How the Universal Guitar Fret Slotter Works

The system used to give the accuracy is the Vernier rule. A long accurate steel rule has a small engraved Vernier that slides alongside the main scale.

Current setting shows a reading of 379.2 mm
This is attached to the high quality brass guides, so the measurement is immediate.
The guides sit on a threaded carriage and is locked in position when the exact measurement is reached by using the hand-wheels.
The work is held in position by simply fixing it to the location board with two small wood screws from the rear which itself is then fixed to the slotter with two thumb screws.
Now the saw with its own brass slides, that also controls the depth of cut, is placed between the guides and the slot of 0.023 inch width is cut in the finger board.   Shown cutting a 14 inch scale length finger board for a mandolin.

How accurate is the Fret Slotter?

The slotter uses a metric scale (Though an imperial inch system is also currently being developed) with the main rule measuring whole millimetres. The Vernier measures to the nearest 0.1 mm (0.0039 inch). But the claim is to get well within 0.1 mm (0.004 inches). And has the potential to be within 0.05 mm (0.002 inches). So how is this achieved?

The fret calculator rounds up or rounds down to the nearest 0.1mm. For example, from a 14 inch mandolin scale length, the first fret position is 19.96mm: the calculator rounds this up to 20.00 giving a discrepancy of 0.04mm which is 0.0016inches. The tenth fret position is 156.01: the calculator rounds this down to 156.0 giving a discrepancy of 0.01mm which is 0.0004inch. The ninth fret position is 144.15: The calculator rounds this up to 144.2 which gives a discrepancy of 0.05 which is 0.00197 inch. So it is possible in the worst case to measure to within 0.002 of an inch. Even allowing for a slight miss-sighting of the Vernier of say 0.001 and thermal expansion of +/- another 0.001 inches giving a total of 0.004 inch discrepancy, this still falls within the tolerances claimed by the hole plate guys.

Disclaimer: The above accuracy can only be achieved provided the user follows the easy to use instructions. However, once familiar with its use, the Slotter gives the great consistency.

Quick, simple and easy to use!

Once familiar, a fingerboard is usually cut in around 10 minutes. Necx Products have found that the best way to avoid measuring errors is to mark the scale length to the nearest whole millimetre on the steel rule with a spirit based marker. This then only leaves the Vernier to be set to one place of decimals from the chart. It’s very simple and easy to use. The marks are removed with a solvent such as cellulose thinners ready for the next scale length.
Fret Slotter Accessories Make your OWN Hole Plates! If you decide however that you prefer to use a hole plate system, accessories can be purchased to allow you to drill your own custom hole plates. This includes an accurate hardened steel drill bush and screw that locate in the side of the carriage block.
Brass bar is screwed inside the channel and drilled after accurately setting and locking the vernier scale to the correct position. An ordinary pistol drill is used, but the drill bush guide is what gives the great accuracy.
The drill bush is then replaced by a highly accurate locator pin.

Additional uses

The Necx Fret Slotter can be used also to cut evenly spaced linings for acoustic instruments. By drilling two holes in the side of your own tenon saw, the brass slides attached to the fret saw can be swapped to the tenon saw so that wider slots can be cut.

Coming Soon

How to machine a highly accurate finger board radius in less than two minutes! This can be done in your garden shed! Honestly. Look for the article and drawings will be for sale.