Coleman Leather pump cup die

thingiverse

Updated: I noticed a problem with durability causing cracking when tightening (due to the high pressure) so I've updated the design. Best printed with PETG at 100% infill. The larger version (stl and 3mf included) are specifically sized for the newer style pumps that use the clip on nylon base. They will work with the screw on style metal base. Usage of the mold/die remains exactly the same however. This is a simple mold and die to make leather pump cups for your Coleman lantern or stove. I used 14-20 hardware as it was what I had on hand and SAE is really cheap. It uses one 1 1/2" 14-20 bolt (fully threaded), one 14-20 nut and two 5/8" washers (1/4" hole). The washers work best if heat-set into place. I put the washer onto the bolt and put the bolt into the mold or die (depending on which one I was doing). I heated the washer up with a small torch. Not super hot but enough to soften the plastic. Then using the bolt, press the washer into the inset around the hole. They should fit right into place. Tighten the nut down just enough to make sure the washer is fully seated and flat. Let it cool and then repeat with the one for the top of the die. The washers are important to prevent the nut and bolt from chewing up the mold and die as you need to really tighten them when you're pressing the leather. The bolt will either need to be heat set into the die or screwed in. It's a tight fit on purpose. If you screw it in be VERY careful that you do not crush the die or deform it. I prefer to heat-set it at the same time as the washer. I don't think I need to warn you to be careful when you're heat setting the washers and bolt. They do need to get hot...like 200°C hot. Don't burn yourself doing this. You'll need 1mm thick tooling leather. I have scraps and most are around 35mm wide so I just cut them into squares. Soak in water for a few hours to make them pliable. Punch a 7 or 8mm hole in the centre. The smooth side of the leather goes against the mold (the larger puck) and then the die (the smaller disk) goes on top of the leather. It forms kind of a sandwich. The head of the bolt will on the die side, it goes through the leather and then comes out the bottom of the mold. The nut goes on the bottom of the mold. Slowly tighten and this will pull the leather into the mold. Tighten until it stops. You'll have to really crank down on it but you'll know when you're all the way there as it will stop all movement. Let it sit 10-12 hours to dry and set the shape. Overnight is good. The next day use a very sharp knife (xacto is good) to trim the leather flush with the top of the mold. Be VERY careful as it is easy to slip and cut yourself. Ask me how I know. Once it is trimmed unscrew the nut almost all the way but not completely. Leave it on the bolt to protect the threads as you'll need to tap against the nut (possibly quite hard) to pop the die and cup out of the mold. Let it sit out for another hour to dry fully and put it back in and tighten it back up. Leave it for a few more hours to finish setting the shape. Unscrew the nut again as before and tap the die loose. Now remove the nut completely and take the die fully out of the mold. The leather might be stuck to the die but that's fine. Gently peel the edges back and it should eventually come off the die. You should now have a perfectly formed leather pump cup ready to install into your Coleman lantern or stove pump assembly. I prefer to soak them in neetsfoot oil overnight before installing. They should last for decades if you don't allow them to dry out. I added a second mold and die. The first one is best suited for the older/vintage pumps with the screw on style base. The V2 version is suited for the nylon press on base (basically the current style). The nylon base is larger in diameter than the older metal base and needs a slightly wider cup. V2 still uses 1mm leather.