Official Luthiers Forum!

Owned and operated by Lance Kragenbrink
It is currently Thu Mar 28, 2024 2:24 pm


All times are UTC - 5 hours


Forum rules


Same rules apply to all forums at the Luthiers Forum.




Post new topic Reply to topic  [ 11 posts ] 
Author Message
PostPosted: Thu Oct 05, 2017 10:33 am 
Offline
Koa
Koa
User avatar

Joined: Tue Oct 17, 2006 3:52 am
Posts: 1242
City: Lawrence
State: Kansas
Zip/Postal Code: 66047
Status: Amateur
Looking at the Antes plans for a soprano Uke.
The scale length is called out at 13.625.
When I measure the print the front of the bridge is at 13.625 to the nut.
The front of the saddle is 13.753 to the nut.
I checked some other dimensions they all seemed to be very close.
What am I missing?

_________________
Say what you do, Do what you say.


Top
 Profile  
 
PostPosted: Thu Oct 05, 2017 12:14 pm 
Offline
Cocobolo
Cocobolo

Joined: Thu Feb 09, 2012 4:10 pm
Posts: 272
First name: Chris
Last Name: Reed
City: Stowmarket
State: Suffolk
Zip/Postal Code: IP14 2EX
Country: UK
Focus: Build
Status: Amateur
The difference is the compensation, because the string stretches as you fret it and that increases its tension and thus raises the pitch of the note it sounds. If you could fret without stretching, both lengths would be the same.

If you measure the plans you will find that the length from nut face to 12th fret is 13.625/2, whilst the distance from 12th fret to saddle peak is a little longer (2 to 3mm, or a little under 1/8 inch). This extra is needed to compensate for the stretching.

The amount in the plans is broadly correct, but the precise amount of compensation needed varies depending on what strings you fit, because different string materials stretch differently.

Many builders do the final shaping of the saddle top after stringing up, so they can place the saddle peak at the right spot for that type of string. Some (me included) give differential amounts of compensation for individual strings - the C is the fattest, and requires its saddle peak furthest from the nut.


Top
 Profile  
 
PostPosted: Thu Oct 05, 2017 3:14 pm 
Offline
Cocobolo
Cocobolo
User avatar

Joined: Fri Dec 01, 2006 6:44 pm
Posts: 471
Location: Australia
First name: Allen
Last Name: McFarlen
City: Mt. Sheridan
State: Qld.
Zip/Postal Code: 4868
Country: Australia
Focus: Build
Status: Professional
And DO NOT measure off the plans directly to build an instrument. They are for a reference only as paper will expand, contract with changes to humidity, as well as the vagaries of printers.

Use the measurements that are specified for critical things like scale lenght.

_________________
Allen R. McFarlen
Barron River Guitars & Ukuleles
Facebook
Cairns, Australia



These users thanked the author Allen McFarlen for the post: Bryan Bear (Thu Oct 05, 2017 3:20 pm)
Top
 Profile  
 
PostPosted: Thu Oct 05, 2017 3:25 pm 
Offline
Brazilian Rosewood
Brazilian Rosewood
User avatar

Joined: Thu Feb 12, 2009 12:12 pm
Posts: 3290
First name: Bryan
Last Name: Bear
City: St. Louis
State: Mo
Country: USA
Focus: Build
Status: Amateur
Allen McFarlen wrote:
And DO NOT measure off the plans directly to build an instrument. They are for a reference only as paper will expand, contract with changes to humidity, as well as the vagaries of printers.

Use the measurements that are specified for critical things like scale lenght.



That is always good advice and something that many may not know since it is not inherently obvious. That said, it would appear that in this case it led the OP to another (not inherently obvious) fact -- string compensation.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.



These users thanked the author Bryan Bear for the post: Dave Rickard (Thu Oct 05, 2017 8:15 pm)
Top
 Profile  
 
PostPosted: Thu Oct 05, 2017 4:34 pm 
Offline
Contributing Member
Contributing Member
User avatar

Joined: Sat Jan 31, 2009 8:50 pm
Posts: 2246
Location: Seattle WA
Focus: Build
Status: Semi-pro
I highly recommend compensating the saddle. Maybe even use a thicker one than recommended. 3 mm?

_________________
Pat


Top
 Profile  
 
PostPosted: Thu Oct 05, 2017 5:03 pm 
Offline
Koa
Koa
User avatar

Joined: Tue Oct 17, 2006 3:52 am
Posts: 1242
City: Lawrence
State: Kansas
Zip/Postal Code: 66047
Status: Amateur
profchris wrote:
The difference is the compensation.


Wow talk about a brain fart.
Can I plead old age?

