Alulu Tenor Ukulele Kit Build

Pete Howlett said:

I am unclear what's going on here and the advice being given. From the nut to the 12th fret x 2 is the scale length. The string length is usually longer than this and as someone who achieves good if not excellent intonation I can affirm that the stew mac compensation is not quite correct.

On my bridges, from the front of the 3mm saddle slot to the leading edge of the bridge is 2.8mm. Add 2.8mm to 1.5mm (the centre of the saddle slot) and you get 4.3mm which in my experience is too much compensation. What I do is make a line perpendicular to the centreline 432.5mm from the nut. This is where I place the leading edge of my bridge. Intonation is near perfect with this amount compensation. I find it easier and much more logical to work to edges I can see rather than those I cannot.

I hope you find a way to get this right as there is nothing worse than a ukulele tuned re-entrant that doesn't intonate past the 5th fret!

Click to expand...

Thanks for your input Pete. Just to be clear, your saying that you place the leading edge of the saddle at 432.5mm for a nominal 432mm scale length when using a 3mm saddle thickness. Is this correct?

I had been concerned that the stewmac compensation was a fraction long myself but I didn't have any good data to challenge the stewmac recommendation with.

No and I don't think I made it quite clear:

• 217mm x 2 = 434. This is MY scale length
• 2.8mm from the front edge of the bridge is the front edge of the saddle slot
• My saddle slot is 3mm wide therefore its centre is 1.5mm from either long edge
• 4.3mm is too much string length compensation
• My compensation that works for me and the Worth browns I use is 3.3mm

Pete Howlett said:

No and I don't think I made it quite clear:

• 217mm x 2 = 434. This is the scale length
• 2.8mm from the front edge of the bridge is the front edge of the saddle slot
• My saddle slot is 3mm wide therefore its centre is 1.5mm from either long edge
• 4.3mm is too much string length compensation
• My compensation that works for me and the Worth browns I use is 3.3mm

Click to expand...

Thanks Pete. Stewmac are quoting 434.55mm +/- 0.5mm at the string BREAK point as the correct compensation for a nominal scale length of 432mm so thats roughly in the range of 2 to 3mm. Your going a fraction longer not shorter than stewmac recommends.

Because my scale length is 434.... Compensation is anywhere between 2.8mm and 3.5mm with this scale length. It's not a science. I have found what works for my scale lengths by trial and error.

Thanks, I'll take onboard your info and carefully measure again.

Having just taken accurate measurements, I came up with the following :- scale length 424mm
front of saddle slot to leading edge of bridge 4.28mm
Width of saddle slot 3mm
1.5mm centre of saddle slot
5.23mm compensation?

To me that sounds as a bit too much. I add between 2.5 and 3.5 mm to my scale lengths to get great intonation.

Also I get a bit confused by your measurements, sorry. I will write what I would do if I was to do your job. Please don't think I'm being patronizing.

1. Carefully measure the distance from the face of the nut (the end of the fretboard) to the middle of the 12th fret (the crown of the piece of fretwire).
2. Multiply that distance by 2 and write it down as the scale length.
3. Measure from the face of the nut to the middle of the saddle slot in the bridge. Write down that measurement as your string length.
4. Subtract the scale length from the string length. You should end up with 3.5 mm.
5. Since the saddle slot is 3 mm you will have the possibility to file the saddle and get a compensation for each string anywhere from 2.0 mm to 5 mm if you need that much.
6. If you get another number in step 4, re-position the bridge to get the center of the saddle slot where you need it.
(7. I would also enter the scale length from step 2 into the Stewmac fret calculator and check all the fret locations.)

Note that no measurement is taken to any point on the bridge itself. I would only measure to the saddle slot. The bridge could have any shape or dimensions.

Best of luck / Sven

Many thanks Sven, I'll start measuring....again.��

This is what I've come up with:-
Nut -12th fret 212mm x2 =424mm (scale length)
String length 427mm
Subtract scale length from string length = 3mm
Stewmac fret to fret calculator shows each fret at the correct distance. Will I now have to move the bridge?

I wouldn’t move the bridge then. I would finish the build and make some music.

Thanks Sven and all the other contributors. I now have buzzing on some of the strings, so now on to solving the next problem.