Violin Forum/Message Board

[Geemac]

I have no training for instrument making. I just started making violins a couple of years ago to pass the time while looking after my wife, who had a stoke and severe rheumatoid arthritis. But, I digress.

The above statement is made to justify my neophite questions. Please patient with me as I am only making my fifth instrument.

The question:
How the heck do you folks get such a smooth surface on your violins before you apply any finish? I have, the correct tool as well as sandpaper and blocks as well a furniture scrapers, but I still get humps and hollows here and there. I'm thinking of backfilling them with shellac.
_________________
GeeMac

[Mark Sullivan]

I am new also. From what I have read and am beginning to experience, you need low angle light to show the humps and hollows and a very sharp scraper to remove the humps. On the recommendation of a maker with some experience, I have been grinding my scraper edge over 45 degrees. Then polishing the front of the scraper (the same as polishing the back of a chisel) and using a 45 degree block to guide the bevel or edge of the scraper on a fine waterstone. Then turn a very slight bur. Takes some practice but I have been able to remove humps in practice wood with it.

Mark

[Oded Kishony]

I think Mark's got it right. I use a .016" thick scraper made of blue tempered spring steel. I sharpen it with a file, single bevel no hook. I change the angle of the bevel depending on whether I'm scraping spruce or maple. Spruce gets a shallower angle.
When you have the light shining in a dark room at a low angle, try to get the surface as even as possible using finger planes, then try not to create any additional bumps/ hollows as you scrape.

This is definitely one of the more difficult skills to master. If I recall it took me several DAYS of scraping on my first violin to get it looking half way decent.

Oded

[Mikes]

As everyone has said so far sharpening is number one. After that it helps to think of scraping as a two step process. First you fair the surface by removing the bumps and hollows while looking at the continuity of the surface. This can best be accomplished by scraping at a skewed angle across the grain, you'll have to play with this until you find which direction and angle works best and you'll have to adjust that angle depending on where on the surface you are scraping as the direction will need to change as the grain of the wood changes. The next step is where you work to produce a quaility consistent surface finish by removing any areas of torn out grain and you shouldn't need to be removing much wood either. I usually do these two steps before the plates are glued to the rib set then one final light scraping just before finishing.

Enjoy
Mike S

[Oded Kishony]

Working in a dark room with the light at a low angle, step back and look at the plate. You'll see hollows. draw a circle at the perimeter of the hollow, now, with very light strokes, scraper away the pencil marks, look again, is there still a hollow? Is it smoother? Expect to spend several hours doing this. IIRC I spent about 16 hours getting my first top smooth this way.

Oded

[Dave Chandler]

I was reading an article recently about a violin maker in the Copper Canyon area of Mexico, that was working with rudimentary tools, and included was mention of using glass for scrapers. I found some broken window glass and tried it out, it works great, extremely sharp. I've taken some pieces with long clean archs and broke them down into smaller pieces about 3-4 inches long and theywork great on the curved areas too. Still, can't replace my small steel scrapers for the channel edge, and that is still one of my weak points.

Definitely, a high intensity light at low angle to check for flaws. Amazing how some can escape you until you start building up some gloss in the finish process.
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[mikemolnar]

Scrapers are key to preparing the surface. I follow Oded's method. I also use a table lamp to watch for the shadows and smooth contour.

I follow this up with 150 or 240 grit sandpaper on a stiff foam block. Never use your fingers to support sandpaper or you will get uneven grooves that show up as shadows.

Another tip for good surfaces is careful gouging. Never let the gouge run down into the grain which can pry out a chunk of wood - the infamous gouge mark.

Nevertheless, I still make goofs.

Mike

[Oded Kishony]

Most professional makers don't use sandpaper to finish the surface. Sandpaper leaves a fuzzy surface while a scraper cuts the fibers cleanly.
If you want a crisp, clean looking surface, skip the sandpaper.

Oded

[byacey]