Taps/Easy outs

Then there's a style of tap that the flutes look like a drill, and spiral up around the tap. These are designed for machine tapping, and require proper conditions for it, and I've found are also prone to breaking if not used right.

The style that I prefer, and would suggest to most of you, is usually a 2 flute, with a 'spiral point'. These seem to be the strongest, as they have the most material through the cutting area of the tap. One thing with these is that they are really designed for through holes, as they push the cuttings ahead of the tap. In blind holes, which is what we are dealing with a lot of the time, you can still use them, but, you need to back them out often and blow the chips out.

Someone also asked where to buy good taps and left hand drills and the like. Especially with left hand drills, you will have to go to an industrial supply house that sells cutting tools to the machine shops. I'm sure there are some available online, maybe someone can post some links for us. If there are a few machine shops in your area, there will often be a small supplier that may have them in stock, or can order them.

Left had drills were originally used for 'screw machines', they could drill while another operation was being performed at the same time. (They can also do it with right hand drills, but sometimes the spindle is reversed for certain operations.) As more and more computer operated equipment is in use, I would hae to guess that the demand for left hand drills is dropping. Been a while since I saw prices on them, but, last I recall, they seemed to be 2-3 times the price of the same size rh drill.

Mark

Hey, isn't that why we have discussion forums like this? To help share our knowledge and experiences?

Mark

When you go to drill a hole that you want to thread, there is a specific size of drill required depending on the thread size (diameter) and pitch (TPI, or threads per inch on standard imperial threads).

I'm sure that most of you have done a bit of wrenching on the tractor, or car, or whatever, and have realized that most bolt sizes can be either a fine, or coarse thread. The tap drill sizes for those 2 taps WILL be a different size. There is a whole bunch of math you can do to figure out the size, but, the easiest way is to look it up in a tap drill chart. If you go to an industrial supplier, they often have these charts available for you, often free. Get one, and make use of it. I also found a good one on the net, the link is below. If you only have a basic set of drills, here's another bit of advice....when you go to buy a tap of a certain size, buy a couple of the right size drills for that tap, and keep them all together. That way you won't have to look it up each time, and they be together when you need them.

Another thing that I would recommend that you guys get, is a variety of 'centre drills'. These are little short stubby drills with a small pilot on them, and they are designed to start a hole for the drill to follow. Tired of having a drill wander around when you go to drill a hole? Centre punch it, then use a centre drill to get started. They are strong enough that they won't generally break if you put some sideways pressure on it to get a hole started where you want it.

Mark

• tap drill chart

scott#2

You're also right, thay are not for use in steel or cast iron, I believe they only work in non-ferrous metals, such as aluminum and zinc. I don't know if they work in brass or opper, I can't recall seeing them used, but maybe with the right applications they can be.

Mark

Thanks for the posts, informative as usual. :>)

scotty

scotty

Mark

Mark

• Link

Mark