The gearboxes we wanted to order were out of stock, which inspired me to design our own. It’s about as simple as a gearbox gets, with a single stage 1:6 reduction. It’s also a lot cheaper than for us to buy gearboxes. The total cost of materials for the gearbox (not including the motor or encoders) is just under $30.
That’s really cool!
How’s it mounted to the chassis? We’ve had a lot of success extending the tabs on the front plate to fit into slots in the chassis to precisely align it.
I really like this. Is there any more information available of how you design with plywood like this? What machine do you use to cut it?
It fits right into these rectangular cutouts on our chassis. The bolts already on the gearbox loosely hold it together while it is on its own so that it does not fall apart, but there are four more bolts that secure it firmly with the chassis.
A student on our team first started designing robots like this for the 2013 season, and I have continued to do the same after he graduated. There isn’t much to designing parts like this in CAD. You just have the edge of one part meet the face of another, extrude a row of regularly spaced teeth, and make the corresponding cut on the other part. Then it all comes down to deciding how to position the panels of wood. I haven’t seen much in the way of resources for designing for laser cutting, but it wouldn’t hurt for our team to make one, now that I think about it.
There are two machines we have used for laser cutting this year. One is an Epilog Helix 24 (18"x24", 60W) which we use for small parts like the gearbox, while the chassis was cut on a Kern HSE100 (100"x52", 400W). (We do not own these machines.)
I can’t speak for 1899, but we’ve been using laser cut plywood extensively this season.
We use .25" 5-ply baltic birch plywood cut on a ~75 W Trotec Speedy 300 with a 29"x17" bed.
If you’re curious how we like to make things (which is a little different from how 1899 does), we’ve released lots of documentation on our work:
-Our off-season drivetrain engineering journal
-Our off-season drivetrain CAD
-Our 2015 engineering journal
Edit: Here’s another great resource for laser-cut design (and more): http://www.instructables.com/id/How-to-Build-your-Everything-Really-Really-Fast/
Im digging the wood! Literally it is awesome can not wait to see the fully assembled robot!
I think your team would be a great match for that new FRC Behind the Designs book that’s coming out-- maybe you should look into that?
More beautiful work. Can’t wait until I can see it in person.
That would looks so cool!!! How much cheaper is that than cutting metal?
OK…details and pics of your laser bed! Wow…How big is it? We are looking at possibly making some capital improvements. We have a small laser 14*9 or so…but wow!
Oh…and the laser cut gear box is giving me some ideas for the near future. Nice work guys!
We do the laser cutting ourselves, and are fortunate enough to have access to the machines for free. The only cost we have is to buy the materials. The chassis was cut from a single 4’x8’ sheet of plywood, which we bought for under $25. I have no idea what the cost of metal for an equivalent chassis would be.
The big laser cutter is located at University of Washington, and students there can get training to use it. One of our alumni mentors is conveniently a UW student, so he can go cut parts for us. The machine is the HSE 100 model on this page, with a 400W laser. It costs $150,000, so it’s not exactly feasible for a FIRST team to own.
As I’m sure you’re aware, you’re currently halfway between two cities that would make your life much easier.
Nevertheless, there’s maker spaces in bellingham and seattle with laser cutters. You could always reach out to them and see if they’ll sponsor your team with free or discounted time on a laser.
The Foundry in Bellingham
SoDo Makerspace in Seattle
The biggest downside is obviously that they’re both about an hour drive from you. But I’m sure a 120W laser an hour away is better than nothing.