Gravity Vehicle C

[xiangyu]

I see everyone is talking about using aluminum for their chassis. I'm thinking about using Carbon Fiber filament to print mine. Would that be weaker than aluminum?

Also, since no one talked about this yet, would a 3 wheel vehicle design have an advantage since there will be less friction?

I was planning on doing the exact same thing, though I'll be ordering carbon fiber rods online instead of 3d printing them (can't say I wouldn't be jealous if you actually have access to a 3d printer that can use CF ). Obviously the size of the rod/stick used will make a difference in the strength, but aluminum still has the edge when it comes down to durability and strength.

In my opinion, yes, 3 wheels are optimal for this year. If you have done pinewood derby before, it's the same thing as slightly lifting one wheel up so the car rolls down on 3 wheels instead of 4. However, the reason to use 3 wheels is not reduced friction, since the weight on each wheel just increases (therefore about the same amount of friction). The real reason is rotational inertia, meaning that 3 wheels are better than 4 wheels in the sense that you need to get one less wheel spinning. Please forgive me if I messed up my physics.

Ahh right. Yeah I just watched a Mark Rober video that explained the exact same thing. What could be the downsides to using 3 wheels? Instability?

Also, I think most 3d print are able to print carbon fiber. I believe you just have to change to a special nozzle.

[chessbucket]

I see everyone is talking about using aluminum for their chassis. I'm thinking about using Carbon Fiber filament to print mine. Would that be weaker than aluminum?

Also, since no one talked about this yet, would a 3 wheel vehicle design have an advantage since there will be less friction?

I was planning on doing the exact same thing, though I'll be ordering carbon fiber rods online instead of 3d printing them (can't say I wouldn't be jealous if you actually have access to a 3d printer that can use CF ). Obviously the size of the rod/stick used will make a difference in the strength, but aluminum still has the edge when it comes down to durability and strength.

In my opinion, yes, 3 wheels are optimal for this year. If you have done pinewood derby before, it's the same thing as slightly lifting one wheel up so the car rolls down on 3 wheels instead of 4. However, the reason to use 3 wheels is not reduced friction, since the weight on each wheel just increases (therefore about the same amount of friction). The real reason is rotational inertia, meaning that 3 wheels are better than 4 wheels in the sense that you need to get one less wheel spinning. Please forgive me if I messed up my physics.

Ahh right. Yeah I just watched a Mark Rober video that explained the exact same thing. What could be the downsides to using 3 wheels? Instability?

Also, I think most 3d print are able to print carbon fiber. I believe you just have to change to a special nozzle.

[MadCow2357]

I see everyone is talking about using aluminum for their chassis. I'm thinking about using Carbon Fiber filament to print mine. Would that be weaker than aluminum?

Also, since no one talked about this yet, would a 3 wheel vehicle design have an advantage since there will be less friction?

I was planning on doing the exact same thing, though I'll be ordering carbon fiber rods online instead of 3d printing them (can't say I wouldn't be jealous if you actually have access to a 3d printer that can use CF ). Obviously the size of the rod/stick used will make a difference in the strength, but aluminum still has the edge when it comes down to durability and strength.

In my opinion, yes, 3 wheels are optimal for this year. If you have done pinewood derby before, it's the same thing as slightly lifting one wheel up so the car rolls down on 3 wheels instead of 4. However, the reason to use 3 wheels is not reduced friction, since the weight on each wheel just increases (therefore about the same amount of friction). The real reason is rotational inertia, meaning that 3 wheels are better than 4 wheels in the sense that you need to get one less wheel spinning. Please forgive me if I messed up my physics.

Ahh right. Yeah I just watched a Mark Rober video that explained the exact same thing. What could be the downsides to using 3 wheels? Instability?

Also, I think most 3d print are able to print carbon fiber. I believe you just have to change to a special nozzle.

Instability definitely. There's a reason why cars nowadays have 4 wheels instead of 3. I may be wrong, but I think that there is another possible disadvantage to 3 wheels. windu said that a large wheelbase is less prone to drifting (wheel slippage and stuff), so my guess is that a 3 wheeled design is more prone to drifting since the triangular wheelbase significantly decreases the area. Can someone clarify this?

[T&J101]

I was planning on doing the exact same thing, though I'll be ordering carbon fiber rods online instead of 3d printing them (can't say I wouldn't be jealous if you actually have access to a 3d printer that can use CF ). Obviously the size of the rod/stick used will make a difference in the strength, but aluminum still has the edge when it comes down to durability and strength.

