Official Luthiers Forum!

I am working on a commission that has very highly figured (fiddleback) maple back & sides.
I've used this maple a couple of times before & found that after a year or so the figure created ripples in the surfaces.
After finishing, they were smooth. This only happened over time.
This time, I have avoided the use of power sanders & block sanded the whole instrument.
Are there any other ways to minimize or eliminate this effect?
The two previous instruments were built in well controlled humidity, (45 -50%) using wood aged at least two years. One was finished with Nitro & one with catylized polyurethane. Both show about equal amounts of rippling.
TIA. Dan

Highly figured wood by its nature is somewhat unstable - at least more unstable than the same species in straight grained. Its wood, it takes on, and loses, moisture .. it will move. Since the figure is undulating waves of grain, possibly (and most likely) varying in density, it will move in a non linear fashion .... you simply treat it as best you can when working and finishing, but once its out there, its going to react to the different evnvironments it lives in .... out of a cold car and into a warm house, from an air conditioned home to outside inthe summer .. whatever. I doubt you can stop it.

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Thanks Tony. That's kinda what I figured. (no pun intended)
I think the block sanding will improve the situation 'cause it'll start out flatter, but the rest, as you say, is the nature of the beast.

Tony gave you great advise as always!
Also before you do your final sanding dampen the surface with a wet cloth(not dripping wet)and this will raise all the grain -even the low spots and then let dry awhile before you sand .
You will still get a bit of grain topography but it will be less then if you did not dampen the wood.

Mike
Dan still have any salvaged Spruce???

_________________
Mike Collins

Why would hand sanding vs powered sanding make a difference?

Thanks,

Mike

Mike - depends on what/how you power sand ... most ROS these days have a dense foam pad that the paper attaches to. This will still follow contours/ripples more than flatten them out - or in the case of an acoustic top, sand a ridge next to the binding/rosette as the binding is usually harder than the top wood. I usually sand with a hard wood block to get rid of them, or in the case of a carved top electric, a hard piece of rubber tubing in the dished area

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

I had no idea! But I have noticed this. I wonder if they make a hard rubber plate for ROS tools? This most def just got entered in to the "lessons learned" category.

Mike

Thanks for the great comments, guys.
I hadn't thought of dampening before final sanding, but I'll give that a try. Do you do that on the top as well, Mike?
Yeah... I've got some of that Sitka left. I am doing the grain filling now on a pretty little Brazilian rosewood parlour with that spruce for the top. So far, I'm pleased with the tone. It's more like a really nice Engelmann top than old growth Sitka. Lots of ring, for a tiny little top.
The more I play with this soundboard material, the more I like coarser grained wood. The stiffness to weight ratio is often (certainly not always) better than the really fine grained stuff! It has that cool "vintage" look too.
Well look at that... I hijacked my OWN thread!
Thanks again guys.
Dan

Mike "O";
I have almost stopped using my ROS for guitar work. Rough levelling & some shaping tasks, but when it comes to surface sanding, I'm using a variety of plywood as well as hard & soft rubber blocks. Various sizes of PVC pipe for waist & cutaways. PSA sandpaper is my new best friend. (Sad, isn't it?)

I am about to make a 1/8 inch thick aluminum plate to velcro to the bottom of my PC ROS, then velcro the paper to that .... should be better. I heard from a friendwho visited Kevin Ryan he has a CF plate on his, to level stuff out ... i just dont have any Cf plate kicking around !!!

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

I like useing UHMW plastic for sanding blocks.It would probably work well for ROS sanding as well.I do put a small camfer on the edges, as it helps the sandpaper last longer.A sharp edge there would cause wear alot faster.

Hey Mark;
Have you found an adhesive that works on UHMW?

I personally like my guitars to look like real wood.
Not a dipped in finish look!
So some ripple makes the wood feel like it looks !

They're wood -great pieces of wood .
The finish should not hide this fact.
Or cover it up !
The factory guitars of the last 30 years have made us all nervous about our finishes!
They can afford the new finishes (which were developed for the auto industry).

It's time for us small time makers to just make sure we finish our guitars to insure that they look great and protect the instrument !
The owner should make sure the instrument is carefully taken care of !!
Just like we do with any item we value


Mc

_________________
Mike Collins