cutting cardboard tubes well

I want to slice a cardboard tube, certainly easy enough, but want a flat and straight cut. This time around it is 3 inch and definitely large enough to show ugly gaps and ridges where it is joined back with a coupler in the completed rocket.

It would be great if I had some kind of table mounted and hinged power saw, but my tools and workshop are not even close to that level. What other techniques could I apply to get a nice straight cut?

Precisely measure three points around the tube. Then, take a hose clamp and use it to position these three points--minding the bump from where the worm gear is mounted. Use this as your guide--use an X-acto with a good blade, light passes. After a few, you'll break through, then rotate to take care of the worm gear bump. I've used this on every size up to 7.5"


Later!

--Coop

You can get somewhat the same effect by mounting a razor blade to a pair of boards in an 'L' shape with at stop at the opposite end. Roll the tube across the blade, pushing it against the stop and take multiple passes so that you cut, rather than crush, the tube.

Depends on the material the tube is made from...

One trick is to get a hose clamp (worm screw "radiator hose" type clamp) and put it over the tube, and align the edge with where you want the tube to be cut, and cut through the tube in MULTIPLE LIGHT PASSES with a sharp hobby knife, using the steel clamp as a "guide" to keep the knife straight and true.

Of course the "worm section" is not cut during these passes-- leave a little bit uncut and then once the tube is cut MOST of the way through, loosen the clamp, turn the worm screw part to an already-cut section, carefully realign, and tighten the clamp back up, and then proceed to make multiple cuts over the uncut area where the worm screw had been located.

Remove the clamp and make a few more light passes to completely cut through the tube and sever the two pieces from each other. Dress the cut end with some 220-400 grit sandpaper if needed, making a few light passes to remove any unwanted material or unevenness...

Good luck! OL JR

The clamp trick has been used successfully for years. it does require a minor adjustment, slipping the ring to allow completing the cut covered under the wormgear.

Another option is the current Estes two piece tube cutting jigs. they work best with an internal mandrel but like all tube cutting options can be used without.

But any method of cutting cardboard tubing should be done the same way the Tubing Manufactures do it. That is with in INTERNAL mandrel to prevent cutting delamination breaks and ragged edges.
Any sharp X-acto or razor blade with give a perfect flat, square edge cut if used in conjunction with internal mandrels.

Any 90deg angle "jig" will work well, My Tube Anniliator 42000 is a bit more precise but still built from scrap aluminum stuff Laying around in the basement.

Mandrels by the way are vary easy to make and once done will last many many years. I am still using BT-5, BT-20, BT-50 andB BT-55 mandrels made back in the early 1970's. Over time I have collected Mandrels for all body tube sizes I use from T2 (.246") to BT-101 and 5" heavy cardboard tubes, Takes a few turns on the heavy wall stuff but works well.

The Tube Anniliator 42000 also Clean cuts Clear and Colored various Plastic, Polycarbonate and styrene tubes.



View attachment Cutter-f2a-sm_Tube Anniliator 42000 Decals BT-50_06-24-08.JPG

I just mark the tube with one of those old yellow Estes tube marking angles with the pencil mount in the side. Once the cut line has been marked, I make very short strokes with a fine tooth Zona razor saw along the line. Keep rolling and cutting until on or about the third, fourth, fifth revolution of the tube, the blade breaks through. I lay down a sheet of sandpaper on the plate glass work surface and carefully sand the edges smooth. Verify the cut is true by rolling a piece of printer paper around the tube and matching the edges.

In the past I have used a cutoff saw on some 54mm tubing which worked okay. I've not yet tried cutting tubes on the band saw but will report back when I do.

Of course... you could just use a chop saw like I do and not bother with all of this crap. Just throw the tube under the chop saw, pull the trigger, and you are done.

