Thread created automatically to discuss a document in the White Papers.
2 speed, Shift-on-the-fly TechnoKat Gearbox by Andy Baker
Just to let everyone know, I just posted the 2003 TechnoKat gearbox in the white papers section on this site and under the “Resources” section on the TechnoKats site. This is the “2 speed, shift-on-the-fly gearbox” that worked well for us this year.
It is a significant improvement over our 2002 model. Most significant are the changes made to make it easier to fabricate (no EDM needed, etc.). The document includes an extensive writeup, assembly prints, BOM, and detail prints.
Download and enjoy. I will have hard copies of this at IRI (enough for 1 for each team).
If you use or improve upon this design, please let me know.
Andy B.
Thanks Andy, been waiting for this one 
Thanks Andy!
There does not appear to be any write-up with it. I am interested to know if you have any disassembly/assembly fixtures for removing/installing the press-fit gears on the drill and CIM motors.
I hope to have my simple dual motor white paper posted by the end of the month.
Thank you so much.
Initially, I uploaded the wrong version of this paper. My buddy Ricky Q. notified me right away, and then I got the better version uploaded. Thanks Ricky and Brandon for being “on the ball”.
Andy B. - the absent minded engineer
*Originally posted by Andy Baker *
**Andy B. - the absent minded engineer **
I would definitely not say that, especially considering the quality of this work.
Great job. 
Keep up the great work.
Awesome job, Andy. Its always great to see teams releasing stuff like this to share their success. One little discrepancy that I noticed while browsing it is that the stall torque is higher in high gear than low gear. I think the numbers were just reversed. Dont mind my nitpicking 
Great job!
Cory
what kind of mill do you have?
great release Andy, i cant wait to get enough time to look over everything and see if i can duplicate this in my spare time…
~Mike
*Originally posted by dez250 *
**great release Andy, i cant wait to get enough time to look over everything and see if i can duplicate this in my spare time…
~Mike **
Mike,
There are 2 comparable shift on the fly systems sitting in Colonie HS. Check out the Shen 1997, 2000, 2001 and 2002 robots. It’s not overly difficult to add a 2-motor combiner to one of these. Believe it or not, 250 has much of this technology in the closet… literally.
Andy,
Great paper, the reliablility of your “dog shifter” design is certainly making me re-think my “pin shifter” design. We (229 drivetrain guys) are definitely going to have to sit down in the fall and decide what direction we’re heading in next. It’s amazing for me to think that because of your posts, whitepapers and work, you’ve had a similar (catalyst) effect on teams across the country. You always help raise the bar!
So what’s next for 2004? 
Thanks Again,
Your team’s openess is an inspiration to us all,
John
john i know we have things like this literally in the closet, i just wanted too have fun at my house/in the shop in my free time and just use some things i have and see if i can do it myself, or with help from some others to make it for a practice bot I’m looking to build… Yeah that prob wont happen though since i don’t have much free time…
~Mike
“Learn from the experience of others…”
*Originally posted by dez250 *
**john i know we have things like this literally in the closet, i just wanted too have fun at my house/in the shop in my free time and just use some things i have and see if i can do it myself, or with help from some others to make it for a practice bot I’m looking to build… Yeah that prob wont happen though since i don’t have much free time…
~Mike
**
It’s not just the time. It’s the money. Otherwise my team would be building one right now. We figured it would be about $250 for just gears for one gearbox. Of course that was with some slightly different ratios that we came up with.
yeah the money matters, but the time is first, and having access to what i need now, which for a change i have in my storage…
~Mike
Wow … I came up with valid ratios in about 2 days with spacing considered Casue for your 2 speed you cant have 12 driving a 24
and for your other speed say on that same shaft a 32 driving a 30
All in 2 days work… Whats taking so long??? he he
Thanks for the replies… here are some answers:
Jim - you would be suprised, I can be a space case sometimes.
Cory - thanks for the nitpicking, it is needed. I will make the change and wait for other stuff that may need updates… they I will re-post it after a while. Since it is in “public domain” it needs to be right. If you or anyone else finds errors, please let me know.
Tytus - a CNC end mill. Our high school machine shop made the parts that needed CNC’ed on a Haas machine, I believe.
John - thanks for the support. The good thing about the machine dogs is that they are permanent… you don’t have to worry about them once they are made. Sure, they take a little more time to machine as opposed to putting in dowels, but it is worth it. As for 2004… it will have more recution and reduce parts. We would’ve liked to have about 25% less rpm on the output shaft.
