Tech Tips Index

RASK CYCLE  TECH TIPS

DRILLING AND TAPPING

Anyone who works on their own motorcycle, sooner or later will have to drill a hole in something. while it sounds pretty simple, there are a couple of things to consider.

Number one, most important item is a SHARP drill bit. It is unbelievable the difference that a sharp bit will make. Drill bits are fairly cheap, especially the smaller sizes that are need for motorcycle repair. so if you are having trouble drilling a hole in something, the first thing you want to do is, make sure that you are using a bit with a good cutting edge. If you are not sure, go buy a new one.

Second thing, is to use some type of cutting fluid. There are many different brands on the market, but we usually use tap magic. Some cutting fluids are made specifically for certain metals, so make sure you are using the proper fluid for the type of metal you are drilling. Before you attempt to start drilling a new hole, ALWAYS center punch the material you are drilling to keep the drill bit from walking around all over the place when you are trying to get it started. If you can't get a good indentation in the material with a center punch, then the metal is probably too hard to drill and you will only screw something up if you keep trying. this is especially true when trying to remove broken bolts. It usually cost much less to pay someone with the proper equipment to remove a broken bolt than it does to pay them to remove a broken drill bit or broken tap and repair the extra damage caused by a drill bit walking off center or an unlubricated tap breaking off inside of a hole that has been drilled to the wrong size, then had a drill bit run in beside the tap and broken off in a half-assed attempt to remove it.

Threading holes requires 3 things to do it right.

Check the chart below to find the right size drill bit to use with the tap size you are working with. Taps come in sets of 3. the proper way to use them is: 1) Drill the proper size hole. 2) Using the #1 or starting tap (the one with the most taper) Start the threads about a turn and a half, add some cutting fluid, then run the tap in a couple more turns. then you want to back the tap back out about half to a full turn, this breaks the chip. run the tap in a couple of turns then back it off again. do this until you have reached bottom or have gotten the desired length of thread. don't forget to add fluid as you go. Repeat this operation with the second (#2) tap, (the one with the medium amount of taper), then finish with the bottoming tap (#3), the one with almost no taper.

One other thing: Its is a lot easier to run a tap straight with a tap wrench than a adjustable wrench. When you break off a tap because you insisted on using a adjustable wrench or a pair of vise grips, remember I told you so!

DRILL EQUIVALENTS (Decimal)

TAP DRILL SIZES

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04/06/07
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