My never ending quest to find a lasting articulated arm design has finally ended. I regularly use the PCB Workstation with Articulated Arms to hold my PCB projects. Unfortunately, all of the arms I have made with printed ball and socket joints quickly loosen to the point where they can hardly hold their own weight. I have tried several ball and socket designs and many filament types and I can't get any arms to last. That is until I found out about flexible coolant pipe.

Flexible coolant pipe is used in the metal fabrication industry to spray coolant over a work piece while machining. The pipes must be liquid tight so the fit between the ball and socket is very snug. They also are made from a durable plastic without the striations that cause 3D-printed joints to wear so fast. The pipes can be bought from Ebay and other places for cheap. I got my pipes for less than $1 USD each including shipping. It is best to get the type without the valve at the bottom since it is of no use. Here is an Ebay search link:

Search Ebay for flexible coolant pipes

The flexible coolant pipes I bought have 1/2"-20 threads at one end and a nozzle at the other end. The joints are very snug but you can remove pieces with pliers. I designed four adapters to fit the pipes to the PCB workstation:

• Base Joint Adapter - This adapter is for mounting the pipe on the base plate and requires removal of the threaded piece on the pipe. The ball snaps into the bottom socket on the pipe.

• Base Socket Adapter - This adapter is also for mounting the pipe on the base plate but it uses the existing threads on the pipe. This provides a stiffer and longer lasting joint. The inside of the socket is threaded 1/2"-20 so the pipe simply screws in. You may have to chase the threads with a bolt or tap depending on the material and your printer.

• Ball & Socket Adapater - This adapter snaps onto the end of the pipe after the nozzle is removed. It adapts the larger ball on the pipes to the smaller ball used by the PCB workstation accessories.

• Ball Insert Adapter - This adapter slides into the end of the pipe and has a ball sized for the PCB workstation accessories. This adapter provides a more durable connection to the accessories than using the ball & socket adapter. The shaft should be a tight fit into the pipe. You can use a drop of super glue to hold it in place if it starts working out.

All four adapters are done in OpenSCAD so you can customize them to fit whatever pipes you get. I proofed these using PLA and printed the final versions with PETG for extra durability.