Resulting RFT

Waterpipe GEM

The fork mount appeared to be somewhat complex to build, so as an experiment I bought some regular plumbing stuff in a building market. The various brass parts meant for connecting pipes appear to be machined fairly accurately. The 22mm pipe connector and T parts can be used to receive a 22mm outer diameter to 15mm inner diameter converter plug, which fits snugly and can function as a slide bearing.

Proto RFT Waterpipe GEM

Both the declination and hour axis are based on a 15mm copper waterpipe (red). The housing of the hour axis is made from 22mm copper pipe (red). All the complex parts are brass (yellow, grey), it is amazing what tolerances can be reached with mass production of such parts.
The declination axis business end is terminated with a 15mm brass endcap, with a 3/8" threading, normally used to connect to a tap. I chose the threaded endcap to facilitate screw mounting the scope cradle. The pipe rotates in a housing made from a 15mm to 22mm T-piece. The bearings (grey) are cut from a converter piece normally used to mount 15mm pipes in 22mm connectors. The connector has to be cut in half to allow the 15mm pipe to pass through entirely. Finally, the construction is terminated with a half 15mm straight pipe connector, which can be fixed with a set-screw (preferred) or just soldered on.
The hour axis is soldered in the 15mm end of the T-piece. Care must be taken to make this connection as square as possible!
For the rest the bearings are identical to the declination axis. However, in order to withstand higher torque the housing length is extended with a 22mm pipe connecting the two 22mm straight pipe connectors.

PipeGEM drawing

The real thing

After using an old Vixen mount, I decided to go for simple yet luxurious: a low profile simplistic GEM to be operated from a chair.

Simple mount

The Pipe GEM mountin can be seen, as well as the original pier. However, the pier is now suspended under an angle equal to the local latitude (in my case approximately 52°). I made an A-shaped support, which is fixed on the top and with an additional spacer beam. Extremely simple, fairly stable, with the eyepiece precisely at the right height.

Simple mount  Simple mount  Simple mount

The pier has an adjustable foot, so small changes in polar alignment can be made. For the RFT use, just scanning the sky, this is probably overdone though...

Simple mount