6/8 Wheel Extra Features

[MichaelBick]

This year, we really like our 6 wheel drive. We wan't to improve it for next year, including increasing performance in general, and by maybe adding some extra features.We had some questions about these features, if anyone has used these before, including:

2 in thich Wheels

• Is there a notable increase in turning scrub?
• Is the increased traction noticable? In what ways?
• Have you found that it improves your defensive/offensive performance?

Drop down casters
(I heard that 987 has done this previously. Correct/incorrect?)

• How effective is it at getting out of t-bone pins?

Drop Down Outer Wheels
(I heard that 469 has used this previously. Correct/incorrect?)

• Is the increased traction noticable
• Have you found that it imroves your offensive/defensive performance?

Obviously, in qual matches, these would most likely have little to no effect on performance. But in elims, it seems like there could be a significant improvement in performance.

[Chad987]

Originally Posted by MICHAELABICK

Drop down casters
(I heard that 987 has done this previously. Correct/incorrect?)

Yes we did. We used it quite a few times last year, extremely useful.
We would have one this year, if we had the weight.

[Peter Matteson]

Originally Posted by MICHAELABICK

This year, we really like our 6 wheel drive. We wan't to improve it for next year, including increasing performance in general, and by maybe adding some extra features.We had some questions about these features, if anyone has used these before, including:

2 in thich Wheels

• Is there a notable increase in turning scrub?
• Is the increased traction noticable? In what ways?
• Have you found that it improves your defensive/offensive performance?

Drop down casters
(I heard that 987 has done this previously. Correct/incorrect?)

• How effective is it at getting out of t-bone pins?

Drop Down Outer Wheels
(I heard that 469 has used this previously. Correct/incorrect?)

• Is the increased traction noticable
• Have you found that it imroves your offensive/defensive performance?

Obviously, in qual matches, these would most likely have little to no effect on performance. But in elims, it seems like there could be a significant improvement in performance.

2 inch wide wheels don't make as big a difference as tread material, and they can make turning a little screwy.

We used drop down omnis instead of casters and the drivers loved them. They did help against defense.

[MichaelBick]

Originally Posted by Peter Matteson

2 inch wide wheels don't make as big a difference as tread material, and they can make turning a little screwy.

Are you referring to turing scrub? Has anyone else used 1.5 in wheels with success?

Also, what do Drop Down Outer Wheels provide?

By dropping your outer wheels, you theoretically are able to gain more traction when you are trying to push through defense or stop offense.

[Hawiian Cadder]

Some tips learned from our drive-train this year:

Hollow tubes make for great axles, These were tapped so that there were no collars on any of the drive axles, it also saved a ton of weight, we used .495 OD with roughly .1 walls.

Track width, our 6 inch performance wheels were less than .125 from the edge of the 28 inches, it made turning much more forceful.

Maximizing traction, blue tread from Master on 6 inch performance wheels has a LOT of grip.

Choosing the proper gear ratio, our high and low gears were 16.6 and 6.7 ft/s this is NOT traction limited in low gear, enabling us to push robots with lower gear ratios when they broke traction due to overzealous driving.

Drop down casters sound interesting, our driver never got stuck on other robots, but if he ever got close/parallel to a wall it was difficultly to quickly get UN-stuck.

[JesseK]

Originally Posted by Hawiian Cadder

Hollow tubes make for great axles, These were tapped so that there were no collars on any of the drive axles, it also saved a ton of weight, we used .495 OD with roughly .1 walls.

Exercise caution in future years and apply the material for the year rather than using the "we always do it this way" way of thought. I'd be concerned that the outer axles would bend if it came off the bridge or bump incorrectly. Did you do any simulation or calculations to figure out the tensile stresses your axle could hold?

On a flat or predictable field like 2005, 2006, 2007, 2008, 2009, & 2011 this isn't a concern.

[Hawiian Cadder]

Originally Posted by JesseK

Exercise caution in future years and apply the material for the year rather than using the "we always do it this way" way of thought. I'd be concerned that the outer axles would bend if it came off the bridge or bump incorrectly. Did you do any simulation or calculations to figure out the tensile stresses your axle could hold?

On a flat or predictable field like 2005, 2006, 2007, 2008, 2009, & 2011 this isn't a concern.

