How do y’all make your triangle ramps consistent for picking up rings? Do you guys use laser cutting, hand cut, or have an intake build that’s generally consistent? Thanks guys.
My school’s teams use our laser cutter, although some did use a dremel. Personally, i would recommend a laser cutter if you have access to one, as it allows for repeated precision on cuts.
I would highly recommend avoiding laser cutting Lexan.
The MSDS for Lexan from GE states:
SECTION 3: HAZARDS IDENTIFICATION
• Can burn in a fire creating dense toxic smoke.
• Fumes produced during melt processing may cause eye, skin, and respiratory tract irritation. Severe over-exposure may result in nausea, headache, chills, and fever.
I will not allow it to be cut on my school’s laser cutter. Even with adequate ventilation, it makes thick yellow smoke that can coat the optics of the laser and significantly affect the performance of the laser.
In addition, I have strong concerns that when it is cut using a laser, the burning changes the chemical structure of the Lexan along the cut edges and makes it motelike to splinter and/or shatter. Since the game design committee allows the use of Lexan because it is non-shattering, this could defeat the purpose.
A much better material to use in a laser cutter is acetal monopolymer (aka Delrin). It cuts beautifully in the laser and makes no fumes and is anti-static on your robot.
Be extraordinarily careful using a laser with any plastics. ABS, for example, will released cyanide gas.
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Thank you so much. Really appreciate your help. Now I’ll just need to learn how to use one. lol Thanks tho.
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So is delrin the safest material to be cut via laser cutter? Thank you so much Mr. Erbland. I would’ve asked you this in person but as I couldn’t come in, I asked on a forum. Thanks once again.
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I’ve heard that you need a file to be used to accurately laser cut? Can anyone specify what I’d need to do in order to create a cad file or a file that has the depiction of what I want to cut out? Thanks
If you want to be consistent at picking up rings, there are a few key things:
- Flex wheel height–having the flex wheels barely contact the top of the ring before the intake ramp ensures better pickup
- Ramp angle–make sure your ramp angle is not very steep (also try to keep a flatter surface if you can, bending plastic can make it harder to go up from my experience). Have you plastic go as low as neccessary without contacting the foam tiles.
- Type/Number of flexwheels–try to use the 30A (light gray) flex wheels, and don’t make them go too fast
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Oh ok thanks. We used the white 30A flex wheels and our ramp is ok, I wouldn’t its steep. We have a comp on saturday and next Saturday so we’re probably gonna add it for the latter comp. We have midterms this week so its kind of a killer right now. Thanks tho, I’ll take the advice.
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IMPORTANT SAFETY NOTE: ONLY LASER CUT PLASTIC WITH ADEQUATE VENTALATION.
I agree that it is a bad idea to laser cut Lexan (polycarbonate) as it can release harmful gas. Delrin, however, also releases harmful gas (formaldehyde - which is toxic and flammable) when cut with a laser. That being said, Delrin sheet can be cut safely and effectively and works well for robotics parts, but make sure you are taking proper precautions with adequate ventilation.
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We are lucky to have a CNC as opposed to a laser. No gas but lots of plastic dust instead 
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How does a CNC work? I’m not really experienced with this machinery. its sounds cool tho.
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Thank you so much. Safety is a big thing that is risked by engineers and its important for safety.
It has a bit similar to a drill bit. This is on a router and spins very fast. Then that’s on a core XY rail system with the router able to move on the Z. This makes it move in X Y and some Z and cut plastic or other materials like a saw or drill. Think of it as a laser but add z axis, remove the laser, replace it with a drill bit
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One way to do a laser cut is to start with a CAD file, but it is not the only way. It really depends on the type of laser cutter you are going to use. The more modern ones will work with pdf and many other graphic files, so you may be able to start with something like Inkscape which is a free vector graphics program. On my Epilog Helix 50 Watt machine, I create a sketch of the part I want to cut in Onshape, then I export it as a DXF file, import it into Inkscape where I make the changes/adjustments for the cutting job, then save as a pdf, export again and import into Adobe where I can send the job to the cutter. As others have mentioned laser cutting is not something you should do unless you understand or have been trained by someone who knows all the safety requirements of operating one. All materials cut by a laser will generate harmful smoke and fumes. We use an air assist and a Quatro fume extractor with a 4 stage filtration system and vent that outside of our room.
A much simpler way to cut plastic is with a Dremel tool and a Dremel Work Station. It gives better control of the cut than using the standard 565 cutting attachment, but you may run into trouble cutting large parts on it, in which case the standard cutting attachment can be used. A little practice or pointers from someone who has used one will be needed, but you should be able to get the shapes you need.
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So if you don’t have access to any of those tools, you can also use scissors or pliers as long as they are sharp, especially for the thicker sheets. For the thinner sheet, you can use any scissors or shears.
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My team used some branch cutters on one of the old games plastic from turning point and filed it to be safe.
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what is the model of the laser cutter your organization is using?
My organization uses our school’s laser cutter, but it is a Thunder Laser. I don’t know the actual model, unfortunately.
However, depending on the budget, it is worth noting that a Thunder Laser machine can run upwards of $15,000. I would recommend getting a machine like a glowforge or an Xtool as they are more portable and considerably less pricey while still being excellent machines.
We have a Dremel Digitech LC40 Laser Cutter and Engraver. I don’t think that Dremel makes laser cutters anymore though, so probably not super helpful info for you. It was provided by our district’s CTE office so I had no choice in what we got, so I can’t say that I did a bunch of research and decided on this one. I will say that it is easy to use and works well for our needs.