Post by Derek the Admin on Nov 8, 2018 18:58:02 GMT
As Bruce said, this is indeed a fascinating project. I love to see all the effort that goes into creating a mechanical system and getting a peak into the brain that's trying to balance all the goals and work within particular constraints. I think if you and Ray ever got together we'd all be in trouble.
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Well this looks promising... one thing interesting is how it looks more like a dragster than with the other wheel. I even compensated for about 1/4" height to help make it more level. The main reason for this is that the Omni wheel is more rigid, and some of the tires need to be aired up again. The other is the deflection happening on the rockers, which I may redo with thicker gussets. Luckily I anticipated this as there is a 3D printed part that can adjust the height, but it will be a real pain to swap out (probably take over an hour to do). So I'll just leave it like this for now.
So far so good... I'm leaving jacks under it (about an inch below so all the load is on the Omni wheel) for a couple of days just to be safe (you can see one of them in this picture). If all goes well it should be drive-able, and then it's onto CNC'ing the motor mounts (click here for GrabCad link). And making some repairs (e.g. swerve motor mount) .
Hey everyone, I've needed to take a break from CNC'ing for a while due to the robot build season; however, I was able to make this part with the M3, and the folds using a brake. This part holds together the gearbox and needs to be rigid (using 1/8" 5052o) because the gearbox sprockets to the wheel (on a #35 chain). This is our first CNC part with a 90 degree fold. Looking forward to testing the precision on the fold using the etching technique. I'm still taking a break until our competition robot is completed, as well as the code. Then I'll come back to this and continue this project.
Pretty cool project. I just read through your whole thread and wanted to make a comment. You mention early on that you get bad results trying to bore your holes with a ball end mill. I get very good results when I use a flat end mill for boring. I don't find I can go very fast with any ball end mills in aluminum. They don't seem to cut nearly as well, and when I use them I have to slow things down a LOT. Of course I have only used 6061 and 7075 aluminum so far, both of which I think are harder than the stuff you are using..
Pretty cool project. I just read through your whole thread and wanted to make a comment. You mention early on that you get bad results trying to bore your holes with a ball end mill. I get very good results when I use a flat end mill for boring. I don't find I can go very fast with any ball end mills in aluminum. They don't seem to cut nearly as well, and when I use them I have to slow things down a LOT. Of course I have only used 6061 and 7075 aluminum so far, both of which I think are harder than the stuff you are using..
Ah I believe you are talking about the entry on 9/23... since that time with a bit more practice and experience with good feed, speed and depth. I know I can probably do just fine with a 1/8" flat end carbide (still shying away from 1/16th as I can't get a good sfm). The bigger the hole the better the chance of the heat to dissipate and not gum up the bit. I have not considered spraying lube yet, as this would also be a solution for that... I want to avoid that though if I can.
While I'm here I have taken a sneak preview of MasterCam and may try to use it in the near future... it has some custom setting for pecking techniques for the drilling that i'm interested in trying... to see if its possible to automate drill operations. Its ability to nest with tabs can't be ignored as this is definitely a need for what we do. I'm still taking a break from CNC work but looking forward to getting back into it soon.
In this video I have it moving forward autonomously approximately 2 feet. It wasn't quite tuned properly (that's why the middle wheels started to peel out), but actually it is cool to see that it has more power. The robot weighs roughly 175 pounds and I have it ramping around 5mps^2 acceleration.
So mechanically speaking its in good shape, good enough to move on to electric and software tasks. I will want to strengthen the rocker bridge joints eventually so I'll keep y'all posted. I'll get a better video demo as well... with it driving more, and picking up a sample. So stay tuned...
(Note: these things take longer to do... due to family obligations)