Saddle position

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Redbloke1956
Wandoo
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Joined: Tue Jul 16, 2019 8:49 pm

Re: Saddle position

Post by Redbloke1956 » Mon Aug 31, 2020 10:55 pm

Thanks all for helping a newbie, I ended up shaving a couple of mm off the top of the bridge, plugged holes 1 and 6, put a thicker piece of Rosewood on top of bridge then redrilled holes with 1 and 6 aligning with 2 and 5 respectively. A little tidying up still to do, very happy so far.
Thanks again from a very relieved amateur 🤙
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Mark McLean
Blackwood
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Location: Sydney

Re: Saddle position

Post by Mark McLean » Tue Sep 01, 2020 6:10 am

Looks like you have arrived at a solution. Well done,

Redbloke1956
Wandoo
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Re: Saddle position

Post by Redbloke1956 » Tue Sep 01, 2020 12:12 pm

TOTALLY confused now, I have read everything I can find on positioning of the saddle and still don’t get it.
This is my first build and I am following (what I can) the Gore/Gilet build book.
I have gone with:
Steel String
Scale Length 645.2 mm
Falcate Braced
Bolt on-Bolt off neck
Saddle only Compensation (therefore nut to 12th fret is 645.2 / 2 = 322.6mm)

Not fully understanding compensation, I can’t figure out:
Wether I need a 3mm or 5mm saddle,
Wether I skew the saddle at an angle to forward edge of bridge
Distance from UNcompensated nut to leading edge of Bridge

Section 20.3.1 states: ”For a saddle-only compensated steel string guitar allow 3mm for compensation plus an additional 0.5mm for structural deflection (3.5mm total).
Add this amount to the scale length and the total is the distance between the nut end of the fretboard and the front face of the saddle slot on centreline of the guitar” and then the 2.5mm skew is applied.

Have I missed something or is this all I have to do to determine saddle position?

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lamanoditrento
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Re: Saddle position

Post by lamanoditrento » Tue Sep 01, 2020 2:07 pm

So I think you are pretty much there.

322.6 + 3.5 = 326.1mm from the centre of the bridge to the 12th fret. I would put some tape on the bridge and mark that position perpendicular to the centre line. Then mark the low e string position on that line and measure and mark 1.25mm behind the line. Then mark the position of the high e and mark 1.25mm in front of the line. Now join those to lines up and you have your skew angle for the front of your saddle.

For normal compensation you do not need a 5mm saddle slot but if you got one, no harm.

Normally I would like the front edge of the bridge to be 5mm from the centre of bridge.

So, SL 645.2 + compensation 3.5 - 5mm = 643.7mm from the nut or 321.1 from the 12th.
Trent

Redbloke1956
Wandoo
Posts: 16
Joined: Tue Jul 16, 2019 8:49 pm

Re: Saddle position

Post by Redbloke1956 » Tue Sep 01, 2020 3:06 pm

Hi Trent,
Sorry mate I am not quite following this
“ Normally I would like the front edge of the bridge to be 5mm from the centre of bridge.”

And also this
”So, SL 645.2 + compensation 3.5 - 5mm = 643.7mm from the nut or 321.1 from the 12th.”
So, Is the measurement from the 12th fret to the front of the saddle 321.1 or 326.1?
Maybe I’m not reading this right🤦🏻‍♂️🤷‍♂️

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Mark McLean
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Location: Sydney

Re: Saddle position

Post by Mark McLean » Tue Sep 01, 2020 9:45 pm

Since your bridge is already glued on, I suggest you now only need to concentrate on where the saddle needs to go. The calculations that you make will indicate the position of the front (soundhole side) of the saddle slot. This calculation is as mentioned before. The books give a method of calculating your scale length (we have already determined that for your guitar this is 645.2mm), then adding say 3.5mm for compensation (648.7) and saying this will be the position for the saddle in the midline of the guitar. The saddle will actually be slanted so that the 1st string will have the saddle 1.5mm shorter than this length (which is the same as scale length +2), and the 6th string 1.5mm longer than this length ( which is the same as scale length +5). The slot is not parallel to the front of the bridge.

Remember that this is the front edge of the saddle slot. The next question is how wide to make the slot. Most steel string guitars have saddles of 1/8 inch or 3mm - but this is totally arbitrary. Some people use wider saddles, even up to 1/4 inch (6.25mm) and shape it from a bone blank. You can buy pre-shaped saddles in tusq or bone or plastic, like this sort of thing, which have compensation built in to account for the difference between the top two plain strings and the other four wound strings. These things are usually 3mm or 1/4” wide.
F9C1DD25-79CD-49B4-B324-44B58665EADD.jpeg
You mentioned using a 5mm saddle. That is OK, but is wider than you need. A wider saddle is useful if you are anticipating tricky compensation adjustment - like you might have with a multiscale guitar or unusual gauge strings. But you probably don’t need that. Your simplest option is to route a 3mm or 1/4 inch slot and use one of those prefab saddles. Be aware that a 1/4 inch router bit tends to make a slot a tad wider than 1/4 inch and you can then find your saddle is a bit loose in the slot. It is better to have it slightly too tight. It is easy to rub your saddle on some sandpaper laid flat on the bench and make it a bit thinner to fit a tight slot.

When Trent mentioned measurements from the front of the saddle to the front of the bridge (ideally at least 5mm) he is meaning that it is not good if your saddle slot ends up too close to the front of the saddle. However, you are not going to have that problem. Quite the opposite - we started this whole conversation because you realized that your saddle will be positioned further back than you expected. I am sure you will have more than 5 mm of bridge timber in front of the slot - which is what you want.

The final question is how deep to make the slot? You want the slot to be at least 4mm deep to give the saddle stability, as the strings will be trying to tip it towards the soundhole. Also, the top of the saddle needs to be about 5mm above the plane of the frets (which is indicated by the straightedge in your photo), to give appropriate string action, and also a decent break angle over the saddle. This is why most of the preformed saddles are about 9mm tall, on the assumption that the correct neck angle will result in a fret plane that lines up with the top surface of the bridge. If your setup requires something a bit taller you can add a shim of hardwood to the bottom of the saddle.

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TallDad71
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Re: Saddle position

Post by TallDad71 » Mon Sep 07, 2020 3:40 am

One other idea for getting the saddle in the right place is to build an intonator like this one from Stewmac.
A bit of Brass block and some
M3 SCREW DOOR HANDLE Brass Chrome Connecting Sleeve Screws / Bolt Roses Knobs

Cost nothing. Bit of work with a drill hacksaw and pliers soon had it done.

https://www.stewmac.com/luthier-tools-a ... nator.html
Alan

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