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  #1  
Old 03-14-2009, 07:23 PM
Jeff Walther Jeff Walther is offline
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Default Dichloro-difluoro methane: Is this Freon?

I found a can in a box in the garage. I probably bought it back when I did all my own car work. I didn't think I had anything from that far back though, so I wouldn't be surprised to find that it's a later refrigerant.

What does this have to do with Kit Collecting?

I bought a cold-power Shrike glider on Ebay and gave it to my son for his birthday.

We just finished balancing it with modeling clay out at the playground. Those are nice gliders.

The package was still unopened but the propellant had all seeped away. I will hunt down the Vashon/Valkyrie site which discusses other propellant options, but since I have this stuff on hand...

On the other hand, I have no way of breaching the can in a controlled manner. If I ever had the hose for it, I must have thrown it away long ago. The can has a flat/domed metal top which is recessed into a ~1.5" diameter depression and there's a rolled metal lip around the depression. No threads anywhere. The connector must punch a hole in the metal top somehow.

If this isn't freon, does anyone know if I can still get a hose/connector thingy for it.

By the way, is there a way to make home copies of styrofoam shapes? I know that one can do the resin casting and molding for home plastic parts. How about styrofoam or whatever the Shrike glider is made of.

I had one when I was a kid and I still have the little rocket, but the styrofoam glider is long demolished. Just balancing this one, the nose is getting chewed up a bit.
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  #2  
Old 03-14-2009, 08:17 PM
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Mark II Mark II is offline
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Quote:
Originally Posted by Jeff Walther
I found a can in a box in the garage. I probably bought it back when I did all my own car work. I didn't think I had anything from that far back though, so I wouldn't be surprised to find that it's a later refrigerant.

What does this have to do with Kit Collecting?

I bought a cold-power Shrike glider on Ebay and gave it to my son for his birthday.

We just finished balancing it with modeling clay out at the playground. Those are nice gliders.

The package was still unopened but the propellant had all seeped away. I will hunt down the Vashon/Valkyrie site which discusses other propellant options, but since I have this stuff on hand...

On the other hand, I have no way of breaching the can in a controlled manner. If I ever had the hose for it, I must have thrown it away long ago. The can has a flat/domed metal top which is recessed into a ~1.5" diameter depression and there's a rolled metal lip around the depression. No threads anywhere. The connector must punch a hole in the metal top somehow.

If this isn't freon, does anyone know if I can still get a hose/connector thingy for it.

By the way, is there a way to make home copies of styrofoam shapes? I know that one can do the resin casting and molding for home plastic parts. How about styrofoam or whatever the Shrike glider is made of.

I had one when I was a kid and I still have the little rocket, but the styrofoam glider is long demolished. Just balancing this one, the nose is getting chewed up a bit.

Yes, it is Freon. (See here and here.)

If you want to make your own styrofoam gliders, you can purchase blocks of the material and a hot-wire cutter from a craft store like Michael's, or from Micro-Mark.

MarkII
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  #3  
Old 03-14-2009, 10:55 PM
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If you've never handled Freon and don't know what type of hose and can tap to use, then I wouldn't bother. For one thing, discharging Freon to the atmosphere is now illegal (not that I care- down with the man and the stinking federal jackbooted thugs!) but that is something some people are concerned about, so whatever floats your boat. One can of freon isn't going to wipe out mankind....

Basically, there were a few different types of can taps. Most of the ones we had consisted of a little bracket with a locking cam on it, and a threaded hole for the can tap. You would unscrew this off the hose and valve and put it on the top of the can, on the little center rim surrounding the raised center, and then push the locking cam over as tight as you could with your thumb. Then you screwed the can tap vavle and hose into the cam lock bracket hole centered just above the raised part. It had a rubber O-ring that sealed the tap to the raised part. You hooked up the hose to your A/C filter/dryer or compressor low pressure suction fitting (depending on the car) and then screwed the valve in, which had a sharpened tip that punctured the top of the can, and then you screwed it back out, which pulled the sharpened tip out of the hole and allowed the Freon to flow through the hose and into the AC system of the car. When the can was empty, you unscrewed the hose from the system and then removed the can from the cam lock bracket.

