Layering LRT/ CPH chamber

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Killer 7
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Joined: Sat Jan 05, 2008 4:22 am

Layering LRT/ CPH chamber

Post by Killer 7 » Sun Jan 06, 2008 2:38 am

I hope this guide is helpful, and I'm sorry there are no pictures yet. All questions are welcome. Sorry if it is a bit confusing. It will be hard the first time you try it so be patient, but after some practice (now it only takes me and my dad about 15 minutes) it should yield some very good results.

LRT (to be layered) must all be equal in length, and the ID of the larger has to match the OD of the smaller, or else this method will not work.
High strength string ( I used 20 lb. test fishing line)
Ice cube
2 hose barbs
1 threaded end cap (to match the hose barb's threads)
Teflon tape
Piece of wire or stiff rod ( this will be used to push or pull as it may be the string through the LRT)
small piece of dowel (to use as a handle)
Duct tape
2 Hose clamps they should be larger than your largest piece of LRT's OD.

1. Get your first piece of LRT and select a hose barb that is slightly larger than it's ID. This is so the hose barb does not constrict flow as much.

2. Next shape one end of the ice cube into a cone shape, Run some hot water over the hose barb, and melt the other end of the ice cube (the end opposite the cone) onto it so all of the edges of the ice cube are at least level with the hose barb.

3. Run some water through the inner layer of the LRT, and push it up the ice cone and onto the hose barb. This is the method I used to get the LRT onto a hose barb of a larger diameter than the LRT.

4.tie a very strong knot in your string so it forms a large loop. It should be longer than the length of the LRT by 8" or so skip this if you use a rod.

5. Get the next layer of LRT ( It should have the same Id as the OD of the previous layer), and push the loop all the way through the inside of the LRT. THen tie a slip knot or something similar in the string on either end protruding from the ends of the LRT. Put the constricting area of the Knot around the end of the smaller LRT (the inner layer) about 1/4" from the end.

6. get a small piece of dowel or something like that to use as a handle so the string doesn't cut into your fingers. Insert this into the end of the loop opposite the end with the slipknot.

7. This next step takes 2 people, I suppose you could do it with one, but it would be very difficult. run some water through the middle of the larger piece of LRT to lubricate it, it is also reccommended that you do the same to the outside of the smaller piece. Get one person to hole the handle on the string, and the other to hold onto the hose barb.

8. Put enough tension on the string so that it stretches the LRT making the OD smaller. Then pull the larger layer over the smaller until the ends closest to the hose barb line up. I suppose you can do this until you are satisfied with the thickness, but it gets difficult after two, and is even harder after three layers. I plan to make a chamber using this method that has a wall of nearly 3/4".

9. Repeat steps 5-8 until you have put on your last layer of LRT. Then take your other hose barb ( the Id of the inner piece of LRT should be the same as the hose barb) put the teflon tape on it and screw on the threaded end cap. This plugs the end of the CPS Chamber. Insert it into the end of the LRT that is still open.

10. Take a strip of duct tape about 1" wide and wrap it around the end of the chamber directly over the hose barb. Do the same on the other side. Then tighten the hose clamps over the duct tape. They should be very tight.

11. Now enjoy your newly made CPS chamber.

A method similar to this could be used to colossous a cylindrical CPS gun more effectively than short strips of LRT if you can get the sliding part off of it.
Last edited by Killer 7 on Sun Jan 06, 2008 3:35 am, edited 1 time in total.

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Re: Layering LRT/ CPH chamber

Post by Silence » Sun Jan 06, 2008 4:30 am

That's quite a clever technique. I see you've done your research, as you've already glanced at the method that uses short strips of LRT. Long layers are better because the rubber should be able to stretch lengthwise, too.

The general procedure with constant pressure homemades is to use outer layers that are a good bit wider than the inner layers, rather than approximately the same size, to completely avoid friction. Nobody has yet built a machine that can efficiently layer small tubing over large tubing (which would be ideal since you could get more layers that way).

Good job of detailing your layering process! My only suggestion would be to use oil or talcum powder for lubrication. I'm guessing water could allow the rubber layers to stick to each other a bit.

Where did you get your latex rubber tubing? We generally recommend McMaster-Carr, which also sells other hardware, as they have sell relatively short lengths of it in various diameters. Those tubes also come fairly thick. I'm not sure how easy it would be to layer thick tubes in this manner, though.

Once again, thanks for the guide! :cool:

EDIT: Nevermind, I just saw in the other thread that you had gotten the right LRT from McMaster-Carr.

Killer 7
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Joined: Sat Jan 05, 2008 4:22 am

Re: Layering LRT/ CPH chamber

Post by Killer 7 » Mon Jan 14, 2008 5:00 am

I thought about using other lubricants other than water, but the trouble I saw with using them is that they would stay sandwiched between the layers where they could cause problems. ie I learned from one of my parents friends that over time Vaseline can break down certain types of rubber, so I avoided them altogether.

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Re: Layering LRT/ CPH chamber

Post by SSCBen » Mon Jan 14, 2008 5:08 am

I seem to have missed this thread. Interesting and very simple method. I'll have to try it out. This could be revolutionary! Hopefully this will help popularize more powerful CPS homemades. ;)

More later because I'm going to bed.

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