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| Author: | Dave Livermore [ Mon Jul 13, 2020 8:25 am ] |
| Post subject: | Saddle compensation |
I’m curious how much compensation many of you build into your bridges. Using various calculators around the google, and reading different texts, I find that the recommendations vary widely from 2.5 to 6mm on the bass side of a 25.4” steel string with light gauge strings. Please share your data Thanks, Dave |
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| Author: | Mike Collins [ Mon Jul 13, 2020 8:57 am ] |
| Post subject: | Re: Saddle compensation |
2mm for high e 2.5 for b 1.5 for g 1 for d 3 for a 3.5 for e String height also plays a factor. Usually more comp. is needed for higher action. This with a 3mm saddle width. Mike |
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| Author: | jfmckenna [ Mon Jul 13, 2020 9:09 am ] |
| Post subject: | Re: Saddle compensation |
I slot the bridge at a specific angle and then place it .1in further then the scale length and it comes out perfect every time. Well, we all know it's never perfect but it's so close that even the professional musicians that have my guitars don't complain about it 
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| Author: | Colin North [ Mon Jul 13, 2020 9:10 am ] |
| Post subject: | Re: Saddle compensation |
I've used the SM calculator and have not had any problems, at least with light gauge strings and a reasonable action. |
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| Author: | doncaparker [ Mon Jul 13, 2020 9:32 am ] |
| Post subject: | Re: Saddle compensation |
The StewMac fret calculator is always a good resource. |
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| Author: | bcombs510 [ Mon Jul 13, 2020 10:25 am ] |
| Post subject: | Re: Saddle compensation |
Anyone used this? https://www.liutaiomottola.com/formulae ... sation.htm I used it on the last few (3 ukes and 1 guitar) and they turned out well. I used the calculator to establish the angle on the 6 string and then fine tuned the saddle. On the ukes it was helpful because one was low g and one was high g and the calculator accounts for that. Sent from my iPhone using Tapatalk Pro |
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| Author: | Terence Kennedy [ Mon Jul 13, 2020 4:29 pm ] |
| Post subject: | Re: Saddle compensation |
I just use a 1/8” drop back on the saddle from treble to bass. 1/8” saddle and mark compensation points with the bent unwound part of a low E string after the guitar is set up with appropriate action and strings. For bridge location I put a StewMac straightedge against the nut, Mark the center of 12 with a pencil and a second mark downstream in the appropriate location. Typically around 0.12” or so measured in the midline. Works for me. To rout a slot on the guitar with a new bridge I have a crowned 1/8” metal bar 1/8” high to use for a surrogate saddle and when the two e’s are right I mark it and that’s where I cut the slot. I am sure there a lot of more elegant methods out there. |
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| Author: | Colin North [ Mon Jul 13, 2020 5:51 pm ] |
| Post subject: | Re: Saddle compensation |
[quote="Terence Kennedy"...................... To rout a slot on the guitar with a new bridge I have a crowned 1/8” metal bar 1/8” high to use for a surrogate bridge and when the two e’s are right I mark it and that’s where I cut the slot......[/quote] Much the same here except I use hard maple, touch of CA to hold it in place and then ihat routs off when cutting the slot. |
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| Author: | bluescreek [ Mon Jul 13, 2020 6:13 pm ] |
| Post subject: | Re: Saddle compensation |
I will make this short EACH GUITAR IS DIFFERENT there actually the best thing I can tell you is to make a model of a neck put a fret board on a 2 by 4 and make a saddle movable you only need to do one string at a time, The variable of this are Gauge Height neck relief it is about the string and the fret plane the higher your action and more neck relief the more compensation you need. I learn formulas don't work as they don't take into consideration these variables. once you male this thing and play with if you will see the point on intonation. the higher up the neck the more important this can be. I can't tell you what you need no one can with certainty you have to figure this out for yourself. I personally allow .1 in compensation length then work the saddle for each string once the guitar is set up. I use 5 7 9 and 12 and adjust for the best at those points. I also use some nut compensation as well. |
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| Author: | Alan Carruth [ Wed Jul 15, 2020 2:55 pm ] |
| Post subject: | Re: Saddle compensation |
I made up a similar device, but a bit more complicated, to determine the correct compensation for the nut as well. Fretting the strings makes all the fretted notes go sharp. You can get the lower fretted notes to play in tune by moving the frets closer to the nut, but rather than figure out how far to move each fret it's easier just to shift the nut forward, toward the first fret. This reduces the need for saddle compensation, so you actually have to do both at the same time. Trevor Gore goes into this in detail (with equations!) in his book. You can get most guitars 'arbitrarily close' to perfect intonation on every note this way, but it's probably not possible to get to perfect. For one thing,the bridge is glued down to a top that's moving more at some pitches than others, and that messes up individual notes. |
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| Author: | jfmckenna [ Wed Jul 15, 2020 3:33 pm ] |
| Post subject: | Re: Saddle compensation |
