Friday, December 28, 2018

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

Saturday, December 22, 2018

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. 


  • 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 
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

Tuesday, December 18, 2018

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 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

Please let us know what you think.

- Spectrum

Monday, December 10, 2018

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.

Friday, December 7, 2018

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.


  • 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

Sunday, November 25, 2018

FIRST Choice and KOP Vouchers

The Kit of Parts (Collection of Parts?) includes a lot more than just the totes each team receives on Kickoff.

The FIRST Choice system and KOP vouchers allow teams to have the flexibility to choose what they get from a wide selection of options. This can often be very daunting for new teams.

We've put together a list of items for FIRST Choice and your vouchers that we recommend teams selecting. You don't have follow are recommendations but it should give you a starting point if you are struggling to figure everything out.

We want to thank Andrew Hartnett and Pearadox FRC#5414 for putting together the full spreadsheet of FIRST Choice items and figuring out a lot of the items value.

The full document can be viewed here and it will be updated as the season goes on. We have also embedded it below.

Friday, August 10, 2018

What we bought - July 2018

We often get asked what we purchase to prepare for the season, etc. So we thought we would run down some of our July 2018 purchases.

WEN 3410 3-Speed Remote-Controlled Air Filtration System

This was added to go along with our laser cutter to cut down on some of the smells from cutter plastic and wood on the laser cutter. It should also help with some of the 3D printer fumes and the general dust that is generated in the lab.

IWISS Crimping Tools for Dupont
We needed a new crimping tool for crimping PWM connectors and the latching PWM connectors that we use for our CAN cables. This seemed to get very good reviews and was reasonably priced. 

We need some extra countersinks and this set seemed go enough for what need it for. A few different sizes and enough that we can some lend them out or lose some and not worry about it.

Mophorn 1800W Electric Brushless DC Motor Kit 48V
This one isn't FRC related at all. The plan for this is to start testing it for using it for the Power Wheel Racing Series. The idea is to build a couple small Go-Karts as a fall project to prepare the team for building FRC robots. We can use a lot of the same build techniques that we need for FRC in a fun way.

OTG Safety Glasses and Cleaning Wipes
Just some restock for the coming the year.

Fire HD 8 TabletWe already mentioned these in a previous post but we bought Fire HD 8s to use for scouting next season.

We also purchased a USB Charger Station for that them as well.

Aibecy Intelligent Biometric Fingerprint Password Attendance Machine
Simple way to keep track of team hours. It has a learning curve but we were able to get all the names loaded in and then start loading finger prints. We also made a quick google sheet to take the text file we can download off the machine and view everyone's hours. You do have to pull the data off with a thumb drive every time.

TinaWood SSR-40DA 40A Solid State Relay DC to AC 40A
This is for a project that will likely get it's own blog post. We converted the heated bed on our Airwolf 3D printer to us an AC Heater. That lets us dramatically reduce the time it needs to heat up letting us print parts faster.
A couple other items from that project 
5 PCS SF214E SEFUSE Thermal Cutoffs
10 Amp Glass Fast Blow fuses 5 X 20MM

We want to be able to have better photos and also back grounds for when we do event casts. So we purchased.
- LimoStudio 10Ft Adjustable Backdrop Support System Stand
- Green Screen
- White Screen
- Black Screen

Gigabyte Geforce GTX 1050 Ti OC Low Profile
The computer we use for streaming events and sometimes for CAD work needed a new graphics card. It's in a low profile rack mount case so we went with a Geforce 1050 TI low profile. It's enough power for what we need at a reasonable price, we got it as an Amazon Warehouse deal which are normally just damaged packaging or returned items but usually work well. 

Aurum Ultra Series - High Speed HDMI Cable (50 Ft)
At some point this year we lost our other two 50ft HDMI cables so we needed to get replacements at around $20 each these seemed like a good price for a well reviewed cable.

DJI osmo mobile 2 Handheld Smartphone Gimbal
We have had some issues with shaky video footage in the past and wanted to help solve that. The DJI gimbal is pretty cheap and with the quality of smart phone video now its easy enough to use one instead of a DSLR on a stabilizer or a much more expensive gimbal. 

These will be used when we have commentators on live streams or when doing any other skype calls or shows. Also used for recording voice overs.

