Chord playing does not require a 6+ fret.  Nor does it require D-A-D tuning (or other 1-5-8 tuning).   If you choose to play chord-melody style, you can do it without the 6+ fret.  And you can do it out of D-A-A (or other 1-5-5 tuning).  The use of D-A-D tuning and its association with chord-melody style is a matter of choice, not necessity. 

You said you would like to probably experiment with chord playing, so i strongly suggest adding at least the 6.5 fret. (And it's 'octave companion' 13.5 fret if you get up that far)

Thanks for the responses. I am building this for my own use and am coming from a background of finger style guitar so I may be best building in flexibility. If I never used the 6+ it probably wouldn't matter to me (?).

I shall read Dusty's 'what are half frets?' thread. This is all an explore for me, don't even know how this first build will sound! My guess is rather bright - I've done some things that are not traditional like a graphite reinforced floating neck... sorry!!

Briefly... (maybe). The 6 1/2 fret is not necessary for chording or playing more modern music.  Check out the playing of Robert Force, Dan Evans and the late Roger Nicholson, none of whom use/used a 6 1/2 fret. Is the 6 1/2 convenient?  You betcha. I have more instruments without the 6 1/2 than I do with (I think) and tune to 1-5-8 as much as 1-5-5.  BTW, If you're in 1-5-5 an interesting tuning is to raise the bass string a whole step giving you a 5-1-1 tuning in the Mixolydian mode. Now, after saying I would be brief, I must go practice and try to figure out what I'll play on Sunday.

Douglas -- the dulcimer isn't "fretted for a mixolydian scale".  As Dusty says, a dulcimer is traditionally fretted Diatonically -- does not include the half intervals of a full Chromatic fretboard like a guitar. As he also says,  back in the 1970s builders started adding the 6+ half interval to allow them the play both a Mixolydian Modal scale and an Ionian Modal scale from the same tuning.

If you are building this dulcimer for personal use, then the question of whether to include the 6+ fret depends on your playing style and musical choices.   

IF you tune DAd (or any Mixolydian tuning) and play Chord Melody style -- fretting across all courses, THEN I would include the 6+ fret (and possibly the 1+ fret as Dusty suggests).

IF you play Noter & Drone or Fingerdance style -- fretting only the melody string, THEN I would forego the 6+ fret and learn to quickly change the tuning of just the Melody string to switch between all of the Modal tunings as needed. 

Alternatively you can forego the 6+ fret and tune to a Unison or "dropped Unison" tuning (ddd or Ddd for example).  This does for those of us who do not have the 6+ fret, what that half fret does for people who only tune DAd -- that is allow us play more than one scale from the same tuning.

As far as an appropriate place for your question -- it's always better IMHO to start a new thread with a new question rather than "riding the coattails" of someone else's Q&A.  That way others who have your same question can more easily find it and our responses to you.

Douglas, as I think you know, the dulcimer was originally a diatonic instrument.  Some time around the early seventies or so, the 6-1/2 fret started to become pretty common.  It is now the most common configuration of frets on a dulcimer.  It allows people tuned in what was a mixolydian tuning to also play the ionian mode or major scale.  The second most common "extra" fret is the 1-1/2 fret, which you are referring to as the minor 3rd.  I like that extra fret because in a 1-5-8 tuning you get the lowered third on the melody string and the lowered seventh on the middle string, so it's conducive to playing the blues. 

A while back I posted a piece called " What are Half Frets and Do I Need Any ?" It will likely answer your questions.

Is this the right place for my question? I'm new to dulcimers and want to understand why some frets are left out but others included. In particular is seems it's fretted for a mixolydian scale, plus the  6 1/2 fret (major 7 of root/open). It appears some makers delete that major 7, and some keep it and add a minor 3rd.
I'm making a dulcimer at the moment and am approaching the fretting stage - so, keep the 6 1/2? add a minor 3?, leave both off... 
It may help if I say I come from guitars and am likely to want to try chords and finger style, minor keys as well as major, explore various modes etc. The one I'm building is 4 tuner, but I'll probably string it 3 at first (can change bridge & nut easliy later to adjust string spacing).

