Richard commented on the scraping I had done on a dovetail and the scraper I had made and wanted me to write something about it.
The following is what I have and how I use them. That does not mean it is the only way or the best way.
Below are pictures of the hand scrapers I use. On top is a solid shank Anderson scraper. In the middle is an Anderson tubular scraper. The bottom scraper is a Dapra scraper with the plastic handle replaced with a wooden one. The picture does not show the 5 inch sanding pad that can be attached to make a “body” push comfortable.
Here is a view of the modified handle of the solid shank Anderson scraper. The notches allow it to be gripped between my fingers as shown.
Here is the scraper I believe Richard was referring to. It is made up of a Dapra 130 M toolholder and a Dapra KL 170 toolholder extension, which has a wooden handle attached. The blade in the picture is one that I made. I also use it with a 6 inch Dapra blade, which makes it 3 inches longer I already had the toolholders, so it was easy to assemble to see how it worked. It would be easy to make your own and not use the Dapra parts. That would allow you to have a series of holes to secure the handle, and vary the distance from the handle to the blade tip.
The scrapers I prefer to use for small dovetails are the solid shank Anderson with the handle modified for a between the fingers hold and the Dapra 130M/KL 170 with the vertical handle. Both are short, and being closer to the work helps me see where to scrape. More important though, are the handles. The “between the fingers” hold especially positions the scraper the same way every time, and it becomes an extension of my arm. It is much easier to know and control the tilt of the blade in relation to the blued surface. A controlled tilt of the blade is what I use to scrape to the back of the dovetail. I get a better feel for the tilt of the blade from my right wrist than from the fingers of my left hand wrapped around the shaft.
Here are the blades I use for small dovetails. The upper two have the top of the carbide beveled to allow the cutting edge to reach the back of the dovetail. The bottom two are ones I made. The Biax blade and the middle blade have a radius of around 15 to 20 mm in the center and increasing to about R 10 to 15 mm on the edges. They started out at R 90 or R 60 and were ground down until they reached where I wanted. The shape is closer to an elipse.
The very small blade has a radius of around 10mm. The only time I use it is if I have a specific spot to pick off or where the other blades do not work well.
The rectangular pieces are shims which allow the home-made blades to be used in any of the handles. Clamping the blade with a tightening screw works best as I am both tilting the blade and moving it sideways. The tubular Anderson scraper can have the blade shift with the sideways movement. With the right shim the solid shank Anderson scraper can be made tight enough to work, but it may take several tries.
The diagram below represents a 3/8 in dovetail with one of my dovetail blades at various angles. The large arrow is in the middle of the blade, and the small arrow is where the blade reaches the back of the dovetail.
A: The center of the blade reaches the back of the dovetail, there is no need to tilt the blade- but unless you move sideways as you go in, the scrape marks do not cross.
B: You can go in straight with no tilt – but the corner of the blade hits the back about ½ way through the dovetail. Because the sides of the blade are higher than the middle the blade will hit sooner than the diagram shows- and you could put scratches in the vertical surface. You could tilt the blade to bring the corner down- but the edge digging in is very likely. The scrape marks cross at 90 degrees.
C: You can go straight in and get more of the width scraped before you hit in the back. The scrape marks cross at 58 degrees. If you tilt the blade you can scape at 45 degrees all the way to the back- but tilt a little too far and you could get a scratch.
D: You can go straight in and cut a little further back than with C- but the scrapes now cross at 45 degrees. Tilt the blade and you can scrape at 45 degrees for 90 degree crosses. You can reach all the way to the back with less risk of the corner digging in than in C.
For scraping at 45 degrees using the side of the blade (C and D) you need a sharp blade so it will not want to skate out of the cut.
With a dovetail every cut at the edge is “into” the edge and I find those challenging
On a good day I can start the cut as in B, and during the cut tilt and rotate the blade progressing to C and then D.
Most days are not good days. The center is easier to cut -so I tend to end up with the rear 1/3 taking blue, a dip in the middle and the outer 1/5 taking blue. I will use D at 45 degrees for the rear 1/3. For the front edge I will hold the blade between my thumb on top with my finger underneath and up against the dovetail edge, and rock the blade until the contact point is right at the edge, then make a short stroke, and move to the next high spot.