Emek/Gamma Core Pump - Proof of Concept

[nak81783]

***I guess I should have reserved more initial posts. Please review the first four posts from time to time for new information. I'll probably rearrange the information and structure it better as time permits. For now, I just want to get the info out there, so people can start building stuff, if they so choose.***

This is the Gamma Core pump concept I've been working on. Thanks to cstx_pb for donating parts. As time permits, I will continue with my design/prototype, describe issues yet to be addressed, share the CAD files, further explain how it works, answer questions, etc., but I'm hoping the talented folks on MCB can use this to make some really cool stuff.

The key is in the color-coded barbs on the transfer block and "pump valve" housing.

Video: https://drive.google.com/file/d/1blp...ew?usp=sharing

The trigger and safety are removed in the video to allow the hoses to run out the sides of the marker through the safety holes. I'm just pushing on the 3-way pin to fire the marker.

[nak81783]

References:

Link to original idea - bullet point 4 in post #7. I didn't realize it was almost a year ago. - https://www.mcarterbrown.com/forum/p...477#post531477


Link to previous concept thread - https://www.mcarterbrown.com/forum/p...ain#post647353

The two images in the first post of the above linked thread are essentially what the "pump valve" accomplishes - isolating the forward and aft channels of the transfer block. I just also added a pressure imbalance with different oring sizes to act as the pump return "spring".

The Excel chart, I believe, still lays out the firing sequence correctly.


Another reference thread on pump stroke - https://www.mcarterbrown.com/forum/p...ngth-and-force

[nak81783]

Issues:

1. The pump stroke can be short-stroked, resulting in a partial charge/low fps shot. The good news is, if you think you short-stroked, you can pump it again to finish charging the Gamma Core. More good news, since it's open bolt, pumping again won't double feed.

2. Routing the air to the "pump valve" at (what will eventually be) the front of the marker is causing a velocity issue. Either the added volume throws off how the Gamma Core is designed to function, or that air is needed for the shot and can't get through the hoses fast enough to contribute to the velocity. Using the nylon riot balls I typically use in velocity testing, I was getting 272 fps quite consistently (if I didn't short-stroke the pump per #1) with the regulator maxed out.

3. I was concerned the hoses would blow off the barbs, and I would have to put hose clamps on. This didn't happen with the reg maxed out; we'll see if this holds true as the hoses expand/lose flexibility from extended use. Barbs wouldn't be too bad on the "pump valve", but it'd be tight on the transfer block.

4. This currently only works with the original 3-way trigger valve with the taller transfer block, and there's no hole for the retention pin in the barbed transfer block. However, the pressure from the gaskets when the marker is assembled seems to keep the barbed transfer block sturdily in place, and, for comparison, I don't think the Deadly Wind hAir valve requires the retention pin. The FL 3-way transfer block doesn't have enough vertical real estate for 4 barbs. You might be able to offset them on the front face of the FL 3-way transfer block, but that complicates machining even further.

5. Internal routing of the hoses is going to be more difficult than expected, especially without the retention pin for the transfer block (per #4). If I get the hoses where I want them, it tends to pull the transfer block out of position, preventing marker assembly.

[nak81783]

Notes:

1. The gasket pockets, I believe, are .015" shallow on depth and .010" offset inboard along the perimeter. This was to accomplish two things. First, the extra compression on the gaskets helps hold the transfer block (that doesn't have a retention pin) in place. Second, because the spacing of the barbs causing some hole break through into the gasket pockets, as shown in the picture in post #1, the extra compression ensures a seal around the break through and the walls of the pockets. Basically, I didn't know where this could leak, since there's extra opportunity for a leak, so I compressed the gaskets more. It's a bit of a pain to install the gaskets in the transfer block. Best method was to start at one end, and run your fingernail around the perimeter while pushing the gasket in. This method slowly seated the gaskets.

[iamthelazerviking]

Video worked for me. Interested to see how this develops!

[automeister]

interesting project

[Jordan]

Man, that's cool.

Is it going to be open bolt, then?

[cstx_pb]

Nice progress!

[nak81783]

Man, that's cool.

Is it going to be open bolt, then?

Yes. It just isolates the charging and venting of the trigger 3-way, such that it requires “pumping” between each shot.

[Jordan]

Yes. It just isolates the charging and venting of the trigger 3-way, such that it requires “pumping” between each shot.

Very cool.

I'm firmly in the "open bolt pump" camp, with how terrible paint can be at times. I'll be following this thread for sure.

[Chuck E Ducky]

Hell yeah that’s Cool!

[nak81783]

Very cool.

I'm firmly in the "open bolt pump" camp, with how terrible paint can be at times. I'll be following this thread for sure.

Exactly. Terrible paint is what spurred my open bolt Azodin NAKDIII and this project.

[nak81783]

I added some info to posts #2 and #3.

[cheapguitarscheapthrills]

That's awesome, I'm sure some 3D print guys could take this to the finish line. Or maybe mix some brass in there Jordan

[Jonnydread]

You have my attention and turgidity