I forgot, I move the nut forward to the first fret too. How much do you guys who do that move it? I simply cut the zero fret nut face end of the FB with my fretting saw so it's about half a saw kerf forward which is about .012in. EDIT: and when I started doing that I wondered how to measure compensation. Do you take half the scale length and add to that or do you measure from the nut face to the 12th fret which now is a hair shorter and add to that? I have done the former. |
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| Author: | Terence Kennedy [ Wed Jul 15, 2020 4:43 pm ] |
| Post subject: | Re: Saddle compensation |
I move the nut forward the usual 1/2 the kerf of the fret saw or about 0.012 and measure to the center of 12 and add my compensation to that. |
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| Author: | bluescreek [ Wed Jul 15, 2020 5:10 pm ] |
| Post subject: | Re: Saddle compensation |
my allowance is about a .030 slant to the bass side that gives me a bit of room to intonate the nut in the 1st position Alan I would love to hear what you are doing. |
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| Author: | Colin North [ Thu Jul 16, 2020 9:22 am ] |
| Post subject: | Re: Saddle compensation |
Just reread this thread and it prompted me to tune up and check the intonation on my last OM as I do things a bit weird these days. Intonation at nut, 1st and 12th fret are good, within ~1 cent everywhere, so it seems to be working. |
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| Author: | jfmckenna [ Thu Jul 16, 2020 10:33 am ] |
| Post subject: | Re: Saddle compensation |
So just to be clear I will use easy fake numbers. Say your scale length is 100mm. You cut the end of the fretboard 1mm shorter to compensate the nut end. and on the saddle end you will compensate with 3mm If you then measure from the nut face to the 12th fret you now have 49mm. So to compensate the saddle you would measure from the 12th fret to the saddle center 49mm + 3mm for compensation = 52mm OR You take your 100mm scale length in half 50mm. So to compensate the saddle you would measure from the 12th fret to the saddle center 50mm + 3mm for compensation = 53mm ? |
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| Author: | Colin North [ Thu Jul 16, 2020 10:39 am ] |
| Post subject: | Re: Saddle compensation |
jfmckenna wrote: So just to be clear I will use easy fake numbers. Say your scale length is 100mm. You cut the end of the fretboard 1mm shorter to compensate the nut end. and on the saddle end you will compensate with 3mm If you then measure from the nut face to the 12th fret you now have 49mm. So to compensate the saddle you would measure from the 12th fret to the saddle center 49mm + 3mm for compensation = 52mm OR You take your 100mm scale length in half 50mm. So to compensate the saddle you would measure from the 12th fret to the saddle center 50mm + 3mm for compensation = 53mm ? Introducing nut compensation reduces the requirement for compensation at the saddle. Nut compensation is introduced to correct intonation on the lower frets, but will lower the note at the 12th fret, so saddle compensation will need reducing. |
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| Author: | Tim Mullin [ Thu Jul 16, 2020 11:58 am ] |
| Post subject: | Re: Saddle compensation |
The topic of compensation has been here many times. If you want a thorough treatment, then certainly Gore/Gilet discuss various approaches for both steel string and classical guitars. I recommend these books strongly. For my classical guitars, I follow the Gore/Gilet methods for empirical intonation, including the optimization of intonation across all frets. I prepared a calculator that uses this approach with Excel. You need to load the Solver Add-in. I can email the example shown in Gore/Gilet Design page 100-103 to anyone who asks. Classical strings vary tremendously, so you need to do this with a target brand and gauge, but know that intonation will likely change with a different string type. For steel string guitars, I find the StewMac calculator works pretty well for standard tuning and scale lengths. I prepared my own "neck specification" calculator that includes a compensation calculator that reproduces the SM factors for saddle compensation, but also gives me control over simple nut compensation and saddle thickness: https://www.mullinguitars.com/calculating-guitar-fret-spacing-fingerboard-dimensions-and-string-setback.html Things are more tricky when you try to work out compensation for other scales and tunings. As John stated, every guitar is different -- and every string! Brad gave a link to a very good online calculator by Liutaio Mottola. I tried to adapt the the Mottola calculator for a fanfret baritone and got frustrated with the fact the the internal operations aren't transparent. Instead, I adapted the work of Saajk Elmendorp (2010: American Lutherie 104: 56-60) and made my own spreadsheet. His calculations do work, but you will need to generate some specifications for strings that are not readily found on packages or online, including tension, core diameter and weight per unit length. I found I could start with data published by D'Addario for their strings, sacrifice a set to get the weight data, and apply these under the assumption that other manufacturers strings will be ... similar. That's worked well for my baritones. Even better of course would be to build a neck mock up where tension can be measured for your particular string and scale. If you want to go to the trouble, my calculator is linked: https://www.mullinguitars.com/2015/10/compensation-calculator-for-steel-string-guitars.html |
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| Author: | Alan Carruth [ Thu Jul 16, 2020 3:18 pm ] |
| Post subject: | Re: Saddle compensation |
