Automag PPK (Printed Pump Kit)
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So after trying to purchase a pump kit for a mag for the last year with no success I decided to create an economical one out of 3d printed parts and widely available hardware. The end result is a kit that ended up costing about $100 to prototype and could possibly be under $50/kit if made in mass. All hardware was purchased through McMaster-Carr and a decent chunk of the cost is due to separate shipping charges and certain parts being only available in excessive quantities.
The design is mostly based off the original AGD kits that used a round guide rod replicated with 3/8" diameter aluminum rod, a shoulder screw and a standoff inserted through a 3d printed pump handle with internal return spring and attached to the marker using a 3d printed mounting block with heat-set threaded inserts. Everything is threaded for 1/4-20" threads so it works with existing Automag AM/MM vertical foregrip screws (though you need a longer one to use a foregrip under the mounting block). My pump rod is made out of a wire clothes hanger which was easy to form but also easy to disform if mishandled. I found the proper tool steel rod on McMaster but did not have the tools to properly form and harden a pump rod to AGD specs. I did use a fancy high tolerance stainless screw for the front shoulder screw but later found a much cheaper option that should work just as well.
All prototyping was done using a pump milled minimag body, an AM/MM Teth rail with pump milling, AGD single trigger carbon frame (though it also fits with Intelliframe and the block could be sanded to fit other frames if necessary).
Issues:
1. Future designs may would have a guide rod that doesn't allow pump handle to twist. There is twist that is not really noticeable while shooting but is obvious when you are just handling the marker. The plan would be to either use the AGD Gen 2 design that will require 3d printing a third part to form an oval guide arm or find a standoff that has full length hex sides and print a hex path in the handle that will prevent it twisting/spinning.
2. Find a way to make pump rods to AGD specs. Turns out cut up wire hangers are prone to bending. Also turns out W1 tool steel is harder to hand form then expected. Harder pump rod also may solve issue of pump handle twisting on guide rod. I also had to drill into the handle where the pump arm turns in since 3d printing the hole into the handle was too messy.
3. Heat set inserts are a a little tricky. You have to make sure they melt in level and flush while also not melting the plastic so much that the mounting block starts to warp around insert. I had to sand down the block a bit to get it flush to the rail due to a little warp. You also normally need a soldering iron to set the inserts, but I just used the nozzle on my 3d printer to heat and set them.
Thanks to alpha_q_up23's for taking measurements off an AGD kit for me to help with design.
Below are all the parts and files necessary to create the kit. I don't plan on producing the kits at this time, but anyone else is free to. It does make the most sense for someone to purchase the hardware from McMaster is bulk and then ship it out to others to greatly reduce shipping costs and break up the packages that come in high quantities. As far as the 3d printing goes I used an Artillery Genius with Cura to slice the 3d models with pretty default settings and printed with Sunlu PLA filament. I did up the infill to 50% and used a wall count of 5 for the mounting block so that the heat-set inserts had plenty of material to melt into without deforming. The pump handle also has a sacrificial support layer that needs to be drilled through the guide rod path with a 3/8" bit after printing.
Let me know if you have any questions on creating your own kit and i'll help to the best of my abilities.
Google Sheets McMaster-Carr parts list with price breakdown
Fusion 360 design files
Pump Handle 3d model
Mounting block 3d model
https://youtu.be/unZomgzz-eQ
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