Splice Trouble

Water Rockets NSW

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BLKKROW
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Splice Trouble

Postby BLKKROW » Tue Dec 22, 2009 11:09 am

Well I have been going off of AirCommandRockets to recreate his splice technique. But everything I try I still get a little tiny leak. Which impedes me from reaching any decent PSI. My steps:

Im Using 2L PET Bottles.

Start with 3 cut them down to the proper lengths with two to splice and one sleeve.

Curl the edges of the bottles, apply PL premium and Sixaflex. With the bottles sanded.

Wait 10 days to test, and I still get leaking am I doing something terribly wrong?

I am very limited on tools, keep that in mind.

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Postby air.command » Tue Dec 22, 2009 1:01 pm

Hi BLKKROW and welcome to the forum,

It sounds like you are using the symmetrical splicing technique. Are you shrinking the bottles with the curled edges before inserting them into the sleeve? You would need to do that if the sleeve is made out of the same bottles otherwise you will get some buckling of the bottles and potential leaks. Or is the sleeve bottle a little bit bigger?

We have always found PL premium to be a little porous and it is worse if you assemble the splices in higher humidity conditions as the PL will bubble more. That's why we use the sikaflex to seal the joint.

We've always had good luck getting the 1.25L bottles spliced using this technique, but 2L bottles are a different story as we too have had quite a few leaks. I think it is due to the stretching under pressure.

I'm not sure if you have tried the new splicing technique we have been experimenting with here:

http://home.people.net.au/~aircommand/day81.htm#splice (we're using asymetric splice #5 now)
and here:
http://home.people.net.au/~aircommand/day82.htm (See the "splice tests continued" section)

This technique has been working very well for us without any leaks so far. I want to put together a new video of this technique in the coming months after we've had enough construction/flight experience with it. If you want to have a go before then, I'm happy to walk you through it.

Do you have pictures of your splices that you can post here? It's easier to comment on what you could try if I can see them.

cheers

- George
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Postby BLKKROW » Wed Dec 23, 2009 4:37 am

Well i will read over that, I am not shrinking the bottles cause I have no real way of doing so, so I am just kinda forcing the bottles into the sleeve but I am also nto forcing to much. The last bottle I tryed I got no buckling But still a tiny fracture leak.

So i will read through and try to find what works the best. Cause 1.25 Liters are really hard to find.

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Re: Splice Trouble

Postby BLKKROW » Wed Feb 17, 2010 4:16 am

Well I know your busy with your new build and everything I was just wondering if you have a guide for the new Splice technique yet?

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Re: Splice Trouble

Postby air.command » Wed Feb 17, 2010 8:39 am

BLKKROW wrote:Well I know your busy with your new build and everything I was just wondering if you have a guide for the new Splice technique yet?


Hi there,

We haven't posted the full set of instructions yet, as we want to make sure the technique works properly, and if any steps need changes or modifications. It has been a bit of slow going, but we have more data on the splices now that we have made more of them. We want to evaluate them in a number of rockets before we post the detailed procedure.

If you want to have a go yourself, here is a quick writeup of the steps involved in making the splices:

Materials:
- 4 identical 2L bottles.
- Sikaflex 11FC glue
- PL Premium glue
- Glass Strapping tape

Tools:
- Knife
- Scissors
- Electrical tape - used as masking tape because it is stronger than regular masking tape.
- Sandpaper (400-800)
- Methylated spirits
- Mineral Turpentine
- Thermometer

