I've never had to work on pneumatics gear before, but a current project involves quite a bit of it. And just about every other type of plumbing, sigh.
Anyway, I'm trying to find a cheap (China) source of 6/4 mm nylon & copper tubing compression fit brass olives and the reinforcing 'spigot' (edit: corrected from 'double g' spelling error) tubes. Mysteriously, these things seem to be entirely missing on Aliexpress and ebay. Surely I'm just using the wrong search terms or something?
The term 'spigot' for those little brass tubes seems weird. But that's what the guys at my local Pirtek shop (pipe fittings) insist they are called. Which makes about as much sense as the term 1/4" BSP-T for a common brass fitting thread, which is most definitely not 1/4" dia.
Also the "-T" means tapered thread, and there is BSP-P (parallel) which looks almost the same but is not really compatible.
Pic 1 shows stepped "olives" for compression fit tubing joints. I can find those on ebay (but not Aliexpress.)
Also the little brass tubes, for when you want the joint to absolutely never leak. They are a tight fit inside the nylon tube, and prevent it from collapsing. People commonly omit them in joints, because the 6mm OD, 4mm ID black nylon 'air brake tubing' is pretty tough and generally doesn't need them. But if you want to be ABSOLUTELY sure...
Those I cannot find at all on Aliexpress or ebay. And that's my question - are there *really* none, or am I just failing to search right? There are some smaller ones, that are used in modern bicycle hydraulic brakes. But no general 6/4mm pneumatics ones.
Pic 2 is the two general types of connection. The top one (orange) is a 'push-fit'. They are neat, and can be released as easily as connected. Some steel barbs lock onto the plastic tube, and pressing the rear ring in makes the barbs release. Theoretically very convenient but sometimes they won't release, and then it's a world of pain.
No problem with getting any number of the push-fit ones on Aliexpress.
Oh, and Pic 3 shows two of the several different styles of olives.