Foregrips for Picatinny Rail (Stubby)

I recently printed a few of the excellent Lynx nerf dart blasters by Orion Blasters.  These are a pump action spring-air blaster, with a 1913 style rail on the pump handle, to which the user should attach the foregrip of their choice.  I looked over the options for grips on Printables, and since I was working to deadlines (two of the blasters I made were for birthday presents), I picked out the grip that I disliked the least, and worked through the hardware issues it ended up having.  It wasn't a bad design, it just took more post-processing than I liked, and it could have been stronger.

Deadlines past, I designed my own grip with the goals of easier hardware installation, reduction of highly loaded joints, and layer orientation to maximize strength.  It became apparent that the best way to achieve these goals would require splitting the grip vertically, and joining the two halves after printing.  In this way, strength of the grip can be maximized, and need for printing supports or a separate mount assembly can be eliminated.

There are two basic sizes.  Both are the same width, and the same vertical length, and overall contours.  The smaller of the two grips has had 10mm removed from the center.  Both grip sizes will take 4 each M3 threaded inserts, 5mm OD by 4mm in length (aka “Voron” inserts).  Both are held to the rail by 2ea M3x30mm socket headed cap screws.  To hold together the bigger grip, I used two M3x12mm SHCS, while I had best results with M3x10mm for the narrower grip.  The grips with the halves held together by screws are my own preference.

Since I know that some people will not want the screw counterbores on the surface of their grip, I also prepared versions which may be glued together.  These incorporate holes for 3mm alignment pins.  I have not tested or printed these, but I offer them for use should you prefer this method of assembly over the screwed together halves.  You will still need 2 each threaded inserts for attaching them to the rail.  As with all of my 3D models, use is entirely at your own risk; the end user is wholly responsible for determining safety and fitness for purpose.

Once the two halves have been assembled, the grip is installed by sliding onto the rail, and installing the M3x30mm SHCS.  Do not overtighten these screws.  I printed my parts out of Polymaker ABS on my Voron 2.4 using a 0.4mm nozzle, 4 perimeters, and 20% infill.  Other filament types should also work fine but I would not recommend reducing the perimeters or infill below these values.  You will need to download both halves of whichever grip you choose.  Grip 1 is the full size unit, while Grip 2 is the slimmed version.  The STLs intended for glue/pin assembly are denoted by “pin” in their filenames.