World Web shooter shop class - Part 4

[White_widow13]

Next, you need to focus on "daisy chaining."

If you decide to go with a 9v, then you don't need to worry about this step.

If you decide to connect 4 "3v batteries" then you need to follow a certain procedure.

This website will help you understand how to make that work:http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel

"daisy-chaining" is another way of saying "connect the battery in series".

 

[mastheon]

The one I was gonna use you sent me a link to. So why does it say 110v on it but doesn't need that? It's the first link that you sent for the 1/4 in one.

 

[mastheon]

I didn't see the 12v required to power it woops.

 

[mastheon]

Could i possibly put tube fittings on either side of the valve that the one side leads to the heated silicone tubing and the other leads to tubing that is connected to the pressure vessel? The pressure vessel could be in a backpack.

 

[mastheon]

So I still need to daisy-chain for a 12v.

 

[Wadaltmon]

So I still need to daisy-chain for a 12v.

Not necessarily. There are some 12V batteries you could use instead of daisy-chaining several power supplies together.

 

[White_widow13]

I'm getting excited y'all. Only 12 more days, and I fly back home. Then, I can start on the wrist unit with my protege. I'll need to get a job before I work on the plunger based pressure vessel.

 

[Wadaltmon]

I'm getting excited y'all. Only 12 more days, and I fly back home. Then, I can start on the wrist unit with my protege. I'll need to get a job before I work on the plunger based pressure vessel.

If you don't mind my asking, what's your schooling situation? If you are going to a college or university, they may have some resources available there.

 

[White_widow13]

I don't mind at all. Right now I'm studying at BYU. We are in finals week right now. We do have a pretty sick mechanical engineering lab, which I am authorized to use, but the parts that I need to assemble the wrist unit are back in north Carolina. I already used the lab to bend my tubing. I just need to use a miter saw to cut an old car tire I have.

 

[White_widow13]

You know what I've kind of noticed working on this project here?

I've tried to come up with rectangular pressure vessels, chemically created pressure, a custom check valve, and most recently a coiled network of tubing. I think I'm tired of trying to over complicate this project. I'm going to try to build a simple device using parts from home depot and amazon. If it's taking this long to create custom parts, I guarantee that some of the younger folks here won't be able to recreate my work. I am going to keep things as rudimentary as possible, and, God be willing, we can make a shooter that Parker could've made in his basement.

 

[Wadaltmon]

You know what I've kind of noticed working on this project here?

I've tried to come up with rectangular pressure vessels, chemically created pressure, a custom check valve, and most recently a coiled network of tubing. I think I'm tired of trying to over complicate this project. I'm going to try to build a simple device using parts from home depot and amazon. If it's taking this long to create custom parts, I guarantee that some of the younger folks here won't be able to recreate my work. I am going to keep things as rudimentary as possible, and, God be willing, we can make a shooter that Parker could've made in his basement.

Wouldn't the rectangular vessels just expand outward or burst at the seams when pressurized? I feel like a cylinder would be better, IMO.

 

[White_widow13]

yeah. That was kind of my point. Since the beginning, I've been trying to over complicate it by doing silly things like that.

 

[White_widow13]

Hey, has anyone seen the new Spider-man on the scene? His name is Aaron Aikman. He looks like the disciple of Peter Parker and Iron man. I thought his suit, though ugly, was functional:

https://www.flickr.com/photos/126246048@N05/16947060517/

https://www.flickr.com/photos/126246048@N05/16966909430/in/photostream/

 

[mastheon]

Yeah the bulkiness of the suit annoys me.

 

[mastheon]

I ordered a few parts which were: silicone tubing, some tube fittings, solenoid valve, micro button, battery holder pre-wired, power jacks, and nichrome wire. I also ordered a soldering iron. I didn't order a battery to heat the nichrome yet because I don't know the solvent of my fluid yet.

 

[White_widow13]

way cool! Which silicone tubing did you end up buying?

 

[White_widow13]

I'm so excited y'all. I think I've figured out how to simplify this project so that I can get the mechanical part done in 2 months. I'm not sure I will, but if my partner at home is as into it as I am right now, it's going to be done.

 

[Wadaltmon]

I'm so excited y'all. I think I've figured out how to simplify this project so that I can get the mechanical part done in 2 months. I'm not sure I will, but if my partner at home is as into it as I am right now, it's going to be done.

That's good to hear. Will you be making videos on it when it is done?

On an unrelated note, has anyone here ever used Shapeways?