In my opinion, yes, 3 wheels are optimal for this year. If you have done pinewood derby before, it's the same thing as slightly lifting one wheel up so the car rolls down on 3 wheels instead of 4. However, the reason to use 3 wheels is not reduced friction, since the weight on each wheel just increases (therefore about the same amount of friction). The real reason is rotational inertia, meaning that 3 wheels are better than 4 wheels in the sense that you need to get one less wheel spinning. Please forgive me if I messed up my physics.

Ahh right. Yeah I just watched a Mark Rober video that explained the exact same thing. What could be the downsides to using 3 wheels? Instability?

Also, I think most 3d print are able to print carbon fiber. I believe you just have to change to a special nozzle.

Instability definitely. There's a reason why cars nowadays have 4 wheels instead of 3. I may be wrong, but I think that there is another possible disadvantage to 3 wheels. windu said that a large wheelbase is less prone to drifting (wheel slippage and stuff), so my guess is that a 3 wheeled design is more prone to drifting since the triangular wheelbase significantly decreases the area. Can someone clarify this?

Yea it makes sense, any small deviation in the axle angle would be amplified by aggressive wheel base design.

Also this year start height of the car isn’t measure so would it be ok to walk off both sides? I’m thinking I should attach spring loaded rollers to both walls for a clean, straight run.

[Arbiter604]

Ahh right. Yeah I just watched a Mark Rober video that explained the exact same thing. What could be the downsides to using 3 wheels? Instability?

Also, I think most 3d print are able to print carbon fiber. I believe you just have to change to a special nozzle.

Instability definitely. There's a reason why cars nowadays have 4 wheels instead of 3. I may be wrong, but I think that there is another possible disadvantage to 3 wheels. windu said that a large wheelbase is less prone to drifting (wheel slippage and stuff), so my guess is that a 3 wheeled design is more prone to drifting since the triangular wheelbase significantly decreases the area. Can someone clarify this?

Yea it makes sense, any small deviation in the axle angle would be amplified by aggressive wheel base design.

Also this year start height of the car isn’t measure so would it be ok to walk off both sides? I’m thinking I should attach spring loaded rollers to both walls for a clean, straight run.

What would be the advantage of spring loaded rollers vs. conventional ones? I've thought about this idea earlier but the hard part seems to be designing the channel the rollers slot in as it would need to match the profile of the ramp.

[chessbucket]

Ahh right. Yeah I just watched a Mark Rober video that explained the exact same thing. What could be the downsides to using 3 wheels? Instability?

Also, I think most 3d print are able to print carbon fiber. I believe you just have to change to a special nozzle.

Instability definitely. There's a reason why cars nowadays have 4 wheels instead of 3. I may be wrong, but I think that there is another possible disadvantage to 3 wheels. windu said that a large wheelbase is less prone to drifting (wheel slippage and stuff), so my guess is that a 3 wheeled design is more prone to drifting since the triangular wheelbase significantly decreases the area. Can someone clarify this?

Yea it makes sense, any small deviation in the axle angle would be amplified by aggressive wheel base design.

Also this year start height of the car isn’t measure so would it be ok to walk off both sides? I’m thinking I should attach spring loaded rollers to both walls for a clean, straight run.

Can you clarify "walk off both sides" ?

[sciolyperson1]

Also, I think most 3d print are able to print carbon fiber. I believe you just have to change to a special nozzle.

Most are, however carbon fiber is a lot more difficult to print given the temperature range. The filament itself costs a lot, and the nozzle costs 30 or so dollars; there's so many better places to spend 60 dollars on.

I see everyone is talking about using aluminum for their chassis. I'm thinking about using Carbon Fiber filament to print mine. Would that be weaker than aluminum?

CF is a bit more brittle because it's stiffer, I'd stick with aluminum or just normal PLA/PET/ABS if I were you.

I actually thought about using CF for my '18 Buggy, but decided against it due to cost, time, money, and lack of experience w/ a printer. Simply using PLA/ABS or aluminum shouldn't be an issue.

[MTV<=>Operator]

Ok, that makes much more sense. But the way I've been attaching bearings and metal spacers into the chassis is by forcing it into the wood and 3d printed chassis. This year aluminum chassis is basically a must because of the increased forces but how would you attach it into the chassis. All I've thought off is to add a 3 printed block with the bearing to increase the width of the aluminum chassis and increase the stability of the bearing. Any thoughts?

As for how to attach the bearings to the chassis, I believe you could just 3D print bearing blocks and bolt them to the chassis as you said. I am planning on simply press-fitting the bearings into the blocks and then holding the bearings in place with shaft collars.

