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scale length error
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Author:  Cablepuller [ Sun Apr 05, 2015 3:55 am ]
Post subject:  scale length error
Hi

Another newbie question again im afraid

I am building a OM guitar from grellier plans i got through

I was planning on a scratch build but decided to save time on the fretboard by getting it preslotted (the restof the order is just lumps of wood :/ )

Having got the fretboard it appears my measurements were slightly out to the plans
I should of ordered a 25" - 20 slot
But ordered a 25.5" - 21 slot (doh)

My question is can i still continue with this fretboard (moving the bridge position accordingly)
Also what would the difference be in ease of playing/action

Its not to late to return and order another if necessary

Thanks in advance :)
Author:  bluescreek [ Sun Apr 05, 2015 6:45 am ]
Post subject:  Re: scale length error
to make it easier I think you should return and stay as close to the print as you can. It is one less variable that you will have to work with. Getting the first one done is the hardest . You have a whole building process to learn.

If you decide to keep this one think of it this way. The bracing will move in relationship to scale length. So with you using this board you can cut off the 21st fret . Setting the 14th fret on the body line you know where the nut is, Once you know that you now know where the saddle should be. Therefore you know where braces should be moved to. It won't be much but bracing placement is also scale length oriented , and now you just move it accordingly. Also the sound hole should be set to the proper fit for the board.

You can now decide what will be best for you. Just think of it this way , the nut goes up and the braces and plate slide down to match the longer scale. Also the bridge will move to mate to the new scale length.
Author:  kencierp [ Sun Apr 05, 2015 7:20 am ]
Post subject:  Re: scale length error
I am thinking that the fret board needed for that design and drawing is actually a 24.9" (short) scale which is common on many OM (000) size guitars. When compensation is added you then have a total nominal scale length of 25" --- Many of the suppliers stock the normal 24.9" boards.
Author:  Clay S. [ Sun Apr 05, 2015 7:28 am ]
Post subject:  Re: scale length error
OM's originally were long (25.4) scale instruments. If you decide to use it you will gain a better understanding of how the components of the guitar work together by making the adjustments John has suggested. With a little head scratching and drawing the new positions of the bridge, bracing and soundhole on the existing body plan you will see what changes you need to make. There is some latitude in brace placement, so small errors are not fatal. Not moving the bracing and only moving the bridge down might give you something closer to "forward shifted" bracing, but drawing things out will help you decide.
As far as ease of playing, the longer scale will be a bit stiffer for a given string gauge, but the longer scale will allow you to use thinner strings to tune to the same pitch, so with a decent set up there shouldn't be too much difference in playability. The longer scale does require a greater stretch for some chords.
If you do decide to order another fretboard you could keep the long scale for your third guitar. [:Y:]
Author:  kencierp [ Sun Apr 05, 2015 8:00 am ]
Post subject:  Re: scale length error
Clay is correct - Martin's of all shapes originally were short scale. But they lacked the power and volume needed to compete with other instruments in a band. So across the board long scale (25.34) Orchetra Models were introduced. Today the OM nomenclature is common for the 000 14th fret style guitar shape but even Martin offers that size and shape in both long and short scale versions.
Author:  Bryan Bear [ Fri Apr 10, 2015 2:27 pm ]
Post subject:  Re: scale length error
The Greiller plan is long scale. Actually it is listed as 645mm (25.3837"). make sure you measure the scale of your fretboard and confirm that it is 25.5" scale. It should measure 12.75" from nut to 12th fret if it is. If you have a 25.5" scale fretboard and put it on a 645mm (25.3837") plan you are looking at a difference of 0.1163". Further, more than half of this will be on the neck side. You won't need to adjust the brace locations to account for the bridge moving back 5 hundredths of an inch or so. You may want to make the bridge plate a little wider (towards the tail side) to make sure you don't get your pin holes too close to the edge of the plate. Make sure you are aware the the neck will be a touch longer and locate the bridge based on your scale length. Don't worry about the braces. Also, make sure you understand compensation and saddle location before you place the bridge.
Author:  kencierp [ Fri Apr 10, 2015 7:16 pm ]
Post subject:  Re: scale length error
Sure enough I looked at the free down too 645mm right on the drawing. Cable what made you think it was a 25in scale -- just courious
Author:  Cablepuller [ Sat Apr 11, 2015 1:07 am ]
Post subject:  Re: scale length error
kencierp wrote:
Sure enough I looked at the free down too 645mm right on the drawing. Cable what made you think it was a 25in scale -- just courious

Hi Ken

Really cant for the life of me understand why i made such a big measuring messup.. spent loads of time checking plans ..i know i measured the fretboard on an old acoustic i have here to compare, maybe thats where it went wrong..not being to hard on myself though had a bad couple of months with family bereavement. . Still i will make the best of it (or an expensive cricket bat lol).. hopefully scale length will still play ok... what do you reckon
Cheers
Author:  Cablepuller [ Sat Apr 11, 2015 1:08 am ]
Post subject:  Re: scale length error
Bryan Bear wrote:
The Greiller plan is long scale. Actually it is listed as 645mm (25.3837"). make sure you measure the scale of your fretboard and confirm that it is 25.5" scale. It should measure 12.75" from nut to 12th fret if it is. If you have a 25.5" scale fretboard and put it on a 645mm (25.3837") plan you are looking at a difference of 0.1163". Further, more than half of this will be on the neck side. You won't need to adjust the brace locations to account for the bridge moving back 5 hundredths of an inch or so. You may want to make the bridge plate a little wider (towards the tail side) to make sure you don't get your pin holes too close to the edge of the plate. Make sure you are aware the the neck will be a touch longer and locate the bridge based on your scale length. Don't worry about the braces. Also, make sure you understand compensation and saddle location before you place the bridge.

