Scrambler C

[bernard]

[pumptato-cat]

Hey, what are you guys using for frame material?(of ETV)
I've used all types of wood and they generally don't work well at all...
Balsa: too soft, if the chassis is handled roughly the axle holes will warp and enlarge. also hard to keep the frame in the same position without any warping/shifting if yk what I mean...
Poplar/any other dense sturdy wood: worked well, but very hard to adjust... frame was too rigid
Was considering using carbon fiber and/or 3d printing, thoughts?

[knightmoves]

How are you going to do the adjustment?

One set of wheels that can rotate with respect to the other set? Bend the frame? Adjust the position of one wheel?

[JonB]

Hey, what are you guys using for frame material?(of ETV)
I've used all types of wood and they generally don't work well at all...
Balsa: too soft, if the chassis is handled roughly the axle holes will warp and enlarge. also hard to keep the frame in the same position without any warping/shifting if yk what I mean...
Poplar/any other dense sturdy wood: worked well, but very hard to adjust... frame was too rigid
Was considering using carbon fiber and/or 3d printing, thoughts?

Using pultruded carbon fiber is a great choice- cheap, easy to work with, and extremely light and rigid. Using carbon fiber sheets/plates is extremely expensive and more difficult to make a frame from. 3D printing materials can be really, really great. You can use 3D printed pieces to join the pultruded carbon and make wheel hubs, etc. Just be ready to revise your 3D printed parts over and over again (print with low infill until you are happy with the product).

[pumptato-cat]

How are you going to do the adjustment?

One set of wheels that can rotate with respect to the other set? Bend the frame? Adjust the position of one wheel?

I was considering bending the frame... not sure if that would work. It's been pretty fiddly to work with in past years, but I can't think of another option :/
(for mtv I split frames in half)
"Adjust the position of one wheel?"
what do you mean by that?

[pumptato-cat]

Hey, what are you guys using for frame material?(of ETV)
I've used all types of wood and they generally don't work well at all...
Balsa: too soft, if the chassis is handled roughly the axle holes will warp and enlarge. also hard to keep the frame in the same position without any warping/shifting if yk what I mean...
Poplar/any other dense sturdy wood: worked well, but very hard to adjust... frame was too rigid
Was considering using carbon fiber and/or 3d printing, thoughts?

Using pultruded carbon fiber is a great choice- cheap, easy to work with, and extremely light and rigid. Using carbon fiber sheets/plates is extremely expensive and more difficult to make a frame from. 3D printing materials can be really, really great. You can use 3D printed pieces to join the pultruded carbon and make wheel hubs, etc. Just be ready to revise your 3D printed parts over and over again (print with low infill until you are happy with the product).

Thanks! Really appreciate the advice! :) Yeah, my school has a printer I might be able to use(it's for robotics unfortunately, scioly funding is low :(... maybe they'll let me use it!)

[knightmoves]

How are you going to do the adjustment?

One set of wheels that can rotate with respect to the other set? Bend the frame? Adjust the position of one wheel?

I was considering bending the frame... not sure if that would work. It's been pretty fiddly to work with in past years, but I can't think of another option :/
(for mtv I split frames in half)
"Adjust the position of one wheel?"
what do you mean by that?

Some designs for car events have had a rigid frame with bearing blocks attached to carry the axles. One of the bearing blocks has been adjustable in position forward and backward, and tweaking that position has been used to align the steering. Yes, when you move the position of that block, the axle is rotating in the other bearing - that's not really a problem, as it's just a small adjustment and there's a little bit of play.

[pumptato-cat]

Thanks! Makes a lot more sense now. One issue with a rigid frame that I've found is that if you don't have a drill press and screw up on your axle holes, one wheel won't touch the ground, causing traction/steering issues Struggled with this issue for 3 years, tried everything from weights to cutting the frame in half. -_- Only figured it out 2 weeks before states 2022... so idk how a rigid frame would work

[JonB]

Thanks! Makes a lot more sense now. One issue with a rigid frame that I've found is that if you don't have a drill press and screw up on your axle holes, one wheel won't touch the ground, causing traction/steering issues Struggled with this issue for 3 years, tried everything from weights to cutting the frame in half. -_- Only figured it out 2 weeks before states 2022... so idk how a rigid frame would work

If you connect the pieces of your frame with 3D printed parts, then it "should" be okay. Keep in mind, there could be 40 other things that still could be causing the steering issue, even if the frame is straight. If you 3D print structures to hold the bearings/hubs, then this can help.

[knightmoves]

Thanks! Makes a lot more sense now. One issue with a rigid frame that I've found is that if you don't have a drill press and screw up on your axle holes, one wheel won't touch the ground, causing traction/steering issues Struggled with this issue for 3 years, tried everything from weights to cutting the frame in half. -_- Only figured it out 2 weeks before states 2022... so idk how a rigid frame would work

If you have a hand drill but no drill press, you can do a reasonable job by first drilling a hole in a (hard wood) guide piece, and then using that guide piece to guide and position the drill as you drill holes for each of your axles.