Mike - it would be great to see people build these in their free time. Better yet, improve upon the design and post your findings. (one of my favorite quotes: “If I have seen further, it is by standing on the shoulders of giants.” - Issac Newton). Take what we have done here and improve it… that is what Newton meant.
Sanddrag - the gears actually don’t cost that much. Keep looking around for suppliers. These gears can be purchased, off the shelf, for about $90. Two sources that I used are Martin Gear (20 pitch, purchased through Applied Industrial) and Rino Mechanical (32 pitch, purchased direct).
Joe - good for you. Designing a gearbox in two days is not easy. However, quickness in design can cause errors, just as you made errors while criticising our design. We did not use a 24 or 32 tooth gear. Also, I am not sure why you say “what took so long?” Do you have your design posted on the web? If so, please reply with a link. Also, I trust that you are a good designer, but it would be helpful if you wrote with more clarity. It’s somewhat hard to understand what you are trying to say.
Again, thanks for the comments… keep them coming.
Andy B.
Andy thanks for the words of encouragement, i was thinking about changing some of the gearing ratios around and just tinker a little to see what i can do with the output. i am wondering if i make it so the output has higher torque and less rpm’s, what it may do on the voltage input, if it may draw more or if it could cause a stall on the motor or what may happen…
~Mike
“Make Failures and LEARN By Them, DO NOT Let Your Own Failures, Get You Discouraged…”
*Originally posted by Andy Baker *
Sanddrag - the gears actually don’t cost that much. Keep looking around for suppliers. These gears can be purchased, off the shelf, for about $90. Two sources that I used are Martin Gear (20 pitch, purchased through Applied Industrial) and Rino Mechanical (32 pitch, purchased direct).
I was a little off. I actually came up to $205 for each gearbox using gears from Berg and SPI. My 20 pitch gears were in the following tooth counts 16, 40, 60,20, 80. I plan to use bigger gears than you did for some slightly different ratios. That 80T gear is like 75 bucks alone from Berg. I’ll check with your suppliers if and when my team builds this thing.
As for your note about the CNC machines, HAAS are wonderful. They are such a joy to work with and so user friendly. (I am just starting out on one).
*Originally posted by sanddrag *
**It’s not just the time. It’s the money. Otherwise my team would be building one right now. We figured it would be about $250 for just gears for one gearbox. Of course that was with some slightly different ratios that we came up with. **
Sanddrag, take my advice and go to your local Motion Industries and get the Martin Gears. We were buying them from Small Parts & Boston and their prices were over twice as expensive as Motion Industries plus they were in stock.
Andy, great job on the prints, to show the level and detail as well as a complete model in Uni-Graphics surely took a great deal of your time, and I for one appreciate it.
I might tinker around with it a bit and see if I can incorporate any of the features we used this year. One thing I really want to test out is the spring loaded shifting linkage with the hobby servo. If I can get it to mount and work on the side of the tranny I will post it to give an alternative to pneumatics. Gear job of eliminating the wire-edm parts, it opens up the design to many more teams.
Along the same lines to teams out there: looking through the design it appears you could make most of the parts on a regular mill with a digital readout. I tried making one of the gears with the pocket dog mates at home on my machine (which is CNC) but I did it by hand with a rotary table and you can do pretty well without the CNC. I can’t wait for one of our schools (Troy Athens) to have their CNC machine at school making parts for us this year.
One thing I am not really clear on is the mount of the drill motor. We had to make an aluminum carrier so we could screw into something (Also made a fantastic heatsink too!) , how are yours mounted in the 2003 gearbox? Also love the carrier on the CIM motor, fantastic idea.
Great tranny, ohh so small too.
*Originally posted by dez250 *
**Andy thanks for the words of encouragement, i was thinking about changing some of the gearing ratios around and just tinker a little to see what i can do with the output. i am wondering if i make it so the output has higher torque and less rpm’s, what it may do on the voltage input, if it may draw more or if it could cause a stall on the motor or what may happen…
~Mike
Mike,
If you change the ratios to lower the RPM and increase the torque this will only help out the motors even more from stalling and they will draw less current than if you geared it up for higer RPM’s. Keep in mind teams out there you can build this tranny exactly to the print and add any output stage to the wheels that you want, up or down. We reduced ours by 3:1 last year with 6" brecoflex sprockets and it was pretty much too hot to handle in high so we will also go a little lower for 2004 which will give you even more torque.**