Deaver Mounting Method for AM Plaction Wheel Treads
Also Follow up on more wear resistant treads.
For the 2010 season the 4 wheel steering pivot drive used 4" AndyMark Plaction wheels. Our design of the pivots originally allowed for the removal and replacement of the wheel treads without disassemble of the pivot. The original treads that came with the wheels used staples to join the ends. We continued with this method. This meant that the side plates of the pivot had to be removed to change the treads. This is a very time consuming process. Also, there is the chance to incorrectly assemble the pivot. This happened before PARC and resulted in a failed bearing. To remedy this problem we came up with using 6-32 threaded brass inserts and Pan head screws to hold the treads on. The McMaster part number for the insert is 99362A300 and the Screw part number is 91770A147. The thread inserts list a .191 hole. This is too big. A .181 to .183 hole works best. This PDF can be printed out and used as a template to drill and screw in the inserts. It can also be used to locate the holes in the tread. AndyMark Tread Template
Tread length for the 4" AndyMark Plaction wheels is 11-11/16 inches.
The following pictures show the method.
After the summer, it was accepted that the inserts and screws were an improvement and durable tread mounting method. However, the problem still remained that while the ANDYMARK conveyor belting treads had good grip and performed well, they wore down fast. They had to be change quite often. Changing treads in the heat of competition is not desirable. Some time in October after input from many team members, we came up with bonding a bike tread to the conveyor belting with the rubber ground down to the nylon backing. The bike tread was bonded to the nylon base with super glue. The tread worked well surviving allot of practice driving and ramp riot. At the Dec. open house the tread delamenated from the nylon base. Several solutions were suggested. Different glues were tried and peel tested. Super glue was still the best but, it was evident that there was not good bonding to the bike tread. It seams that there is a release agent used in the molding of the tire. Because of the high vulcanizing temperature needed to vulcanize the rubber a silicone based release agent was probably used. Silicone based release agents are very hard to remove. After testing many different solvents it was found that lacquer thinner removed the coating reasonably well with out softening or dissolving the rubber. Peel test after cleaning with lacquer thin showed an excellent bond with the rubber tearing before bond failure. As an extra precaution sewing the tread on was explored. First try was with heavy thread. It turned out to be a cotton thread and not acceptable. I then used a nylon coated Kevlar fishing line and results are acceptable. I'm also not a very good sewer. A better sewing patern needs to be developed. This should result in a very durable tread for the pivot design.