Cuban Mahogany and Lutz Spruce 00

[johnnparchem]

Very nice. I will be interested to know how the nut compensation works out once it is on a guitar.

[Darryl Young]

John, per David Collins advise in a post a year or two ago, I'll subtract 0.25" from the amount of saddle compensation I normally use to balance the nut compensation. Here is a link to the post if it interests you:

http://www.luthiersforum.com/forum/view ... mpensation

And here is a pic of a chart David posted that shows the tuning error at each fret using 0.025" compensation on the nut and saddle adjusted forward the same distance:

[Darryl Young]

Thicknessed the back tonight........and found out my used Performax I got such a good deal on doesn't quite sand level. It sands about 0.018" - 0.020" thinner on the closed end than it does on the open end. So for now instead of putting the entire back through at once, I fed a little over half of it though and left a bit less than half hanging out the open end.......so I had to run it though twice to sand one side completely. This left the back about 0.010" thicker in the middle than it is on either side. I stopped when the middle was at 0.100" (wings at 0.090") and will think about it some before moving forward. In one way, it's not that big of deal to have the middle thicker......so I'll ponder on it.

[Jim_H]

Darryl,

Not sure which performax you have. I have a Jet 16/32.

When I got it, the first thing I did, per the manual, was level the drum to the table (this model is open on one end). There are some bolts you have to loosen and an adjustment screw. I've had mine almost two years now, and as far as I can tell, there is no measurable difference from one side to the other.

If you don't have it already, you might look for the manual online and see if you can find the leveling process for it.

Also, when thicknessing small stuff like headplates, or even backs and sides, it's a good idea to use a platen. Cut a slot in the back edge of a piece of MDF and put a strip of hardwood in it that sticks up just slightly. This will keep your sander from launching your guitar parts across the room.

platen.jpg

[Kevin Sjostrand]

Darryl,
Ten thousands is not going to be much problem on the back. I would not worry about it.
I have the Ryobi version of that sander, and mine is off too, but only about .003 off. I have yet to adjust and shim it, but I need to. I'm most concerned on the tops, but even there, the amount is pretty minimal. Not building a jet aircraft here.

Kevin

[Jim_H]

KEn brings up a good point.

I had a problem with getting a ridge on the edge of a soundboard I was thicknessing.

I found out the belt had slipped and bunched up on the right side of the drum, creating a high spot where the paper folds down into the clip.

Just something to keep an eye on.

[Darryl Young]

My drum sander is an older model Performax and doesn't have a built-in adjustment mechanism like the newer models do. Looks lik my only option is to shim with something. On a Google search, I found one guy that shimed with paper as in the pic below. Maybe I'll try something similar with index cards or playing cards.

PerformaxAdjustment.jpg

[Kevin Sjostrand]

Darryl,
The Ryobi model when new came with metal shims to use, cut to fit around the bolts on the open side of the conveyor belt. The guy I bought it from used paper......not sure why, and I don't have the metal shims, but I do have SS foil that is .002 that I am planning on using, in layers if needed. You could also use aluminum foil in layers, or.........?

Kevin

[Darryl Young]

I had some 3x5 file cards on-hand so I measured one and it is 0.007" thick. I loosened the two top bolts that connect the motor and drum carriage and tried a single thickness but it wasn't enough so I doubled the thickness and it worked much better. Still a piece sanded on the closed end is about 0.008" thinner than that same piece sanded on the open end but I sure didn't want the drum slanted the other direction (actually, if 2 thicknesses moved it roughly 0.012", 3 may be just right). I don't mind the middle being slightly thicker than the edge anyhow. So I carefully lowered the drum in tiny increments and thinned the back a little more ending up with the middle 0.006" thicker than the edge. I'm happy with that.

So how thick to leave this Cuban Mahogany back is the big question. I decided to go with Mario Proulx advice and not be afraid to let mahogany sound like mahogany.....and took the middle down to 0.092" and the edges are 0.086". A bit out of my comfort zone but what the heck, it's a 00 body which is small so it will probably work fine. I'm hoping for that reverby quality I hear Cuban is known for!

[Darryl Young]

Well, thanks to David and John's help (and Colin S. from the OLF) I have the spacing for the back braces.

I retrieved my go bar deck from the garage, dusted it off, and mounted it back on my building stand inside the house. Ahh.....this brings back fond memories.

I drew a fine line down the centerline of the back so I could see where it is and layed out the back braces. Below is a pic after I drew the location of the 4 cross grain braces. Now that this back is sanded, I like the interesting grain in the dark areas along the sides. I'm sort of wishing I had joined the back along that edge so this grain was in the middle of the back. You can't see it very well in the pic but this back sure pops when you wipe it with mineral spirits!

Should I go ahead and cut out the body shape on the bandsaw before I start glueing braces? Seems it will cut easier before the braces create a radius in the back and I can't think of an argument for not doing this. Thoughts?

LayingOutBackBraces.JPG