How do YOU find the hole?

C'mon guys, how can you do this to me? I ask an "honest" question and these are the responses i get??? : )

Honestly though, i've got a couple tables here that i need to get set-up. With 6 different linear tracker's, i've not lost the faith. These tables aren't for me hence the "back-sliding" into pivoted arms. As such, i need to know what type of "universal" tools work most effectively at finding the right spots to drill various arm / table combo's. I'd like to keep something on hand just in case something like this comes up again. At the same time, i don't want to spend more than i have to as i don't intend on doing this on a regular basis. Know what i mean ??? Sean
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I like to let the hole just find me.

Aw, c'mon Sean, that one was just too easy the way you asked!! Whady'a expect man?

Marco

Sean,

You need access to a drill press. As mentioned above Forstner bits are preferred. It's been my experience that these bits bore perfectly from the top BUT clamp the piece securely to another piece of sacrificial wood on the bottom for the bit as it exits the armboard. This will eliminate any chance of splintering. A single Chinese bit will cost about $10 but an entire set can be had for around $25. They are available in English and metric sizes. Buy the right one and you will save yourself the trouble of having to sand the hole by hand for final fit. Oh yeah, drill a small pilot hole first.

I've got Forstner bits and a drill press, but i need to know how to locate the correct location for the hole. Sean
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Sean...I know that I have seen writeups on all the angles and forces involved with a pivoting arm. In fact a lecture I went to about how to set up a pivoting arm is what convinced me to go to linear tracking. It is impossible to get everything right across the recorded range of the LP.

If I had to do it....I would set the tracking angle so that it is correct at the midpoint of the LP recorded range. To accomplish this:

1. Make a template of the plan view (looking down) of the arm. The pickup is mounted at an angle on the arm, or the arm has a bend in it.

2. Put the template on the armboard with the stylus point at the radial distance from the turntable spindle that corresponds to the midpoint of the recorded area.

3. Draw a line tangent to the groove at the point where you located the stylus. This is orthogonal to the radius out to that point.

4. Pivot the template around the stylus point until the arm pivot point lies on the line which you drew.

5. Drill away.

You might want to compare an existing deck (that you know is right) to what my method would yield.

It might theoretically be slightly better to set things up for a point nearer the end of the recorded area, on the basis that things get tough for the pickup towards the inner grooves, and it might help to have tracking angle more optimum at that point. However, I don't think that there would be any significant improvement by doing this.