Please take a look at some of the preseason work we did this year! I have to say I’m pretty proud of the students for their work on this. We had a couple of goals in mind for this. 1) To design and build a three falcon gearbox that is similar gear ratio to the KOP gear ratio and that would be a bolt on replacement to the KOP gearbox. 2) To learn to go from our Solidworks model to our Acer knee mill with Accurite G2 controls. We found that the plug in for HSM works to Solidworks has a post processor for the Accurite G2. It took a bit of work for us to figure out how to set HSM works to not use any Z axis because our machine only has two axis CNC control. Once we did, it wasn’t really too bad and was very nice for the program to come up with the tool paths rather than us moving the machine.
From the link attached the .step file is there so that we are compliant with R15. If you are able to see it, there are two inner plates for the chassis shown there, an AM14U3 and AM14U4. We have both at our shop, so we needed to see what the specific differences were. In the link there are multiple pictures of the one machined component we’ve made and a video of a portion of one of the toolpaths (plus the youtube video is here: https://youtu.be/SEaLQLfd4ZA ) . We were hoping to have the Falcons in time to try it out, but as we all know they aren’t available yet.
And yes we have read the other forum topics on three Falcons are too many, but in this design it would be very easy to leave out the top motor and just run two. We wanted to keep our center of gravity of the motors as low as possible, and still mount to the KOP chassis, so keeping them low was more of a priority that flipping them and putting them above the frame rails as others have done.
Hope you like it! And of course suggestions / comments / attaboys are welcome!
Oh and I forgot, here’s the stock simulation for making the gearbox: https://youtu.be/xO_OkgIQizI But this toolpath would be in our precision machining classrooms HAAS Mini Mills.
We did have to change the toolpaths quite a bit from this video because it uses the same origin, obviously we have to flip the part. This is really just for showing the tool paths that are there and correct to machine the whole part.
Yes it was. As I like to tell me newer students, the seniors went digging for a part in aluminum and they found the part they wanted!
As far as time, that’s hard to say really. It took us a long time because we were learning the process flow and how HSM works, and how it interacts with our mill. There were several setups on the mill plus it was a job for one of my seniors that still had classwork and this was an additional project for them.
Hopefully our precision machining class can come through and make this on their HAAS Mini Mills also.
Oh and final weight was 0.95 lbs for the Aluminum.
On that toolpath, there appears to be an aggressive 60 IPM full DOC slot at around 1:50 in the video. How well did that cut in real life? That seems like some insane material removal for the endmill.
That video was the first pass before reviewing it with our machining class. That definitely got changed, plus every single tool path. The HAAS Mini Mill - EDU only has 4000 rpm and we kept the IPM down to 12 and the “carry over” (I’m forgetting the correct term right now) to about 20%. So, a lot changed in the tool path that they have, but didn’t have a chance to get to before Christmas break.
On our knee mill, that specific tool path we did manually with the mill or the student just did simple program on the accurite to clean up that face (I don’t remember which he did - he’s been using mills for many years now, so he’s at the point where I let him make the decisions on that).
This is really cool. Personally, I would redesign the gearbox when the game is revealed so that there isn’t a top motor mounting point so less material and less weight. When redesigning, you could also reconfigure the gear ratio to be more optimized for the upcoming game.
On the second setup, there’s a removal for the mounting flanges which starts from the center and leaves the outside edges for last. Did you have issues with chip evacuation there? It looks to me like it might have been easier to remove material from the outside in there.
Yeah. From my (probably inaccurate) math, the only advantage besides maybe acceleration of 3 falcons vs 2 is that with 3 you’re drawing 38 amps per motor, meaning you wouldn’t trip a 40 amp breaker when pushing something for a sustained period of time. That doesn’t really matter, though, as you’d wind up tripping the 120 amp breaker at roughly the same point with each configuration. Plus, there’s not a lot of times when you really need to sustain pushing for more than 5 seconds or so. I’m not really sure about the acceleration of 2 vs 3 motors though.
Disclaimer: I’m probably wrong in some of what I said, feel free to correct me.
Assuming 228 amps of draw from the 6 motors and around 12 amps of draw from various other places on the robot (for sake of an easy 200% of rated power or 240 amps), you would trip your main breaker in somewhere from 5 to 40 seconds on a robot that has been driving a bit during the match. On a completely cool robot, it would take 10 to 40 seconds according to the CB185-120 datasheet.
You will not be drawing 228 amps from the 6 motors during normal operation (what you described as “driving a bit during the match”). That is the “total pushing current draw” and presumably represents the current drawn when pushing an opponent.
I’m perfectly aware of that. The data sheet times are from a “cold start” or basically room temperature (of 77 degrees F, admittedly a bit high). Since this is a thermal breaker, it will likely not be running from a cold start if you have been driving a bit during the match and thus may trigger the breaker earlier than the rated 10 seconds.
If the robot has been driving during the match, you should expect the breaker to trip at 240 amps after around 5 to 40 seconds after beginning a pushing match. With a “cold start” at the beginning of the match, you can happily rely on the data sheet’s rating of 10 to 40 seconds after beginning a pushing match.
This design seems ripe for Delrin to me. Since the spacers are integrated into the plate, the usual issue of needing additional plate support for a plastic gearbox is gone.
