In response to asid61:
First of all, that looks really nice, great render! Your modules look beefy even if they are a little tall, and your 3x3 siderails look strong as well.
Thanks, the modules are a bit tall. This is for a 2014 like game, so I might find a way to lower them later on.
Some possible changes you could make:
-4 cim + 4 minicim, 1 of each on each wheel. This lets you have omnidirectional motion. As you have it right now you can move in only 2 axes, and 4/4 gives you even slightly more power than 6 cims. That being said, I really like the form factor of your CIM gearbox.
I was thinking of 8 mini cims, but that’s even better. I didn’t realize how much movement I was sacrificing with the 6 CIM config; I don’t really understand how swerve movement works yet. I should probably look into it.
-Are those HTD profile or trapezoidal profile timing belt pulleys (looks like the latter)? HTD and GT2/GT3 are much better due to the greatly increased working load if you are using trapezoidal.
Those are trapezoidal pulleys; I kinda just threw in whatever I found on McMaster Carr. Ill make sure to swap them out in the future.
-I can’t open your assembly that I downloaded from Grabcad. If you want other people to be able to look at your full assembly, you need to use File -> Pack and Go and upload that. That will put all the parts and assembly into a single folder, and update all references. Or, upload a step file (but the former is easier for SW users to deal with). Right now I can only view the file in GrabCAD’s viewer.
Interesting… I saved with all parts referenced. Ill make sure to use the pack and go method as well as upload a .stp file.
-You *may *not need a 2-stage VP for rotation. You get a speed of 220rpm for turning each module with just a 10:1 x 84:14 reduction, but it’s your call what suits you of course. Changing would result in a 7A draw on the BAG motor normally.
I should have mentioned this, but those are actually single stage (10:1) reductions with an additional stage for versa encoders. I was a little worried about torque, but it seems like it should be fine.
-Double shielded or double sealed bearings are much better than open bearings for your shaft support, simply because stuff doesn’t get into to them as easily. Look into using 6800 series metric bearings as well; they can be super handy due to their decreased OD (and resulting lower weight). I don’t know if you need to switch for sure though, due to the low turning speed and orientation.
Ill definitely take a look into metric bearings; I kinda got scared away by the idea of metric units
-Why the spacer in between the caster box and the 84t gear?
Partially to hold the caster tube in place (holds down a flange on the tube) and partially to provide clearance for the versa planetary gear and shaft from the top of the module. Really the caster mechanism is in general sort of sketchy; that will be the first thing I will be fixing.
-Using long screws to clamp on a tube to connect the corners will not be very strong. You should stick an insert inside there to prevent crushing (plastic is ok)
I was actually intending to use short bolts on the inner wall of the tube; Do longer bolts offer significant structural benefits?
-Your free speed looks like 19fps, is that correct?
Thats what if was originally, but I forgot that I lowered it to about 15.25 ft/s (~19 ft/s with a 19% speed loss constant)
-Nice attention to detail relieving the corners for the VPs! I really like the amount of thought you’ve put into this. The attention to small details really is amazing.
Thanks! Thats one of the biggest things I learned this build season. The killer lies in the details.
-You may or may not want a bellypan, as the sheer (shear) strength of the frame rails might be enough.
I’m planning to add one.
Many thanks for your feedback! You should know that you are a huge help to the CD and FRC community.