A place for general potato gun questions and discussions.
-
jackssmirkingrevenge
- Five Star General

- Posts: 26216
- Joined: Thu Mar 15, 2007 11:28 pm
- Has thanked: 576 times
- Been thanked: 347 times
Wed May 24, 2017 5:43 am
The problem is that you are trying to empty the pilot area while simultaneously continuing to feed from the air supply. Ideally you want a three way valve that opens the pilot area to the atmosphere while simultaneously shutting off the main air supply:

hectmarr wrote:You have to make many weapons, because this field is long and short life
-
farcticox1
- Sergeant

- Posts: 1081
- Joined: Sun Mar 31, 2013 12:37 pm
- Has thanked: 69 times
- Been thanked: 96 times
Wed May 24, 2017 3:24 pm
This is the valve I am using as a trigger, 3/2 with ported exhaust, so the main supply is cut off when the QEV is vented to atmosphere

-
jackssmirkingrevenge
- Five Star General

- Posts: 26216
- Joined: Thu Mar 15, 2007 11:28 pm
- Has thanked: 576 times
- Been thanked: 347 times
Wed May 24, 2017 5:51 pm
That's the ticket... perhaps it has poor flow. Alternatively it would be worth checking your QEV piston/diaphragm for damage. If a QEV flutters then either the pilot valve isn't venting vast enough or air is getting past the piston from the chamber into the pilot area.
hectmarr wrote:You have to make many weapons, because this field is long and short life
-
farcticox1
- Sergeant

- Posts: 1081
- Joined: Sun Mar 31, 2013 12:37 pm
- Has thanked: 69 times
- Been thanked: 96 times
Wed May 24, 2017 6:20 pm
I'm using 4mm OD tubing on the pilot lines, I'll try going to 6mm OD

I have a silencer in the trigger as well, may cause a slight back pressure

-
jackssmirkingrevenge
- Five Star General

- Posts: 26216
- Joined: Thu Mar 15, 2007 11:28 pm
- Has thanked: 576 times
- Been thanked: 347 times
Wed May 24, 2017 6:30 pm
I have a silencer in the trigger as well, may cause a slight back pressure
You mean connected to the venting port? If so I'll wager this is causing the issue.
hectmarr wrote:You have to make many weapons, because this field is long and short life
-
farcticox1
- Sergeant

- Posts: 1081
- Joined: Sun Mar 31, 2013 12:37 pm
- Has thanked: 69 times
- Been thanked: 96 times
Sat Jun 03, 2017 3:40 pm
Tinkering with BFG a bit, still experimenting with sights, decided I have to move the stock a bit lower as well to get a better cheek weld. Anywho decided to finally build a decent target to catch all the BB's flying around, back stop is a thick piece of rubber which deflects them down into the bottom.
EDIT have gone back to the original sight, will finally get it to work

Also good for tin can ally

-
farcticox1
- Sergeant

- Posts: 1081
- Joined: Sun Mar 31, 2013 12:37 pm
- Has thanked: 69 times
- Been thanked: 96 times
Tue Jun 27, 2017 5:18 pm
It will be for airsoft (6mm) only gonna be at 125psi ish, probably going to need more flow than I can supply at the moment, this is my long term back burner project at the moment, probably finished around 2020

I'll be happy if something comes out the barrel when I pull the trigger

-
jakethebeast
- Corporal 5


- Posts: 945
- Joined: Sat Jul 03, 2010 4:20 pm
- Location: Jakes cave
Wed Jun 28, 2017 2:33 pm
Quick question.
Brushless RC motor with a 40mm 3 blade quadcopter rotor to went a 7.8 Liter combustion chamber? Good or bad idea?
Est Sularus Oth Mithas
-
Gippeto
- First Sergeant 3


- Posts: 2504
- Joined: Sat Jan 19, 2008 10:14 am
- Location: Soon to be socialist shit hole.
- Has thanked: 2 times
- Been thanked: 17 times
Wed Jun 28, 2017 5:29 pm
Won't claim to know diddly about combustions, but....you're half way to an edf already....
https://hobbyking.com/en_us/hobbykingtm ... rsion.html
Will certainly move some air. 7.8L works out to 100mm x 1m (roughly 39" of 4" pipe)....not really huge.
"It could be that the purpose of your life is to serve as a warning to others" – unknown
Liberalism is a mental disorder, reality is it's cure.
-
jakethebeast
- Corporal 5


- Posts: 945
- Joined: Sat Jul 03, 2010 4:20 pm
- Location: Jakes cave
Thu Jun 29, 2017 1:24 am
The venting is done via 2" camlock at the end of a chamber and as I want the fan to be serviceable I bet its much better to have an RC motor with 40mm rotor than a 40mm PC case fan.... Also dont feel like spending more than 5 seconds for wenting

Est Sularus Oth Mithas
-
jackssmirkingrevenge
- Five Star General

- Posts: 26216
- Joined: Thu Mar 15, 2007 11:28 pm
- Has thanked: 576 times
- Been thanked: 347 times
Sun Jul 02, 2017 8:12 am
jakethebeast wrote:Also dont feel like spending more than 5 seconds for wenting

Unless you're making a semi-auto, this seems like overkill. That being said, you're an overkill sort of guy, even for a Finn

hectmarr wrote:You have to make many weapons, because this field is long and short life
-
qwerty
- Corporal 2

- Posts: 678
- Joined: Sun Apr 12, 2009 2:16 am
Sun Jul 02, 2017 5:36 pm
Still here, arrived when I was 12 and now I'm 20. Time flies.
I swear it never leaves you, I still have an odd fascination with valves and pipes and all sorts... I'll build something someday.
I visit occasionally to make unrelated posts.