[ChuckDickerson]

Jim,

Thank you for posting the white paper on the Killer Bees 2004 4 speed automatic transmission! The paper is excellent! I have read, re-read, and studied the paper and all of the CAD drawings until I think I just about have all of the dimensions memorized! I am amazed at the elegant simplicity of the transmission. It is truly a work of art! Our team has never built any type of multispeed transmission before but I think we might give it a try this year. We have been gathering the various parts and materials in the BOM in your white paper and are working on building a prototype to play with and see if we think it will be something we can tackle for the robot this year. Hopes are high! Needless to say, we are eagerly awaiting the companion software paper on the automatic shifting code. In the mean time I have 4 specific questions that I hope you or someone here on CD can answer.

1) The BOM in the paper calls for qty 4 3/8" wave washers. I have studied all of the drawings and can't seem to figure out where they go. What am I missing?

2) The BOM also calls for qty 16 5/16" aluminum washers which are used on the shift shafts. Is there a reason these should be aluminum (other than to save a tiny amount of weight) or could we just use standard steel or stainless steel washers? I ask because I assume there must be a reason you specify aluminum but I just don't understand at this time and that would be one less special item we have to order. Maybe it will become clear when we get the prototype/test gearbox built.

3) I am sure that this will be covered in the companion software paper but I am wondering about the Grayhill 61K64 64 pulse per revolution encoders. The 61K64 encoders have output pins designed for a PC board, which seems rather inconvenient to use on a robot unless the interface to the controller requires additional circuitry not covered in this paper. Digikey also sells a 61K128-050 encoder which appears dimensionally equivalent in all of the critical dimensions but is 128 pulses per revolution and has a cable output which seems like it might be easier to wire up than PC board pins. Is there any reason a 128 PPR encoder wouldn't work just as good or better than a 64 PPR encoder? Since these are about $50 each I haven't ordered any yet until I am sure the 61K128-050 will work.

4) In the paper you mention that you had some of the gear/shaft assemblies hardened after welding. Could you provide more specifics on the hardening process you used? Our machine shop says they can heat treat "up to 2000 degrees" but need to know what "process" you used. This is not my area I am just trying to pass along the question from the machine shop guys. Is this a special process that must be sent out to a special heat treater or is it something we can do ourselves? If it must be sent out where do we send it and about how much does it cost?

Again, thank you very much for posting the white paper on the transmission. I think there are many teams drooling over it!

Thanks,
Chuck