Official Luthiers Forum!

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Sanding, to me, is a one of those tasks that just has to be done, and done well at that, even though it seems very dull and is also pretty hard work sometimes. I've been teaching myself to think of these tasks as an art form. As such, I try to take them seriously and get excited about it. I also try to make it as much of a intuitive art as bracing or bending sides. Depending on what mindset you're usually in, if you really concentrate on what you're actually doing you can make it an exciting and interesting process. Helps fuel your spirit and you might do a better job too.

Had an apprentice back in the 80's who thought it would be all kinds of fun to work in a guitar shop.
When he found out it was a lot of sanding, polishing, and actual work he changed his tune.
The kid was a quick learner, and would have surpassed my skills easily if he had applied himself, but he couldn't handle the expenditure of elbow grease.

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"Act your age, not your shoe size" - Prince

This covers a lot of stuff.

Unless you can really get meditative about it, the fact is that sanding is tedious, repetitive, and leaves you with sore arms. But it also (to be done well) demands constant attention to the workpiece, good technique, and a lot of skill and feeling for your material. Because of the negatives, in most woodworking shops it gets given to the newest, lowest paid, least skilled person; ironically, the one least able to do it right.

As Bruce said when we talked, a lot of sanding technique is sort of obvious, or seems like no big deal, but it's little things that matter.

Getting to the list:

1&2: Drum sander. Keeping the rosette level is an ongoing issue whenever the top gets sanded, though.

3 mostly ROS. Medium hard pad--the one that comes with it. Two things are key to keeping a level surface when power sanding: not pressing hard and using new, sharp grit paper. Pretty much let the weight of the sander apply the pressure. Also when using an ROS, start the sander with it sitting on the surface, don't go from an edge inward, and when doing the edges, let less than half the sander's surface hang over the edge, so it doesn't tilt down and round or gouge the edge.


More to come. I hope others contribute.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Not much I can add, but here's something for #6.

My mantra upon inspection after the seal coat has been, "I swear I sanded those out." What I discovered was that my lighting was too good, so that a lack of shadows made it hard to see flaws. Now I turn off the shop lights when sanding and just use a gooseneck lamp with a clear incandescent bulb (I have a feeling it's time to start stocking up on those). A raking angle, where the path of the light is at a shallow angle with respect to the surface I'm working helps too, along with keeping the path of the light at least 90° from my line of sight to enhance shadows. For those of us with an abundance of birthdays, an Opti-Visor or something similar might help.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

This information is very helpful. Sanding may not be that thrilling to do or to discuss, but it's important.

One thing that everyone may not know is that, when hand-sanding spruce, you should sand at an angle to the grain to avoid creating a corduroy effect.

A question: any guidelines on when you switch from ROS to sanding by hand?

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Tim Allen
"Never hurry, never rest."

^I needed that. Thanks

Why would one use an ros on such a small project as a guitar is beyond me.
In half an hour one can sand by hand, with blocks,
and be done .
My 2 cents.

You could think of the ROS as a tonerite on steroids. If it can't wake the box up, nothing will.

-jd

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We were on the subject of wood prep before the box is made, but I use an ROS (5" Bosch variable speed 8-hole) on the box, too.

Why? Less time, less effort, better surface quality.

Why not?

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

I'm with Howard on this one....I find that it does a cleaner job too, especially if you move it quickly across the surface.
Dark inlay and purfling wood tend to be less ground into the spruce as well.

Most of you may take this for granted but I sand most all of my parts to 220 before assembly. It's easy to sand the parts before they are assembled and it makes final sanding a lot easier.

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Steve Smith
"Music is what feelings sound like"

Maybe I'll give the ros a chance next time.
While we're on the subject of sanding
what grit do you think is the best for a glued surface?
Say for instance final grit where the braces and bottom of the top meet.

I don't know since I don't raise the grain, but I would think they would.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

I don't like using grits courser that 220 on the ROS. If I go to 100 to try to get things flattened quickly I end up spending more time than I saved getting rid of the pig tails. Also be sure to use clean fresh paper as a glob of glue stuck to the pad will make a mess in a hurry.

-jd

I use the ros to get where it needs to go fast then follow up hand sanding to remove the pigtails for each grit up to 400 then i hand sand only with 400 and beyond when needed. The important thing when sanding is not to skip grits as you want the current grit to remove the scratches made from the previous grit all the way to the end.

I now use a ROS when ever possible. Turn it on a lower speed, put on my dust mask, and have at it. Lighting is also key and I usually have all the lights off other than a drafting light at a low angle and do a lot of that eyes closed feeling stuff.

But what about all the dust? What technique here. Sorry if this is derailing...

Best,
_Mike

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_Mike Tracz
MCT Guitars
https://www.instagram.com/mustcreatethings/
https://www.youtube.com/mustcreatethings

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Interesting thread! I've read thru it fairly quickly and may have missed it but I'm surprised no one mentioned hearing the instrument resonate when sanding. Even when hand sanding the neck I hear resonance from the body.

Re sanding spruce at an angle to the grain to avoid getting corduroy effect: I think it's an interaction of sandpaper grade and hardness of block. Coarser sandpaper, softer block leads to dishing out the soft parts of the grain, while a harder block and finer sandpaper keeps everything flatter. My feeling is to keep a hard or at least very firm block up to about 220, but I haven't tested this systematically. It would also depend on the hardness of the wood you're sanding.

I'm appreciating this thread. In particular, I wouldn't have thought of hand-sanding with a hard block before the ROS, and I'm looking forward to trying that.

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Tim Allen
"Never hurry, never rest."

A also use a 5" ROS for top and back, and a small "mouse" sander for the sides. Cutaways get the hand treatment. It pays to have an assortment of blocks, different in hardness and shape. 1" and 1 1/2" cut dowels faced with cork are great for tight curves. PSA sandpaper rules.
To avoid the corduroy effect on spruce I find it better to sand cross grain until, and including, the very last grit (220 for me, and if I sand by hand, which occasionally happens). Then do a few passes along the grain. A hard block helps.
I have a run of the mill DeWalt 5" ROS and I connect my VAC to the back, it is the cleanest you can get and I have no use for a downdraft table. The combo is heavy and perhaps cumbersome, but I have two hands, and how long does it take to finish sand a guitar?
In terms of technique, 2 simple things works for me: change the paper often and sand lightly (do not dig in) in order to avoid deep scratches. Let the paper do the work. Last passes are always along the grain.
I dry sand the finish with 400 grit until the penultimate coat, I then switch to wet 600, then wet 1000 before the last coat. I wet sand 1000 and 1200 before buffing with Menzerna olive, then ivory bars. If I missed something wet sanding, I dry sand the area with 2000, and go back to the buffer.
Buy the best (and correct) paper you can get, it pays in the end.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Laurent, I think I'll try your sanding schedule.
If you didn't have a buffer,
what would you use to buff by hand?
Also, where would rottenstone fit in there,
if at all?
I'm not looking to get a super high polished finish.
Thanks!