!! 😀
What are your tolerances on the other rings? 1/4" o-ring is very very big and is much harder to compress.
I have made a 3" version where the o-ring was a -232 (3.012 x .139 x 2.734) For that one I would make a plate or step on your bulkhead that the o-ring fits snugly over - you should not have to stretch it at all. 2.75" is probably about right, maybe just a bit smaller. I would make the step between .0625 and .075 tall. This allows the o-ring to compress and expand outward enough.
This type of retention takes much more finesse than others, but when you get it right you can't move it at all. I took my 3" version and put it into the middle of the tube, put a piece of PVC that fit the tube to press against the e-bay and used a post driver on the tube. I crumpled the tube and it didn't budge. It is very secure once you get the tolerances dialed in.
Edward
Got some orings yesterday. Turns out 3/16" work for me. 2-7/8 od.
I tapered the disc at a 45 to push up as they sqwezed together.
It will lock it in tighter than a drum, especially with it at both ends.
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