Lesson Plan Industry Sector
Agriculture & Natural Resources

## Try Square Project

### Lesson Plan Overview / Details

This is a small 3"x 5" try square that can be used to practice measurement accuracy, review cold metal hand and power tools, as well as layout, drilling and tapping threads.

Time
3 Hours

### Objectives and Goals

• Students will be able to identify mild steel and aluminum.
• Students will be able to accurately measure and layout the project as specified
• Students will assemble a square with the correct dimensions and a right angle

### Activities in this Lesson

• What is Square - Hooks / Set

Last week we took a look at all the welding joints that we will be practicing throughout the year.  I mentioned that the fit of the joint is just as important as the quality of the weld.  After all, if you are hired to build a building and put the welds in the wrong places, your building will fall down!  It came to my attention though that we do not have enough tape measures and squares for you all to have your own.  So we are going to make our own TRY SQUARES!  This is a nice little project that you will be able to square your T Joints, measure your welding coupons, and layout any measurements you might need.

(While speaking I model the use of a try square for each of the above.  This project is a review for several tools that the students used in agricultural mechanics 1 in our program.  I use it in my welding class to help ease the burden of only having 8 welding machines and 30 kids.  Plus they can use it.)

• With the printed materials below while still in the class room I review the information and check for questions.

• Try Square Procedures [ Download ] Procedures for Try Square
• Try Square Drawing [ Download ] Detail Drawing of Try Square
• Try Square - Demo / Modeling

The procedures are fairly straight forward on the handout.  I use 1"x 1/8" (or 1/4") flat bar steel and aluminum for this project.  Fastener size will need to be adjusted to the thickness that you choose.  I typically use a countersunk machine screw because it looks cleaner than a bolt head or rivet head sticking out.  My colleague last spring used copper rivets and then machined the handle flat which made a very stylish project.  So the fasteners are at your discretion.  Use of different fasteners in each hole can also have merit in teaching multiple skills.  These items can be purchased at any hardware store, along with the basic tools.  But purchasing from a steel yard in quantities of 20 linear feet will save you a lot of money.

I like to really focus on the accuracy of layout for this project.  You need to stress that if the layout does not match, their project will not be square!  Sharp scribes or scratch awls work best, with steel rulers for measuring.

The thinner material is cost effective because you will get longer drill bit life, and tap life.  Taps on this project tend to break easily if you don't do a good job of explaining the proper technique.  I have  also found that using the smallest tap handles will prolong the tap life as the students wont be able to torque as hard.

Explaining that two different size holes need to be drilled, one as a through or clearance hole and one of smaller diameter needs to be done for project success.  A drill and tap guide can be found in most text books or online, but here is the formula if you are ambitious to do a math problem!

In lieu of a tap drill chart, it is possible with inch sized taps to compute the correct tap drill diameter as follows:

$TD = MD - \frac{1}{N}$

where T D is the tap drill size, M D is the major diameter of the tap (e.g., ? inch for a ?"-16 tap), and N is the number of threads per inch (16 in the case of a ?"-16 tap). For a ?"-16 tap, the above formula would produce 516 as a result, which is the correct tap drill diameter for a ?"-16 tap. The result produces a tap drill size that results in an approximate 75 percent thread.

• LOOKS GOOD - Closure

Have the students check their work by holding a speed square or combination square to their try square.  Have a contest for the most correct project and give out a prize of a pair of safety glasses or welding gloves.  Again demonstrate how this new tool will be used for fit up of welding assignments throughout the year.

### Assessment

Assessment Types:
Projects,

Finished Try Square.  My grading standards are included on the procedures page.