 

[White_widow13]

That's good to hear. Will you be making videos on it when it is done?

On an unrelated note, has anyone here ever used Shapeways?

I probably will when I have some testing done.

Shapeways is good and reliable but super pricey.

 

[the.Amazing]

111

 

[White_widow13]

Good call. It seems that only polypropylene and silicone are very susceptible to butane.

http://www.omega.com/pdf/tubing/technical_section/chemical_chart_2.asp

As for butane vs isobutane, I'm not sure which is the most common. It seems that it can come in two isomers and can be mixed with other additives like propane. Which formulation of butane are you asking about? Pure or mingled?

 

[the.Amazing]

111

 

[the.Amazing]

111

 

[White_widow13]

So isobutane is most commonly sold in fuel as a mixture of isobutane and propane, but I get mine as a refrigerant in 100% purity on Alibaba. Butane is sold as lighter fluid and I think its pure.

I don't think I'll use butane because its vapor pressure is too low for a shooter. Isobutane is pretty good (I'd say the best there is) as a propellant, its already used in shaving cream.

Only problem is I think isobutane might be unlikely to be a solvent for polymers as its structure isn't very chain-like.

Acetone, I'd say the most used solvent in this project (even if it shouldn't be), has a similar structure to isobutane, but maybe isobutane's extra carbon is the culprit.

I still gotta find more out about this. It took me a long time to figure out a decent formula, and I can say chemical compatibility tables are my nemesis.

Theres no way of finding out solubility of a polymer in a solvent without trying it, which really bums me out. For instance, every source says Isobutane has a severe effect on EPDM rubber, but that doesn't mean it dissolves.

I believe any of the hydrocarbons can act as good solvents in the right conditions, but they are generally the best for non-polar substances.

Unfortunately for us, the best polymers contain strong hydrogen bonds (which make is more polar) or their chains are so well cross-linked that they are hard to break with solvents (like nylon or kevlar)

I agree with the acetone thing. The only cheap quick way to make portable pressure vessels are with PVC pipes. Steel works, if cost, weight, and tools are no issue.

As for data tables, it has been astoundingly hard to find good data on this. It seems that this is such a unique application, that most chemists haven't tried it. It makes sense though. They opt for the cheaper stuff.

Now for your next post, I will hold off responding for a little bit. Math is not my forte, and I need a little bit more time to process that data.

 

[White_widow13]

Ok, Here I'm gonna do MATH (please someone point something out to me if something is wrong)

isobutane density in the condensed phase: 0.61415 g/cm^3
molar mass: 58.1222 g/mol
molar volume in the condensed phase: 58.1222/0.61415 = 94.638443377 cm^3/mol
enthalpy of vaporization: 21.3 kJ/mol = 5090.82218 cal/mol

cohesive energy density = (5090.82218 cal*mol^-1)/(94.638443377 cm^3*mol^-1)

(mol^-1 cancel out)

= 53.7923279203 cal/cm^3

Hildebrand Solubility Coefficient = (53.7923279203 cal/cm^3)^0.5
= 7.33432532141 cal^(1/2)*cm^(-3/2) (this is the common unit for this parameter)

If you look at this link you can see other chemical's parameters:
http://en.wikipedia.org/wiki/Hildebrand_solubility_parameter

Apparently chemicals whose parameters are very close should be miscible or soluble or at least have some effect. From the look of the list, isobutane should be miscible with pentane and hexane (understandable), but also might dissolve POLYETHYLENE.

I doubt this is the case, maybe theres something else?

Alright. I just checked out your units and the base numbers of isobutane. They all check out. Other than sig-figs, your work is flawless.

According to the numbers, Polyethylene should be miscible or soluble. The only limiting factors are these from wikipedia:

"From the table, poly(ethylene) has a solubility parameter of 7.9 cal1/2 cm−3/2....(However, PE only dissolves at temperatures well above 100°C.)"

This suggests that you'd still need alot of heat to do this, yet still keep butane in a liquid state. You'd have to create a unique pressurized environment.

"Materials with similar solubility parameters will be able to interact with each other, resulting in solvation, miscibility or swelling."

Which leads me to believe that it could behave at least three different ways.

If you can work around these things, polyethylene would be an amazing choice. It's so hard to work with on a low pressure scale, but if you could figure it out, you could then work on mods like UHDPE which is freaking strong.

This is probably the best way of predicting which polymers would work, other than just pure experimentation.

Good find!