CHIPS

[roboteer49]

thanks everyone

after reading all ur responses i realized that chips running at 9ft/sec will be destroyed in the matches.(fast but no torque) Even though I want to stay away from drill gearboxes ive decided to give them another chance. Here's what im thinking. drill in high and chip connected to a output shaft inbetween them, a 3.5:1 ratio between the drill and chip but the gear on the output will be larger(haven't determined the size yet) Also i was thinking about chain and sprockets and then my dad suggested belts, what do u think, anyone ever used belts in a gearbox?

it will look kinda like this ( o0o )
if that makes sense, drill and chip on outside,output in middle . so what if its crude picture.

[sanddrag]

If anyone wants to see the inside of the Chia there are a couple pics here http://team696.org/forum/category.php?cid=5&page=3

For a simple drill-chia drivetrain I would recommend something like this http://team696.org/forum/image.php?iid=166
another pic http://team696.org/forum/image.php?iid=164

It uses the drill in high gear

If you are using large wheels, or don't have room for a large final reduction and would like to run the drills in low with the Chias (or just the Chias by themselves), I would recommend the team 716 2003 single speed gearbox (found in the whitepapers) Team 980 and 696 used it this year with great success. It is a little more complicated to build than the pics I linked to above but it is very reliable, small, efficient and lighter. It has a nice slow output speed of 460 rpm.

Attatched is a pic of ours.

[Mike Ciance]

since chips come to a rolling stop, they make a robot much harder to drive than a drill motor robot

[Joe3]

I agree with most of what has been said in this thread, but there is one major difference between the Chips and drills that I have not seen mentioned thus far.

The Drills are air cooled motors, cooled by a fan in the back of the motor near the brushes. Since it is air cooled, it will continue to give full power when it heats up, and after it stalls, untill it burns up.

The Chips, on the other hand, are not air cooled. They have a variable resistor (a brass colored plate) in the motor so that as the motor heats up, the resistance increases in the plate, giving the motor less current so that it wont burn itself up. Basicly, as motor heats up, its power output decreases. While this helps greatly with durability of the motor, it hurts in an application such as what we are using them for. If you get in a pushing match and you stall your motors for a 2nd or two, the Chips will heat up, and put out less power for the rest of the match. Do this a a couple times, and you will definately notice the power loss. On our 2003 robot, we had 4 motor drive, with the chips powering the rear wheels and the drills in the front. Due to our weight distribution, our rear wheels had the most traction, so the Chips were mostly responsible for turning. Many times when we got to the end of a match, the robot would have difficulty turining because the chips got hot and therefore their power output was cut accordingly.

Just another thing to think about. Oh yeah...did I mention that those suckers are HEAVY.

[Rob Colatutto]

Originally Posted by afflictionblade

since chips come to a rolling stop, they make a robot much harder to drive than a drill motor robot

Any motor will do that if you set the speed controller to Coast mode and have a high efficiency gearbox with it. Typically when a team uses the Bosch with its stock gearbox, the drive has lower efficiency than the Atwood does when you make a simple 2 reduction gearbox for it. The lower efficiency causes energy and momentum to be lost faster, which you probably had with your Bosch experiences. Either motor can be incorporated into a high efficiency gearbox and give you plenty of rolling after the power is cut off.

[edit] In further reading of your post, it appears you like the quick stopping feature of the Bosch as opposed to the higher efficiency of the Atwood. High efficiency is always good in your drive. You can create the same stopping effect with the Atwoods by switching the speed controller into Brake mode. [/edit]

[Pat Roche]

Ok lets recap this alittle.
Drills give more power for a longer period of time under stress BUT will burnout
variable speed with gearbox..high rpm without
CIMs dont burn out very easily...or in some cases at all...are more power efficient and are high RPM.

So I guess this means you have to make deicisions. Do you want to risk possibly burning out your drill motors? Or would you rather risk losing some power with the atwoods?

For my team we would rather risk losing some power from the atwoods..


OOO...let me share something with everyone. Last year at river rage we slapped together a new robot to test our new tranny. at one point we lost one cim due to wiring errors and burnt out the last of our drills cept for one(it was a two motor drive) Coincidently the two motors were on oppisite sides of the robot. It drive great with the two motors opposite of each other...had great power and drove the straightest it had all day.

-Thought I'd share...


-Pat