You can even use a table saw if you have one by using the miter attachment and fence together, use fence to set length and the miter gauge with an extension board to keep the tube perpendicular to fence and blade, start cutting tube once cut is about a quarter inch deep stop pushing miter gauge and roll tube toward you while keeping it tight to fence and miter extension boards, a sharp blade can make a perfect cut with a little practice.

blackbrandt said:

Of course... you could just use a chop saw like I do and not bother with all of this crap. Just throw the tube under the chop saw, pull the trigger, and you are done.

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I do this but go slowly as I find it gives a cleaner cut. after that give a quick sand to get rid of the fuzzies, apply CA to the ends and you have a perfectly square cut.

watermelonman said:

It would be great if I had some kind of table mounted and hinged power saw, but my tools and workshop are not even close to that level. What other techniques could I apply to get a nice straight cut?

Click to expand...

+1 on the hose clamp method

I know you say you are looking for options other than a power miter saw, but you might consider this more. Even a cheapie like a 10" Ryobi ($99 Home Cheapo) - I have one of these. Its not what a purist would call accurate, but for most things it works well - particularly after you replace the blade with one of the Freud Diablo carbide tipped blades (I have the 60 tooth mounted right now) - nice clean cuts. Not only do I use that for cutting carboard, but also phenolic motor liners, fiberglass tube, and lots of stuff for the house, even have cut small pieces of aluminum (slowly) - its really a useful tool.

I use this made from two pieces of poplar wood from Home Depot and some scraps. Everything is wood glued together except the velcro which is epoxied on. I've used it over the years to make many nice clean cuts, mostly on 2.5", 3" and 4" LOC paper tubing these days. The X-Acto blade has been flipped in the holder for the larger tubes:







If I had to do it over again, I'd definitely use this type of "velcro" attachment stripping to avoid the very slight blade holder angle wander that can occur due to the play in the hook and loop type of velcro when cutting thicker-walled tubes. Come to think of it, I will be gluing wood strip "stops" on what I've already built to fix this. However, I don't think that would be needed of this type of "velcro" is used which I've seen at Walmart, Home Depot, Lowes, etc., and which I already use in my R/C aircraft hobby:

https://www.amazon.com/dp/B00347A8EO/?tag=skimlinks_replacement-20

If you have access to a radial arm saw, you can cut tube very cleanly, very fast. I used to be able to use the saws at the wood shops on either Eglin AFB or Hurlburt Field, but unfortunately, both bases closed their wood shops.

Rob Campbell said:

If you have access to a radial arm saw, you can cut tube very cleanly, very fast. I used to be able to use the saws at the wood shops on either Eglin AFB or Hurlburt Field, but unfortunately, both bases closed their wood shops.

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In my experience, the cut isn't very clean and the paper delaminates. However, the blade I used wasn't proper for the task. From what I'm told, blades with many teeth should be used for "finishing" work, like this one:

https://www.harborfreight.com/10-in...op-bevel-design-circular-saw-blade-38544.html

That said, I do need to cut very heavy tubing (like 38mm motor tubing) with a radial arm saw as my cutter shown above can't handle it.

Funny you should ask.....

I'm in the process of cutting several hundred tubes right now!



I use the 2 boards ="L" with a box cutter blade screwed on the end.
Screw the 2 boards together with 3 sheetrock screws.
A simple "C" clamp and 2x4 scrap for the block that sets the length.
Ain't very pretty...but does the job as well as anything.





Push tube against , block, back of jig & blade, turn several times and the cut is as clean & square as it gets.
I mark block position for repeatable cuts & easy placement.



My old one finally died and I went to Home Depot yesterday for new parts...cost a whopping 2.38 for boards & blades!
They will cut it free for you. I got a scrap 1x4 from the reject bin and had them cut 2...2ft sections out of it
If your going to be build rockets for awhile.... it's worth the small bit of time to make one. This cuts tubes as large as 4in & small as 1/4 launch lugs.

Edit: PS thanks to John [Micro] I learned the mandrel trick for getting perfectly clean cuts. I could not have done the 1/4 lugs any other way so cleanly & easy! I must do 200 of those.

I also wrapped my block and the 2 "L''boards with clear packing tape, makes a nice slick surface for the tubes to roll.