Search found 270 matches

by kjjohn
Mon Apr 11, 2011 9:11 am
Forum: General How-To & Discussion
Topic: machining the MiniBoy MarkI
Replies: 25
Views: 5933

If you feel a bit entrepreneurship like I am, know that I refunded the package + a workshop full of tools (drill press, band saw, grinder, you name it...) after 2 years selling items I machined with it. What kind of things have you sold? I am thinking of buying a mini milling machine and doing sort...
by kjjohn
Fri Dec 31, 2010 5:49 pm
Forum: Off-Topic Hobbies
Topic: Happy New Year 2011!!
Replies: 9
Views: 1262

Is it already midnight in your time zone? It's not even 5 pm here in Wisconsin!
by kjjohn
Sun Dec 26, 2010 12:17 pm
Forum: Off-Topic Hobbies
Topic: Merry Christmas, What did you get??
Replies: 76
Views: 4124

I got a Traxxas Rustler RC truck Nice car, what model, was it the brushlss version? It is the 3705 model - not the brushless one - however, over the summer when I get a job I am going to save up some money and buy the Velineon brushless conversion kit. I'll have to get some practice in first - 70+ ...
by kjjohn
Sat Dec 25, 2010 5:45 pm
Forum: Off-Topic Hobbies
Topic: Merry Christmas, What did you get??
Replies: 76
Views: 4124

I got a Traxxas Rustler RC truck, pair of snowshoes, seasons 1 and 2 of 24 (the best show in the world), the Jason Bourne trilogy, and a new set of combination wrenches.

EDIT: Also got $50 worth of Gander Mountain gift cards and a Steven Hawking book.
by kjjohn
Fri Dec 17, 2010 8:07 pm
Forum: General How-To & Discussion
Topic: Liquid C02 Cartidge?
Replies: 4
Views: 1700

Liquid C02 Cartidge?

Would it be possible to have a cartridge filled with liquid C02, and use perhaps an electrothermal-type effect to vaporize almost all of the liquid at once? If so, this could have a much higher power density than other compressed-gas cartridges. The cartridge could be as simple as a small metal cyli...
by kjjohn
Sun Dec 05, 2010 2:55 pm
Forum: Off-Topic Hobbies
Topic: What are you hoping Santa brings you this year?
Replies: 33
Views: 1694

Already got a drill press for my birthday, so...An abrasive chop saw, a band saw, a MIG welder, a tap & die kit, or a Ruger SR9c.
by kjjohn
Thu Nov 25, 2010 7:05 pm
Forum: General How-To & Discussion
Topic: Automatic Piston Hybrid Design
Replies: 11
Views: 2037

If the exhaust valve opened before the fuel mix enters, the pressure would not be higher on the chamber side. Fuel behind the piston would be 1x mix, so you wouldn't have to worry about losing very much fuel through the exhaust port, although, like in a two-stroke engine, there would always be some ...
by kjjohn
Thu Nov 25, 2010 6:05 pm
Forum: General How-To & Discussion
Topic: Automatic Piston Hybrid Design
Replies: 11
Views: 2037

Automatic Piston Hybrid Design

I was doing some research on free piston engines, when I got this idea for a piston hybrid. It functions like a two-stroke engine, except instead of a crankshaft, you have a spring that resets the piston. Orange = O-rings Blue = Venturi-fed Fuel Intake Check/Reed Valve Green = Check/reed valve Red =...
by kjjohn
Wed Nov 24, 2010 9:10 pm
Forum: Combustion Cannons
Topic: Developing District 9 style cannon, chamber help.
Replies: 12
Views: 1702

I believe he means using the propane tank as a sort of reserve tank to fill the chamber. This has been done before, and seems to work fairly well.
by kjjohn
Wed Nov 24, 2010 5:41 pm
Forum: Combustion Cannons
Topic: Developing District 9 style cannon, chamber help.
Replies: 12
Views: 1702

I remember from the movie there were several distinct types of alien guns. The one pictured is the one the shoots green fire. There was also the lightning gun, the gun that shot grenade-type things, and the sonic blaster.
by kjjohn
Wed Nov 24, 2010 3:21 pm
Forum: Combustion Cannons
Topic: Developing District 9 style cannon, chamber help.
Replies: 12
Views: 1702

District 9 is my favorite movie, I would like to see a cannon modeled after one of the alien guns.

You want to shoot at someone? I would not recommend that.

However, I would download HGDT. It's a combustion gun simulator that should let you figure out an optimal chamber size, etc.
by kjjohn
Sat Nov 06, 2010 11:42 pm
Forum: Pneumatic Cannons
Topic: Smoothbore Barrel?
Replies: 13
Views: 1001

Soldering is fairly easy to learn, and only requires a propane torch. It should only cost you about $10 to get started.
by kjjohn
Sat Nov 06, 2010 2:11 pm
Forum: Combustion Cannons
Topic: First Cannon, love it, but want better.
Replies: 6
Views: 670

Welcome to Spudfiles! 1. You can power a standard 12v computer fan with a 9v battery, though I prefer to use rechargeable RC batteries. It sounds like you are using a spray n pray, so a fan probably isn't going to make much of a performance difference, but you mentioned ratios and "vapor injectors",...
by kjjohn
Sun Oct 31, 2010 12:05 am
Forum: Pneumatic Cannons
Topic: "Excalibur" QEV Cannon
Replies: 6
Views: 1657

Actually, my cartridge design includes a disk.
by kjjohn
Sat Oct 30, 2010 7:58 pm
Forum: Pneumatic Cannons
Topic: "Excalibur" QEV Cannon
Replies: 6
Views: 1657

Thanks. If you look closely at the tee, you can see that it is already plugged. I will be replacing the tee with a normal 2" coupling soon, at the time a tee was the only thing I had on hand that would work.

What kind of paint sounds best: desert camo, or flat black?