mcarterbrown.com  

Custom Projects / Custom Questions How do I customize? What do I customize? What do I use? Share you experiences and faults here!

Reply
 
Thread Tools Search this Thread
Old 02-27-2013, 11:59 PM   #1 (permalink)
Old, but not slow.
 
reepneep's Avatar
 
Join Date: Oct 2011

Need a Machinists Opinion



I'd like to pay a machinist to build this. I've never worked on such a thing before and would like some feedback on the design. It's an insert for the valve chamber of a Trilogy sniper. The goals are to devolumize the valve chamber and allow for the use of stock autocker valve springs. Total valve chamber volume comes to 3.7in down from about 6in (this should be enough space at ~500psi?). Based on my measurements, the spring should be compressed by about 20% (.25in) when the gun is at rest.

The o-rings serve (at least I hope) to keep the insert from rotating as well as keeping gas out of the front block area.

The 10/32 socket is for installing and removing the insert. I was planning on using the cocking rod.

Yall see any obvious problems with the design? The only thing I'm a bit worried about is the outer diameter. I can't get my calipers into the valve chamber but a dowel, an o-ring, and an allen wrench, all 7/16, have been tried and its a VERY tight fit. I don't know what kind of tolerances should be used, so someone who has experience would be of great help tweaking the dimensions. I'm pretty confident with the other measurements, measure twice, cut once and all that.

I was also thinking about adding a lip on the end to act as a spring guide, just to keep it from walking (maybe 1/16" past the tip?).

Here's a picture of my baby. Don't make fun!

Thanks in advance!

Last edited by reepneep; 02-28-2013 at 12:10 AM. Reason: added a pictar
reepneep is offline   Reply With Quote
Old 02-28-2013, 12:44 AM   #2 (permalink)
Lathe Fiend
 
sniper42's Avatar
 
Join Date: Sep 2008
Location: Huntington Beach, CA

Seems easy enough. Why do you need an o-ring groove wide enough for two o-rings?
__________________
Anonymous Assassins Paintball TeamJust look for the pink shirts

Quote:
Originally Posted by BigOldSkool View Post
CNC's are for nerds...
MCB Feedback


Sheridan Misc FS: Grips, bodies
sniper42 is offline   Reply With Quote
Old 02-28-2013, 08:34 AM   #3 (permalink)
Old, but not slow.
 
reepneep's Avatar
 
Join Date: Oct 2011

Extra friction to make sure it didn't rotate after it was installed. If only one is really necessary, than one it shall be.
reepneep is offline   Reply With Quote
Old 02-28-2013, 09:01 AM   #4 (permalink)
Post Whore
 
Bartman's Avatar
 
Join Date: Aug 2007
Location: Fishers IN.
Send a message via AIM to Bartman

AKA Fan
so you need s round part that excepts a stock size cocker vale? that shouldn't take much material at just some time.

Bart
__________________
Bartman
The devils Brigade
www.compulsivepaintball.com
Its always better with a pump, and camo
http://www.mcarterbrown.com/forums/f...l#post2603541y
Bartman is offline   Reply With Quote
Old 02-28-2013, 10:30 AM   #5 (permalink)
MCB Member
 
Spider!'s Avatar
 
Join Date: Dec 2008
Location: Houston, TX

If you are just looking for de-volumizing, consider an insert that looks more like a banjo bolt with a gas passage ring and four ports. You could make it the right length end to end so that it can't move, with a counter bore for your spring length. Then you can make the OD loose enough to fall out, and it could all be delrin.

I can't remember if there are steps in that bore. I whacked my front end off pretty quick. It would be a pain to have to put the insert in from the valve side.
__________________
My Feedback
Spider! is offline   Reply With Quote
Old 02-28-2013, 12:23 PM   #6 (permalink)
The Man With No Plan
 
super_stanchy's Avatar
 
Join Date: Nov 2008
Location: Oregon City, OR

CCM Fan
PBN Fan
make it rotatable

instead of the input hole, put a groove, and drill 4 holes (2 cross holes)
orings on each side of it if your worried about air moving it around

adds a little more into machining....
but saves ALL the headache
super_stanchy is offline   Reply With Quote
Old 02-28-2013, 10:07 PM   #7 (permalink)
Old, but not slow.
 
reepneep's Avatar
 
Join Date: Oct 2011

Quote:
Originally Posted by Bartman View Post
so you need s round part that excepts a stock size cocker vale? that shouldn't take much material at just some time.

