Posted by nuts4first.
Engineer on team #340, GRR - Greater Rochester Robotics, from Churchville-Chili and Nortel Networks.
Posted on 3/22/2000 10:13 PM MST
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F L A S H B U L L E T I N
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If you have taken Dr. Joe’s advice by producting a replacement drill gearbox output shaft as described in ‘Dr. Joes Drill Advice’ step # 5 and as seen in the drawing ‘Dr. Joes Drill Shaft’ (in the lower right hand corner) be warned!
The drawing is missing a critical cut at the aft end of the shaft, in the middle of the 4 pins. If you are using this technique in your robot’s drive system be cautious. A ~
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 3/28/2000 5:00 AM MST
In Reply to: WARNING…Dr. Joe’s advice on the drill shaft is incomplete! posted by nuts4first on 3/22/2000 10:13 PM MST:
Chris,
Congrats on your team’s great run in NJ.
As to the motor mods, all I can say is that I have not had any problem with the parts as they are. In fact, we have 2 of them on CD V. They seem to work for us.
I have a several thoughts as to why you have a problem and we do not.
#1 there could be multiple designs out there – maybe Bosch made a running change to their transmissions and the ones that we got in out kit are different (slightly) than the ones you got in yours.
#2 I have taken out the ring that sits below the last stage of the transmission. With the no-back clutch removed, this ring is only adding weight to the transmission. Perhaps taking this ring out allows for enough room to allow the parts to work even without the indentation that should be there.
Anyway, thanks for the input. I will have to do some more digging to see what changes need to be made to the shaft print.
Meanwhile, Chris, you say that you use O-rings as spacers to lock the transmissions in High or Low. Will you publish the part number from Small Parts Inc.?
Thanks again for the help.
Joe J.
Posted by Daniel.
Coach on team #483, BORG, from Berkeley High School and NASA Ames & UC Berkeley.
Posted on 3/29/2000 1:37 PM MST
In Reply to: Works for me… posted by Joe Johnson on 3/28/2000 5:00 AM MST:
To lock the gear transmissions into high gear you simply have to turn around one of the pieces inside the frontal gearbox section. I don’t have it right in front of me but I can post my ‘discovory’ later. As for low gear, a spacer is needed.
Also, this may not be easier but for teams with fewer resources, the drill output shaft can be extended instead of replaced. Lathe down the threads on the end of the output shaft (but be carefull not to make the walls too thin), drill a hole the size of the modified output shaft in a piece of round aluminum bar stock, put those suckers together with some silver solder and lathe down the result to whatever size you need your shaft to be. This way you have a minimal amount of advanced machine work, in case not everybody has the resources of say chiefdelphi and the other monster teams 
-Daniel
Posted by Dodd Stacy.
Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.
Posted on 3/29/2000 5:19 PM MST
In Reply to: so easy it seems like cheating =) posted by Daniel on 3/29/2000 1:37 PM MST:
: Also, this may not be easier but for teams with fewer resources, the drill output shaft can be extended instead of replaced. Lathe down the threads on the end of the output shaft (but be carefull not to make the walls too thin), drill a hole the size of the modified output shaft in a piece of round aluminum bar stock, put those suckers together with some silver solder and lathe down the result to whatever size you need your shaft to be. This way you have a minimal amount of advanced machine work, in case not everybody has the resources of say chiefdelphi and the other monster teams
:
: -Daniel
Daniel,
I admire and commend your efforts in starting up a team, and I hope BORG covers themselves with glory in Orlando. But I really think you’re tempting fate with your drill gearbox shaft extension technique. I sincerely hope I’m wrong, but I’ve gotten that detail wrong 3 years running and had failures, before finally taking Joe’s advice and just machining one piece extended shafts (without the anti-backup cam/pins) this year.
The resource it takes is a few hours of a good machinist with a lathe and a mill. It’s a nasty place to have a failure and try to recover during eliminations. If you guys retained the drill gearbox’s adjustable output torque limiters, I’d urge you to set them as loose as possible without compromising your acceleration. Good luck and kick bot.
Dodd
Posted by Daniel.
Coach on team #483, BORG, from Berkeley High School and NASA Ames & UC Berkeley.
Posted on 3/29/2000 9:57 PM MST
In Reply to: Cheating Fate posted by Dodd Stacy on 3/29/2000 5:19 PM MST:
=)
I love how everyone here is so careful to say something chocolate-coated along with every critisism they make. You guys are so NICE!
Anyways, as for your comments, I hope you’re wrong too if you don’t mind me saying =). So far it seems to be working flawlessly but we get to do the real test in 11 hours or so when we unpack the bot and start playin’ around. There’s a good amount of contact area and the connection seems pretty solid. there are no stresses along the axis of the part and the stresses in the other direction are pretty well taken care of by the pin insertion technique we used. The twisting is the one direction where we would worry but we did drill the hole to interference fit so it’s pretty solid even without the silver solder (of which there’s a good 3/32’’ band between the two pieces).
Everything in my my gut and my minimal experience tells me this is gonna work fine. I just hope you’re not as clarvoient as my gut.
We’ll see…
Good luck everyone!!
-Daniel
Posted by Bill Beatty.
Other on team #71, Team Hammond, from Team Hammond.
Posted on 3/30/2000 8:46 AM MST
In Reply to: so easy it seems like cheating =) posted by Daniel on 3/29/2000 1:37 PM MST:
We have used the inverted shifter ring to lock it into high for 5 years. It does not need any machining or parts and it seems to improve the mesh of the last stage gearing.
Bill B