Glossary

Before fabricating your clock, it is necessary that you understand the definitions, tools, and manufacturing rules relevant to working with the machines in the Design Studio.

BURRS - These are the sharp edges that stick out from your part after drilling or cutting. Burrs create two major problems. They are unsafe and they do not allow your parts to fit together properly. You can use a file or sand paper to remove them.

CENTER DRILL BIT - This bit looks like a short thick drill bit. It does not drill holes. It is used to start a hole. A drill bit can move around when you first start drilling a hole. If you first start the hole with a center drill bit, then finish it with a drill bit, you hole location will be more accurate. Center drill bits are very useful on angled or curved surfaces.

CLEARANCE HOLE - This is a hole which is larger then the object that goes through it. In the example of the clock: the holes in the Bracket are 0.010" to 0.020" larger in diameter than the screws that go thought them. The holes in the Bracket are called clearances holes. This allows the screws to move freely in the holes.

COUNTER SINK - This allows a flat head screw to be slightly below the surface of your part. In the example of the clock: The bottom of the Base has two flat head screws that fasten it to the Bracket. To create a counter sink hole for a flat head screw you must first drill a clearance hole for the size screw you will be using. Then you must use a counter sink bit (located next to the drill presses in the Design Studio) to drill the cone shaped hole that the screw head will fit down into. The counter sink is deep enough when the head of the screw is slightly below the surface of the part.

DRILL or DRILLING - In the Design Studio we use the drill presses or the cordless drills to drill holes into our parts. There are drill index's (the gray boxes) located by the drill presses with a selection of different diameter drill bits. For safety all parts MUST be clamped down when when drilling holes into them. When drilling the acrylic and aluminum in your kits make sure the cutting direction is set to FORWARD and the cutting speed is set on the FASTEST setting. For safety NEVER, NEVER, NEVER use shop rags of gloves.

FILE - Filing is used to remove sharp edges or burrs that are a dangerous when handling you part. Removing burrs also allows your parts to fit together properly.

PRESS FIT - Two parts are held together by friction. In the example of the clock: the long bearing (0.375") and the short shaft (0.250") are pressed into the holes in the Upright (0.374" and 0.249"). To press fit these parts together you must first create a precision hole using a reamer.

REAMER - Used to make a precision size hole. Reamers usually come in three sizes. On size (example: 0.125", 0.250", 0.500", etc.), over size: (example: 0.126", 0.251", 0.501", etc.), and under size (example: 0.124", 0.249", 0.499", etc.). Reamers are used in the drill press on the slowest machine setting and the part is held by hand against the bed of the machine. A precision hole is needed when you press fit two parts together. Reamers do not drill holes. You must first drill a hole that is 0.010" to 0.020 smaller then the size of the reamer with a drill bit..

SCREWS - Are a type of threaded fastener that come in different lengths, diameters, and types of heads. They fasten or hold together parts. In the Design Studio we use #4-40, #6-32, #8-32, and #10-32 screws the ran in length from 0.500" to 2.000". For example: The #6 in #6-32 refers to the diameter of the screw (witch is a reference to the wire size that the screw was made from) (smaller number - smaller diameter) and 32 witch refers to the number of threads per inch.

TAP or TAPPING - Is the process by witch threads are created in a hole. A tap looks like a cross between a drill bit and a screw. The size of the hole must match the size of the desired tap size. The correct hole size can be found on a chart or on the drill and tap holder in the Design Studio. In the example of the clock: the Upright comes with two 0.123" diameter holes towards the bottom. A 0.123" diameter holes is the size that is needed when you create threads using a 8-32 tap.

THREADS - They come in two main standards: English and Metric. In the Design Studio we use English sizes. The thread sizes that we use in the Design Studio are: #4-40, #6-32, #8-32, and #10-32. For example: The #6 in #6-32 refers to the diameter of the screw (witch is a reference to the wire size that the screw was made from) (smaller number - smaller diameter) and 32 witch refers to the number of threads per inch.

UNDER SIZE - The size of the hole is under a common hole size (example: 0.125", 0.250", 0.500") by one or two thousands (example: 0.124", 0.249", 0.499").