Go Home Device Advice?

[Eric Reed]

Sorry to cross post...I didn't think we'd get enough views where this was originally posted, and I think it's more appropriate here, anyway:

Watching The VCU & KSC webcast our team noticed our little 5 foot home device was no match for the little mini-me robots. We tried to have a go at making one but ran into some problems. If a team built one could tell us what motors they used it would really help us out.

Someone suggested the Keyang...unfortunately we are already using those for a very integral device. We're trying the fisher-price motors, but the 10 guage wire is very cumbersome.

Thanks!

Eric / Steve

De Anza Robotics Team

[Andrew Rudolph]

I noticed at ksc that most of them used the car seat motors or the window lift motors. i think that the seat ones are more desireable due to the speed.



Andrew

[Jan Olligs]

If you are using the keyang mototr for something, which motor are you actually using on your robot, i.e. which motors do you hae available for use?

[Eric Reed]

We're using the keyang motors, two drill motors, two chippies, and two servos. Window motors are free, but they are slloowww. I'm thinkin we'll have to make it work with the FP's

[Jan Olligs]

Well, then there you are. Always keep in mind that you can also gear motors up or down to make them faster or stronger. Also, now that the "real" building and design phase is over, keep the robot weight in mind. You won't have fun reducing it at a competition, it already is bad enough with all the equipment and time you have in a "normal" situation.
Good luck and much success!

[ChrisA]

if you find ur overweight, speed holes may be the answer...

drilling speed holes to reduce weight does make your robot cool looking and if positioned right will make your robot go faster (im still not so sure how effective it is ) but they are a pain in the butt to cut. its not the actual drilling that kills ya its the problem of how many is it going to take, and where can we put these holes so that we can knock off a couple pounds.

if you need any help with this im sure if one of our team members isnt busy we could show ya how do to it properly. (my team has had a lot of experience with this type of thing).

unfortunately youd think wed learn to design things to be lighter in the first place so that we wouldnt have go through all that.

[Jan Olligs]

Remember not to cut too many holes, though. We actually had to put a steel plate on our extender to increase the traction on the wheels, and it is still not perfect. We will have to use belt in addition, probably.
And, yes, of course, figure out how many quarter-inch holes you have to cut in quarter-inch aluminum to reduce the weight by 1 pound (old robotics-math problem)...

[Andrew Rudolph]

You may want to use the globe motors without the gear boxes.



Andrew

[Lloyd Burns]

Originally posted by ChrisA

drilling speed holes to reduce weight does make your robot cool looking and if positioned right will make your robot go faster (im still not so sure how effective it is ) but they are a pain in the butt to cut. its not the actual drilling that kills ya its the problem of how many is it going to take, and where can we put these holes so that we can knock off a couple pounds.

Why not calculate the volume of material you take away, and multiply by the density of the material ? D = M/V doesn't change much, and for many materials such as aluminum, steel, and softwoods, the approximate densities you can find in a library at school should give an adequate indication of the mass you are extracting. Make a spreadsheet program to calculate volumes & masses for holes of different diameters or rectangular areas, for different thicknesses. Then figure out how many holes the job will need.

The other part of the problem, where to put the holes, is more complicated. Staying away from the edges of aluminum angle, is usually a good idea, as is leaving some material around points at which other elements attatch to the one you're lightening. And beware the effect of sharp changes in shape (like square / rectangular holes), which often raise stresses more than nicely smooth hole shapes (like round holes and round-ended slots).