Cutting BT's for fin slots

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rabidsheeep

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Is there any trick to this? i figure cut small so you can fine sand it...

Im gonna be using a dremmel and ive got about 60 bucks worth of stuff custom for this tube so i dont wanna screw up and have that much stuff for a tube i cant use...

Anyone got tricks?
 

DJ Delorie

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The first time I did it, the trick was to put something inside the BT to support it, wrap the template around the BT (like a fin guide) and cut through it with an xacto knife.

The second time I did it, the trick was to buy laser cut BTs ;-)

If you're using a template and dremel cut-off, double-sided tape is probably a good idea. Or print on card stock, cut out the slots in the template with an xacto, then tape that to the BT and trace the cutouts.

Also, find my thread on the SS 3x24 fin can to see about supporting those slots after you cut them.
 

cls

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I cut BT slots all the time by hand. the trick is patience and a sharp knife.

use a brand new, super sharp xacto #11 blade.

don't try to cut all the way through the first time, make lots of tiny cuts. lots and lots. for the first cuts, hold a straight edge such as a ruler along the lines. after the first little cuts the knife will follow in the groove.

can you find some paper towel tubes or other scraps, and practice a few times first?
 

rabidsheeep

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yeah, ive got plenty of tubes (i collect em :D ) so ill try just to do it with a blade, scoring it over and over

thx guys
 

lalligood

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For larger, thicker tubes, I prefer a razor utility knife. The blades are cheaper & much more durable than X-Acto blades (which I save for smaller, more detailed work).

With smaller tubes--especially BT-5, BT-20, & BT-50, I slide an old motor casing inside to support the tube so it doesn't crimp or become crushed during cutting/slotting.

Save the Dremel & cut-off discs for slotting phenolic tubing ;)

HTH,
 

powderburner

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lalligood said:
With smaller tubes--especially BT-5, BT-20, & BT-50, I slide an old motor casing inside to support the tube . .


OK, so do I, and it works great----as long as you remember to save some old motor casings for this when you are cleaning out the range box.
What do you guys use to support the larger BT sizes, like -55, -60, -70, and -80? I have a collection of large wooden dowels and PVC pipe sections, the biggest stuff I can find that 'almost' fills these BT sizes. I wrap them tightly with old paper to bring them up to the biggest diameter that I can still squeeze inside these BTs. After I am done cutting I usually have to remove the paper and re-wrap for the next job. It works, and I can support the BT well enough that I don't crush it while working on it, but this approach is a bit of a PITA.
Does anyone have a better way?
 

rabidsheeep

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i cant really support this tube, but its sturdy enough on its own...
 

Stymye

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What do you guys use to support the larger BT sizes, like -55, -60, -70, and -80?
I stick a nosecone in the aft end, to help keep it round while cutting ,or a coupler

on even larger tubes I've used a power miter saw and a homemade wooden fixture
 

DJ Delorie

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[as long as you remember to save some old motor casings
1. We always recover our spent motors and toss them in the box for later disposal, so they start off "saved".

2. I use spent motor casings for thrust blocks and rocket stands anyway, so I'm always thinking of saving them and tend to keep a small collection around as parts.
 

MetMan

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I use VCP to make a fin wrap and secure it to my body tube. If you use the appropriate thickness for the fins, it makes a nice guide for cutting your slots. Jus make sure you accurately mark the upper and lower bounds on the wrap.

I have more success with a Dremel than Exacto.

MetMan
 
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