Procedure:
1. Clean all 4 bottles with soapy water and rinse off.
2. Remove the cap ring and label.
3. Remove the label glue residue from the bottle with Mineral turpentine.
4. Clean any areas to be glued with Methylated spirits.
5. Cut the base off all 4 bottles and trim neatly.
6. Heat about 2-3cm of water in a flat bottomed saucepan.
7. When the temperature reaches around 72C, place the bottle briefly in the water and quickly remove. This will shrink the bottle slightly. The rate of shrinkage will depend on the temperature. You may need to submerge the bottle for 2-10 seconds. Make sure the bottle is open on top. This takes a little practice, but is easy to master.
8. Test to see if it fits in the other bottle. If not, submerge it again for a little longer. But don't make it too loose. The bottle should snuggly and easily slide in.
9. Curl the shrunken edge of the bottle on warm frying pan.
10. Lightly sand the shrunken section of the bottle.
11. Lightly sand about 2cm of the inside of the second bottle.
12. Fit the two sections together and apply masking tape (electrical tape) around both bottles where the joint meets. This will keep the edge clean, for the next gluing phase.
13. Glue the two sections together with Sikaflex 11FC. (refer to the symetrical splice technique for applying and spreading the glue)
14. Let the splice cure for a day or two.
15. Remove the electrical tape.
16. Cut out a 4cm wide sleeve from the bottom section of a third bottle. (Save the top section)
17. Cut the sleeve open since being the same diameter it will not fit over the existing bottles.
18. Lightly sand the inside of the sleeve.
19. Lightly sand the outside of the glued bottles where the sleeve will fit.
20. You may want to use more masking tape at this point on the outside of the sleeve and along the edges of the sleeve on the bottles. This makes for a neater looking splice.
21. Spread a thin coat of PL premium on the bottles as well as the inside of the sleeve. Wrap the sleeve on the bottles making sure it is centered over the join. There will be a small 3-5mmgap in the sleeve when it applied due to the thickness of the glue.
22. Push out any air bubbles, but it is not critical to get all of them out.
23. Pull the sleeve tight with a piece of tape over the cut in the sleeve.
24. Let cure for 2-3 days.
25. Remove the masking tape from the bottles and sleeve.
26. Cut a 4x4cm section of PET bottle from the bottom of bottle #4. This piece will be used to cover the gap left in the sleeve.
27. Lightly sand around the edges of the cut in the sleeve
28. Lightly sand the inside of the patch and glue it on with more PL premium. Use tape to hold it in place while it cures.
29. Let it all cure for 1 week.
30. Cut the necks off bottles #3 and #4 so that the hole left is just big enough to slip over the necks of the spliced pairs.
31. Cut off the bottom sections bottles #3 and #4 including the ridge mid way up the bottle on some bottles. These become the reinforcing sleeves that fit over the ends of the splice pair.
32. Cut three slits in these sleeves all the way up just past the transition from cylindrical to the curved part of the bottle. This will enable it to fit over the bottle.
33. Slide both reinforcing sleeves over the ends of the bottles as far as they will go. The splits will open perhaps 1 or 2mm.
34. You can either glue them in place, but I prefer to just tightly wrap them with glass strapping tape to hold them in place. You will need to do 2 or 3 wraps. (see previously posted pictures)
35. Pressure test.

When we make the video it will be a whole lot clearer what all the steps are.

I hope that helps. I am happy to clarify any of the steps above.

- George
Crop Circles: ... just a bunch of guys looking for their rockets ....

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Re: Splice Trouble

Postby whipfest » Wed Feb 17, 2010 12:57 pm

air.command wrote: here is a quick writeup of the steps involved in making the splices:


As a "quick writeup" George (35 steps!), I somehow wouldn't have expected anything less from you.. :wink: :D


8)
What were you thinking about as you sat atop the Redstone rocket, waiting for liftoff?

"The fact that every part of this ship was built by the low bidder"

Alan Shepard

BLKKROW
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Re: Splice Trouble

Postby BLKKROW » Tue Mar 16, 2010 3:30 am

Hey sorry i didnt reply when you first posted it, but I am using that technique now Today I am going to try a bottle i spliced for leakage, So thanks George!

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Re: Splice Trouble

Postby air.command » Tue Mar 16, 2010 6:40 pm

BLKKROW wrote:Hey sorry i didnt reply when you first posted it, but I am using that technique now Today I am going to try a bottle i spliced for leakage, So thanks George!


