02 April 2004, 19:02
Bob SmalserStock Finishing - Tuning Card Scrapers
In previous articles, I described rehabbing older Bailey-pattern planes acquired from Ebay to replace all the family�s ancient wood planes�the ones I�m getting tired of inlaying mouths in every decade or so as they wear. I�ll rehab these oldies one more time and pass them on to my oldest boy who�s interested in luthier work�he�ll be the 5th generation of craftsman for some of these. I�ll describe resoling these woodies in another article, but as my card scrapers are essential tools for this work and mine all need a tune-up, I�ll walk you through that process today.
I pull the mahogany filing block out of the bin�any hardwood block the length of the file with a dead square rabbet to serve as a shelf for the file will do� and while holding the chalked file in place with my left hand I run the scraper down the teeth until I�ve filed away all the old wire edge and have a nice fresh, square surface to turn a new edge from. The chalk aids in preventing the single-cut mill file from clogging and I�m careful to not slide the scraper backwards against the file�s teeth�.a practice that dulls files exactly twice as fast as necessary.
A nice, fresh, dead-square edge.
Then moving both block and scraper to the Arkansas stones, I hone the edge dead smooth on coarse and fine stones. The smoother and squarer the edge, the better and more durable the eventual cutting edge.
Then I clamp the scraper to a hard, flat surface and use a burnisher to turn a wire edge inwards on both edges as shown in the sketch. The burnisher? The one I�m using is a luthier design by Timberline Tools of Mendanales, New Mexico, but any hardened and smooth steel will do�.like the back of the old Buck Brothers gouge shown or a valve stem or pushrod from your local junkyard. The burnisher should be oiled for best results.
Then I simply affix the scraper on edge and turn those wire edges outward to make two hook edges as shown in the second sketch. The purpose-built burnisher does that automatically and rapidly�.when using the gouge, I use two hands and rub the edge on a diagonal with the burnisher beginning horizontally and pushing the gouge twenty or so degrees downward during each stroke.
The result? The scraper, held in both hands and sprung a bit toward the body as it is pulled toward you, cuts this hard maple sole like a plane�.only with more control and precision. Learn to use scrapers, and you�ll cut your abrasive paper outlays to a pittance and even that varnish finish coat that egg-shelled on you won�t be a burden. That�s right�properly tuned they can cleanly remove as little as one layer of varnish.
I�m not into unnecessary tools, but this luthier�s burnisher halves the time and effort of tuning the scrapers. You can either buy or make one. How do you harden the 5/16ths drill rod? After it�s cut to length and the edges eased, simply grab it with soft-jawed pliers, heat it to cherry red with a propane or MAPP torch, and toss it in a pint can of linseed or motor oil�.too little oil and it�ll catch fire�.and do it outdoors, OK?