Laser Cutter And FRC

[DampRobot]

I recently got a membership to TechShop in the Bay Area, a hackerspace that has a fairly extensive shop. One of the many machines they offer for members to use is the Epilog Laser Engraver. I was wondering what experiences people have had with this machine in specific, and with laser engravers in general for FRC use. Were there any cool or innovative uses you found for this tool? What kind of parts did you use it to make, and how did they perform?

The first specific use that came to my mind was using this machine to make plastic gearbox plates, out of either polycarb or ABS. Has anyone tried this? What kind of tolerances can this type of machine hold? Is this a good/bad idea?

If I do end up trying to make plates like this, I'll be sure to share the results with the community.

[AlecS]

I've used their laser cutters for a few things, I wouldn't suggest using them for transmission plates. I haven't tried any decent tolerance parts on it, but from visual inspection of other 1/4" things I've done, taper is gonna be a issue. Also the kerf does not always appear to be constant, as at the speeds slow enough to cut 1/4" delrin, heat will build up in non consistent ways. Overall I think your going to have pretty big issues cutting transmission plates with reasonable tolerances. I'd suggest just using their router instead, as that should give you no issues holding tolerances. Good Luck

EDIT: Also you can't cut polycarbonate on those laser cutters, as they do not have adequate filtration to handle the toxic gases they create.

[Cory]

Pretty sure they won't let you cut polycarb due to fumes.

[BEEKMAN]

I recently got a membership to TechShop in the Bay Area, a hackerspace that has a fairly extensive shop. One of the many machines they offer for members to use is the Epilog Laser Engraver. I was wondering what experiences people have had with this machine in specific, and with laser engravers in general for FRC use. Were there any cool or innovative uses you found for this tool? What kind of parts did you use it to make, and how did they perform?

The first specific use that came to my mind was using this machine to make plastic gearbox plates, out of either polycarb or ABS. Has anyone tried this? What kind of tolerances can this type of machine hold? Is this a good/bad idea?

If I do end up trying to make plates like this, I'll be sure to share the results with the community.

Generally the laser cutters can be pretty accurate (about .005, depending on machine/settings) but that's only the center point on the laser. Other issues mentioned above will prevent any highly delicate work to be done.

My general decision on laser cutting VS Milling/watterjet:
Does it need to be done fast?
Is Acrylic/Delrin/Wood okay?
Are the tolerances okay?

Typically, a gearbox plate has a no in all three of those questions!

That being said, I'm uploading pictures now of entire robots I've made on a laser cutter for WPILib as well as classes.

[iyermihir]

I was wondering what experiences people have had with this machine in specific, and with laser engravers in general for FRC use. Were there any cool or innovative uses you found for this tool? What kind of parts did you use it to make, and how did they perform?


We used the TechShop lasers to make timing belt pulleys for our drivetrain this year. We use 9mm GT2 and our pulleys are made out of layers of 1/8" acrylic that are then attached to each other with acrylic cement. These pulleys are very cheap and they allow us to avoid having to wait for timing belt pulleys. One of the biggest benefits to making our pulleys this way is that we can use the laser to cut the hex which we have no other way of doing. The pulleys have not had any issues throughout the entire season. Its is also really easy to bring spares in case something happens as they are both cheap and light. We also used the laser to make the timing belt pulleys for our pick up. This was interesting because one of the pulleys was mounted on a piece of abs tube. The pulleys we cut for that were very flimsy as the bore size was not that much smaller than the outer diameter. After attaching them to the abs with the same acrylic cement, we have not had any issues with them breaking. We have access to a router at the school, but things that require a hex or other special patterns, we use the laser as long as the part will not be taking too much load.

-Mihir Iyer

[sanddrag]

We have a Versalaser that is handy for all sorts of things. It sees very little use for the FRC robot itself, but we use it for small mini-sumo robots for class projects and for engraving giveaways. We have done 1/4" ABS on it but it did not turn out great. Right now I have a problem where the laser is weak and struggling to cut 1/8" acrylic. Need to check it out and get it fixed.

