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View Full Version : Scale and bridge position on a Tenor Uke build



Ukemakinmecrazy
11-28-2016, 06:58 AM
I am at this point on my first build, what should my considerations be on determining scale length? I have seen some uke makers say that 14 frets to the body is the sweet spot and others say 13 or 12, should I even concern myself about this? I just want it to play well. I have seen many sites state tenor scale as 17" but I have noticed that many popular ukes use a scale slightly longer.

Kekani
11-28-2016, 08:03 AM
I am at this point on my first build, what should my considerations be on determining scale length.
I'm taking this as you.haven't started yet?

If you have, now is not the time to be concerned- you're past that time, and hopefully this is not the case.

Many variables here, and important ones.

Ukemakinmecrazy
11-28-2016, 08:12 AM
Nope, no fret slots cut, bridge not glued down.

Kekani
11-28-2016, 08:15 AM
So, you've put the box together?

Ukemakinmecrazy
11-28-2016, 08:31 AM
Yes. Based on the Hana Lima 'IA book pattern. Looks basically like this, well when it is sitting on the seat of a 1971 MGB at least.


95971

Dan Gleibitz
11-28-2016, 09:18 AM
That's one sweet looking ukulele. I'd just stick to whatever scale the plan uses, assuming you haven't changed the neck length.

Ukemakinmecrazy
11-28-2016, 09:30 AM
Thanks! I am really excited about the grain of this cherry wood.

Just found out a friend has a CNC router, awesome. I can't wait to play around with headstock inlays with that thing.
The plan in the Hana Lima 'IA book assumes you bought their kit. I went rogue. I am using a bolt on neck. But I guess as long as the neck above the body is
the same length it should use the same scale?

saltytri
11-28-2016, 09:41 AM
If there is a bridge plate on the underside of the top, that will determine the "landing spot" for the strings. In other words, the bridge should be glued over the bridge plate. Usually, the bridge plate and bridge location are placed so that the 12th, 13th or 14th fret on the 17" tenor scale will land right at the edge of the body. It really isn't necessary for a fret to fall at that point but is more a matter of conventional appearance. If this doesn't clear it up, lets us know and Aaron (kekani) or I or someone else will be glad to help!

Ukemakinmecrazy
11-28-2016, 10:29 AM
That ls a great web site you have there. Elegant and simple, but the info in your workshop section is great.



If there is a bridge plate on the underside of the top, that will determine the "landing spot" for the strings. In other words, the bridge should be glued over the bridge plate. Usually, the bridge plate and bridge location are placed so that the 12th, 13th or 14th fret on the 17" tenor scale will land right at the edge of the body. It really isn't necessary for a fret to fall at that point but is more a matter of conventional appearance. If this doesn't clear it up, lets us know and Aaron (kekani) or I or someone else will be glad to help!

Allen
11-28-2016, 10:45 AM
The scale length for the tenor in that plan if I recall correctly is 17". And you had a choice of 12 or 14 fret to body join. You placed the bridge patch and made the neck based on that choice. Hope you didn't mix them up and did one at 12 frets to body and the other at 14.

anthonyg
11-28-2016, 10:58 AM
As others have already stated. The decision as to whether its a 12 fret neck or a 14 fret neck (or even 13 fret) has already been made. Follow the plans. A 12 fret neck is shorter than a 14 fret neck. You have a neck so the decision is made. Measure it.

At any given scale length, the distance from nut to saddle is always the same. What varies is how much of that scale length protrudes from the body. If your plan is for a 12 fret neck then the neck will protrude from the body to the nut, exactly half of the scale length. I.E. on a 17" scale instrument the neck will be 8 1/2" from the body to the nut. If its a 14 fret instrument the neck will protrude further.

Also the saddle needs to be placed accordingly to maintain the correct scale length.

Don't forget saddle compensation. See, https://www.stewmac.com/FretCalculator.html

EDIT: Also be careful as to whether the plans are metric or imperial. 17" (Imperial) is still common and many people still use the shorthand name of "17inch" when talking about the scale length of a tenor even though it may have been built in metric. 17" converts to 431.8mm. Many tenors are built to 432mm (metric)

Anthony

kohanmike
11-28-2016, 11:54 AM
I really feel the need to clarify the statements made, the scale length is very specific, 17" from the saddle where the strings cross over to the nut where the strings touch, but ALSO, the 12th fret must always be exactly 8.5" from the saddle (half of the scale) and 8.5" from the nut. The 12th fret can be closer to the body or further, as long as the 17" and 8.5" is maintained. You can look at the bridge/saddle and neck as a single entity that always stays 17", with the 12th fret and nut at 8.5".

Ukemakinmecrazy
11-28-2016, 12:15 PM
The neck is real close to 9.5" from the nut to the body. I think it is set up for 14 frets to the body, which is fine.

Ukemakinmecrazy
11-28-2016, 12:23 PM
Saddle compensation?

As others have already stated. The decision as to whether its a 12 fret neck or a 14 fret neck (or even 13 fret) has already been made. Follow the plans. A 12 fret neck is shorter than a 14 fret neck. You have a neck so the decision is made. Measure it.

At any given scale length, the distance from nut to saddle is always the same. What varies is how much of that scale length protrudes from the body. If your plan is for a 12 fret neck then the neck will protrude from the body to the nut, exactly half of the scale length. I.E. on a 17" scale instrument the neck will be 8 1/2" from the body to the nut. If its a 14 fret instrument the neck will protrude further.

Also the saddle needs to be placed accordingly to maintain the correct scale length.

