English Sizes:

Our 5-40 English taps are GH2 and GH3. You can purchase 5-40 taps just about anywhere but these are GH (Ground High) sizes. The GH2 is within tolerance so it is a true 5-40 tap but it has been selected out because it is on the heavy side of the tolerance. It is .0005" (half a thousandth of an inch) larger in pitch diameter than an exact 5-40. The GH3 is a full thousandth of inch larger (.001").

These are very small increments but they make an important difference in how smoothly the screw and eyelet work together. Both of these size taps are important and are good to have on hand to re-tap eyelets that are sticking and not feeding correctly. The GH2 is also good for tapping eyelet blanks that have no threads as yet.

It is best to use the GH2 when tapping a new eyelet or in re-tapping an eyelet that is just a little too tight. The GH3 should be used if the eyelet is still too tight (binding or not traveling smoothly) after the GH2 has tapped or re-tapped your eyelet. It is best to have one of each in your tool chest.

Metric Sizes:

These metric taps are very difficult to find and we actually had these made for us because they are otherwise unavailable. These are standard metric violin bow eyelet thread sizes of 3mm X .7 and 3mm X .75.

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