[JB]

I have seen a lot of teams using them for hex spacers and such. This year we used the engraver to cut wheel treads because it was much easier than doing them by hand or on the band-saw. Also when you buy the big rolls and need to make the notched shape for the new performance wheels it makes it much easier and cheaper.

[Joe G.]

We've used a laser cutter from my college for many things over the past few years.


Delrin Spacers
Belt sprocket flanges
Wood and acrylic prototypes
Frisbee shooter skid plates
Sensor mounts
Other sheet delrin and ABS parts


Don't expect to use it for major structural components, or to do the kind of work a sheet metal shop would, but it's great for a lot of little things. Good tool to have in your back pocket.

They make cool small robots as well. (http://www.youtube.com/watch?v=sF52dWz4-9o)

[Akash Rastogi]

We have access to a router at the school, but things that require a hex or other special patterns, we use the laser as long as the part will not be taking too much load.

-Mihir Iyer

Hex patterns can easily be milled/routered. You just need to open up the corners.

[dtengineering]

Laser? Talk to FRC 1899 Saints Robotics (http://www.saintsrobotics.com/). They know laser.

Jason

[Pault]

We have a Versalaser that is handy for all sorts of things. It sees very little use for the FRC robot itself, but we use it for small mini-sumo robots for class projects and for engraving giveaways. We have done 1/4" ABS on it but it did not turn out great. Right now I have a problem where the laser is weak and struggling to cut 1/8" acrylic. Need to check it out and get it fixed.

Lens might be dirty. At least with the epilog, the lens needs to be cleaned every so often.

------------------------------

We love our laser cutter. We use it for tons of stuff, mainly with ABS. Our team considered ABS gearbox plates, although we did not actually do it because we were using supershifters for the first time and did not want to take the risk. We still believe that it would work out, though.

We did use ABS for other things on our robot this year. All of our sprockets were made using it, and worked really well. Plus they were lightweight.

We had linear actuators consisting of a double pulley moving up and down aluminum c-channel. The entire pulley module was made out of ABS, and although we had problems with them, the problems did not stem from our choice to use ABS.

We then created an ABS template which we used to lay it on top of all the layers of our wood and polycarb arm and drilled in all of the holes. Without the template, it would have been nearly impossible to manually sketch out the dimensions of each and every hole.

Our frisbees traveled down a curved path on our arm. We used stacks of .25in ABS as rails to guide the frisbees. There is absolutely no other way in our capabilities that we could have machined such a thing.

Our wrist was 75% ABS. Besides increased machining capabilities, this also allowed us to have a lightweight wrist.

Finally, we lasercut our "daisy" floor pickups using rubber. What the rubber basically did was whack the frisbee into the arm.

In sum, we basically used the laser cutter and ABS for 2 main reasons: to give our low resource team machining capabilities comparable to high resource teams and to create lightweight components. Next year, we have even bigger plans for this amazing machine.

[Chris is me]

Cutting polycarb on a laser is messy (toxic fumes) and with many thicknesses doesn't always leave a clean cut. It can be... melty. I wouldn't really consider it.

I would not make any competition robotics parts out of acrylic, which is the material most plastic laser cutters are used to cut. There is nothing good that can come out of acrylic on an FRC robot.

I don't know a lot about ABS / delrin laser cutting, but it's much more doable than polycarbonate.

I don't think lasering a gearbox plate on this machine is going to be the best idea. If you're at a good hackerspace, they have higher precision equipment (e.g. a decent router / mill) for this purpose.

[fiona.crush1011]

Besides making things for your robots there is a lot you can do for spirit and for sponsors. Our team personally does not have a laser but some of our friend teams do. This year they made us key chains with our name and number as well as little name tags for all our kids. They also made us plaques to give out to our sponsors. Each plaque was engraved with the sponsor, their level (depending on how much they donated), a little sentence about thank you and our logo. The sponsors loved them! They really like having something that they can hang up in their office and show off to everyone that comes in.

[roystur44]

Damp,

If you wanted to make a nice compact 3 CIM ABS/Delrin gearbox housing with a PTO port. Think about repackaging the VexPro Ball shifter design.

