Any tips on slotting tubes?

Discussion in 'Low Power Rocketry (LPR)' started by Gunstar, Jul 10, 2019.

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  1. Jul 10, 2019 #1

    Gunstar

    Gunstar

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    I want to add slots to a BT-80 so I can have through the wall fins. Any tips or tricks on doing that well?
     
  2. Jul 10, 2019 #2

    kuririn

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    After you've measured and marked your slots on the tube:
    1. Use an angle tool to get straight cuts with your knife.
    2. Use a sharp, preferably new, #11 blade.
    3. Make several passes, cutting deeper with each pass.
    4. Since the standard BT-80 is not a thick walled tube like the midpower ones consider using a sacrificial coupler inside when making your cuts. This supports the inside of the tube and guards against paper tear through when the blade goes through the inside.
    I look at slotting tubes like I do assembling plastic parachutes: not particularly difficult but B-O-R-I-N-G!
    I tend to use pre-slotted tubes and assembled parachutes whenever possible. Cheers.
     
    hcmbanjo likes this.
  3. Jul 10, 2019 #3

    K'Tesh

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    For me, I mark the tube with a mechanical pencil, using the appropriate guide. To insure that the lines are straight, I use a piece of angle aluminum. I then mark top of the slot and the bottom of it. I cut the tube along the marked line, then use the fin (pressed into the slit) to mark the width of the slot. Finally I cut the other slit... Taking care to make sure that I stay on the same side of the slits for all the slots... and finish the slot.

    It is important to use a sharp Xacto blade, and make several light passes to cut the slits, rather than trying to cut it in one single hard pass.
     
    Last edited: Jul 10, 2019
  4. Jul 10, 2019 #4

    JJSR

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    Inside I use rolled up newspaper or old catalogs, so not too tear through.
     
  5. Jul 10, 2019 #5

    JonathanOtt

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    Once you have measured and marked, measure again, then once again.

    I measured and marked a 4" tube out for three 1/4" slots. I cut it, and when finished and doing a dry fit, realized that when marking the tube, I somehow got 1/4" off...resulting in one slot 1/4" off, and the third 1/2" off.

    Turns out that once I marked the three lines on the tube, then went to mark another line 1/4" from each line, I apparently marked 1/4" to the right of my mark for one slot, then marked 1/4" to the left of the next one. :eek:

    Yeah.

    :mad:
     
  6. Jul 10, 2019 #6

    heada

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    Backing up the cut with either a coupler or something like rolled up newspaper will give a much cleaner inside surface and help prevent crushing the tube if you use too much force. Much easier to make several light passes that way too.
     
  7. Jul 10, 2019 #7

    rharshberger

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    +1, I keep a few extra couplers of each size on hand, both for cutting slots and for cutting tubes in my jig (Kuhn-style jig?). The coupler makes for nice clean cuts and no tearout on the interior of the tube.
     
  8. Jul 10, 2019 #8

    neil_w

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    What I like to do is make a plunge-cut at each end, and then put in the coupler (or whatever) and do the long cuts.
     
  9. Jul 11, 2019 #9

    A & B Model Rocketry

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    I did those on a build and I used part of a toilet paper roll cut to size and mounted inside to fortify the body tube walls. Also helped to give a little more strength to the fin attachment.
     
  10. Jul 24, 2019 #10

    JeromeK99

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    Honestly.... I'm sure to get a bit of flak for what I'm about to suggest. Lol

    Don't sweat it to much. You can simply use a sharp (new) #11 blade and make piercing cuts. One blade height at time. Take your time and follow you guide lines as closely as possible. It doesn't need to be perfect, just close. You should be adding fillets anyways, so your minor imperfections will not be seen.

    Optionally, a Dremel with a cutoff wheel cuts Estes tubes like butter.

    I know a lot of modelers have OCD or at least fairly meticulous. I get it. Most of the time I am as well.

    You will develop your own methods as you progress in the hobby. But as an old timer once told me when I was a boy many years ago, "Beat it to fit and paint it to match!"

    I don't mean that in an extreme way. Just that little things can be fixed easily.
     
  11. Jul 24, 2019 #11

    Nytrunner

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    I'll bite, how do you get that to work without murdering the tube? Backing required?
     
  12. Jul 24, 2019 #12

    rharshberger

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    Dremel 543 cutting wheel is my favorite for Estes, Loc, and also FG tubes, it cuts on the edge and sands on the flats, super easy to cut slots then widen them as needed.
     
  13. Jul 26, 2019 #13

    JeromeK99

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    The key to using a Dremel is you don't push hard. Let it do the work. With the wheel, just move it lightly back and forth over your guide line.
     

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