90 degree adapter prototype

We purchased a Milescraft 1303 Drive90PLUS right angle drill adapter from Amazon to see if it would work as a 90-degree adapter for FRC applications.

This FRC#33 instructable inspired us to look at other adapters.

The Milescraft adapter is slightly more compact than the DeWalt, and it uses bearings instead of bushings.

We unscrewed the main handle form the miter gearbox and pulled the snap rings to get to the internals of the mechanism. They appear to be sintered gears which are weak under impact, but for many FRC applications, this should be acceptable. There aren't any thrust bearings in this device so you shouldn't be pushing against either in the input or output features either.

 This is the main assembly with the bearings held in with internal snap things.

Here is one of the gears and bearing pulled from the housing.  

Here is a picture of both of the gears and one of the bearings.

Here we drilled a hole in through the input side of the housing to allow for perpendicular outputs. 

Here is the final output with a 1/4" hex shaft going all the way through the input.

Also in this photo is a 1/2" hex tube with 1/4" hex internal bore from McMaster.

You would likely need to 1/4" hex broach the output of a gearbox for this to work in many applications but some application may only need hex to hex on both ends, and the McMaster tube can be used in those applications. 

We haven't used this on a robot yet, but it's a useful tool to have in your design toolbox.

- Spectrum

What we bought - Fall 2018

A lot of teams ask us where we buy stuff, so occasionally we'll just post about the things we bought and where to get it. 

Amazon

• Snap Ring Groove Cutters .043" - These are for cutting heavy duty snap rings on 1/2" shafts or regular snap rings on 3/4" shafts
• 4 AWG Wire - New Battery wire, flexible 4 AWG.
• White and Black 12AWG Silicone Wire -  Similar to what comes pre-installed on Talon SRX speed controllers. This is our go to wire for motors.
• Allen Wrench Folding Set - Very useful during the season and reasonably priced.
• Gallon of cutting fluid - Used in our horizontal bandsaw we also have some squirt bottles with a very diluted mixture in them for other cutting and drilling tasks. The gallon container will last you multiple seasons.
• Bob Smith 103 Super Glue - This is really good super glue
• Cheap Needle File Set - great for fixing up 3d printed parts, or getting into hard to reach places
• Double Stick Polyimide Tape - Used for sticking 3d printed build plates your heated bed
• Nice 3D print removal tools - We have a couple $1 store paint scrapers that work okay but these are better but cost more.

McMaster.com

• 1/2" Snap Rings
• 9/16" Snap Rings - Useful for going on hex shaft without first turning it down to 1/2"
• Tubing Connector for 7/8" tube - 7/8" aluminum tube is a similar OD to 1/2" PVC so we can use it for stronger Protopipe mechanisms.
• 5/16" O-Ring - These can go over 1/2" thunderhex shaft and work similar to VEX IQ rubber shaft collars. This is useful for quick prototypes or places where you might need to adjust often or you just don't have shaft collars. 
• 1/2" OD - 1/4" ID Aluminum Hex Tube - This is 6061 hex shaft that for us at least came in slightly undersized so it fits in bearings and hubs easily. It also comes with a 1/4" hex hole so you can you it as a spacer for 1/4" bolts or an adapter down to 1/4" hex if you need to make a small mechanism. The 3/4" to 1/2" is also useful if you need a bigger hex profile.
• High Flow Solenoids 1.0 CV - These are the high flow solenoids that we used on our 2018 cube launcher mechanism

Zoro.com 

• Tstack Big Drawer - Stackable tool boxes that we use at events
• Tstack Double Drawer
• Tstack Large Top Box
• PETG Sheets 2'x2'  - 1'x2' - PETG is a great plastic for the laser cutter, it's 70-75% the strength of Polycarbonate but a lot cheaper and works with the laser cutter much better.
• Acetal Sheet 1'x2' - Acetal (or Delrin) is an engineering grade plastic that cuts very cleanly on a laser cutter.
  

This is just a sample of the items we purchase, hopefully this will give you an idea of some of the things you can buy to help your FRC team.

- Spectrum

Guide to the FRC MCC

We have been asked multiple times to put together a list of items teams should have on hand to build their robot. That is a hard question to answer because there are so many different goals and build methods for FRC teams and robots.

We decided to approach this problem by thinking about an average team trying to build a competitive robot with a limited budget a few tools (possibly the list of tools from 1000.Spectrum3847.org). From there the goal is to figure out what that robot would look like and what items do teams building it need.

We decided that the concept of the Minimum Competitive Concept (MCC) perfectly fit the goals of the team we were imagining. MCC is a concept first put forward by Isaac Rife, IKE on CD in 2012. Isaac describes the challenge of the MCC as such "It is often easy to identify all the possible tasks you could have a robot do. Prioritizing those tasks, and realizing it in the form of a competitive robot is in my opinion much more impressive. Assumptions are that one of the primary goals of the MCC is to play in elims (not necessarily win on Einstein), and you team has mid-pack to lower fabrication resources."

We identified examples of MCC robots from the past and found qualifies that they all shared. We then looked through the wide array of possible build items and techniques to find the most useful for teams on a limited budget and with limited fabrication resources.

Our complete guide can be found on CD or at 

MCC.Spectrum3847.org

Please let us know what you think.

- Spectrum

FRC Powder Coating Guide

We have released a Powder Coating Guide for FRC teams. It shows you how we powder coat our parts in our lab and all the equipment you need to do the same.

Download it from Chiefdelphi here.
https://www.chiefdelphi.com/media/papers/3511?

Protopipe: Rapid Prototyping System

We have been working on creating a system to allow us to quickly and easily design mechanisms that let us solve the problems given to us in the FIRST Robotics Competition. This past season our prototypes worked well but they took a long time to modify and adjust and that led to our design process taking more time than we would want.

We listed some goals for the system.

Goals

• Rapid iteration
• Easy to remove and add parts
• Easy to reuse parts in the next prototype if needed
• Inexpensive
• Try to avoid using expensive parts such as bearings, etc.
• Use a cheap base material that is locally available
• Easy adjustment
• Clamp systems for small adjustments of spacing and belt and chain tensioning
• As few unique parts as possible in the generic system
• Easy to make custom parts for each unique application if needed.
• Able to quickly make rotating parts such as intakes, ball paths, etc.
• Powered by a hand drill or by a Versaplanetary (or 57 Sport if you like)
• Able to quickly attach to pneumatic cylinders for making wrists, small arms, catapults, etc.
• Able to make a rough linear slide system for prototyping stackers / elevators (2015)
  

Basic System Explanation

We decided on using 1/2" PVC pipe and 3D printed connectors. 1/2" PVC is widely available at most home improvement stores for very little cost (a few dollars for 10 ft lengths). 3D printers are becoming very common among FRC teams and the filament is getting much cheaper as well ( <$20 / kilogram). So these parts seem like they would work well. 

The connectors allow you to connect the pipe to flat parts as well as hold 1.125" bearings for making systems with hex shafts, etc. To connect the pipes to the connectors you can either use short self-drilling screws or hose clamps to clamp them on. The clamps allow you to easily adjust certain parts to move items and figure out the best measurements for your system.

The full system is described in the google doc explanation here.

Link: Full System Explanation, Examples, and Notes

CAD Files

We have uploaded all of the Solidworks part files, STLs, and STEP files for the different parts as well as a few STEP files of the example prototype/bench tests that we have designed. 

Link: CAD Files

Examples of the System