Another type, which I had for filling cotton picker A/C units there at the last, was a plastic handle which clamped around the can near the top, with a pair of 'scissor handles' on one side that locked together. On the opposite side of where it clamped around the can from the handles, it had a sharpened steel tube like a hypodermic needle, about 1/8 inch in diameter, with a fat O-ring seal around it. You opened the handles, slipped it over the top of the can to the cylindrical part, and then snapped the handles closed, which punctured the side of the can and pressed the O-ring tightly against the hole to keep it sealed off. Then you could screw the hose onto it and the system fitting to put Freon in the A/C.

When they introduced R-134 Freon replacement, they changed all the fittings on the cars and hoses and stuff from plain 'Shrader valves' and screw on hoses to 'quick connect' air hose/tool type fittings of slightly different size and design to prevent hooking up older A/C stuff up to new systems, and used different sizes for high pressure side fittings from the low pressure side fittings to keep morons from blowing cans of freon up in their face like some guys used to do in the old days, if they hooked the freon can up to the high pressure side of the system, which in the old days used identically sized screw on Shrader valve type fittings. The new can taps and hoses are pretty similar to the first style, except in the fittings that actually connect it to the system. I've retrofitted a few older cars we had to R-134 fittings with screw-on adapters, but the older systems didn't work very well with 134. Better to use the cheap propane-type R-12 replacements, unless you're too scared...

Anyway, I'm not an expert on the Vashon engines, but IIRC they used their own sorta proprietary type fillers for the cold propellant motors, so I don't know how much good either an old or new style car filler would do you. Seems like they used a basketball type air needle and valve to fill them or something like that, which I doubt an old style standard car AC tap would work with, and I KNOW a new style R-134 tap wouldn't work with it....

Use airbrush propellant, keyboard duster propellant, etc. for cold power propellants. They work just as well... OL JR
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  #4  
Old 03-15-2009, 09:54 AM
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Quote:
Originally Posted by luke strawwalker
One can of freon isn't going to wipe out mankind....

But two or three might, so he'd better be careful!
(Do I need to insert an emoticon here?)
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  #5  
Old 03-15-2009, 10:23 AM
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The original Coldpower "propellant" was Freon R-12 (dichloro-difluoro-methane) that was banned from use in Automotive Air Conditioning and Aerosol cans long ago due to it's supposed ozone-depletion properties.
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Old 03-16-2009, 12:31 PM
Jeff Walther Jeff Walther is offline
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Thank you, Gentlemen. If I could find a way to dispense it, I would not hesitate to use this single can of freon. As it is, I'll keep it as a curiosity, I guess and hike over to Walmart for one of the alternative gasses.

Oh, regarding making foam gliders--I want to make an exact copy of the Shrike. So some kind of molding is in order. I'm near 100% certain I'd never get the shape right doing a by-eye trim and cut job.
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Old 03-17-2009, 11:43 PM
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blackshire blackshire is offline
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Quote:
Originally Posted by Jeff Walther
Thank you, Gentlemen. If I could find a way to dispense it, I would not hesitate to use this single can of freon. As it is, I'll keep it as a curiosity, I guess and hike over to Walmart for one of the alternative gasses.

Oh, regarding making foam gliders--I want to make an exact copy of the Shrike. So some kind of molding is in order. I'm near 100% certain I'd never get the shape right doing a by-eye trim and cut job.


Here are links to an article I wrote about resin casting (see: http://ninfinger.org/models/rms_tips/resin_cast.html and http://ninfinger.org/models/rms_tips/rmsfaq.18.html ), which also applies to producing RTV (Room-Temperature Vulcanizing) rubber molds from foam masters such as your Shrike glider. (The two versions of the article have different resources lists.)

