Chief Delphi - Wheel Envy?

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- Robot Showcase (http://www.chiefdelphi.com/forums/forumdisplay.php?f=58)

- - Wheel Envy? (http://www.chiefdelphi.com/forums/showthread.php?t=82304)

Quote:

Originally Posted by JaneYoung (Post 917155)

Wisdom.

Teasers, in general, are pretty boring. They may provide some interest but they rarely inspire or intrigue. The photos in this thread provide an opportunity for discussion and curiosity to grow. If I were going to be at a competition where 2865 was competing - I would take the time to visit their pit and check out their wheels. Maybe ask some questions about the oven/baking process. If one is going to make any assumption when posting a teaser, it would be a good idea to assume that the viewer/audience/general public doesn't know as much as you may think they do and that you are the bridge to understanding or creating enough interest to become that bridge. 2865 has done that.

Jane

I 2nd that

Quote:

Originally Posted by Joe_Widen (Post 916945)

Actually, showing off the whole wheel vs a teaser is better for your team in this case. If I were to see your robot on the field without have seeing this thread, I'd figure ooo, you have some andymark mecanums, cool.... and move on. Had I only seen say a roller (as the "teaser") in this thread, I probably wouldn't even had remember when it comes time to regionals.

This is generally my opinion on most matters on keeping some things under wraps versus posting a lot early. Posting a lot early guarantees you attention, while keeping things under wraps until regionals only gets you attention if you stand out at the event.

The average team isn't 1114 or 111, so they're not going to be automatically focused on. Posting stuff like this raises interest and attention for the other teams. If you're worried about stealing your ideas, (1) It's week 5 (2) Imagine if your idea ended up on Einstein!

All that aside, are you worried about the forces on the very tip of your mecanum rollers in competition? The cantilevered roller design will, for short periods of time, put all of the robot's weight on the tips of the rollers.

Well personally I have a pretty strong dislike for Mecanum drive; but these wheels are just too sweet to ignore! Awesome work guys ;-)

those are pretty nice... not a big fan of Mecanum wheels, but those look very nice

Quote:

Originally Posted by Chris is me (Post 917195)

All that aside, are you worried about the forces on the very tip of your mecanum rollers in competition? The cantilevered roller design will, for short periods of time, put all of the robot's weight on the tips of the rollers.

As I'm not on design/build/anyone who would really know, this isn't final. But I believe the words of Mike (one of our mentors) were, "Dude, these things are bomb proof."

:eek: WOW those are amazing for custom made wheels... also fairly sweet color.

Quote:

Originally Posted by Chris is me (Post 917195)

I think we generally share the same opinion but I think there are times when showing off too much is a bad thing. I would agree that posting early does guarentee you a lot of attention, but sometimes that attention is bad. An example of that is 148 last year, whose amazing video led to a ton of defense. Would they have faced that much defense if they did not post their video? I'm not sure and I'm not sure I am willing to take that chance.

Secondly, if you post some early videos of prototypes or before you had a chance to debug or improve your robot, those images stick in people's mind. Like if team 46 posted a video of their kicker that went 3 feet, my first impression would be 'man, what happen to 46 this year?!'. They may since improved their kicker to make 100% of their cross field goals, but that first impression still sticks with me. The commonly held view of the importance of first impressions is pschologically sound.

Reminds me of what my team did back in 2006, before mecanums were all the rage, and were not available at *any* price

Here's a picture of ours:

Questions:
Is there any reason that you decided to use 7 rollers?
Did you mill this from a solid block of aluminum?

They still look awesome, I hope it matches the other colors of your robot.
Oh, and FYI - we still use the wheels we originally made as a practice bot for our most newbie members, even though they're 4 years old. I think that we used the same rubber, I remember baking the rollers. They're no longer anywhere close to as shiny and yellow, but they still work.

Props!

Most impressive! Can you describe more about how molding the rollers works? Do you have any pictures of that process?

efoote868, Not sure why 7, I'll let someone else explain why... And yes it was made out of a solid chunk of aluminum.

Sanddrag, we have a gallery of the process on our website: http://www.roboteknix.com/home/galle...ls.php?album=9

I didn't mean to stifle my team members into silence...far from it. I was suggesting that not EVERY detail be revealed before the regionals play out. Being that we're in a week 1 regional...that's not too far away.

Rubber: We cast in a Mold Max 20 silicone and not knowing the nature of this material to inhibit the cure on the PMC 780 urethane rubber when the mold is new we have had to add some Post Cure processing. Essentially we've since baked our silicone molds at 150 deg F for 4.5 hours and we've post-cure processed (baked) our early rubber rollers for 4 hours at about the same. This has resolved the tackiness issues of the surface of the rollers. The Mold Max does an awesome job...captures every detail (or defect) and so some of our rollers are absolutely perfect (aluminum mold master) and others were cast from wax copies of the aluminum master (therefore some surface bubbles in the rubber...but tiny ones). Now that the silicone molds have had the alcohols or other chemical agents baked out of them the rollers come out nearly perfect with little to no post cure processing needed (but it is still done to improve the properties of the rubber). We're almost to 56...and a few spares... Each batch of silicone and rubber was vacuumed after mixing and after pouring to remove as many air bubbles as possible...so far only one detectable defect in a roller after 40+ have been poured.

It'd be much more scientific if we had programmable ovens and the like but a $8.25 toaster oven from the thrift store does the job in a high school shop. We disconnected the top elements to avoid direct melting or scorching issues.

Word the the wise...we have a great ventilation system and have been running it continuously. The cure accelerant "Kick It" is good at curing rubber fast and clearing sinuses faster if you don't have ventilation. Don't play with this stuff in your household or basement if you know what I mean. PMC-780 even has warnings about "not intended for household use".

As far as the very tips of the rollers go the geometry is such that I don't believe they will have any issues...we're dying to have these cured up so we can run them around. The chassis is bare until the rollers all cure!

Why 7 spokes? because it worked in SolidWorks. They were machined from solid T6 6061 by a sponsoring company for us. We want to cast them to make molds for duplication purposes when we have the time and materials...they do not need to be this strong (but they are, so that's nice). SolidWorks also revealed the weight of the assembled wheels before we had even cut or cast a part...and now we know it was right.

I'll make sure Brandon posts pics of the process and we'll reveal all once the documentation is completed and posted to the site. More pics of everything will be revealed as soon has he has them in his possession I am sure.

www.roboteknix.com

Just beautiful! In the theme of sustainability, checking interference and weight in a SolidWorks assembly is a better option than making multiple prototypes. Thank you. Marie

I will update the site as soon as I can. And beware, the smell of the rubber sticks with you... I've smelt it for 2 days straight now @_@

Here are the pics of the chassis:

Looks like it's going to be a beautiful robot, wish I could see it in person.

I take it you have brackets coming down from that frame to hold the mecanum wheels? Any reason you didn't try to have them integrated into the frame?