As a result of Hein's note, I have just purchased 10 of these bearings (Not cheap at £4 each with a minimum order of 10.)
- But they are very simple to fit. (I tried just a 5.0 mm drilled hole but this may be little oversize - they are designed as a press fit.)
- They are self lubricating. (The lubricant is combined into the plastic material.)
- They seem to be good for linear bearings also. (A lot of web references to their use in 3D printers.)
I am planning to retro-fit some on my subs to see how well they work.
I still have to get rid of this note: In my models (except for SUSHI) all ball bearings on the propeller shafts have been replaced by IGUS plain bearings. If they are installed according to the manufacturer's specifications, they are even watertight, but not necessarily pressure-tight. There are lip rings for 4 mm shafts: 4 x 8 x 2 mm.
Please note the lower half of the company website: sleeve bearing, sleeve bearing with flange in mm and inches, thrust washer and more.