Jun 28, 2020     polymer       Category: Controls

June side note: ordered plastic for the Rudder Bushings. A few varieties of plastic is available. According to the plans “Teflon” is called for. In 1969 Teflon was probably a more available and less expensive product. Now more plastics are available. Some builders use Delrin (an Acetyl Homopolymer) some sites use the terms Acetyl Copolymer and Acetyl Homopolymer as interchangeable. The other plastic that is used in industrial settings for bearings is UHMW. I examined the characteristics of a few of these options and fortunately had a structural engineer working for me part time in my office (the New York Naval Militia). He compared the plastics and recommended the UHMW. Delrin was available in 3 inch diameter rods. This would make turning the bearing very easy but one side effect to Delrin is an increased porosity at larger sizes. Some forums identified mold showing signs of growing on the Delrin. I decided to order a �nch thick piece of UHMW 4” x 48”. These I will try to cut into 4” square pieces and turn on the lathe to 2 �nch stepped rounds for bearings.