Joining cardboard tubes

I'm cheap. Not by choice, I'm broke. To save money, and still be able to fly, I've been collecting cardboard tubes. These range in size from just over BT-20 (nice slip fit), to 4 inches or more. Nosecones I might be able to turn on my drill press (haven't tried), or make from found objects (Christmas decorations and Easter eggs!). What I need is a way to join two sections of a tube if I cut one apart. I have a variety of wall thicknesses - thin walled mailing tubes, to tubes thick enough that they could be made into engines. Need a cheap way to do this, preferably with free materials if possible. Ideas?

They don't call me El Cheapo for nothing. I love spending money but things are tight now, too. I get more joy making rockets out of recycled materials than anything else. Making your own couplers Is easy. I'm on my phone now but will tey to post a link if someone doesn't beet me to It.

I'm not sure if I understand correctly exactly what your after but....

IF you are trying to essentially find a custom coupler (to join two of the same size tubes together to make one longer tube), well that's easy/simple/free:

All you need to do is to cut a short length of the tube itself (say a one inch length for a BT-50 type tube). Make a slice lengthwise in that bit. Overlap the two adjacent just cut edges (so that you are making a slightly smaller diameter tube with it). Insert that into one of the tubes you want to join and let it spring open. You will see that you almost have a coupler. All that you have to do now is to trim off the overlapped amount and voila, you have a perfect fit coupler.

You actually don't have to trim that overlapped edge exactly. Even if you trim off more than necessary, the coupler will work just fine as is.


Of course, if this is NOT what you are asking to do, this info/tip is basically useless to you. But I hope it helps.

s6

(cough)apogee video(cough)

Well it sure seems like the Utah/Arizona contingent is up late surfing around on TRF tonight.

s6

I'll 2nd what stealth 6 said. However, I glue the removed section to the inside of the newly formed coupler to make a self contained unit. I use them to join tubes and to form shoulders for payload sections or weird home made nose cones. If you don't want too tight a fit, trim the removed section a little larger than necessary. As was also mentioned, this doesn't hurt anything. After trimming and before re-gluing, wrap some tape around the coupler, insert it into the end of a tube, and then attach the inside section. Works GREAT!

Aksrockets said:

(cough)apogee video(cough)

Click to expand...

Here, have a piece of hard candy for that cough
Do you have a url for the video?

One way to rocketry on the cheap is with paper rockets. Check out my Project Paper in the Cardstock Rocketry section of this forum. I am currently working on making printable card stock components (tubes, nose cones, fins, etc.) that you print on 110# card stock, cut out and assemble - kind of a Designers Kit for card stock if you will. Right now I have a couple of nose cones in the BT-50 size (I use metric numbers so they are easy to label), one in the BT-20 size, a couple of tubes in each size, three different fin sets and a page of centering rings and other components. I plan to keep adding to it as I have the time and inclination. All files are editable pdf files that you can print out directly with your computer and printer. Get some sewing elastic for shock cords (or kite string, carpet thread, whatever you have), some straightened paper clips for motor clips, cheap trash bags or space blankets for parachutes and streamers, some white glue a straight edge and a hobby knife and you're in business.

I would caution against trying to make your own motors. Yes, it can be done, but is outside what we can discuss here for various reasons. Making your own motors can be dangerous and really isn't that much of a savings by the time you buy all the chemicals and supplies you need to do it, not to mention that fact that creating delays and ejection charges make things a hundred times more difficult. Even if you are pinching pennies (or whatever currency they use where you are), use anything you save on found materials to buy commercial (Estes, Quest) motors. Trust me - the hobby is more fun BECAUSE OF the availability of commercial motors, not IN SPITE OF it.

The easiest way to do this is to simply cut off about 2 inches of the tube you want to join (or another one the same size) and then put a vertical line on it (the old door-jamb trick if you don't have an angle to put a vertical line on the piece of tubing) and then cut the tube vertically along that line. Overlap the cut a bit so it "shrinks" the tube down a bit, and stick it in the end of the tube you want to join. Spread it back apart again to get it tight to the tube-- you don't want a sloppy loose coupler. Mark the overlap with a pencil, flip the "coupler" and repeat again.

Now you should have a couple marks just behind the cut line (usually about a quarter inch or less). Connect the two marks with a ruler and cut along this second line. Test fit the coupler in the tube... the ends should butt together nicely and it should be snug in the tube.

Pull the coupler out of the tube and put some white glue on the back of the strip you cut off the edge of the coupler. Glue it inside over the butt-splice where the two edges of the coupler butt against each other for reinforcement.

Works like a champ... I use that trick quite frequently. Makes a coupler as good as storebought, for any size tube you have, want, or need.

Later and good luck! OL JR

luke strawwalker said:

The easiest way to do this is to simply cut off about 2 inches of the tube you want to join (or another one the same size) and then put a vertical line on it (the old door-jamb trick if you don't have an angle to put a vertical line on the piece of tubing) and then cut the tube vertically along that line. Overlap the cut a bit so it "shrinks" the tube down a bit, and stick it in the end of the tube you want to join. Spread it back apart again to get it tight to the tube-- you don't want a sloppy loose coupler. Mark the overlap with a pencil, flip the "coupler" and repeat again.

Now you should have a couple marks just behind the cut line (usually about a quarter inch or less). Connect the two marks with a ruler and cut along this second line. Test fit the coupler in the tube... the ends should butt together nicely and it should be snug in the tube.

Pull the coupler out of the tube and put some white glue on the back of the strip you cut off the edge of the coupler. Glue it inside over the butt-splice where the two edges of the coupler butt against each other for reinforcement.

Works like a champ... I use that trick quite frequently. Makes a coupler as good as storebought, for any size tube you have, want, or need.

Later and good luck! OL JR

Click to expand...

Ditto Lukes post:
This is the way many of us make couplings for Odd size or custom made airframes. I almost always use the same piece of removed tube to form the inside seam stiffener. held in place with masking tape until the glue as setup.

sooner.boomer said:

Here, have a piece of hard candy for that cough
Do you have a url for the video?

Click to expand...

Video: Make Your Own Coupler

-- Roger