27-12-2015 23:40

Mike Marandola

Re: paper: JVN's Mechanical Design Calculator 2016

Awesome to see a new version! Can't wait to play with it.

27-12-2015 23:53

pilleya

Re: paper: JVN's Mechanical Design Calculator 2016

The unique sheets for each WCP/VEXPRO gearbox should make things a lot more straightforward

28-12-2015 00:27

GeeTwo

Re: paper: JVN's Mechanical Design Calculator 2016

Thanks for keeping this up to date! I've learned a lot just from puzzling out your earlier versions. I'll definitely have to dig in this year on the calculations for the heteromotored gearboxes.

28-12-2015 01:23

feverittm

Re: paper: JVN's Mechanical Design Calculator 2016

Very nice and clear update. I like the changes, Thanks very much.

28-12-2015 01:31

orangemoore

Re: paper: JVN's Mechanical Design Calculator 2016

I'm not sure I understand the Articulating Drive. What is it for exactly?

This is another awesome resource.

28-12-2015 01:55

yarden.saa

Re: paper: JVN's Mechanical Design Calculator 2016

Thanks! It's a great resource

28-12-2015 02:09

Ginger Power

Re: paper: JVN's Mechanical Design Calculator 2016

I would assume for butterfly, grasshopper, octocanum etc. Drivetrains with articulating wheels.

28-12-2015 05:00

marshall

Re: paper: JVN's Mechanical Design Calculator 2016

My favoritest release this season so far!

28-12-2015 09:00

PayneTrain

Re: paper: JVN's Mechanical Design Calculator 2016

This is the key to having more success.

26-01-2016 14:30

JVN

Re: paper: JVN's Mechanical Design Calculator 2016

Just posted an updated version:

• Added RS-550 Motor Data which will be up on motors.vex.com
• Changed the Motor selection lookup formula on the "non VEXpro" sheets to better allow for multiple iterations on the same sheet
• Added additional "All MiniCIM" motor selection options on VEXpro sheets
• Fixed some formatting that no one else would notice but was driving me nuts

Thanks to everyone who provided feedback. Enjoy and Good luck!

26-01-2016 17:23

Michael Hill

Re: paper: JVN's Mechanical Design Calculator 2016

Wow @ the 550 power. I now get why we had issues with our elevator last year. Thanks for testing the 550.

28-01-2016 18:28

chapman1

Re: paper: JVN's Mechanical Design Calculator 2016

Thanks for the effort you put into - and for sharing - this universally valueable tool

25-06-2016 22:17

izz

Re: paper: JVN's Mechanical Design Calculator 2016

This is the first time I have worked on a drive base, and so I wanted to make sure that I was doing everything correctly.

1. For the "Weight on Driven Wheels", that weight is distributed evenly among wheels, right? (say 25% if there are 4 wheels)
2. What is the "Speed Loss Constant"?

Thanks in advance!

25-06-2016 22:46

Max Boord

Re: paper: JVN's Mechanical Design Calculator 2016

Speed loss constant accounts for the difference between actual speed and free speed of the motor. You can pretty much leave it at 81% for most FRC applications.

For "weight on driven wheels" if you have a 4WD robot with all wheels being driven then you would set that at 100%. If 2 of the wheels where non driven casters that would be 50% assuming a perfect weight distribution. Also for the purposes of this calculator omni and mecanum wheels are the same as traction wheels and wheel drop is ignored.

25-06-2016 22:46

asid61

Re: paper: JVN's Mechanical Design Calculator 2016

Can a brother get more stages in the Rotary Mechanism tab for the 2017 version? I need more than 4 stages please.

26-06-2016 09:03

Ether

Re: paper: JVN's Mechanical Design Calculator 2016

It's an empirically-determined value, and will "vary from robot to robot".

The 81% value is "about right" for the robots that team 148 builds.

"This is all very inexact. The calculations end up being "about right."
"About right" is totally okay for a FIRST Robot."

Stuff in quotes are excerpts from an old JVN post.

Your team can measure this speed loss constant for robots that your team builds, and eventually to get an idea if a different number would be more suitable for your team's robots. The number depends not only on type of drivetrain and the design details, but also on craftsmanship.

17-01-2017 11:45

Karthik

Re: paper: JVN's Mechanical Design Calculator 2016

Just wanted to bring this resource everyone's attention. I've had a lot of teams contacting me this year asking for help on selecting gear ratios and motors for drivetrains, intakes, and hangers. The easiest way to walk teams through these calculations is the JVN calculator. It has tabs set up for commonly used gearboxes, rotary mechanisms, linear mechanisms, and much more. It also has motor specs for many of the commonly used FRC motors pre-loaded. I highly recommend that all teams take it for a spin. It's a huge time saver and a great educational tool.

17-01-2017 11:55

Chris Fultz

Re: paper: JVN's Mechanical Design Calculator 2016

From our builds and testing, we have found the 80% overall 'efficiency' is a very good number to use. With so many COTS gearboxes available, the gear fits and alignments are great, so it is straightforward to put together a very good drive system.

Absolutely agree with Karthik. This is a great resource. We have used it extensively in the past, used it for our drive and lift in 2016, and are using it now for our drive and lift for 2017. In fact, a training session is on the agenda tonight for a wider group of students.

17-01-2017 12:09

marshall

Re: paper: JVN's Mechanical Design Calculator 2016

Chiming in too. We use this thing a lot and love it. We couldn't build robots without it. Will also mention the VexPro load ratings guide for the VersaPlanetary gearboxes. Also very important.

17-01-2017 12:18

Chris is me

Re: paper: JVN's Mechanical Design Calculator 2016

Has any free technical resource had a greater impact on the design quality and competitiveness of FRC robots than this calculator has? I seriously doubt it. This continues to be an essential tool for any FRC designer, and I'm so glad it continues to exist and be updated with useful features.

17-01-2017 12:41

EricLeifermann

Re: paper: JVN's Mechanical Design Calculator 2016

Greatest tool in my FRC toolbox for sure.

17-01-2017 12:53

PayneTrain

Re: paper: JVN's Mechanical Design Calculator 2016

It's such a fantastic cheat code. I assume the existence of the calculator is JVN's property so it shouldn't get re-hosted where he wouldn't want it... but that being said, I wish that if I could pick one resource to put on any and all FIRST related websites, any tangential email blast, write in the sky, etc., it would be this.

I am not an engineer or studying for a career in engineering but this tool has unlocked a lot of doors for me and my team.

17-01-2017 14:47

wireties

Re: paper: JVN's Mechanical Design Calculator 2016

Thanks John! Great work, super helpful to us EEs!