I would be willing to lend you a hand and get you some Engineering and CNC machining time. I wanted to make a video for our team to show how a Solidworks design is imported to Gibbs Cam and how the geometry is used to create the tool paths and G code and how the part would be made on the CNC mill.

[gracie.]

We've cut our electronics board with the exact same machine as you now have access to (epilog laser engraver) for two years now. We used 1/4" ABS both times, and learned some lessons between the two. The first year (last year), we had lots of issues with fire/smoke and the lens of the laser. Burnt ABS has just a lovely smell! The lens would get clouded, we'd have to replace it, etc. I was in the shop til Midnight and my mentor was there longer finishing it (I got called out by my parents).

The key with 1/4" ABS is to make multiple passes (like 4, maybe 5 just to be safe) at a lower power to minimize the burning and the lens issues. I could get the exact settings we used for you if you ever want to use this thickness of ABS. The electrical team is in love with the stuff, because modification is easy, and laser cutting it makes assembly really smooth and we can just plan and execute the whole thing from CAD. I now have a(n unhealthy) love of lasers. Hopefully I can save you some trouble if you're ever using this material.

I know my team's cut 1/4" acrylic on one of these (or similar), but that was before my time.

[DampRobot]

Damp,

If you wanted to make a nice compact 3 CIM ABS/Delrin gearbox housing with a PTO port. Think about repackaging the VexPro Ball shifter design.

I would be willing to lend you a hand and get you some Engineering and CNC machining time. I wanted to make a video for our team to show how a Solidworks design is imported to Gibbs Cam and how the geometry is used to create the tool paths and G code and how the part would be made on the CNC mill.

Roy,

Thanks for the offer. We might take you up on that. I was already considering doing a 6 CIM gearbox like that, with the VP shift shaft and delrin plates.

Thanks to everyone else for the ideas and comments. (Now I won't kill myself with toxic fumes.) While TechShop does have other much more appropriate machines for cutting gearbox plates, they currently aren't available to me. As a minor, I can't use most CNC tools, except for the laser cutter, and I was hoping not to have to have a mentor present to work on our summer project. Even if the machine doesn't work out for gearboxes, we can still use it for electronics boards, sprockets, pulleys, etc , as others have suggested.

[fb39ca4]

Laser? Talk to FRC 1899 Saints Robotics (http://www.saintsrobotics.com/). They know laser.

Jason
Yup. This year we made our entire chassis from laser cut plywood, and the year before, we made belt sprockets with the laser.

[craigboez]

It sounds like Delrin and ABS are the two goto materials. Is there a reason to pick one over the other? Are there specific advantages for certain applications?

[Nate Laverdure]

It sounds like Delrin and ABS are the two goto materials. Is there a reason to pick one over the other? Are there specific advantages for certain applications?
Absolutely! They're on opposite sides of the pyramid (http://www.plasticsintl.com/documents/thermoplastics_selection_guide.pdf) (pdf link).

[DonRotolo]

One great use for a laser like an Epilog is to make templates. You use the laser to cut a small X where the center of a hole is to be located in paper, tape the paper to your metal, and center punch almost perfectly. Also great for cutting templates, just follow the dark line...

[roystur44]

Roy,

Thanks for the offer. We might take you up on that. I was already considering doing a 6 CIM gearbox like that, with the VP shift shaft and delrin plates.


I've seen a transmission plate made from Delrrin. It was light weight but it wasn't as stiff as a aluminum one. I think making a two piece enclosed housing similar to the molded VexPro one would be better and stronger.

[Mk.32]

I have a similar facility that I am allowed to run around in.
http://www.makerplace.com/

They have laser cutters up to 150watt with 5x5 feet bed sizes as well as all the other CNC mill/router goodies. Personally I use very little laser cutting on the robot, and stick mostly to the CNC router to do my plastics (a good chuck of which is polycarb which is NOT laser-able in these shops). And the mills/lathes to do the metal stuff.