- Spectrum

Tuesday, July 24, 2018

Scouting Tablets and Storage

Amazon Fire HD 8

Spectrum is moving to a digital scouting system next year. We purchased 9 Amazon Fire HD 8 tablets on Prime Day for around $420 total.

We worked on a quick system to get all the software installed on the tablets and configured and a storage solution for them as well.


Install Script for APKs

We wrote a quick batch script to install all the APKs located in a folder using ADB (Android Device Bridge).

Here is the link to our folder of APKs, the necessary ADB files, and our script.
You can download any other APK and have it install on your device as well. For us we installed the Google Play store and necessary dependencies, several FRC scouting apps, Google Drive, Excel, etc. We also installed launcherhijacker and Nova launcher to make them feel more like stock android tablets. You will need to make sure you enable USB debugging in the developer options of your table. 

Building the Dividers with the new laser cutter


You can download the CAD model for this assembly here.
Grabcad link

We laser cut the wood on our new ThunderLaser laser cutter and assembled it. The parts fit nicely together and we didn't even need wood glue since it won't be under much load.

We spray painted it black and we also laser cut some carpet/felt to line the dividers to protect the screens.


We used spray adhesive to keep the fabric on to the sides of the dividers.

The dividers all fit inside a 15 Qrt Sterlite bin


We are going to add a 10 port USB charger that uses an external 12V power adapter so that we can charge the tablets using that power supply or by making a cable to connect it to a FRC battery while we are in the stands at competition.

Wednesday, July 11, 2018

Spectrum - This Fri and Sat - FRC All-Star Game

View this email in your browser

Indiana Robotics Invitational July 13-14

Watch the action live:

Event Results and Matches: The Blue Alliance

Spectrum is heading up to Indianapolis for the 2018 Indiana Robotics Invitational, 70 of the best teams from around North America will be attending. This Spectrum's 3rd appearance at IRI and we are excited to see and compete with so many great teams.

The action will start at 9am Friday and Saturday and wrap around 5pm both days. 

Follow along on social media (links below) for updates, photos and videos from the event. 

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Service/Outreach Opportunities

Getting students excited about Robotics is one of the most important things we do! 

Summer is the perfect opportunity for new students to join the team. If you know someone who might enjoy being on the team, have them come help out to TRI and our outreach activities. Great time to learn!

Sign up for the Summer Events Here a great way to get service hours for NHS, etc:

  • Solarcraft Tour and Demonstration: June 19th Sign Up
  • Collaborative Partnership between Microsoft & Spectrum 3847 -  Throughout the summer. The Championship judges recognized our work with Microsoft. This year, the students will help teach programming with an Ohbot, a programmable robotic head,  that encourages children to experiment with making, computer programming and interacting with their environment through technology. 
  • SPECTaculaR - First two weeks of August (tent) Two week free summer camp benefiting the Boys & Girls Club. Since 2012 our students have designed and implemented a curriculum for SPECTaculaR, a summer robotics program at the Spring Branch Boys and Girls Club that teaches engineering principles to children in the third to eighth grades.
2018 Season Highlights

Summer Tournaments:

  • Indiana Robotics Invitational - IRI. The 2017 Indiana Robotics Invitational is Friday and Saturday, July 14 – 15. Leaving Jul 11 (wed) returning Jul 15 (Sun). Trip will be $350 please pay as soon as you can. It's possible that it ends up being $400 if we don't fill out the bus with enough people.

Need for Summer Socials:

If you would like to host a bbq/pool party, please let us know. We have done these every summer but we need a host for this year. We could also have a parent plan some type of activity like bowling/paintball/ice skating, etc.

Thank you!
If you have any questions, please contact us.

Allen Gregory IV
Spectrum 3847 Engineering Coach/Mentor

Jacob Walker
Spectrum 3847 Mentor

Suanne Bouvier
Spectrum 3847 Marketing Mentor

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Saturday, June 16, 2018

Projector Speaker Stand Mounts

As we prepare for our off-season event we are updating part of our AV system. One of the things we really like is being able to easily mount our projectors on to speaker stands so that we can adjust their height and angle quickly. We make custom mounting solutions to be able to do this.

We start by CADing the whole pattern for the mounting screws on the bottom of each projector.
This mounting pattern also includes holes to mount it to a TV Wall Mount. We route the pattern into a piece of 1/2" plywood using our CNC router. We use the TV wall mount to give us some angle adjustment on the projector.

