33 Killer Bees 2019 Offseason Swerve

From my knowledge it’s not a kit per day it’s more that you trade in your current printer for the new one and pay the differential. So onyx one to mark 2 (or whatever the 7k one is) would cost you the onyx and additional 3.5k

The supplier we got our printer from said there was a kit, and I guess I was never clear on if it was to be able to do fiberglass or CF. Either way, we haven’t looked into it further because we knew it would cost at least as much to upgrade as another Onyx One, and like I said we haven’t really come across the need for continuous fiber of any kind and preferred to increase our overall throughput by getting a second Onyx One.

Do you make many gearboxes with nylon plates? How do they fare as opposed to aluminum.

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Yes, our swerve modules in 2018 utilized nylon plates, our drive and climber gearboxes this year also utilized nylon plates.

Links to our 2018 swerve module example can be found here

Links to our 2019 drivetrain gearbox and other 2019 material can be found here

Links to our 2019 offseason version of our 2019 gearbox can be found here

We use nylon over HDPE and UHMW because those tend to bend a little easier. Delrin would work just as well, but nylon is a decent amount cheaper so we have committed to nylon as our primary plastic material of choice.

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Do you have any adjustment system built in to tension the belts? Or do you just have to replace the belt?

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If you use the proper C-C distance for belts, there’s no need for tensioners or replacing the belt. Unlike chain, belt wont stretch over time*. As long as you make the belt loose enough that you can get it mounted but tight enough that it doesn’t skip, you can run it forever** without any problems. There are calculators on CD and other internet places to help you figure out what this distance should be for your application (mine is here).

* Technically, chain doesn’t stretch either. The bushings and pins wear down, meaning the distance between the rollers in each link grows by a few micrometers which adds up over the whole length. But effectively, it stretches.
** Well not forever, but for longer than the rest of your robot will last

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Have y’all had any problems in the past with the relative encoders for steering, specially with on field calibration or do y’all have a special process?

Correct me if I’m wrong, but I believe they use CTRE mag encoders, which have an absolute mode on them.

I was not aware they had that setting. It was to my knowledge they didn’t.

http://www.ctr-electronics.com/downloads/pdf/Magnetic Encoder User’s Guide.pdf

See the chart in section 5.3.1 and 5.3.2 for understanding when the absolute mode is available.

For the drove belt we have an extra threaded hole designed in the top plate so we could add a spacer there to tension the drive belt if needed.

We don’t anticipate the steering belts needing any additional tensioning. There shouldn’t be enough resistance on that to make the belts skip.

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Nick,
is your swerve sample going to be at IRI again?
I’d like to bid via remotely if possible. :slight_smile:
Also, can you send me details of your Markforged?
I plan to buy a newer updated one right when school starts up again.

-Glenn

Sadly we will not have a swerve module available in the IRI auction this year.

We will hopefully bring the first version of the module we are bringing now. We are currently assembling it right now and finding a few minor lessons learned as we go.

We have a Markforged One. Nothing else really specific there, we just ordered a second one recently.

Shucks.
Thanks for the info on the printer.
I hardly have time to follow up on the latest and greatest anymore.

How is it possible to use a GT2 pulley with a GT3 belt? Maybe I just don’t understand belt profiles correctly.

HTD, GT2, and GT3 can all be intermixed.

See RCs post below.

Thanks for the clarification

Im not 100% sure this is right…

GT2/GT3 are likely similar enough, but I thought HTD was a distinctly different profile?

They may work but it’s less than optimal?

Correct, less than optimal.

Tooth profiles (HTD, GT, etc) are a game of thousandths, so as long as they’re all the same pitch (tooth spacing) they’ll work OK.

EDIT: I am wrong - check out RC’s post below and this explainer on GT2/GT3 and why it changes within product lines: http://gatesbeltsandapplications.blogspot.com/2015/10/whats-difference-between-gt-gt2-and-gt3.html

I wouldn’t necessarily mix HTD and GT profiles professionally, since I would likely run into trouble if I tried to submit a warranty claim, and mixing profiles will likely result in more belt wear, more noise, shorter product lifetime.

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This is incorrect.

HTD Pulleys can accept:
-HTD, GT2, GT3 Profile

GT Pulleys can accept:
-GT2, GT3

The GT pulley is not deep enough to accept the HTD profile. Also you will lose some strength when running GT belts on a HTD pulley, for FRC use case on most mecahnisms its not an issue. Currently our team uses only VEXpro pulleys and mixes and matches belts on them.

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