Bart
Nah, a stock valve spring. Normal Trilly valve springs are like 3 1/2 inches long and run from the cup seal to the base of the LPR. I've had a devil of a time trying to get one light enough to keep it from farting. With these dimensions there will be exactly 1" between the cup seal and the end of the insert. Standard valve springs are 1 1/4" long so I can use them instead. Should make tuning much easier.

Quote:
Originally Posted by Spider! View Post
If you are just looking for de-volumizing, consider an insert that looks more like a banjo bolt with a gas passage ring and four ports. You could make it the right length end to end so that it can't move, with a counter bore for your spring length. Then you can make the OD loose enough to fall out, and it could all be delrin.

I can't remember if there are steps in that bore. I whacked my front end off pretty quick. It would be a pain to have to put the insert in from the valve side.
There are steps in the bore. You've got about an inch from the seal side of the valve before it drops from 11/16" to 7/16". It stays like that for another 2 5/16" where it passes the VA, then flares out again for the socket the LPR screws into. I am guessing they narrowed it to act as kind of a spring guide, and to give more room for milling the 4-way into the VA. If they left it at 11/16, it would have been awfully thin, if it didn't go all the way through.

Quote:
Originally Posted by super_stanchy View Post
make it rotatable

instead of the input hole, put a groove, and drill 4 holes (2 cross holes)
orings on each side of it if your worried about air moving it around

adds a little more into machining....
but saves ALL the headache
So, two votes for a banjo bolt. How deep should the groove be? Or a better question: whats the minimum practical thickness for delrin, in your experience? And how much should be shaved off of it's OD to make it slide freely without leaving enough space to wobble?

Another question is the tip design. Maybe something like this?

It would slip right into place and keep the spring from walking.

Something else is the volume. How much would actually be enough? The old rule of thumb goes 10 shots/cubic inch @3000 psi. That corresponds to 1 shot/cubic inch @ 300 psi. I'm sure its more complicated than that, but how much of a buffer is strictly necessary? Since recharge isn't a factor I could use some really narrow air passages.
reepneep is offline   Reply With Quote
Old 03-02-2013, 12:21 PM   #8 (permalink)
Active Member
 
newmaticarsenal's Avatar
 
Join Date: Oct 2008

I would recommend making it a banjo bolt with an O-ring channel above and below the slot with the 4 holes. Add a 3rd o-ring channel at the tip. Channel should be 70-75% of the cross section of the O-ring. The hole through the center should also be reduced to 5/32 - 3/16. Your tip redesign is good. Volume can be balanced with pressure. It is simpler to make the passages small and open them up till you find the sweet spot you want. If you're still looking for a machinist PM me.
newmaticarsenal is offline   Reply With Quote
Old 03-02-2013, 12:33 PM   #9 (permalink)
The Man With No Plan
 
super_stanchy's Avatar
 
Join Date: Nov 2008
Location: Oregon City, OR

CCM Fan
PBN Fan
I'm driving right now...

Google wwa mini pump kit airflow mod
(think its a nation thread)
Same idea as that
super_stanchy is offline   Reply With Quote
Old 03-04-2013, 10:53 PM   #10 (permalink)
Old, but not slow.
 
reepneep's Avatar
 
Join Date: Oct 2011

WWA mini pump kit mod
Is this the thread? I'm not sure what the takeaway from it is. Guns with really small valve chambers (like a mini-cocker with what amounts to a devolumizer) need good flow to the regulator? Or that a single 5/32" passage is enough? Too many variables, imo. Still, that's some clean mod work.

newmaticarsenal:
I'll send you a pm. Gonna be super busy these next two weeks though, it'll be a little bit.
reepneep is offline   Reply With Quote
Reply

  mcarterbrown.com » Custom » Custom Projects / Custom Questions

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump


All times are GMT -4. The time now is 01:04 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO
© MCB Network LLC