How to keep an axle from flexing

From: Jason Brett:

So with axle flex you’re usually dealing with some form of three-point beam bending. The deflection of the shaft is — as you’ve pointed out — affected by both length and thickness. The thickness comes into play as the “moment of inertia” of the beam… for a square shaft the formula is proportional to the fourth power of thickness. Doubling the thickness will result in a 2^4 increase in resistance to bending, and therefore deflection should be reduced by a factor of 16.

Length, however is a cubic factor. Reducing the unsupported length (from bearing to bearing) by a factor of two will result in an 8 fold reduction in deflection. It might actually be a bit higher than that because these formulas assume a point load and a uniform beam… your beam is thicker where the wheels are and the load is distributed across that width. But the general concept applies…. shorter is better, and cubic factors make a huge difference! Simply reducing your unsupported span from 7″ down to 5″ will give you (5/7)^3 of your current deflection… about 36%. Reduce it to 4″ and you’ll be down to 18%.

Do BOTH… reducing your unsupported shaft length to 4″ AND doubling the shaft thickness and you’ll be at 1-2% of your current deflection… assuming, of course that load remains constant. If you aren’t able to compress either the tread on the wheels, the balls, or move the support on the other side of the balls, then you’re still going to have the same amount of deflection… because something has to give somewhere! This brings up the third factor in deflection… the load. Perhaps a little less “squeeze” will be sufficient to reduce your shaft flex. Keep in mind, however, that load is only linearly proportional to deflection… you’d have to reduce the load by 50% to cut deflection in half.

UNO’s Fundraiser on December 13th!

Visit UNO Pizzeria & Grill in Framingham for lunch, dinner or take-out and support FHS Robotics!

On December 13, just bring this flyer and up to 20% of your check will be donated to them!

Catering, take out and lounge purchases included. Call ahead for parties of 6 or more, 508-620-1816. Uno’s deliver locally for orders over $100.

Visit to view their menu.


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Clean out your closets and help FHS Robotics June 17th

As you already know, for a small fee, the FHS Robotics Club will take anything with a cord and recycle it. But starting this year, we will also take your gently used clothing and other household items for free!

We are teaming up with Savers and they will make a contribution to FHS Robotics for every pound of clothing we deliver to them. We’ll accept gently used clothing, shoes, bedding, towels, hats, mittens, scarves, ties, socks, purses, wallets, backpacks, bags, belts, jewelry.

On Saturday June 17th from 9 am – 3 pm we will in the main parking accepting both electronics and clothing. But you can save a trip and drop off items Wednesday June 12th through Friday June 16th from 11 am-3 pm.  Please bring clothing in a standard 13 gallon kitchen trash bag.

The fees for dropping off electronics are:

$1 Portable Items – Cell phones,MP3 players, telephones smoke detectors, calculators, routers, modems, speakers less than 12” tall, or USB hubs

$3  Small Items – External hard drives, external CD/DVD drives, or speakers 12-15” tall

$5 Medium-sized Items – Inkjet printers, VCRs, scanners, DVD Players, radios, stereo components, boom boxes, toaster ovens,  game console, or speakers 15-22” tall

$10 Medium-Large Items – Laptops, fax machines, laser printers, or speakers 22-34” tall

$15 Larger items – Computers, microwaves, humidifiers, dehumidifiers, all-in-one printers

$20 Large Items – All computer monitors or TVs 27” diagonal and under and speakers over 34” tall,

$25 Very Large Items – TVs over 27” diagonal, air conditioner (home wall/window units)

$35 Wood console/ projection TVs

Ridiculously Large Items – Office copiers, large AC units, refrigerators, washers, dryers, etc.  are priced by size (H+W+D) in inches:

Size < 70” – $15
70”-80” – $25
80”-90” – $35
90”-100” – $45
100”-110” – $55
110”-120” – $65
120”-130” –$75

Things we take:

  • Plastic TVs, Wood TVs, Laptops, computer monitors, computers, CPU boxes, all computer parts and accessories, keyboards, mice, cell phones, speakers, video games and systems, camera/video/audio equipment, fax/copy machines, printers, wires, plugs, drives, cards, servers.
  • Household Appliances, including all white goods including refrigerators, freezers, water heaters stoves, dishwashers, washers and dryers. Household appliances including toasters, irons, hair dryers, and microwaves.
  • Metal Items (less than 8 ft long)
  • Metal poles, metal desks, barbeque grills (no propane tanks), pots

Things we won’t/can’t take:

  • Automobile parts  (Tires, mufflers, fenders, etc.)
  • Beds & bedding parts (Hide-a-beds, bunk beds, mattresses, box springs, waterbeds, coil springs, etc.)
  • Construction materials (Lumber, pipes, floors, tubs, cabinets, carpet, doors, windows, etc.)
  • Damaged furniture (Torn, soiled or in need of repair)
  • Flammable products (Any items that operate on or contain fuel including: gas cans, propane cylinders, lawn mowers, weed trimmers, camp stoves, tiki torches, etc. )
  • Hazardous materials (Batteries, paints, chemicals, cleaning products, poisons, any liquids, etc.)
  • Infant products (Car seats, cribs and related products)
    Marine vessels (Boats, canoes, kayaks, etc.)
  • Weapons (Firearms, explosives, ammunition, flares, etc.)
  • Other items (Swing sets, food, animals)


We made a cone!