The amount of compensation you will need at either end depends on the strings, scale length, and action height, at least, so it's hard to give general rules. I generally cut the nut slot about 2 to 2.5 mm forward of it's 'theoretical' location, and use a somewhat wider nut to allow for adjusting the compensation later. As Gore points out, anything you do along these lines is likely to be better than doing nothing. One 'quick and dirty' method that works well: If you've only been compensating the saddle, try splitting the difference. Move the nut up toward the first fret by about half the amount you've been shifting the saddle back, and then shift the saddle half as far as you've been used to. One of my students came in with a modern reproduction of an Elizabethan 'bandora'; a sort of bass cittern with metal strings. It was very popular during the lifetime of it's inventor, and went out of use after that. Modern ones, based on wood cut illustrations and the like since there are no surviving originals, have terrible intonation issues, and this was no exception. The bridge had already been re-slotted once, and there was no room to move the saddle any further, so we thought we'd try the nut end. We played around a bit with toothpicks under the strings, and finally decided to re-cut the nut slot at slant of something like 5-6 mm from treble to bass. It worked very well. Several other of the local early music players have commented that it's the best bandora they've heard, mostly, I suspect, because it plays more or less in tune. Interestingly enough, when my student went looking for the old wood cuts, they all showed a clearly angled nut. I suspect that people making the modern copies thought: "That can't be right!", and cut the nut straight across. Maybe the old boy knew better. |
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| Author: | Ken Nagy [ Thu Jul 16, 2020 4:51 pm ] |
| Post subject: | Re: Saddle compensation |
I haven't REALLY done compensation, the arch top has the bridge you can easily file to correct; and I haven't noticed any problems with it since I made the new bridge that is set up for the nylon strings I have on it. I'm an easy customer. But I'm reading stuff to be prepared; some day I'll make a classical or a steel string with frets, and not moveable frets, and I'll need to know. The other day when I read about bridge rotation; something I STILL don't understand how you can measure something so small; I found this AWESOME beast. What do you call it when the scale is RADICALLY different from first to last string? Luckily it has a compensating bridge/saddle. A little of that might be interesting, but full out crazy is pretty outlandish. It does look cool. I bet it's heavy! Torzal natural twist. 15 degrees at the bridge, and 20 degrees at the neck, and the "fanned scale?" Attachment: Torzal_Guitars_Natural_Twist_Content_3.jpg
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| Author: | ballbanjos [ Thu Jul 16, 2020 5:14 pm ] |
| Post subject: | Re: Saddle compensation |
Making the most of some twisty problem wood? Nah--actually that's pretty cool. Really nice laminations. Dave |
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| Author: | Colin North [ Fri Jul 17, 2020 2:18 am ] |
| Post subject: | Re: Saddle compensation |
Ken Nagy wrote: I haven't REALLY done compensation, .................. I found this AWESOME beast. What do you call it when the scale is RADICALLY different from first to last string?................, and the "fanned scale?" Attachment: Torzal_Guitars_Natural_Twist_Content_3.jpg It's know as a Fan Fret, or multiscale. |
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| Author: | jfmckenna [ Fri Jul 17, 2020 9:17 am ] |
| Post subject: | Re: Saddle compensation |
Do you guys actually set up to a specific string set though? I've always figured an average is what we should be going for. If you set up someone perfectly for 11's what happens when they switch to 13's? |
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| Author: | Tim Mullin [ Fri Jul 17, 2020 9:52 am ] |
| Post subject: | Re: Saddle compensation |
jfmckenna wrote: Do you guys actually set up to a specific string set though? I've always figured an average is what we should be going for. If you set up someone perfectly for 11's what happens when they switch to 13's? All things being equal, heavier core strings will require more compensation. This becomes really obvious when you intonate heavy strings on electric guitars with adjustable saddles and run out of adjustment. Even same gauge strings from different manufacturers can have different core diameters, and hence different ideal compensation. Lesson of the day: 3/32” saddles on acoustic guitars are a bad idea. Sent from my iPhone using Tapatalk |
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| Author: | Dave m2 [ Fri Jul 17, 2020 11:33 am ] |
| Post subject: | Re: Saddle compensation |
Ken the way you measure bridge rotation is to fix a lightweight lever to the bridge, I use a length of 600 mm stuck with bluetack (poster putty, whatever), then keeping everything steady, drop the string tension and the ends of the lever move a few mms. Quite enough to measure. A bit of trigonometry gives the change in angle. You are looking for around 2 degrees on both SS and Classical. I find it useful as a test - obviously after completion- as to whether I got the stiffness of the top right. Like any beginner I overbuilt my first few. Cheers Dave |
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| Author: | Colin North [ Fri Jul 17, 2020 12:14 pm ] |
| Post subject: | Re: Saddle compensation |
Dave m2 wrote: Ken the way you measure bridge rotation is to fix a lightweight lever to the bridge, I use a length of 600 mm stuck with bluetack (poster putty, whatever), then keeping everything steady, drop the string tension and the ends of the lever move a few mms. Quite enough to measure. A bit of trigonometry gives the change in angle. You are looking for around 2 degrees on both SS and Classical. I find it useful as a test - obviously after completion- as to whether I got the stiffness of the top right. Like any beginner I overbuilt my first few. Cheers Dave I just use the inclinometer app on my phone and bluetack. Free and to 0.1 degrees. |
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