Also, in terms of aluminum, would a rectangle made from 1 cm x 1 cm extruded aluminum be strong enough? I want the chassis alone without the weights to be as light and as strong as possible. I don't know if a 6 mm thick abs plate would serve as a better chassis than aluminum or not.

I would recommend another option if you don't have access to a 3d printer, or just don't want to use your time to design bearing blocks. ServoCity has an excellent selection of bearing blocks (aluminum ). I bought the 1/4" quad blocks last year for battery buggy, and they worked great. Personally, I never found the need to secure the axle to the inner ring of the bearings, but you could try liquid nail (recommended by a Home Depot dude).

1 cm extruded aluminum should definitely be strong enough. I used 3/4" by 1/2" last year for battery buggy, and it worked fine. Not sure how being extruded would affect the strength though. I wouldn't use ABS over aluminum since it warps a ton.

Just clarifying, when you said ABS warps, were you referring to 3D printed ABS or solid ABS? Sorry for being unclear earlier, but I was talking about laser cutting a sheet of solid ABS.

[MadCow2357]

As for how to attach the bearings to the chassis, I believe you could just 3D print bearing blocks and bolt them to the chassis as you said. I am planning on simply press-fitting the bearings into the blocks and then holding the bearings in place with shaft collars.

Also, in terms of aluminum, would a rectangle made from 1 cm x 1 cm extruded aluminum be strong enough? I want the chassis alone without the weights to be as light and as strong as possible. I don't know if a 6 mm thick abs plate would serve as a better chassis than aluminum or not.

I would recommend another option if you don't have access to a 3d printer, or just don't want to use your time to design bearing blocks. ServoCity has an excellent selection of bearing blocks (aluminum ). I bought the 1/4" quad blocks last year for battery buggy, and they worked great. Personally, I never found the need to secure the axle to the inner ring of the bearings, but you could try liquid nail (recommended by a Home Depot dude).

1 cm extruded aluminum should definitely be strong enough. I used 3/4" by 1/2" last year for battery buggy, and it worked fine. Not sure how being extruded would affect the strength though. I wouldn't use ABS over aluminum since it warps a ton.

Just clarifying, when you said ABS warps, were you referring to 3D printed ABS or solid ABS? Sorry for being unclear earlier, but I was talking about laser cutting a sheet of solid ABS.

I meant 3D printed ABS, though I suspect laser-cut ABS may have the same warping problems. It's the same material after all. If you do decide to go with the ABS plate, let me know how it works. I'd be interested to know everything goes!

[sciolyperson1]

I would recommend another option if you don't have access to a 3d printer, or just don't want to use your time to design bearing blocks. ServoCity has an excellent selection of bearing blocks (aluminum ). I bought the 1/4" quad blocks last year for battery buggy, and they worked great. Personally, I never found the need to secure the axle to the inner ring of the bearings, but you could try liquid nail (recommended by a Home Depot dude).

1 cm extruded aluminum should definitely be strong enough. I used 3/4" by 1/2" last year for battery buggy, and it worked fine. Not sure how being extruded would affect the strength though. I wouldn't use ABS over aluminum since it warps a ton.

Just clarifying, when you said ABS warps, were you referring to 3D printed ABS or solid ABS? Sorry for being unclear earlier, but I was talking about laser cutting a sheet of solid ABS.

I meant 3D printed ABS, though I suspect laser-cut ABS may have the same warping problems. It's the same material after all. If you do decide to go with the ABS plate, let me know how it works. I'd be interested to know everything goes!

Plastic warping occurs when the plastic on the printing bed is cooled too rapidly and doesn't stick to the bed; try using a light glue (glue sticks work, obviously a very thin coat), and make sure to wipe down the surface of the bed with a damp paper towel before and after printing. Moreover, if the printing bed isn't heated, consider getting a heated bed, which allows the plastic to cool down at a slower rate. If that all doesn't work, make sure the nozzle when printing is close enough to the bed to allow the filament to stick to the bed. If it isn't, calibrate it on the Z axis (most printers should have this function).

So yea, in no instance should ABS warp unless there's an issue with they way the user is printing it, I suggest making modifications to the way you set up the printer before and after each print.

And if that all of that somehow doesn't work, break up the print into two or multiple smaller parts, so that the pieces don't warp as easily.



Oh, and after printing make sure to not keep the printed parts in hot places (like the underside of a bus in the summer lol), it'll warp. Doesn't just apply to just printed builds, but every build all together.