Thanks Bryan
Author:  Quine [ Sat Apr 11, 2015 4:33 pm ]
Post subject:  Re: scale length error
You can adjust the bridge patch location and braces to fit the 25.5" fingerboard. The only thing is that 21st fret. It might look funny depending on where it lines up with your soundhole rosette. You should have plenty of room to the soundhole for 21 frets anyway
The difference in scale length is not really a huge difference in playability. 0.5" is only like 2% of 25.4". Its something you might feel when fretting barre chords and some say the longer scale length has a faster response for fast picking. Again...not night and day different, but subtle. Unless you play with some extreme style I don't think most people could really tell the difference.
Whatever scale length you THINK you're using, its probably off a bit. Your body length will also be off a bit with errors making the mold, bending sides etc. Trace your completed rim onto the top and measure the bridge position from the actual neck joint position. Same with the neck, measure the neck joint to nut length using the cut fretboard. Then it won't matter if its 25.5", 25.4", 25.38754827595983" or whatever.
Author:  Cablepuller [ Sat Apr 11, 2015 4:36 pm ]
Post subject:  Re: scale length error
Thanks quine.. good to hear it shouldn't matter to much... will push on with build
Author:  Bryan Bear [ Tue Apr 14, 2015 3:35 pm ]
Post subject:  Re: scale length error
I just want to reiterate the point about locating your bridge.

It sounds like you measured the scale length off the drawing, you shouldn't really do that with drawings. It is okay for noncritical elements like headstock shape and such but you really need to use the measurements listed on the drawing. Not all drawings will be perfectly to scale. You also say you measured the scale length on a guitar you had. There are a lot of ways errors can creap in when doing that too and that guitar may or may not math the plan you have anyway. Quine also points out that you will have variances built into your guitar (especially your first). This is a very analog process; you copy the shape onto a template copy the template onto the mold bend wood to the mold. . . the end result is a copy of a copy of a copy. . . That is totally okay, you just have to understand that locating the bridge/saddle is very important. You should locate the bridge and saddle based on the scale length plus compensation with the neck attached. This is the last thing I do before finishing. I measure from the 12th fret plus my compensation and place the bridge where it needs to be then I can mark the footprint of the bridge. having the saddle in the right place is very important (there is some wiggle room when you set the intonation but you want it very close). the location of the bracing under the bridge is less stringent. You still want to be very close but as long as the bridge plate adequately covers the pin holes and supports the bridge, and your braces cross under the ends of the bridge in someway you will be okay. Forward shifted x bracing is a good example of this.
Author:  John Killin [ Tue Apr 14, 2015 8:49 pm ]
Post subject:  Re: scale length error
Bryan Bear wrote:
I just want to reiterate the point about locating your bridge.

It sounds like you measured the scale length off the drawing, you shouldn't really do that with drawings. It is okay for noncritical elements like headstock shape and such but you really need to use the measurements listed on the drawing. Not all drawings will be perfectly to scale.


Bryan brings up a really good point here. I fell into this trap (even though I knew better) when I made the mold for the body of my L-00 from the Grellier plan. I checked part of the plan and it was right and traced the body outline directly from the plan. I made my templates and mold. I liked the size but ended up with the body length being short and the body with being only 14". Try finding a ready made case for that. [headinwall]

I realized the mistake before I started working with the guitar wood. I liked the size and since I was already set up to build that shape and size I went ahead and built it. I had to keep in mind that measuring from the plan wasn't going to work. The body was short so I had to lay out the bracing plan and sound hole based on the scale length.
Author:  Cablepuller [ Wed Apr 15, 2015 12:41 am ]
Post subject:  Re: scale length error
John Killin wrote:
Bryan Bear wrote:
I just want to reiterate the point about locating your bridge.

It sounds like you measured the scale length off the drawing, you shouldn't really do that with drawings. It is okay for noncritical elements like headstock shape and such but you really need to use the measurements listed on the drawing. Not all drawings will be perfectly to scale.


Bryan brings up a really good point here. I fell into this trap (even though I knew better) when I made the mold for the body of my L-00 from the Grellier plan. I checked part of the plan and it was right and traced the body outline directly from the plan. I made my templates and mold. I liked the size but ended up with the body length being short and the body with being only 14". Try finding a ready made case for that. [headinwall]

I realized the mistake before I started working with the guitar wood. I liked the size and since I was already set up to build that shape and size I went ahead and built it. I had to keep in mind that measuring from the plan wasn't going to work. The body was short so I had to lay out the bracing plan and sound hole based on the scale length.

John

Ok will bear that in mind. . How did it turn out in the end?
Author:  John Killin [ Thu Apr 16, 2015 8:38 am ]
Post subject:  Re: scale length error
It worked out great and is a very comfortable guitar to play. I'll definitely be making a few more with that size and shape.
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