pic: drive base idea

[IKE]

Originally Posted by dbell

Yes, Only the 2 center wheels are powered.



To answer the comments about 6wd vs 2wd:
This drive base design was meant to be simple and light. Part of meeting this goal meant not powering the corner wheels.
For 3 out of the past 4 years, 1519 has used a 2wd drive, powering the center wheels only.

We have had good success with this design. The only drawback of this drive system is, like IKE points out, it cant climb ramps.

I like 6wd, but this design is meant to be the simple, light, stick-with-what-we-know design.



DB

I edited out a lot of your post, but I would like to challenge you that if you are spending the time to do an upfront design, figure out how to power at least 4 of those wheels. There are some extremely simple and cheap ways out there and then you will drive better and be able to climb ramps (or bumps).

We have excluded teams in the past (06, and 07) as picks for having only the center 2 wheels driven from our elimination selection list. If you need some pictures of how to get 2 more to drive, let me know and I will send them your way.

[=Martin=Taylor=]

Originally Posted by IKE

I edited out a lot of your post, but I would like to challenge you that if you are spending the time to do an upfront design, figure out how to power at least 4 of those wheels. There are some extremely simple and cheap ways out there and then you will drive better and be able to climb ramps (or bumps).

We have excluded teams in the past (06, and 07) as picks for having only the center 2 wheels driven from our elimination selection list. If you need some pictures of how to get 2 more to drive, let me know and I will send them your way.

Who says there will be ramps next year.... or bumps... (or dry land for that matter)

On a more serious note... Is that a sprocket or a gear on the center wheel?

If you aren't gonna power the outer wheels why not get rid of chains all together and incorporate the wheel directly into the tranny?

What trannys are you planning to use anyways? The kit ones perhaps?

[RyanN]

Originally Posted by dbell

Thanks to everyone for their comments.
Somehow the description didn't get posted when i uploaded the picture. What you see weighs 19 lbs. I haven't decided what gearboxes to use, but i have AM toughboxes or DeWalts in mind. The frame is 1x1x3/16 square tube, and will be welded.


Yes, Only the 2 center wheels are powered.

I was not planning on using 80-20 because it would make it heavier than i want this design to be.

The angle aluminum that supports the axles is 3/16 inch thick.


InfernoX14 explained dead axles.


Do you mean done in CAD, or built?
I will probably continue CAD of this design and similar ones until 2009. I don't know when i'll be 'done'.


To answer the comments about 6wd vs 2wd:
This drive base design was meant to be simple and light. Part of meeting this goal meant not powering the corner wheels.
For 3 out of the past 4 years, 1519 has used a 2wd drive, powering the center wheels only.

We have had good success with this design. The only drawback of this drive system is, like IKE points out, it cant climb ramps.

I like 6wd, but this design is meant to be the simple, light, stick-with-what-we-know design.



They are custom 6 inch aluminum wheels with roughtop or similar tread material.


They are 'poor mans omnis'. I'd like to get away from using them too, as are heavy.


Poor mans omnis are a lot cheaper than regular omni wheels, and they slide laterally very well, but not better than omnis.

Ryan, thanks for your advice about torquing the frame. Where would you recommend putting the round tube?

Comments are welcome
DB

I saw your request. I have go run some errands and then draw it up. Really, a few inches inside the frame will work. I'll try to autocad it up quickly.

EDIT: As promised, here is a drawing. Of course, you can move the tubes to wherever you want, but towards the ends makes it the strongest, however, having it on the very end may not be the best idea because your mechanism may not be able to work properly.

[dbell]

Originally Posted by IKE

I edited out a lot of your post, but I would like to challenge you that if you are spending the time to do an upfront design, figure out how to power at least 4 of those wheels. There are some extremely simple and cheap ways out there and then you will drive better and be able to climb ramps (or bumps).

We have excluded teams in the past (06, and 07) as picks for having only the center 2 wheels driven from our elimination selection list. If you need some pictures of how to get 2 more to drive, let me know and I will send them your way.

I agree, center wheel drive is limited because it cannot climb ramps. However in a game without such obstacles (eg. 2002, 2005, 2008) center wheel drive is fine. Other years, some teams have used a drive system that cannot negotiate obstacles, and have still done well. eg: cheesy poofs in 2004. They could hang on the bar without climbing the stairs.)