Don't forget saddle compensation. See, https://www.stewmac.com/FretCalculator.html

EDIT: Also be careful as to whether the plans are metric or imperial. 17" (Imperial) is still common and many people still use the shorthand name of "17inch" when talking about the scale length of a tenor even though it may have been built in metric. 17" converts to 431.8mm. Many tenors are built to 432mm (metric)

Anthony

resoman
11-28-2016, 12:48 PM
Saddle compensation, the center of the saddle, is the amount needed to be added to a string to compensate for the change in pitch when the string is pressed. A lot of factors influence the compensation like if the string is nylon or steel, the height of the strings over the frets, stuff like that. The StewMac fret calculator has worked well for me or you can get really technical and go the route of Dr. David Hurd at ukuleles.com.

anthonyg
11-28-2016, 07:55 PM
Saddle compensation?

17" is the theoretical scale length from nut to saddle. If you had PERFECT strings then you would make the scale length exactly to theory.

Strings aren't perfect however and if you fit real world strings to an instrument made to the theoretical scale length then the intonation goes SHARP, everywhere.

There are a LOT of instruments made to theoretical specifications on the market and they ALL have sharp intonation. Rookie mistake that some have been committing for YEARS.

So, what you do is position the saddle a couple mm further away from the theoretical mark to flatten the intonation so thereby compensating for the less than perfect strings. To get it spot on the skinnier strings need less compensation and the thicker strings need more compensation.

The stewmac fret position calculator I linked to above offers an average saddle compensation to use.

Anthony

anthonyg
11-28-2016, 08:07 PM
The neck is real close to 9.5" from the nut to the body. I think it is set up for 14 frets to the body, which is fine.


My 14 fret to body tenors are just shy of 9 1/2" body to nut.

12 fret to body was the original design and the idea is that this places the saddle right in the middle of the widest part of the body. Fitting a 14 fret neck to a traditional body shape helps with upper fret access but it also moves the saddle towards the neck and into a narrower part of the body which reduces the transmission of the string vibrations to the body a fraction. Some people still like 12 fret neck designs for the reason of better saddle placements however some builders get around this by changing the body design to suit 14 fret necks.

Anthony

Dan Gleibitz
11-28-2016, 09:02 PM
Saddle compensation, the center of the saddle, is the amount needed to be added to a string to compensate for the change in pitch when the string is pressed. A lot of factors influence the compensation like if the string is nylon or steel, the height of the strings over the frets, stuff like that. The StewMac fret calculator has worked well for me or you can get really technical and go the route of Dr. David Hurd at ukuleles.com.

What this guy said.

In practical terms:
- work out where your nut/fretboard will meet
- place the bridge so the mid point of the saddle sits right on the scale length (measure from the inside edge of the nut)
- place the frets where StewMac's calculator says to put them for your scale length

This should give you sufficient saddle in either direction to compensate for whatever strings you out on.

anthonyg
11-28-2016, 11:23 PM
What this guy said.

In practical terms:
- work out where your nut/fretboard will meet
- place the bridge so the mid point of the saddle sits right on the scale length (measure from the inside edge of the nut)
- place the frets where StewMac's calculator says to put them for your scale length

This should give you sufficient saddle in either direction to compensate for whatever strings you out on.

I'm going to have to disagree with you on the saddle placement. There is no time when the saddle contact point should be shorter than the nominal scale length. Only longer. Now yes, builders do want to be able to smooth the contact point so you don't want it exactly at the front edge but you don't want to waste half the saddle thickness either or you will never be able to adjust the contact point far enough back to prevent sharp intonation.

Stewart McDonald (see my link above) recommends the saddle be placed at 17.10". That 0.10" is near enough to 2.5mm. I reccomend that the 17.10" falls in the centre of the saddle placement. Not at the middle of a 17" placement.

Now, this is all assuming that the nut is placed, absolutely, spot on. The nut placement effects intonation as well. If the nut is further away from the centre of the 12th fret than specified this will sharpen the intonation. If the nut is placed closer to the centre of the 12th fret than specified then the intonation will go flat.

I have corrected the intonation of ukuleles that had insufficient saddle compensation (the intonation was sharp) by compensating the nut placement (moved the nut contact point closer to the centre of the 12th fret).

Anthony

Dan Gleibitz
11-29-2016, 12:03 AM
Happy to be corrected!

Ukemakinmecrazy
11-29-2016, 09:00 AM
Ideally, what should the string height at the nut be on a tenor?

resoman
11-29-2016, 10:00 AM
I tend to go 0.015 to 0.020 at the top of the 1st fret and a lot depends on the player. If they are finesse players I'll try to go to the low end. If they are floggers I go for the 0.020 and more. Discalimer, LOL This is what works for me

Allen
11-29-2016, 10:03 AM
You set the string hight at the nut by observing the space under the string to the top of the 1st fret when you fret the string at the 3rd fret. It should be no more than the thickness of a piece of paper. I like it less than that but not touching.

resoman
11-29-2016, 10:29 AM
Allen, I've never tried it that way but I sure enough will. I just measured a piece of regular old printer paper and it was 0.0050

Michael Smith
11-29-2016, 11:33 AM
I like to be about .022. I find if I go right to twenty thousands or less I often get into trouble. I got one of those nifty digital string height gauges from LMI and I like it a lot.

Yankulele
11-29-2016, 12:25 PM
I found this thread, especially Allen's description, quite helpful. Note, Allen puts his drill bit on the fingerboard itself, not the fret.

http://forum.ukuleleunderground.com/showthread.php?72632-Prefered-method-of-setting-up-strings

Nelson