1771's Pushing Power

[nighterfighter]

After many weeks of building, our robot can drive!




http://www.youtube.com/watch?v=XlHAGVlojcs

[Josh Drake]

Looks similar in some aspects
Good luck at Peachtree.

[sdcantrell56]

Unfortunately we will not be in Palmetto. Hopefully we'll get the chance to see each other at the championship though.

[Stephen Kowski]

Originally Posted by sdcantrell56

Unfortunately we will not be in Palmetto.

I am so disappointed. I think some sc teams would love to test your mettle in Greenville on the 20th.

[sdcantrell56]

Originally Posted by Stephen Kowski

I am so disappointed. I think some sc teams would love to test your mettle in Greenville on the 20th.

Believe me we would love to defend our title but there just wasnt enough money in the budget for palmetto this year. Hopefully we will fundraise more next year and be able to return.

Im still waiting to see some pics of your bot. I saw one shot on facebook but it doesnt reveal anything.

[Stephen Kowski]

Originally Posted by sdcantrell56

Believe me we would love to defend our title but there just wasnt enough money in the budget for palmetto this year. Hopefully we will fundraise more next year and be able to return.

Im still waiting to see some pics of your bot. I saw one shot on facebook but it doesnt reveal anything.

Brashier Middle College in simpsonville, sc on the 20th....you can get all the pictures you want, just bring the bot with you

[Josh Drake]

Originally Posted by sdcantrell56

Believe me we would love to defend our title but there just wasnt enough money in the budget for palmetto this year. Hopefully we will fundraise more next year and be able to return.

Im still waiting to see some pics of your bot. I saw one shot on facebook but it doesnt reveal anything.

I have some details on 2815, but I will have to keep quiet or they will tell our secrets too. Stephen is talking about the SC scrimmage next weekend.

[RMS11]

Looks sick guys!!! Do you have a 2Cim and 1FP transmission per side? Really nice setup!

[sdcantrell56]

Yes we do! From what I hear the team loves the set up. We also have 8wd with 1.25" wide roughtop treaded wheels and we are using timing belt instead of chain.

[MrForbes]

looks like the robot is only about 2/3 of it's final weight?

Beautiful chassis!

[sdcantrell56]

Im honestly not sure how they tested that pushing force but I know that value is off. They possibly were testing it on the tile which would explain the drop. It is geared right at 10.5 ft/sec with 4cims and 2fp's so we can definitely push more. Also in the picture it weighs 70ish lbs.

It was all cut by our sponsor on there laser which can handle a 48" by 48" sheet so yes it all fit on the machine. We are using baltic birch instead of okoume this year since its much easier to get and more durable at the expense of heavier weight.

[Chris is me]

So THAT's why you really liked those 2791 chassis cutouts...

Hopefully sometime tomorrow we'll be able to post something like that. Cool to see you guys sticking with wood.

[sdcantrell56]

Originally Posted by Chris is me

So THAT's why you really liked those 2791 chassis cutouts...

Hopefully sometime tomorrow we'll be able to post something like that. Cool to see you guys sticking with wood.

Ha you caught me. This scalloped design has been floating in my head and designs for about a year now and finally we got a chance to use it. I forgot to mention that we are using 4.5" wheels and the entire drivetrain including transmissions is under 6" in height from the floor. Needless to say we are not too worried about flipping.

[dtengineering]

Nice! We're building a "plywood box" robot too. We're using a CNC router for our detail work... looks like you've got access to a laser cutter? Is it big enough to get a whole side of the robot in? Our CNC can only fit about half of one side panel so we have to take care repositioning and indexing everything... a bit of a pain.

As for the pushing force, although it looks like it is doing a great job of pushing, a measured value of 80 lbs is quite a bit lower than the thoeretical maximum pushing force for a robot. I know your team has been around for a while, so forgive me if you've already considered the following.

If you have wheels with roughtop tread, the specified coefficient of friction with carpet is 1.3. That means that a 150lb robot (including bumpers, battery, etc.) with proper gearing and all the weight on high friction drive wheels should be able to generate over 180 lbs of 'push'. Even a standard AndyMark type wheel should give you a coefficient of friction close to 1.0 and up to 150 pounds of pushing force.

Are you using four CIMs in your drive system? What gear ratio (including any sprocket reductions) are you using? If your motors are near stalling at 80 pounds of pushing force and you want to get even more, it may be possible.

Jason