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Slim 01-04-2013 11:49 PM

Fixing the design flaw of the AGD Micro CA II
 
10 Attachment(s)
AGD has always been known for producing quality products, so it came as a surprise to me when I discovered what I now consider to be an inherent design flaw of their old Micro CA II.

Attachment 36856
Attachment 36857

When AGD created the Micro CA II they designed the body to incorporate a loading/ejection port for the 12 gram, and two ports on the opposite side of the loading/ejection port to assist in ejecting the 12 gram. Unfortunately, the back edge of the rear port is positioned too close to the lever opening. The tiny section of aluminum that separates the two holes is about 1/32 of an inch at the thinnest point. Example...

Attachment 36864

The problem is that this thin section will eventually crack from the stress from ejecting a CO2 with the lever. Once this section cracks it will weaken the rest of the aluminum body and, over time, the entire body will crack in half. This may or may not happen under pressure, but if it does, then there is a potential for serious injury.

Examples...

Attachment 36858
Attachment 36859
Attachment 36865
Attachment 36860
Attachment 36861

After spending quite a bit of time examining different Micro CA IIs (and I've seen/own quite a few), I'm wondering if it would be worth it to have new bodies machined in order to prevent the inevitable problems with the old bodies. Basically I'd like to know how much it would cost to do a small run of 10 or 12 bodies to the specs below (note that these measurements aren't exact, but as close as I can get without a micrometer)...

Attachment 36863

At first I was hoping to redesign the body without the 2 ports on the back side, and just widen the load/eject port just like the ACI Power Stock. Unfortunately, due to design of the lever, the back port is needed to help the 12 gram eject. Example...

Attachment 36862

Basically, all I did was decrease the size of the rear port and narrowed the hole where the lever fits into. This should hopefully add enough metal between the two holes to prevent any stress fractures. I also added 1" to the overall length of the body. The original body is 9". Most of the paintball gun stocks out there seem like they were designed for small children, and have a very short overall length. Being a large adult with really long arms, I figured adding an inch couldn't hurt.

I'm not an engineer or a metallurgist so I'm hoping for some expert advise here.

Any machinists out there want to chime in, and give me a ball park idea of what something like this would cost?

Thanks in advance,
Slim

ta2maki 01-05-2013 06:40 AM

Does the rear port have to be a square hole? Looks like a round hole would work and would add more meat to the weak point.

Slim 01-05-2013 08:06 AM

Quote:

Originally Posted by ta2maki (Post 2582767)
Does the rear port have to be a square hole? Looks like a round hole would work and would add more meat to the weak point.

I'm not sure if a round or slightly "pill shaped" hole would allow enough room for the 12 gram to tip back and fall out as it does with the square hole. I'm assuming we'd need to make a prototype for testing. If a round hole works, then that would simplify the process.

Spider! 01-05-2013 10:56 AM

You could try xmt and see what he would charge. It would be neat to see a CNC cut micro ca ii with custom ano. The material shouldn't be too much. Fix that old butt plate while you are at it.

Slim 01-05-2013 11:06 AM

Quote:

Originally Posted by Spider! (Post 2582843)
You could try xmt and see what he would charge. It would be neat to see a CNC cut micro ca ii with custom ano. The material shouldn't be too much. Fix that old butt plate while you are at it.

Yeah, I plan on having a few match-ano'd to use on some of my Phantoms. I can't imagine the material would be expensive at all - I'm guessing a 1" aluminum pipe with a .75" I.D. would be standard material. While I would also match-ano the butt plate, I wouldn't go to the effort of redesigning it. If it ain't broke...

Spider! 01-05-2013 06:34 PM

Quote:

Originally Posted by Slim (Post 2582846)
While I would also match-ano the butt plate, I wouldn't go to the effort of redesigning it. If it ain't broke...

I just see a lot of them bent back is all. With that modular mount, I've often wondered what other things you could mount in there. :rolleyes:

Slim 01-30-2013 11:06 PM

1 Attachment(s)
For Ty...

Attachment 37330

tymcneer 01-31-2013 12:48 AM

The round hole and the same size as the original 12 gram seemed to work well. It does worry me if we make the 12 gram hole longer, as it may allow the cartridge to slip out of the changer after it has been pierced. The hole was made round to try and leave a bit more material in that high stress area.

Call me anytime after 1pm EST. We can figure out the next iteration of the prototypes.

Ty

Slim 02-02-2013 03:48 PM

1 Attachment(s)
For Ty...

OK, I'm feeling pretty confident that this design should work.

4 things...

1) Overall length needs to be 10" - by adding 1" to the back (stock) end

2) Move back-rear access port forward (toward valve) 1/16th of an inch. Keep the size of the access port exactly the same as the original AGD cut.

3) Decrease length of lever port 1/16th of an inch (towards stock)

4) Decrease width of lever port to .4375" wide

Here is my diagram showing the measurements of the original AGD Micro CA II, and then the proposed redesign of the rear access port and lever slot...

Attachment 37381

I'll call to discuss.
Thanks,
Slim

tymcneer 02-03-2013 02:00 AM

I will acquire the new blanks on monday. Unfortunately, to save a few bucks, I had a bunch of 9.5" blanks cut. :(

Ty


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