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Precision for fret position calculations?
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=8075		 Page 1 of 1
Author:  Alain Desforges [ Sat Aug 19, 2006 4:28 pm ]
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How precise do I need to be exactly?

I'm calculating different scale lengths for a fan fret FB.

So let's say for example I have 1.473 for the first fret (26.25 scale). I want to put this in 64ths. When I do the conversion I get 30.27/64. So, once rounded out it's 30/64. This is 15/32. However 15/32 is .468 and not .473, which is normal of course because of the rounding off I performed earlier.

I guess my question is this, Does a 5-8 thousanths of an inch matter much? Or will the compensation take care of this.

I just don't see how I can be more precise unless I go to 128ths, but that might be a bit much, no? I don't have a ruler that precise!   

Thanks for your help folks!

Alain
Author:  Serge Poirier [ Sat Aug 19, 2006 4:49 pm ]
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Some ambitious project for no 3 dude!
Author:  Alain Desforges [ Sat Aug 19, 2006 4:55 pm ]
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Well actually, after having read a few things in the archives (thanks Tony!) it's not all that bad... Takes forever to calculate everything though... Wait a minute... I'm just reminded that Stew-Mac has a fret location calculator on their site!!! DOH!!!

*hangs head in shame...

Oh well, at least now I know how to do it.
Author:  Serge Poirier [ Sat Aug 19, 2006 4:57 pm ]
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I just wish my fret sawblade would do it all for me!
Author:  Tom Morici [ Sat Aug 19, 2006 5:14 pm ]
Post subject: 
Alain
I have no experience with fan frets, .005-.008
is not a lot, unless you measure from fret to fret.
All measurments need to be taken from the same
starting point.(nut)(128th .0078 is the middle between
two 64th marks on your ruler, close enough)
Compensation is for the difference in string diameters
from Low E - High E. Hope this helps.

Tom
Author:  Rod True [ Sat Aug 19, 2006 6:13 pm ]
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I agree with Tom, Alain, as long as you start your measurements all from the same point, the nut, you should be fine measuring to the nearest 64th, otherwise you will pick up or loose too much and you will probably have a fret out of position, which will cause that one position to be sharp or flat, not the entire board, unless of course it's the 12th fret which is what is normally used for setting the intonation .
Author:  Michael McBroom [ Sun Aug 20, 2006 2:46 am ]
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Alain,

I bought a couple of 16R rules (12" and 24") from Wholesale Tool for marking fret positions and other precision work. 16R means one side is graduated in 32nds and 64ths and the other side is graduated in 50ths and 100ths. I use the 100ths scale for marking fret positions and for locating the bridge saddle. Here's a link to the 24" rule I bought.

One of the things I really like about these rules is the graduations are etched into the surface, so you can transfer the measurement precisely onto your fingerboards with an X-acto knife.

I like the 100ths scale better than the fractional scales because 1) it's easier for me to think in decimal values (especially if having to convert back and forth between US and metric measurements) and 2) the graduations are finer than 64ths, giving me a bit more accuracy.

Best,

Michael
Author:  Alain Desforges [ Sun Aug 20, 2006 9:29 am ]
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[QUOTE=Michael McBroom]

...the other side is graduated in 50ths and 100ths... [/QUOTE]

Cool Michael! Thanks a lot for the good tip. I'm going to get one of those for sure.

Regards,

Alain
Author:  crazymanmichael [ Sun Aug 20, 2006 10:11 am ]
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a longer rule, e.g. 36", will also allow you to more accurately locate your bridge/saddle. they are affordable from enco, among others.

also a long, 24" dial or vernier caliper measuring in thousanths will do the job even better. these are often available on ebay for reasonable prices.
Author:  Alain Desforges [ Sun Aug 20, 2006 11:00 am ]
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[QUOTE=crazymanmichael] a longer rule, e.g. 36", will also allow you to more accurately locate your bridge/saddle. they are affordable from enco, among others.

also a long, 24" dial or vernier caliper measuring in thousanths will do the job even better. these are often available on ebay for reasonable prices.[/QUOTE]

I was not aware that they made such long calipers! Cool. I'll keep an eye open on ebay. I would certainly love to have one. (another cool toy/tool).

I do have a good 36" ruler.

Thanks again!
Author:  crazymanmichael [ Sun Aug 20, 2006 1:14 pm ]
Post subject: 
does it measure in .01's or 1/64's?
Author:  Alain Desforges [ Sun Aug 20, 2006 2:15 pm ]
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[QUOTE=crazymanmichael] does it measure in .01's or 1/64's?[/QUOTE]

In 64th's and then, not everywhere at that... So I guess it's not that good!
Author:  Dennis E. [ Sun Aug 20, 2006 2:32 pm ]
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I guess I'm just lazy. I lay mine out using CorelDraw, print it out, trim it to the board and glue it down with watered-down titebond.

The last one I did measured within .007 inch on every slot except one that measured .010 inch. And this was cutting slots by hand using a home-made miter box and an el cheapo saw.

I obsessed about the one wayward slot, but I'll be darned if I can hear the difference. I think I remember Al Carruth posting somewhere that .008 inch was close enough for most ears.Dennis E.38949.9815393519
Author:  Alan Carruth [ Sun Aug 20, 2006 3:07 pm ]
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Yeah, I go for +/- .2mm, which is .008". Works for me. 64ths drive me nuts: I like metric for this, or at least 100ths of an inch.
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