Figuring out how to power the corner wheels is not the issue. With a few more sprockets, some chain and moving the inner rails, i could have a 6wd. However, this design is not 6wd, its a design similar to what 1519 has used for 3 years.

I'd like to point out a few things
-We don't know the 2009 game and we don't know what kind of drive system will be best for this game.
-Both 6wd and center wheel drive have their advantages and disadvantages.

Originally Posted by Hachiban VIII

Who says there will be ramps next year.... or bumps... (or dry land for that matter)

On a more serious note... Is that a sprocket or a gear on the center wheel?

If you aren't gonna power the outer wheels why not get rid of chains all together and incorporate the wheel directly into the tranny?

What trannys are you planning to use anyways? The kit ones perhaps?

I'm planning on using either Dewalts or AM toughboxes.

Its a 36 tooth sprocket.

Interesting idea... To be honest, i didn't really think about a direct drive that way. Mounting the tranny output shaft to a wheel is easier said than done. Especially on the toughboxes. It would be pretty easy for something like the Banebots p80 long shaft. But because the toughboxes have such a short shaft, you would need an extension. something to think about.


With all the comments from everyone, I think i'll start working on another design...

DB

[AndyB]

Originally Posted by dbell

Interesting idea... To be honest, i didn't really think about a direct drive that way. Mounting the tranny output shaft to a wheel is easier said than done. Especially on the toughboxes. It would be pretty easy for something like the Banebots p80 long shaft. But because the toughboxes have such a short shaft, you would need an extension. something to think about.


With all the comments from everyone, I think i'll start working on another design...

DB

AM makes an extended shaft for the supershifter. It actually wouldn't be too complicated at all to modify that shaft for a toughbox. If you want further info, download the cad files of both and look at how similar they are.

[AdamHeard]

Originally Posted by AndyB

AM makes an extended shaft for the supershifter. It actually wouldn't be too complicated at all to modify that shaft for a toughbox. If you want further info, download the cad files of both and look at how similar they are.

We did that this year, a pretty simple operation to do on the lathe.

[Dan Petrovic]

Originally Posted by dbell

I was not planning on using 80-20 because it would make it heavier than i want this design to be.

They are 'poor mans omnis'. I'd like to get away from using them too, as are heavy.

Now, don't automatically go thinking that a lighter chassis is a better chassis.

I explained in another post that having a relatively heavy chassis isn't always a bad thing. It basically forces you to make a lighter manipulator, basically meaning that your CG will be closer to the ground.

For the past two years our chassis (...I've never used the plural form of chassis) have been in the range of 80-90 pounds. We haven't tipped once in those two years.

[Greg Needel]

Originally Posted by dbell

The frame is 1x1x3/16 square tube, and will be welded.

I was not planning on using 80-20 because it would make it heavier than i want this design to be.

The angle aluminum that supports the axles is 3/16 inch thick.

Just a little lesson here.

1 x1 x 1/8" aluminum tubing weighs 0.5132 lbs per foot

1x1 80/20 weighs .5097lbs per foot

so in this case your design weights more than with 80/20 now this doesn't take into account the hardware weight. Also 1x1x 3/16" is not a common size for tubing typically it comes in 1/16 or 1/8"

[dbell]

Originally Posted by Greg Needel

Just a little lesson here.

1 x1 x 1/8" aluminum tubing weighs 0.5132 lbs per foot

1x1 80/20 weighs .5097lbs per foot

so in this case your design weights more than with 80/20 now this doesn't take into account the hardware weight. Also 1x1x 3/16" is not a common size for tubing typically it comes in 1/16 or 1/8"

Thanks for the specs. I confirmed those weights here and here.

Thanks for pointing this out!

Now that i look at my CAD i realize i made a mistake. The square tubing is actually 1/8 thick, not 3/16. It was those dead axle angle brackets that are 3/16. My bad.

I guess i thought 8020 was heavier, and never bothered to weigh it. Although this design with 8020 weighs pretty much the same as a design with 1x1x1/8 tubing, the hardware is the killer. I was planning on TIG welding the square tubing frame, which adds only a very few ounces, and provides a very strong bond. the 8020 brackets are a little heavier. 12 of these brackets would weigh about 1 lb. and still probably wouldn't be as strong as a weld. Then again, a pound or two is a small price to pay for the ease of use that 8020 provides.

I'll certainly look into a direct drive for the super shifters and toughboxes.
I'm guessing this is the long shaft you were mentioning.

DB