If this question belongs somewhere else, please help relocate me!

thanks, Douglas

I'm not sure if you mean a totally fretless fretboard or no half frets so I'll give thoughts on both possibilities. I've only played for 1 1/2 years. In that time I've experimented with noters in varying sizes and materials(wood, metal, plastics, glass). Throughout my experiments I discovered several things. I could immediately rule out a material by how well it slides. If there's too much drag it's out. If it absorbs too much string vibration it's out. I started getting frustrated and that's when I started hitting frets with my noter as I would slide. I had totally lost focus on how I was holding the noter. At that point I started reading about fretless fretboards. I decided against it because I realized the value of landmarks. There's a sweet spot within each fret to aim for. My current noter is a 1/4 inch delrin rod. I use a thumb on top index finger support underneath that slides along the fretboard. Fret bumping is a thing of the past!

I am a diehard diatonic player. My Dulcimer does not have 1/2 frets. I have over 100 songs in my personal tab library all either original DAA or ones I've transposed to DAA. I have played DAA on a chromatic instrument and was confounded by fret spacing.

It is completely logical to keep options open for tunings and or mode that 1/2 frets offer. And the flexibility while playing in a group is almost a necessity!

Randy makes a good point.  Diatonic frets create bumps just as much as chromatic frets do, and decent noter players seem to adjust just fine.

When you slide with a finger--which flatpickers and chorders do all the time--those bumps also exist.  But what's cool about the technique is that our ears play a trick on us. Instead of hearing each of the notes that correspond to each fret, our ears hear those slides as genuine slides, filling in all the microtones as thought there were no frets at all.  That is why a hammer-on sounds so different than a slide.  For example, when you slide from 3 to 4 and when you hammer on from three to four, you are just playing two notes.  But when you slide, our ears hear an infinite number of tones in between those two.  (Having said all this, one can slide in a precise and deliberate manner to approximate the sound of a hammer-on or pull-off, but now we're getting into nerdy nuances.)

As a flatpicking and chording player, I use extra frets all the time and wouldn't want it any other way.  But I understand the history of the instrument and respect deeply those who play truly diatonic instruments in the traditional ways.  That alone is a reason not to add extra frets.  The argument about "bumps" is less convincing to me, for I think you can adjust when you want to slide over the frets you don't need in a particular passage.

Every noter player has already mastered the skill of playing do mi, sliding the noter by, and not sounding, re.

Don't be leery of what you already know.

True, but it sounds better to me without having to bump over that extra fret imho.

Ken

"The dulcimer sings a sweet song."

Having a 6.5 fret won't stop a dedicated noter player from playing traditional tunes on a dulcimer in noter style...and sounding great!

I have dulcimers with and without the 6 1/2 fret. When playing with a noter I prefer the dulcimers without. When playing chords, if prefer the one with. There are exceptions to both of those preferences from time to time.

Ken

"The dulcimer sings a sweet song."

Don't reject an instrument because it has a 6 1/2 fret!

I'm playing one which doesn't have one, but I would prefer to have one. Our group (tuned in DAA) plays occasional tunes which require it.

That answers my question.  Once again, you've come through for me.  Thanks for sharing your knowledge and experience!

What Dusty said.  Personally I don't need it or use it.  But I play very traditionally in Noter & Drone or Fingerdancing style; never play 3-finger chords; and, with some exceptions, play traditional and folk music b ecaue it is what appeals to me.

Steven, if you plan to play traditional music on the dulcimer in the traditional drone style, you don't need a 6+ fret.  You will get used to re-tuning your melody string to get the appropriate mode for each song.

If you plan to play modern music, if you plan to play chords, and even if you just plan to play a lot of tablature written by others, you will probably want the 6+ fret, which has been standard for about 50 years now.

So is it important?  No.  But you might want it.

When looking for an instrument to purchase, is it important to have the 6 1/2 fret?