Search found 29 matches

by Tep
Fri May 22, 2015 3:05 am
Forum: Pneumatic Cannons
Topic: True Bolt Action 6mm Cannon
Replies: 11
Views: 7999

Re: True Bolt Action 6mm Cannon

:oops: Ha ha clearly I can't read :oops:

I was probably too distracted by the pics to read the title (nogunhomo)...
by Tep
Fri May 22, 2015 3:00 am
Forum: Pneumatic Cannons
Topic: Which is quicker, QEV + solenoid or ball valve with spring?
Replies: 6
Views: 4505

Re: Which is quicker, QEV + solenoid or ball valve with spri

There probably isn't a need to get a solenoid with higher flow it's just a matter of reducing the volume of air that the solenoid valve has to evacuate from the back of the QEV.

Smaller pilot volume or faster pilot venting = faster pressure drop behind the valve = faster valve opening.
by Tep
Wed May 20, 2015 8:41 am
Forum: Pneumatic Cannons
Topic: Which is quicker, QEV + solenoid or ball valve with spring?
Replies: 6
Views: 4505

Re: Which is quicker, QEV + solenoid or ball valve with spri

QEV will hands down out perform a ball valve in every way. The QEV in your picture is set up wrong. (the solenoid valve is supposed to be where you have written air reservoir). Pilot volume vs venting speed is the key factor in determining QEV performance (you want the first one low and the second o...
by Tep
Wed May 20, 2015 3:38 am
Forum: Pneumatic Cannons
Topic: True Bolt Action 6mm Cannon
Replies: 11
Views: 7999

Re: True Bolt Action 6mm Cannon

That looks GREAT congratulations! Is it in 6mm? I saw that you mentioned 0.2g bb's so I assume you used air soft bb's? Is there any chance you could satisfy my curiosity with some close up pics of each of the parts? I think I saw you comment on your previous gun that you did most of it with some han...
by Tep
Wed May 20, 2015 3:24 am
Forum: General How-To & Discussion
Topic: Short question topic
Replies: 1502
Views: 657619

Re: Short question topic

GGDT (gas gun design tool) has you covered there Doodmens... http://www.thehalls-in-bfe.com/GGDT/ That program has pretty much everything in it. That said the actual workings of the program are a bit of a mystery so if you have an advanced maths / physics interest (if that's what you mean by school)...
by Tep
Sun May 17, 2015 8:16 pm
Forum: Pneumatic Cannons
Topic: It's never finished...
Replies: 4
Views: 3240

Re: It's never finished...

Sort of... but higher voltage = a harder push from the solenoid (force is proportional to the square of the voltage, minus losses). Changing the number of capacitors (or the amount of capacitance) is what affects the duration of the capacitor discharge time. Using the calculation t=R.C (where t = ti...
by Tep
Sun May 17, 2015 10:57 am
Forum: Pneumatic Cannons
Topic: My first serious project
Replies: 1
Views: 1450

Re: My first serious project

Hi Roy, Great work getting started on a "proper" launcher! Your overall design while deffinatly sound is probably significantly more complex than it needs to be. the main area of overdesign is going to be in that trigger / pilot system you have; in its current set up the spring opening of the ball v...
by Tep
Sun May 17, 2015 8:54 am
Forum: General How-To & Discussion
Topic: Is spudding dead?
Replies: 119
Views: 287113

Re: Is spudding dead?

That tourch gun is awesome!!! I tinker with parts almost every day working on barrel designs etc. but often I don't feel like what I've made justifies a post because so much has been seen before. (Oh look, another blow through bolt semiauto yay...) I tend not to post too much on other people's stuff...
by Tep
Sun May 17, 2015 7:59 am
Forum: Pneumatic Cannons
Topic: It's never finished...
Replies: 4
Views: 3240

It's never finished...

Soooooo.... I took apart the "finished" gun that I posted a few months ago and rebuilt it to feed directly from the regulator paintball style. I also rebuilt the solenoid to QEV attachment: now when the solenoid driver strikes the pin of the presta valve that pilots the QEV the air that is released ...
by Tep
Mon Apr 20, 2015 3:52 am
Forum: Pneumatic Cannons
Topic: QEV Pilot question
Replies: 5
Views: 3703

Re: QEV Pilot question

Ok, here go's. IMG_2044.jpg This is the balanced valve I use to pilot now, it's awesome, literally the best thing I have made. IMG_2045.jpg This demonstrates the hole I drilled through the end cap of the valve, I also expanded the in and out ports of the valve. That tube is 8mm like I showed in the ...
by Tep
Sun Apr 19, 2015 9:47 am
Forum: Pneumatic Cannons
Topic: QEV Pilot question
Replies: 5
Views: 3703

Re: QEV Pilot question

I was having the exact same problem recently and happened upon a solution you might be interested in. I basically created an 8mm cross between a balanced spool valve and a QDV valve from a store bought (or ebay bought) three way valve. I'll do a quick and very rudimentary paint drawing of it for you...
by Tep
Thu Apr 02, 2015 12:30 am
Forum: Pneumatic Cannons
Topic: Random idea - possible ridiculous power / velocity.
Replies: 16
Views: 7426

Re: Random idea - possible ridiculous power / velocity.

Wow that's a great explanation - thank you! Running the calculations for my theoretical 0.2g at 100m/sec in a 1000mm x 16mm barrel gives me 0.5 * (Mp + Ma) * Va^2 = Energy or 0.5 x (0.0002 + 0.00003) x 10000 = 2.5 and with vacuum in barrel Vv = sqrt(((Mp + Ma)/Mp) * Va^2) Vv = sqrt(((0.0002 + 0.0003...
by Tep
Wed Apr 01, 2015 10:28 am
Forum: Pneumatic Cannons
Topic: Random idea - possible ridiculous power / velocity.
Replies: 16
Views: 7426

Re: Random idea - possible ridiculous power / velocity.

Right I see!! thats why I don't get huge improvements in power using a 2g projectile in such a short barrel, the mass of air in the barrel would only be about 2.4 - 3mg I think. I guess greater improvements could be seen with a longer barrel and a lighter projectile like a 0.2g plastic airsoft pelle...
by Tep
Tue Mar 31, 2015 9:01 am
Forum: Pneumatic Cannons
Topic: Random idea - possible ridiculous power / velocity.
Replies: 16
Views: 7426

Re: Random idea - possible ridiculous power / velocity.

My concern with the longer barrel would be running out of vacuum before the ammo leaves the barrel. Thats why I evacuated the air from both the barrel and the shroud, the shroud in theory acts as a reservoir for low pressure keeping the tip of the barrel constantly at close to a vacuum until the pr...
by Tep
Mon Mar 30, 2015 11:40 pm
Forum: Pneumatic Cannons
Topic: Random idea - possible ridiculous power / velocity.
Replies: 16
Views: 7426

Re: Random idea - possible ridiculous power / velocity.

I'm currently trying this and not noticing an enormous increase in power unfortunately... But it could have something to do with the 8mm barrel and light weight ammunition I have. I'm continuing to experiment. Hopefully I'll work something out... Update! There is a definite measurable increase in po...