My experiences with laser-ing Delrin has been pretty good, running the 80 watt laser at about 70 % power and a medium cut speed I can get a clean out on 1/4 plate no problem.

In the end it's all about making what tools you/your team has work for you. I know 2102 this year had a robot that was mostly laser cut on top of an alum box frame, including wood plate gearboxes and plastic pulleys that worked out pretty good for them. You can make a FRC robot that is competitive with laser-ed cut parts.

Also 254 used to do Delrin gearbox plates, however they later switched to pocketed out Alum because it was lighter and stiffer.

[Madison]

I don't have the specific make and model available, but we have a laser cutter in our shop (and are getting a 2nd). We make significant parts of our robot from laser cut plastics -- mostly delrin and ABS, though we'll cut polycarbonate as well since our laser cutter is vented.

Take a look through the galleries here if you want to get an idea for how we do things. Our 2013 robot was made almost entirely from sheets of ABS.

[Cory]

Also 254 used to do Delrin gearbox plates, however they later switched to pocketed out Alum because it was lighter and stiffer.

It's not actually lighter, but it is basically identical.

The Delrin was a pretty big PITA. It was more difficult to hold tolerances on the bearing bores, the bearings could come unpressed more easily, and it flexed a bit. If you wanted to thread one plate to avoid the use of nuts when screwing the gearbox together, you had to use PEM nuts, which students can easily strip if not being careful. We much prefer aluminum.

[Mk.32]

It's not actually lighter, but it is basically identical.

The Delrin was a pretty big PITA. It was more difficult to hold tolerances on the bearing bores, the bearings could come unpressed more easily, and it flexed a bit. If you wanted to thread one plate to avoid the use of nuts when screwing the gearbox together, you had to use PEM nuts, which students can easily strip if not being careful. We much prefer aluminum.

I have tapped delrin for light duty threads, where they not sufficient to hold the gearbox together?

[Cory]

It's not a very robust solution if you're using it to cantilever the gearbox off your frame rail. Especially since you need to be super careful about how much you torque it. We used PEM nuts when we did Delrin side plates.

You also can't effectively prevent loosening due to vibration since you can't use loctite and nylon patch screws don't mix with threads in Delrin.

[roystur44]

It's not a very robust solution if you're using it to cantilever the gearbox off your frame rail. Especially since you need to be super careful about how much you torque it. We used PEM nuts when we did Delrin side plates.

You also can't effectively prevent loosening due to vibration since you can't use loctite and nylon patch screws don't mix with threads in Delrin.


Maybe try Helicoils, Keenserts or EZ-lock hardware, or Pem SI hardware for plastics.

When attaching the parts the trick is to load the force on to the thread of the hardware an and not on the plastic.

There are lots of ways to attach metal hardware to plastics, ultrasonic welding, molded in, press in, etc.

[Cash4587]

I used the Laser cutter today on this, If this helps? lol I find it very useful, Especially since it is a school owned cutter not bought by our team :D
http://www.chiefdelphi.com/forums/showthread.php?p=1278668#post1278668

[MichaelBick]

It's not a very robust solution if you're using it to cantilever the gearbox off your frame rail. Especially since you need to be super careful about how much you torque it. We used PEM nuts when we did Delrin side plates.

You also can't effectively prevent loosening due to vibration since you can't use loctite and nylon patch screws don't mix with threads in Delrin.

Was there any problem with plastic melting? For some reason I remember hearing that when CIMs heated up they melted the plastic and that also was one of the reasons you switched back.

[Cory]

Was there any problem with plastic melting? For some reason I remember hearing that when CIMs heated up they melted the plastic and that also was one of the reasons you switched back.

We were using green loctite to retain some pinions on the CIM shafts where we didn't have length for a retaining washer. We partially melted a small portion of the delrin when we had to apply heat for much longer than normal to break the loctite free to get the pinion off.

We never saw issues due to motor heat though.

[E_puello]

Our team uses our laser cutter to make thank you plaques for our sponsors
they are made of black and bronze acrylic.

https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-ash3/942311_645786775448965_599566798_n.jpg