_________________
Say what you do, Do what you say.


Top
 Profile  
 
PostPosted: Fri Oct 06, 2017 4:58 am 
Offline
Cocobolo
Cocobolo

Joined: Thu Feb 09, 2012 4:10 pm
Posts: 272
First name: Chris
Last Name: Reed
City: Stowmarket
State: Suffolk
Zip/Postal Code: IP14 2EX
Country: UK
Focus: Build
Status: Amateur
Dave Rickard wrote:
profchris wrote:
The difference is the compensation.


Wow talk about a brain fart.
Can I plead old age?


I do, all the time. Very useful on occasions :D

I thought it was worth explaining compensation, because starting builders read these threads and it can be a complete mystery to them.

Looking back at your original post, the numbers there suggest the plans are allowing a bit too much compensation. I make it 0.128 ins, or 3.25 mm (I'm a mixed units builder, inches for big stuff, millimetres for small).

For Aquila Nylgut strings, which seem to me to need the most compensation (cheap nylon requires about the same, but don't use those!), I reckon you need around 2.5mm for the G and A strings, and somewhere between 3 and 3.5 for the E and C respectively. Fluorocarbon strings might be closer to 2mm-2.5. And if anyone is building tenors, longer strings need a bit less compensation, these numbers vary with scale length. Steel strings stretch less, and so require even less.

So I'd be tempted to modify the plans slightly and put the front of the saddle at scale length + 1.5mm to 2mm. A 2mm saddle is enough to compensate each string individually, 3mm (1/8) gives you a little more room.

In which case the front of the bridge needs to move forward, otherwise you don't have much wood in front of the saddle.

If you want to go for a straight saddle and accept that the C string will play a fraction sharp up the neck, I'd set the compensation so the G and A strings are right, as these are most likely to be played higher up the neck.


Top
 Profile  
 
PostPosted: Fri Oct 06, 2017 1:36 pm 
Offline
Koa
Koa
User avatar

Joined: Tue Oct 17, 2006 3:52 am
Posts: 1242
City: Lawrence
State: Kansas
Zip/Postal Code: 66047
Status: Amateur
Thanks Chris, lots of good info there.
This is my first Non steel string so I was trying to wrap my head around the plans showing the saddle being perpendicular to the center line of the neck.
I'm leaning towards a 3mm saddle unless someone steers me in another direction.

A side note when Reagan was president he wanted the US to move to the metric system. My employer at the time started to move in that direction so I have metric and imperial measuring tools. After I got use to metric it makes more sense. Always look to the title block of the drawing to see what it was designed in.

_________________
Say what you do, Do what you say.


Top
 Profile  
 
PostPosted: Fri Oct 06, 2017 4:19 pm 
Offline
Cocobolo
Cocobolo

Joined: Thu Feb 09, 2012 4:10 pm
Posts: 272
First name: Chris
Last Name: Reed
City: Stowmarket
State: Suffolk
Zip/Postal Code: IP14 2EX
Country: UK
Focus: Build
Status: Amateur
The only reason not to use a 3mm saddle is aesthetic - the Martin Style 0 ukes these plans are based on had a narrow saddle (1.5mm?). 3mm looks fine, just not like a Martin.

I was at school when the UK was transitioning to metric (50 years later and we haven't quite finished the transition), and the effects are odd. I can mentally picture an inch/foot/yard very easily. I can also picture 1mm, 100 mm and 1 metre. But 375mm means nothing in my head until I translate it into 15 inches.

So I decide my scale length in inches (13 inches for a soprano, the original Hawaiian scale length) and then convert to mm for actual measuring and cutting. Go figure, as they say.


Top
 Profile  
 
PostPosted: Wed Nov 01, 2017 11:51 am 
Offline
Contributing Member
Contributing Member

Joined: Sat Sep 14, 2013 9:46 pm
Posts: 755
Location: Napa Valley
First name: David
Last Name: Foster
City: Napa
State: CA
Zip/Postal Code: 94558
Country: USA
Focus: Build
Status: Amateur
You can always use the tried and true method..... measure to the 12th fret and then multiply x2.

_________________
https://www.instagram.com/fostinoguitars/
https://www.facebook.com/PuraVidaUkuleles/


Top
 Profile  
 
PostPosted: Tue Jan 02, 2018 3:29 pm 
Offline
Koa
Koa

Joined: Sun Apr 25, 2010 4:46 pm
Posts: 501
First name: Mark
Last Name: McLean
City: Sydney
State: New South Wales
Zip/Postal Code: 2145
Country: Australia
Focus: Build
Status: Amateur
dofthesea wrote:
You can always use the tried and true method..... measure to the 12th fret and then multiply x2.
- and then (for the new kids here) add the compensation.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 9 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB® Forum Software © phpBB Group
phpBB customization services by 2by2host.com