pic: Easy 775pro drive train update

It’s probably still within .03 or so

The last stuff we cut out on it needed just a little bit of adjusting

Is it accurate enough to cut the holes for the bearings? The plasma cutter that DiscoBots had access to was nowhere near accurate enough.

We used it earlier this year for our ball intake, shooter, and bellypan, and everything lined up almost perfect. You just have to deal with the slag, but we’ve found a good feed rate to run it at so that it leaves minimal slag.

On the holes you just need to run a drill through them to get clearance for your bolts.

Cinco did a lot of stuff on it but I haven’t heard weather they had issues or not.

I rate it 8/10

That sounds like it is a lot better than the one Disco was using. That one left so much slag the edges felt like a fine hacksaw blade.

That was probably just feed rate/ amperage issues. It’s hard to get it set when you switch material thickness’ all the time.

We haven’t used it enough to get a big enough sample size, but I know we can get it tuned to where it doesn’t leave hardly any slag and almost no bevel on the edge because I used to work with one that was nearly perfect.

It depends if it’s a conventional or a high definition cutter. If it’s a conventional, OP will need to grind down and clean up all the cut edges. Also, I would strongly recommend against cutting the bearing holes with a conventional plasma cutter. It’s much easier and more accurate to just use transfer punches and a step drill.

It sounds like the plasma cutter Disco had (brief) access to was probably the conventional type.

If one is doing this, it would be best to bolt together the two plates that have to match and drilling them at the same time.

My concern with the VP gearboxes is their low efficiency. I’ve read, but don’t have data, stating each stage is <80% efficient compared with ~95% efficient for a single stage spur gear reduction.
Does anyone have data to prove or disprove what I’ve been told about VP’s?

Planetaries are prone to binding and grinding at times (VPs have been ironed out so this isn’t as much of an issue, unless throwing lots of power through them which you are) and low efficiencies.

Why do we use them? High reductions in a small package. Is this such an application? Heavens no.

Couple that with the poor bearing block setup… if you’re going to run planetaries, run custom so that you can support the output shaft on either side of the gear without inducing binding due to three misaligned bearings.

Get yourself a good spur setup.

It’s only gonna have two bearings in real life, the one in the output shaft housing and another in the outside drivetrain plate.

The versaplanterarys we’re successfully used on drivetrains in SteamWorks so we will see what happens.

I’ve always found that reductions through a VP seem to be less efficient than equivalent spur gear reductions. Part of this is low tolerances, part is that it takes 2 gear reductions plus a plain bearing per planetary stage. However this is a relatively high-speed low-torque application so it might still beat a CIM drive.

Idk about efficiency but you will have 740 more Watts of power with 6 775’s but just under half the combined stall torques compared to 4-cims.

This system can easily be modified to add a fourth 775 on each side if we need too.

It’s not being designed for pushing matches, just to be fast and I’m hoping to turn this into an h-drive anyways.

But the additional gear stage will raise the torque to exceed those of a typical 4 CIM gearbox pair. Unless you have a sophisicated current limited system in place, it is essential that a 775pro drive train be traction limited, meaning that it MUST be able to generate more torque than the robot can effectively use, if only for a few seconds.

Yeah that’s definitely gong to be in the design. It’s probably going to have one traction wheel

New update.
https://www.chiefdelphi.com/media/photos/45176?