TV Mount
Here is the TV Wall mount that we use.

It has worked well for us for the past 3 season of events.

We secure the small mounting plate of the mount to the wooden plate. The large portion of the mount is bolted to a speaker stand mount. 

Speaker Stand Mount

This lets us quickly put our projectors on to speakers stands and adjust their height and angle. With some lens shift and keystone adjustment we are always able to be get a good angle to the screen using this setup.

Here are the 3 projectors that we own.

We mount them on large speaker stands so that they have a stable base and get extra height if needed.

Here is the projector mounted for the 2017 NTX Off-season

Here is a picture of the complete setup in action at the 2017 Remix event.

- Spectrum

"Much ingenuity with a little money is vastly more profitable and amusing than much money without ingenuity." - Arnold Bennett

Monday, April 9, 2018

Alamo Regional Champions

Gold medal awarded to Spectrum 3847, the St. Agnes and Strake Jesuit engineering team, at FIRST Robotics Competition (FRC) Alamo Regional Competition in San Antonio. Team advances to Championships.

Houston, TX, April 9, 2018 - - Spectrum 3847, the St. Agnes and Strake Jesuit engineering team, FIRST Robotics Team Spectrum 3847 won the Alamo Regional Competition held in San Antonio. The team is now heading to the World Championships for the fifth year.

Spectrum 3847 competed against 51 other teams from across Texas and some from Oklahoma and as far as away Beijing, China. The competition was fierce and intense, but the students did an amazing job. Of the 52 teams competing, Spectrum 3847 was ranked 1 with a record of 15-2-0.

As the #1 Alliance Captain, Spectrum chose San Antonio’s Team 3481 - Bronc Botz and Team 5726 - RHUMBOTZ. The alliance remained undefeated through the quarterfinals and semifinals. They went on to win two of three matches in the finals, crowning them Winners of the 2018 Alamo Regional competition. The regional win is the first for Spectrum. Also, Spectrum was awarded the Industrial Design Award sponsored by General Motors. The award celebrates form and function in an efficiently designed machine that effectively addressed the game challenge.

“I am so proud of our team for winning the FIRST Alamo Regional Competition. They worked so hard on our robot Infrared 2018. We look forward to the global competition at the George R. Brown Convention Center in Houston from April 18 to 21, 2018. It’s free admission. Over 30,000 people from around the globe will travel to Houston for the world's largest robotics competition, celebrating STEM and innovation.” said Spectrum 3847 Coach/Mentor Allen Gregory IV.

Upcoming Competitions
  • FIRST World Championships is April 18 to 21 , 2018 at the George R. Brown Convention, Houston, TX.
  • Texas Robotics Invitational - Jun 28 - Jun 30, 2018 Spectrum 3847 will be hosting the off season tournament.

About Spectrum #3847

Spectrum is a FIRST Robotics Team #3847 from Houston, Texas. The team is made up of high school students from St. Agnes Academy and Strake Jesuit College Preparatory two Catholic college preparatory schools in southwest Houston, Texas. St. Agnes is all-girls, and Strake Jesuit is all-boys. and They work together to spread engineering to others, build robots, and have fun. The team is recognized for their hard work, community outreach, teamwork, and promoting Science Technology Engineering and Math (STEM) through robotics workshops, service, & mentoring in Texas and China and their use of social media: Instagram, Blog, Tumblr, Flickr, You Tube, Twitter & Facebook.

The mission of FIRST is to inspire young people to be science and technology leaders, by engaging them in exciting Mentor-based programs that build science, engineering, and technology skills, that inspire innovation, and that foster well-rounded life capabilities including self-confidence, communication, and leadership. FRC is a six-week competition program for high-school students to build 120 pound (54 kg) robots with help from their mentors, both teachers and engineers from a variety of companies. The students learned about engineering, programming, marketing, media, teamwork, cooperation, and much more. Each team is organized like a small business with many different tasks for students to do in addition to robot construction. Teams have only been working on their robots since January 6, 2018 when the game was revealed to all the teams.

It’s a gold medal! Congratulations to Spectrum 3847, St. Agnes Academy and Strake Jesuit College Preparatory high school students, for winning the Alamo Regional Competition. They are advancing to the Championships at the George R. Brown Convention Center, April 18 to 21, 2018.

Spectrum 3847’s “Infrared” robot for the 2018 FIRST Robotics Competition