We made an In the Zone cone in our Formlabs printer. The printer bed is the perfect size, but with the support materials we needed to print it at 96% of actual size. But at least it gives a good idea of the structure.

The link to the file is at the bottom.

Inside the printer


22 hours later, DONE!!!

40 grams of support material removed

Finally, a cone!

Click here is the file for the cone.

Worlds Agenda Published

They moved the game reveal to Saturday during closing ceremonies!

12:00 – 1:00 pm VEX & REC Foundation Open Forum Discussion 1:00 – 7:30 pm Pre-Event Team: Check-in, Pit Area Set Up & Inspection
1:30 – 7:30 pm Practice Fields Open
3:00 – 4:00 pm Girl Powered Social in ULA Ballroom
3:00 – 7:00 pm Skills Challenges Rounds
4:00 – 5:00 pm Team/Driver Meeting with Mandarin Translation in the Math Division
5:00 – 6:00 pm Team/Driver Meeting with Spanish Translation in the Math Division
7:30 pm Pit Area & Venue Close

7:45 am Team Load In – Pit Area, Registration & Inspection Opens
8:00 – 9:45 am Practice Fields Open/Skills Challenges Rounds
10:00 am Team Check-in & Inspection Deadline
10:00 am Team/Driver Meeting in Freedom Hall in English
11:00 am – 12:30 pm Practice Round/Skills Challenges Rounds
12:30 – 1:30 pm Lunch Break
1:30 pm Opening Ceremony/Parade of Nations in Freedom Hall
2:30 – 6:30 pm Qualifying Rounds Begin/Skills Challenges Rounds
7:00 pm Pit Area & Venue Close

7:45 am Pit Area Open
8:30 – 9:30 am Opening Ceremonies/Online Challenge Awards
9:30 am – 12:00 pm Qualifying Rounds/Skills Challenges Rounds
12:00 – 1:00 pm Lunch Break
1:00 – 5:00 pm Qualifying & Skills Challenges Rounds
5:00 – 6:30 pm Skills Challenge Finals & VEX New Product Reveal in Freedom Hall
7:00 pm Pit Area & Venue Close

7:45 am Pit Area Open
8:30 am Simulcast Opening Ceremonies/Division Awards
8:50 – 11:15 am Qualifying Rounds
11:15 – 11:30 am Alliance Selection Process in Each Division
11:30 am – 1:00 pm Lunch Break
1:30 – 3:30 pm Division Playoffs and Awards
4:45 – 6:15 pm Finals, Game Unveil & Closing Ceremony/Awards
6:15 pm Pit Area Closes
6:15 – 11:30 pm Team Party at Kentucky Kingdom* *Ticket Required

34 days until Worlds

Team 9421X, the Intangibles, have qualified for the 2017 VEX Robotics World Championship! It starts April 19 in Louisville, Kentucky. This will be the fourth consecutive year  that an FHS team has qualified for the World Championship

Framingham High School  Juniors Varun Tekur and Kevin Lenzi, Sophomore Connor Neshe and Liam Neal Reilly earned enough points in the Robot Skills competition to qualify them to compete in the  World Championship.  This will be Varun’s fourth trip to Worlds, Kevin and Liam’s third and Connor’s first.

With a Robotics Skills score of 56 (21 Programming and 35 Driver Skills) they are currently ranked 401st in the world and 6th in Southern New England.
The team will travel (along with two teams from Walsh Middle School) to Louisville to compete from April 19-22 against more than 500 of the best VEX Robotics teams in the world.
What is the VEX Robotics World Championship?
VEX Robotics World Championship, now entering its 10th year, will bring together the top 1,400 student-led robotics teams from around the world to Louisville, Kentucky, on April 19-25, 2017.Visit this season’s VEX Worlds event pages for each division to get up to date on all the information needed to prepare for the event.

The New Schedule: The new dates of the VEX Robotics World Championship mark a dramatic program change to provide teams with a superior event experience as they compete in the largest and fastest growing international robotics programs. The VEX Robotics Competition and VEX U will open to middle school, high school, and university teams on Wednesday, April 19, and culminate with finals, awards, and a team party at Kentucky Kingdom on Saturday, April 22. The VEX IQ Challenge will open to elementary school and middle school teams on Sunday, April 23, and culminate with finals, awards, and a team party at Kentucky Kingdom on Tuesday, April 25.

We are very excited to be going back to Louisville.