Our drive was setup so that there was about 1/4 of an inch between the wheels and the bearing blocks. This allowed for the lighter axles, bending was never an issue, one match we even drove off the 24 inch drop made by an unbalanced bridge with no damage to the axles. Keeping the axles short was critical to maintain a robust system.

Edit:
We did test the axles on an our off-season WCD, they were flawless and bending was minimal. We beefed up the axle wall thickness a bit for competition to ensure they would never break.

[O'Sancheski]

Originally Posted by MICHAELABICK

Are you referring to turing scrub? Has anyone else used 1.5 in wheels with success?

If you look several posts higher you will find that someone mentioned 1.5in wheels.

[MichaelBick]

Originally Posted by O'Sancheski

If you look several posts higher you will find that someone mentioned 1.5in wheels.

I saw. I was just wondering if the consensus was that 1.5 in wheels were the way to go.

[Marc S.]

As far as the width of the wheel, we on 973 noticed a big difference in traction with 2" wide wheels vs traditional 1" wide wheels.

In 2011 we used a wcd with 4" diameter, 2" wide weels, with a 3/16" center drop. The combination worked great. The drivetrain allowed us to switch from strict offensive play to strict defensive play with the ability to push every robot we came in contact with. Check out the cad for Titan in my signature. If you like what you see feel free to use our design(s) and pm us if you have any questions.

[BJC]

In 2011 team 33 had an 8wd with the back wheels able to articulate up/down. When they were down it picked up the back of the robot enough to lift the inner 4 wheels off the ground making it very difficult to turn us. When they were lifted up we were an 8wd that could turn on a dime.

Just adding to the mixing pot.
Bryan

Originally Posted by Marc S.

As far as the width of the wheel, we on 973 noticed a big difference in traction with 2" wide wheels vs traditional 1" wide wheels.

In 2011 we used a wcd with 4" diameter, 2" wide weels, with a 3/16" center drop. The combination worked great. The drivetrain allowed us to switch from strict offensive play to strict defensive play with the ability to push every robot we came in contact with. Check out the cad for Titan in my signature. If you like what you see feel free to use our design(s) and pm us if you have any questions.

What kind of wheels, and what kind of tread? And any reason for using 3/16 drop over 1/8 drop? Did you feel it had an advantage? If so, what was it? Any disadvantage?

[MichaelBick]

Originally Posted by SuperNerd256

What kind of wheels, and what kind of tread? And any reason for using 3/16 drop over 1/8 drop? Did you feel it had an advantage? If so, what was it? Any disadvantage?

My guess is that because they were using 2 in thich wheels, they had an amount of turning scrub that they didn't like. By increasing the drop, they decreased that amount.

[Marc S.]

Originally Posted by SuperNerd256

What kind of wheels, and what kind of tread? And any reason for using 3/16 drop over 1/8 drop? Did you feel it had an advantage? If so, what was it? Any disadvantage?

The wheels are custom, we used blue rough top tread. The reason we went with 3/16" drop over 1/8" drop was to ensure better turning capability, less scrub on the raised wheel, etc. The advantages were that we could push every robot we came in contact with (even 469) without any fancy add-on's and without giving up offensive speed. There weren't any big disadvantages with the drive (the only thing that really gave us trouble was the 775 motors (which were removed before champs), if we use the design again we will use 550's in conjunction with the 4 cims).

Though for the moment, emperor swerve is working great for us, so it may be a while before you see 973 using the drive train again.

[Peter Matteson]

Originally Posted by Marc S.

As far as the width of the wheel, we on 973 noticed a big difference in traction with 2" wide wheels vs traditional 1" wide wheels.

In 2011 we used a wcd with 4" diameter, 2" wide weels, with a 3/16" center drop. The combination worked great. The drivetrain allowed us to switch from strict offensive play to strict defensive play with the ability to push every robot we came in contact with. Check out the cad for Titan in my signature. If you like what you see feel free to use our design(s) and pm us if you have any questions.

This is where my team started with the development of our current drive trains that we use. We started with IFI sheet metal 4" X 2" wheels. We then went to custom 4"x2" wheels. After that we did the math on the physics and realized that the difference wasn't that big between 2" wide and going down to 1" wide. Also we had greater variation in traction with various tread materials that we tried out, which is why we currently use 1" wide AM performance wheels with the best traction of all materials we tested. It's one less thing to make and 1" wide wheels package better.