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Homemade Quick Release Design

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Hon1nbo

Mon May 31 2010, 08:37PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040

hey guys,
I designed this simple, relatively cheap, quick release for use with moderate loads. I looked all over and could not find a purpose made quick release, and when I finally do I'm sure it will be expensive, way out of range for an item only used for special purpose.

Well, my design combines the idea of an explosive bolt with a little variation in the method of applying load force and material properties.

Instead of using an exploding bolt, I am using rapid burning (one foot/second) paper fuse. obviously, fuse used as a rope cannot hold very much weight reliably. So, I thought of how I could made the load bearable. I came up with this.
The support block, held up by whatever hoisting means are at disposal, has a slot. The metal bar that bears the cable with load is smaller than this slot, but only by a small amount. The paper fuse goes between the bar and the slot preventing it from falling through. This is where it gets to knowing the material properties. The paper fuse will not stay level and strait, that is near certain. Instead, I WANT it to start to crush, but because the bar is not much bigger that the slot it does not crush very much as their is little room for movement and paper can take compression perpendicular to the plane very well, it is the bending that is for concern.

I just ordered a 100' roll of paper fuse ($15 from Skylighter) to test out with, and I have other uses for it if this doesn't work well.

thoughts? - attached is a basic diagram.

-Jimmy

1275338214 902 FT0 Paper Fuse Quick Release

radiotech

Mon May 31 2010, 09:01PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

The only thing that comes to mind is if the fuze is lit at both, ends, of both fuzes, or at opposite ends of the adjacent fuze issues of
skewed descent may be prevented, should one fizzle. what's the speed of your proposed fuse?

Hon1nbo

Mon May 31 2010, 09:20PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040

radiotech wrote ...

The only thing that comes to mind is if the fuze is lit at both, ends, of both fuzes, or at opposite ends of the adjacent fuze issues of
skewed descent may be prevented, should one fizzle. what's the speed of your proposed fuse?

the fuse burns at one foot per second (in the first post)

if I understand your comment right, there might be an issue of it not descending evenly? - it does not matter how the bar falls once the fuse is lit, only that it falls. both stacks of fuse will be lit at both ends (will kind of bridge them together).
I also thought about putting in a longer burning substance, such as regular paper, with a little accelerator so that if once fuse for some reason does not burn initially the longer burning paper might start it up. (FYI: I thought of paper sooked in accelerate instead of fuse, but it becomes too soggy and tears easily. Paper fuses are relatively thick.

-Jimmy

IntraWinding

Tue Jun 01 2010, 01:41AM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

How about using the fuse (or whatever) to activate a 'trigger', which then releases a much greater load than the fuse itself could support.

For example, you could modify a conventional mouse trap so as soon as the fuse burns the trap fires, and use that to release anything you like.

radiotech

Tue Jun 01 2010, 05:29AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

How long is the fuze? That would give the time. The issue or it burning through one end, and that side of load dropping, while held in the close space by the other unburned part makes it seem it could jam. Also, what is the use for this kind of fuze? Is it for pyrotechnique shows, ie, sequencing mortars?

Steve Conner

Tue Jun 01 2010, 09:40AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

If it helps, I once discovered that the flame from a lighter will make guitar strings snap when they're under tension.

In a similar vein, you could use a heavy current to melt a piece of wire (guitar string, iron, nichrome etc) that held some sort of trigger in place.

Hon1nbo

Tue Jun 01 2010, 05:05PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040

radiotech wrote ...

How long is the fuze? That would give the time. The issue or it burning through one end, and that side of load dropping, while held in the close space by the other unburned part makes it seem it could jam. Also, what is the use for this kind of fuze? Is it for pyrotechnique shows, ie, sequencing mortars?

the support bar is not fixed perpendicular to the load rope, it can rotate to slide through is only one fuse goes off. This sort of fuse is used to control Rapid timing of fireworks (things going off near the same time sort of thing)

@steve

I never knew guitar string would do that, maybe something like that would work - I'll look into it.

-Jimmy

Dr. Slack

Tue Jun 01 2010, 07:03PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

I'm concerned that your block could shear through the paper fuse with very little load.

How fast do you want it to act? My "quick release" design is one-shot, but very strong, and immune to damp (which your fuse ight not be). A nylon or polyproylene webbing strap, which can takes tons, has a few inches of nichrome wire threaded into it. If you smack too much power into it, the wire explodes without melting the webbing, it takes a few seconds of steady heat to melt through it.

You might want to google for how to use an "over center" lock. This gives you an infinite force multiplier, which has to be pushed to be released, perhaps by a solenoid or small pneumatics. Change the design slightly to a "not quite over center" lock and you need a small force to hold it closed, maybe your fuse would be good for this, or the tension in a thin wire which you can explode to release it.

Hon1nbo

Fri Jun 04 2010, 11:10PM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040

I got the fuse in today (fast considering it can't be sent via USPS air), and boy does it burn fast! - I'll do a test using my method, and then I have some guitar string lying around so I'll try that, and I'll look into the suggestion Dr. Slack made.

-Jimmy

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