If you are unfamiliar with resin casting, the best "one-stop" supplier I've ever found is the Bare-Metal Foil Company (see: http://www.bare-metal.com/ ). I don't think RTV rubber harms styrofoam, but they would know with certainty.

They carry the excellent Por-A-Kast and Polytek polyurethane casting resins and the platinum-cure RTV (Room-Temperature Vulcanizing) silicone rubber mold material, which is better than tin-cure RTV rubber. (The platinum-cure RTV rubber produces much more long-lasting molds that have negligible shrinkage, so that cast resin nose cones, fins, transition sections, and boat-tails will properly fit in/on rockets' body tubes.)

Once your RTV rubber mold is made, if you cast a few Shrike "secondary masters" in epoxy you can use them to make new rubber molds after your first one wears out.

If most of the preceding sounded like Sanskrit with a Greek accent < :-) >, Bare-Metal Foil's web site has very good "how-to" articles that explain and illustrate all of this (I learned how to make RTV rubber molds and resin parts from their articles).
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Last edited by blackshire : 03-18-2009 at 12:04 AM. Reason: This ol' hoss done forgot somethin'.
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Old 03-18-2009, 09:13 AM
Jeff Walther Jeff Walther is offline
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Quote:
Originally Posted by blackshire
Here are links to an article I wrote about resin casting (see: http://ninfinger.org/models/rms_tips/resin_cast.html and http://ninfinger.org/models/rms_tips/rmsfaq.18.html ),

(The platinum-cure RTV rubber produces much more long-lasting molds that have negligible shrinkage

If most of the preceding sounded like Sanskrit with a Greek accent < :-) >, Bare-Metal Foil's web site has very good "how-to" articles that explain and illustrate all of this (I learned how to make RTV rubber molds and resin parts from their articles).


Thank you. No, it doesn't sound like Sanskrit--maybe ancient Greek, but I studied that a couple of decades ago...

Once I have a good mold of the Shrike made, any idea if I there's a home method to make new styrofoam instances? Or is that covered in the referenced materials?
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Old 03-18-2009, 10:45 AM
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Quote:
Originally Posted by Jeff Walther
Thank you. No, it doesn't sound like Sanskrit--maybe ancient Greek, but I studied that a couple of decades ago...

Once I have a good mold of the Shrike made, any idea if I there's a home method to make new styrofoam instances? Or is that covered in the referenced materials?


You'll have to use either a two-part rigid polyurethane foam or a spray-on rigid polyurethane foam (sprayed into the mold, with adequate overflow vents in the mold). The Shrike gliders were made of Expanded Polystyrene (EPS). EPS, which is often commonly (and mistakenly) called styrofoam (which is an extruded foam) requires the application of heat and steam to produce. Rigid polyurethane foam (soft polyurethane foam is foam rubber) is a bit denser than EPS, but a Shrike made of it should still glide satisfactorily.
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Old 03-18-2009, 12:32 PM
Jeff Walther Jeff Walther is offline
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Quote:
Originally Posted by blackshire
You'll have to use either a two-part rigid polyurethane foam or a spray-on rigid polyurethane foam (sprayed into the mold, with adequate overflow vents in the mold). The Shrike gliders were made of Expanded Polystyrene (EPS). EPS, which is often commonly (and mistakenly) called styrofoam (which is an extruded foam) requires the application of heat and steam to produce. Rigid polyurethane foam (soft polyurethane foam is foam rubber) is a bit denser than EPS, but a Shrike made of it should still glide satisfactorily.


Thank you, again. I appreciate the guidance. I suspected it wasn't actual styrofoam (feels spongier and denser) but was at a loss for how to describe it otherwise. Expanded polystyrene.

Okay, now I need a place in the near infinite queue of projects to place coming up to speed on resin molding and creating masters of the Shrike... That pesky earning a living keeps getting in the way--but on the bright side, I'm earning a living. :-)
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