Workshop Wednesdays - Scraper Sharpening

Wednesday 5 August 2015

Gary Rogowski shares a technique for getting the edge on your scrapers that everyone talks about

There is no fool like the one at the bench who tries to sharpen their scraper and consistently gets only dust for his efforts. I was that fool. Perhaps I got a shaving or two on one side or the other of this blade. I could get 60% of my scraper sharp, it was just that I couldn't predict which side of the blade it would be sharp on. The key I learned was accurate filing. The blade, the burnisher and the stone, were all of limited importance - it was the filing that was the key to success.

Using the bench hook

What I used to do, and what you may do still, is to put the scraper in the vice and file away at it. It's what the experts tell you to do. The file is straight so your edge will be flat, but will it be square to its two faces? That is the key. So they have you place your scraper in a holder or you buy a file positioner to keep it square to your blade - sometimes this works.

One day, frustrated by my inabilities, I thought to myself, what if? 'What if' leads us to possibilities: what if it takes us to places we hadn't thought of and what if it opens doors? What if I placed the scraper flat on my bench hook and held the metal smoothing file right up against the edge of the bench hook? This was at 90° then and so my filing would be more accurate. And it was. It's a bit tricky to hold onto everything in place here so I adapted this geometry and moved the file to the vice, locked it in place and pulled the scraper past it. And voila! This gave a straight edge again, thanks to the flatness of my file, but it was also square since the vice on my bench was close enough to square with my bench top. With a good edge, and I could tell by the filings turned onto both faces of the edge, I could move on with confidence.

Using a diamond stone

After filing the scraper, there will be fairly coarse file marks left in even by a 'smooth' file. The next step is to remove those marks with a diamond stone. I prefer to use a diamond stone as the scraper blade would cut into a waterstone. I placed a two-sided diamond stone in the vice and using the coarse side first, removed the file marks. Next, I flipped the stone around and polished the scraper edge with the fine side of the stone. I now have a scraper that's ready for cutting. Take this blade, properly filed and stoned and try it - it cuts.

Using a burnisher

If I want a more aggressive cut, then I take my burnisher to the blade. I use a triangular one from Pfeil. When I'm on the road, teaching, I use a push rod out of a 1964 VW engine. It works well, but sputters going uphill. I place my scraper flat on the edge of my bench and first, take any burr off the edge produced by my filing and stoning by holding the burnisher flat to the blade. Then, I raise the burnisher up 5° and consolidate the steel at the edge, mashing it down, and perhaps turning a small edge or burr downwards. Next, I hold the burnisher vertical onto the edge of the scraper and draw it towards me using firm pressure - hand shake pressure - 'I want to get the job' hand shake pressure, firm but not too frightening a grip. I draw the burnisher towards me at 90° and then 87° or so and then 85° and three or four times in that general vicinity and again the French come to mind - voila! I produce for you the edge.

Scraping in action

This hook is now much more aggressive and is felt across the entire edge of the scraper. It is suitable for removing glue, levelling surfaces, cleaning up milling marks, correcting flaws in grammar, or errant scratches in your wood. It can smooth a finish when in the less aggressive mode or take out a chunk of tear-out that looks a mile deep with just a few strokes. Be careful of your thumbs as when using a sharp scraper, your immediate joy in producing shavings will lead you to heating up the blade rather quickly. And since you have an edge along the whole length of the blade, you can use that whole length by simply moving one hand or the other on top of the blade and placing your thumbs where you want to cut. It's in the filing of the edge: get that right and the rest, as they say, is history.