No worries. Make sure you give the splices enough time to cure. I know it may look strong the next day, but PU glues use moisture to cure and the length of splice means that much of the glue is protected from the air. I think it fully cures at a rate of 5mm depth per 24 hours. I guess that is the rate of moisture penetration. Always leave it for at least 48-72 hours before pressure testing.
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Re: Splice Trouble

Postby BLKKROW » Tue Mar 23, 2010 3:38 am

Thanks George Right now I am splicing, to different sets of bottles and letting them sit for a good week. The last splice pair I made I let sit for a good 4 days and it gave me no trouble and i got to around 120-130 Psi with no leaks and no burst bottle. So thanks for all the info, the next step if I can successfully splice some 2L I need to find a coupling to join the two bottles.

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Re: Splice Trouble

Postby air.command » Tue Mar 23, 2010 12:48 pm

BLKKROW wrote:Thanks George Right now I am splicing, to different sets of bottles and letting them sit for a good week. The last splice pair I made I let sit for a good 4 days and it gave me no trouble and i got to around 120-130 Psi with no leaks and no burst bottle. So thanks for all the info, the next step if I can successfully splice some 2L I need to find a coupling to join the two bottles.


Good to hear that you had good success with your spliced bottles.

Last week I ordered some of these: http://www.coolthings.com.au/vortex-valve-tornado-tube.html to see if they can be used in pressurised situations or not.

They haven't arrived yet so I can't make a recommendation one way or another. It would sure be nicer getting them off the shelf than having to make our own.
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Re: Splice Trouble

Postby air.command » Thu Mar 25, 2010 12:19 pm

The tornado tubes arrived yesterday and look quite good. We did a hydro test on one of them to 130psi. We didn't want to go higher because the bottles connected to the tornado tube were not reinforced. The tube held up well without any leaks. We need to do more tests and hope to fly them on a test rocket this weekend to see how they hold up to real world conditions.

- George
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Re: Splice Trouble

Postby BLKKROW » Tue Apr 20, 2010 3:36 am

Thanks for the info George, I also noticed your new test up to 170psi with the tornado tubes. I ordered 2 last week and have them now, plus i drilled out the inside to hopefully fit a 15mm launchtube. Thanks for all the info

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Re: Splice Trouble

Postby air.command » Tue Apr 27, 2010 2:37 pm

BLKKROW wrote:Thanks for the info George, I also noticed your new test up to 170psi with the tornado tubes. I ordered 2 last week and have them now, plus i drilled out the inside to hopefully fit a 15mm launchtube. Thanks for all the info


We have now tested these to 270psi and they are still holding. Out of 8 of them we got one small leak on one @ around 150psi. It's the plastic-on-plastic seal that is the problem. We proceeded to tighten it more and it fixed it, but then we managed to over tighten another of them and it cracked! ... Make sure you don't overtighten them!
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Re: Splice Trouble

Postby air.command » Fri Feb 25, 2011 7:45 am

BLKKROW wrote:Well I know your busy with your new build and everything I was just wondering if you have a guide for the new Splice technique yet?


Well we finally got around to publishing the full bottle splicing tutorial here:

http://www.AirCommandRockets.com/construction_6.htm

I know I know … it took long enough, it's only a year late :)
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Re: Splice Trouble

Postby BLKKROW » Tue Mar 01, 2011 4:34 am

air.command wrote:
BLKKROW wrote:Well I know your busy with your new build and everything I was just wondering if you have a guide for the new Splice technique yet?


Well we finally got around to publishing the full bottle splicing tutorial here:

http://www.AirCommandRockets.com/construction_6.htm

I know I know … it took long enough, it's only a year late :)


It is not a problem I had the splice down since you posted the 35 steps. So no worries for me. I am still keeping myself updated with all your work keep it up.

Hopefully when I get home to Arizona I can help you with some techniques also. Take care


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