Ultralight, Ultra small Cable Cutter

Just finished making a really small cable cutter for chute release

Not as small as yours but I've been using 357's for awhile now.



Tony

.22 WMR and .22LR cases? Very interesting. What does the cutting? Is it just the action of the two cases against each other when the e-match fires with some powder?

And (the other) Tony, when you say 357s, I assume you mean the case and not the cartridge!

Seems like a fun experiment.


Tony

You got it, other Tony. But you have to swage the .22lr down a bit to get a smooth fit. Weighs in at about a gram.
It has to be small for my 24mm carbon rocket. And yes, the sliding action cuts the line.

n27sb said:

You got it, other Tony. But you have to swage the .22lr down a bit to get a smooth fit. Weighs in at about a gram.
It has to be small for my 24mm carbon rocket. And yes, the sliding action cuts the line.

Click to expand...

I wondered about the fit. I wonder if using a .25 caliber case would work with a .22 case without any resizing? I think I have some .25 ACP for a Browning 1905, I'll have to check it out, the fit could be too loose. Good reason to empty some brass.


Tony

Newbie question here! From what are you disengaging the chute? I don’t know much about the higher end of rocketry.

The concept is pretty easy. The fishing line passes through the cases and then ties around a bundled chute.
The chute is deployed by an apogee charge and the chute stays bundled. This causes a fast decent. At a low altitude, say 800ft the cutter is activated and allows the chute to open.

n27sb said:

The concept is pretty easy. The fishing line passes through the cases and then ties around a bundled chute.
The chute is deployed by an apogee charge and the chute stays bundled. This causes a fast decent. At a low altitude, say 800ft the cutter is activated and allows the chute to open.

Click to expand...

Is that fishing line? If so, what weight?

It is 30lb. I use multiple wraps and tie with a square knot. If you melt the ends they ball up and keep the knot from sliding open.

I see! Is this the rumored "dual deployment" I've heard about? What sets off the chute/fishing line cutter? Somekind electronics?

Many types of Dual Deploy. This is just one.

How do you run the wires out of avbay to charge and keep them from getting pulled on or broken?

Thanks

Bundle up everything tight and close to the nosecone

crossfire said:

How do you run the wires out of avbay to charge and keep them from getting pulled on or broken?

Click to expand...

I always zip tie the wires to the closest eyebolt also to give it strain relief.

Here is one I recently machined out of aluminum. It is probably a little bigger at 1.375" long and 0.312" in diameter. It was still a lot of fiddly little parts to machine.

In the past I have soldered some stranded wire onto the e-match, electrical taped that to the harness going to the av-bay, and then wrapped the wire around the base of the harness eye-bolt a few times before entering the av-bay.

Wow, that is really nice, I wish I could machine stuff like that. I have a 3D printer, which is pretty useful for lots of stuff, but obviously not for anything like that. Good stuff in this thread.


Tony

@manixFan
Don't dismiss what your 3D printer could do when it comes to cable cutters for dual deployment. This thread has a discussion on a type of cable cutter that doesn't rely on the property of a pyro forcing a mechanical cutter to slice a cord, but rather the heat from a nichrome wire or heating element to melt an elastic band. Essentially, the idea is a chute release or cable cutter with no moving parts. A 3D printer would absolutely come in handy for something like this.

How do you keep the powder from spilling out the line hole? Or are you just using the energetics of the match?