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bridge/saddle placement
Posted: Sun Nov 24, 2013 5:23 pm
by tim crain
I am new to this forum and this is my first post so I hope I go about it right. I am well into my first acoustic build, a J185 from Scott Antes plans. I am at the point of having to position the bridge so I can mask that area prior to finishing. From my research there seems to be no firm method of determining the location of the bridge/saddle. I have gone through several books, Kinkead, Young, Sloan and they all have slightly different information regarding the amount of compensation. My plans are for a 24.75" scale and call for approx. .130" /3.3mm of compensation at the high E string. With the 3% slant of the saddle that puts the compensation at the middle of the slot (between the 3rd and 4th strings) at approx. .173"/4.4mm. I have seen Cumpiano's information on this and he is at .15"/3.81mm at the same spot though I believe he is working with scales of 25+". I was wondering if any of you have built a J185 from these plans or any 24.75" scale guitar and what amount compensation worked. I am really nervous about this, I am this far into to the project and I know that getting this wrong is a VERY BIG PROBLEM!! Any help will be greatly appreciated. I will post a few shots of my work. Thanks in advance, Tim
Re: bridge/saddle placement
Posted: Sun Nov 24, 2013 5:53 pm
by Mark Swanson
Hello Tim, welcome to the MIMForum. I wish that you had come here and posted earlier that you were building from the Antes plans, we could have given you some tips about things to avoid and that are not the best on that particular plan. Anyway, I don't have any exact figures for you, but if you place your high E string saddle location with 1/16" compensation and the others go back from there as your saddle angles, you'll be just fine.
Re: bridge/saddle placement
Posted: Sun Nov 24, 2013 9:49 pm
by tim crain
Mark, thank you for the welcome and the information on the compensation distance. It seems a bit shorter than what I was thinking but I have seen a fare amount of differences depending on the source. I want to get as much information as I can before I commit. As for the plans, I didn't run into anything that was a problem, in fact for being my first attempt at an acoustic it has gone surprisingly smooth. I'll keep you abreast of my progress and thanks again, Tim
Re: bridge/saddle placement
Posted: Sun Nov 24, 2013 11:40 pm
by Mark Swanson
There are small issues with that plan. It is overbraced, the braces are way too thick, and I can see from your photo of the neck joint that you have no gap between the end of the neck and the bottom of the dovetail. There is supposed to be a gap of about 1/8" of an inch there, if the neck ever needs to be steamed off for a reset that's where the needle goes.
Re: bridge/saddle placement
Posted: Thu Nov 28, 2013 11:57 am
by tim crain
Mark, it seemed liked the two lower braces on the back were heavy but pictures in the Sloan booked showed him using braces of about the same dimension so I followed the plans. The end of the neck joint does not hit the end block but there certainly is not a 1/8th inch gap. Looking at the picture on page 113 of Kinkead's book I see a gap of may be 1+mm so that was what I was shooting for. Thanks for your input, I'll add these to my list of things to do next time. Have a great holiday, Tim
Re: bridge/saddle placement
Posted: Thu Nov 28, 2013 4:00 pm
by Jeff Highland
Tim, I use the stewmac fret calculator which gives a measurement to the break point of the high and low E on the saddle.
Things to watch out for
-some people will quote compensation figures to the front of the saddle slot, others to the middle. Either is ok if you specify, but often this is not given
-Your 24.75 scale is probably not, it could be 2.65 or 2.625 gibson scale lengths are nominal.
-even measuring nut to 12th fret may not give the true figure since the nut end of the board may be half the saw kerf shorter.
Re: bridge/saddle placement
Posted: Thu Nov 28, 2013 5:11 pm
by Alan Carruth
It's not uncommon these days to find the nut moved up a bit, whether deliberately as compensation, or just 'because'. Assuming the frets are right, the distance from the first fret to the 12th will be 44.387% of the full scale length. Measure the distance (from, say the upper side of the 1st fret to the upper side of the 12th, which is more accurate than measuring center to center) and divide it by .44387 to get the true scale. Then measure half that distance from the center of the 12th fret and add the desired compensation to get the break point on the saddle.
Re: bridge/saddle placement
Posted: Thu Nov 28, 2013 8:23 pm
by Mark Swanson
I was referring to the top bracing for the most part. The top braces should be 1/4", or maybe 5/16" but no heavier. The Antes plans show those braces at just about 1/2", and that's too heavy.
Re: bridge/saddle placement
Posted: Fri Nov 29, 2013 10:10 am
by tim crain
I would think Antes dimensions are taken from an actual J185 right?? Well I hope my project doesn't end up sounding like a 2x4 with some strings on it, ha ha. I'll start putting these thing in my little stack of stuff I know versus the mountain of what I don't. Thanks for all the input, Tim
Re: bridge/saddle placement
Posted: Fri Nov 29, 2013 9:10 pm
by Mark Swanson
I would think Antes dimensions are taken from an actual J185 right?
No.....that's why I mentioned it. But you are welcome, and nobody builds just one, so now you'll know better for the next time!
Re: bridge/saddle placement
Posted: Fri Nov 29, 2013 9:59 pm
by Bryan Bear
I have nothing constructive to offer that hasn't been said already. I just wanted to pop in and say that it looks like really good so far. Congrats!