General points:
1. Use the same pitch and pressure angle of gears through out (this prevents the chance of to dissimilar gears contacting)
2. The key is proper mesh to transfer motion, too much or little mesh can cause gear damage or inefficient transfer.
3. Avoid pairing gears made of different materials; the harder gear will wear out the softer more rapidly than two gears of the same material.
About "Mash" transmissions:
Yes, they require less machining but the act of moving a cluster of gears (or an entire shaft) linearly is the greatest challenge in my experience. If you were planning to servo shift then “mashing” is not for you… the force required is too great for the servo to do the job. Also, there are several older threads (2003-04 vintage) that discuss the trade offs of beveling the gears vs. a right angled gear.
About Dog shifting:
The dog and its corresponding surfaces are the most difficult parts of this transmission to craft. The dog and mating gears should be made of a hard material (they will take the most abuse). Several designs that I have seen were shifted by servos and just as many that were shifted by pneumatics.
In conclusion:
It’s a trade-off between servo shift and difficult machining vs. less machining and a tricky linear pneumatic shift, IMHO.
Good luck.
On a side note:
Quote:
Originally Posted by Cory
If you have the money, I would strongly suggest purchasing the Andymarks, then using the summer to figure out what makes them tick, and what you could to do improve them for when you make your own.
Good luck,
-Cory
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Seriously, what poor play from a team with experience with shifting transmissions to just go buy an off the shelf component, we in the FIRST community should be supporting each other’s learning…not …. (My grandmother would be ashamed if I finished this sentence in public.)