Question re: setting compensation with Stewmac Saddlematic

[nkwak]

A friend lent me his Saddlematic and another made me a bridge with a 1/8" precompensated saddle and I'm still confused. I've figured out the centerline of the fingerboard (which is off by 1/64" from the centerline of the body but I can live with it) and have been poring over the instructions at Stewmac and through searches I've done here regarding compensation.

Since the bridge is preslotted I'm operating under the assumption that figuring out the appropriate scale length of the low E is a moot point but I set the pins on the saddlematic regardless. So instead I'm trying to wrap my head around where the front of the saddle slot should be.

Bear with me since I often miss the obvious like a fish misses water but tool is to be adjusted so that the block rests against the end of the saddle and sits on the 12th fret, then I turned the whole thing around 180 degrees to get the ball-park scale length. Since my bridge is preslotted am I correct in assuming that it's safe ignore the front edge of the bridge and set the pin to project about 5/64" beyond the edge of the tool in order to properly position the front of the saddle slot at the high E?

[tippie53]

Here is a video on setting a bridge.
The perfect set up on a new guitar should be about 3 cents flat. As the guitar takes the stress the bridge will rotate forward and it will fall in. If you set up dead true the guitar will go sharp. While I like jigs, this is one thing that I like to trust measurement on.

[Kevin Sjostrand]

Neil,
I have and use the Saddlematic for all my guitars. I will probably have to look at the instructions, but if you set the pins out from the block the amount of compensation for both sides, then you want the pins to fit against the front inside edge of the saddle slot. What I don't remember is what those measurements are. 3/64" for the treble side, and 5/64" for the base sounds right, but I'm not sure. I use a 1/8" thick saddle.

Here are some instructions from the Stewmac site.
Kevin



Locating the saddle slot on steel-string acoustic guitars
The distance from the nut to the saddle is approximately twice the distance from the nut to the 12th fret. Installing the saddle at precisely that point is incorrect, though, and will give you poor intonation. You must add a little more string length for the guitar to play in tune. This added string length is called compensation.

For compensation, a guitar's bass strings need more length than the treble strings. This difference between bass and treble compensation is why steel-string guitar saddles are installed at an angle.

The two pointers on the Saddlematic record the bass/treble compensation, and mark the proper location and angle of the saddle slot. To set the correct intonation, you must be very accurate in adjusting and locking the position of these pointers.

For a 3/32"-thick saddle, the pointer for the treble strings should be set to measure exactly 1/16" (.062") from the body of the tool. The bass pointer should be set for 5/32" (.156"). With these settings, the pointers will indicate the location and angle for the front edge of the saddle slot, not the center of the slot. Marking the front edge means that you won't be removing the reference line when routing the slot.



Be precise: after tightening the set screws holding the pointers, double-check your measurements.

These measurements provide compensation appropriate for both short-scale and long-scale steel-string guitars (24-3/4" to 25-1/2" scale lengths). In theory, there's a difference between settings for short and long scales, but the difference is so tiny that it's impractical to adjust to such tolerances (the short-scale settings would be .060" for treble and .150" for the bass side).

If your saddle width is not 3/32", adjust the pins to take this into account. Example: A 1/8" saddle is 2/64" wider, so set the pins to place the front of the saddle 1/64" closer to the nut. (The back will be 1/64" closer to the bridge pins.) This keeps the center of the saddle in the same position for good intonation.

Tip: Place masking tape along the front edge line, and then locate a second piece of tape at the back edge of the slot to be routed. It's easy to follow your routing progress with the tape marking the front and back edges of the saddle slot.

[nkwak]

OK, so then the pin for the high E should actually be 3/64" from the edge of the tool then, not 5/64". My bad, I added when I should've subtracted. The problem is that those pins are hard to position with accuracy, though. I'm closer than I thought but I figure I'm still probably over by .003" but my eyes are crossing.