Drive train help.
 

So me and a group of friends are planning to build a drive base over the summer meant really only for bashing like you would an rc car and mabey even putting a Frisbee shooter on it. We have a few questions though.

1. We had wanted to use wood for the frame as it is cheap and easy to obtain. We had planned to use either 4x1" or 3x1" wood boards as the plates with the axles going through them. we would use 3x1" wood as cross members if we go with the 3x1" drive plates and 2x4" if we go with the 4x1"(yes I know 2x4's are actually smaller). Our question is this ok for a drive base or should we go for an aluminum based drive base? The tools we have to use are a miter saw, bench top drill press and I can obtain whatever bits we would need. The drive base would use 6 either 8" or 6" pneumatic wheels and we intend to cad the whole thing before we build it.

2. Should we use a receiver and transceiver out of an rc car or would it be a better idea to use something like an arduino. We can do both we just want to hear what the CD community's has to say about these options.

Thank you

Re: Drive train help.
 

For the drive train, I'd use aluminum... Even if wood can be solid, I'm too afraid of it breaking. It's still a viable option and my opinion is not worth a lot in mecanical stuff ::ouch::

I'd use a receiver and a transceiver to drive the robot... If you don't have too much functions, everything can be kept simple and you get a nice range out of it.What would you need to control? The drivetrain, the shooting wheel and something to drive the frisbees into the shooter?

Re: Drive train help.
 

Our intent was to build the drivetrain and then add the shooter mechanism at a later point in time. Our worry with aluminum was it is more expensive than wood so if we were to mess up a whole then it would a fairly pricey mistake. We do see that the rc car system would be easier but our fear with that system would be if the robot starts peeling left or right we don't see a way to correct that. Thank you for the information you provided.

Re: Drive train help.
 

Well, just like in a lot of RC cars, I'd add a small potentiometer on the controller or on the robot to counter the peel...

I agree with you though for the pricce of aluminum... What about using an already existing frame of, for example, a toy car?

http://www.toysrus.com/products/batt...s-for-kids.jsp

Re: Drive train help.
 

We had wanted this to be kinda a learning expience about building a drive train so we had wanted to steer away from prebuilt frames like the one you mentioned and stuff like the kop chassis. I did forget to mention that this would be a tank drive and would likely use chain but are open to belts.

Re: Drive train help.
 

If you intend to make jumps or lots of off road stunts I would use wood as it is much cheaper to replace when it brakes. (aluminum my bend making it a pain to fix) Wood is also quite resilient, and it can take a beating, I would go with 1x4 sides with 2x4 supports Like this. If you intend to do tricks off road or on (like burnouts) you might want to drop your number of wheels down to 4 for less friction. hope this helps!

Re: Drive train help.
 

My team built this wood chassis a few years ago. It was fast and easy to make and very solid.

An RC controller is less work than an arduino, especially if autonomous functionality is not required. Most RC controllers have trim controls that can compensate for the peel. Note that V-tail mixing may be helpful to have "throttle-steering" controls rather than "tank" controls.

Re: Drive train help.
 

Then I think I'd build a steel chassis to support the motors and the wheels and then I'd cover it with wood support it and create a nice look... Steel bars are easily found and can be quite cheap if taken from old objects...

Re: Drive train help.
 

Team 3259 actually assembled their wooden chassis at the Smoky Mountains Regional this year. I don't know that they played in their first few matches, but by the time they got on the field, they had a powerful drivetrain that did well on defenses. If I remember correctly, they used 4 CIM's and two mini CIM's to power it, and it was impressively fast for something that was assembled the day of. If done correctly, wood is a perfectly acceptable material for an FRC chassis. Also, the BitBuckets have shown that wood works.

Re: Drive train help.
 

Unfortunately, we're not quite that fast. We discovered potential issues with the existing gearboxes, as well as the multifunction arm on the practice bot after bag day. We brought in new gearbox parts, as well as the electronics, as part of the withholding allowance, and made several modifications to the arm. We ended up stripping the bot down to the wood frame, and rebuilding it that morning.

As for wood, I think its a fantastic building material for robots; strong*, easy to cut, cheap, and nonconductive. Our method of building robots was inspired by the method developed by 173 in the early 2000s. Our frame parts are cut out of 3/4" birch by our friends on team 3844 on their CNC router, and then we assemble the frame using wood glue and wood screws (we pilot drill the holes to avoid splitting the wood). It's proved very robust over the past few years, including several years where we played some very aggressive defense.


*as with any material, "strong" is loaded term. Put enough holes in the wrong spot, and something will give. Also, we prefer plywood, where as it sounds like you guys will be using lumber. Both have advantages and disadvantages. If your worried about strength, overbuild it. As many have mentioned, wood is much cheaper than aluminum.

Re: Drive train help.
 

Wood is a fine material for off-season construction, just be wary of a few things:

• Axles, even dead axles, will need more support and care than that of an aluminum frame
• Pilot holes are you friend
• If you're unsure of the impact capability of a specific area, wrap it in fiberglass, cure with resin, and sand.
• Measure several times, drill/cut once.
• Wood isn't as "strong" in a tensile manner than aluminum, so care should be taken designing around shear forces and load bearing surfaces
• Wood compresses, (most) aluminum alloys do not. Plan accordingly.

Re: Drive train help.
 

This kit which includes a transmitter and receiver plus a drive chassis might be of interest to you:

http://www.andymark.com/product-p/am-2552.htm

Re: Drive train help.
 

It sounds like you guys are wanting to do this on a low budget.

I'd have a look at some of Hobbykings brushed ESC offerings, it'll end up way cheaper than the compartive Andymark ones( if you don't want the ability to use the parts legally in FRC)

http://www.hobbyking.com/hobbyking/s...d_Car_ESC.html

http://www.hobbyking.com/hobbyking/s...Mode_1_.htm l

The hobbyking transmitter is the exact same as the one Andymark sells and is half the price

Re: Drive train help.
 

Have you verified this will run on 12V? It looks like it's made for 2-cell LiPo packs or 5-6 cell NiMH packs, both of which are 7.X volts.

(full disclosure, I'm typing this from my desk at AndyMark.)

Re: Drive train help.
 

It is our intention to run this on 12v so the ESC's he presented would most likely not work. I've seen esc's rated for a 2s lipo run on 12v which resulted in it being permanently damaged and rendered unusable. This expiriene in now way makes it a definite that his suggestion won't work so we ill probs end up emailing hobby king about it.