Dust Caps for "L" (Lincoln) Style Air Couplings (SCAD)

Are your air tool fittings longer than your friend's? Do you feel left out when you go to shop for couplings and accessories? It's not your fault. I'm here to help. No, not like that.

I keep some tools in the outer shop area, but the insects and spiders love to fill the fittings with mud and detritus. This'll fix their wagon. I printed these in crappy stiff 98A TPU, and they work fine. I've printed some in 90A TPU, and those are much nicer, especially in sub-freezing temperatures. I don't like having the dangly thing in the way all the time, but I like it better than I like having to disassemble tools to clean out mud and larvae.

I don't have a version for the female couplers. For some reason, the critters never vandalize those. Now that I think about it, I really don't know why. They get into the female pressure washer couplers, but not the air couplers. Even old derelict hose scraps hanging on the wall for 30 years have mud in the hose, but no mud in the female couplings. Maybe it's because the aspect ratio of the hole isn't right -- too shallow for its diameter?

Actually, that seems like very strong possibility. Parker ST (literally "straight through") pressure washer couplings are unvalved straight-bore fittings. A decoupled female ST coupler offers a deep bore for its diameter. The same is true for open hose ends, male coupling plugs, and non-push-type female air couplers. Type L couplings are categorically push-type. They have an extension on the poppet which occludes the locking bars, meaning a properly decoupled female coupling has a shallow (roughly 1:1) bore. If true, this hypothesis suggests another reason for the superiority of the type L coupling format and a renewed cause for gloating. Check back in another 40 years for a pretentiously verbose update.