Clean Cuts = Curved Edge
This tip is in response to questions about getting clean cuts,,eliminating or cutting down on the tearouts and fibers left at the bottom of stop cuts and grounding type cuts. That area is where the majority of problems exists,,lets face it. And as we all know that’s the hardest area to reach . Various techniques have been posted on how to get rid of them ranging from riffler files,,to sandpaper folded up a certain way,,to gluing it onto popsicle sticks of various shapes and emery boards.Using a dremel or micro motor with small bits to try and clean it up.Getting really small chisels to poke around and try and get them out or doglegs and what not.
These are all fine,,and do work to some degree.But not one of them adresses solving the problem in the first place.What keeps causing it?
I had recently purchased some new chisels/gouges.And they weren’t bad out of the box,,I could have sort of used them,,but would prefer not to,,,because they were not really great.So I modified basically the entire chisel to make them what I would consider useable.
The one thing that really struck me was that I could not get a decent stop and clearance cut out of a single one of them! I reground the angles to what I like,,tapered the corners back into the sides and then stoned them before buffing.
Now this part might raise some eyebrows but I don’t keep the cutting edge of my gouges straight and perpendicular to the shaft itself. I would imagine many try very hard to keep that edge straight and square as they are sharpening,,but I can’t find any compelling reason to do so.The reasons not to keep it square ,,to me ,,far outweigh any reason to keep it square. Once I made the adjustments to my new gouges I could not help but make perfectly clean stop cuts each and every time. The project I am currently working on is nothing but hundreds of stop cuts and clearancing them.The all have to be clean,,and I have no intention of going back a second time with something trying to clean them up.I’ve got better things to do with my time and patience.
Out in the wide open,,these edges serve no real purpose,,besides that’s not where those pesky little fibers show up is it? It’s in the bottom valleys and creases that they show up. If you stop for a moment and think about what’s happening in those bottom stop cuts you’ll quickly discover that the shape of the chisel is what’s causing this to happen. The entire edge of the chisel cannot meet the verticle stop cut….it can’t. So when you go to pop the chip out,,little fibers remain or are torn off instead of cut and low and behold you have fuzzies in there that you now have to find a way to get out. You’re defeating the purpose of the chisel to make a clean cut.And that’s what it was intended to do.
Why try to go back in there with a knife or any of the other “solutions” when you had a chisel in there in the first place? Get it to do it’s job then you don’t have to bother with the unsatisfactory multiple steps.Cut once and you’re done.
Now I don’t make a radical sweep to this edge as if it were a spoon or something,,but just a gentle arc which will by necessity increase with the greater depth of the chisel. I generally keep this to chisels numbered less than 5..once you go over this ,,say into the 7’s it’s not really necessary as those chisels aren’t used in this fashion..so it’s basically 2,3 5’s that I do this to. The sweep tend to be a bit more pronounced with the wider the chisel ,,as well as the greater the number.
The possibility of unsevered fibers increases with the greater the angle you are driving the chisel at,,so to get around this problem,,if you are trying to take big chunks out quickly using a 7 or 8 is to then go back and simply do the final paring cuts with a shallower chisel.
One other “trick” to getting clean,smooth stop cuts is to not use a flat chisel as the tool of choice to shear the sides of a deep cut.Again,,on my current job there are hundreds of these as well.Dosn’t work,,and in most cases will cause more problems to solve. Virtually ALL the straight cuts I’m making are being done with a curved gouge ,be it ever so slight.A flat chisel though can and does make very nice crisp lines as a final pass at that bottom line. That area and line is the only one your eye catches making you think the cut is arrow straight and perfectly clean.