scrub plane and knots and what to use after

[Steven Lee, NC]

Are scrub planes supposed to be used on knots? I was experimenting on a scrap 2x6 piece of pine from the borg and it tore my blade to pieces, chunks torn out of the blade.

Also, what plane should be used after the scrub plane? I had to stop using the scrub because of how badly the blade was damaged and didn't want to spend time grinding it back down where it would probably get dinged again. At this point one side of the board was able to lay on the workbench without any wobble so I switched to my LV low angle jack and it seems to be taking forever to get down to my line, about 1/4" stock removal left.

At least the LV powers right through the knots with no problems. The scrub is a st james bay toolco scrub I bought 5-6 years ago that was never used till yesterday. I set the LV blade depth lower than I ever have and it's hogging off really long and pretty thick shavings but it seems to be taking forever so I am thinking there is a plane between the scrub and jack I am not aware of.

The LV is like a ginzu knife, able to cut a tomato after cutting a tin can. I had a neighbor come over to see what I was doing so I took a scrap piece of walnut, dialed the LV way back and took off a whisper of shaving to show him how I normally use it. I think I was more impressed than he was since I thought it was about time to resharpen the blade.

thanks..

[David Weaver]

It's nicer to avoid knots in pine, etc, in general.

If you have a blade that's chipping in use, increasing the angle of the last bevel is the way to go. If the blade doesn't hold the edge when the last angle is 35 degrees, then it's either time to ditch the wood or the plane.

scrub planes aren't something you're generally going to use much in regular work. Your first plane should probably be a jack plane with a fairly rank set iron, but shallower curve than the scrub.

I don't know if all st james bay irons are the same, but the hardness spec given with an infill kit I got a while ago suggested the iron wasn't tempered yet, which would cause it to shatter and chip if it ran into something hard (I haven't done that yet, but it would, I'll temper it). You can take your scrub iron and put it in the oven at 375 or 400 degrees for an hour and that should improve it if that is part of the problem. It's unlikely it's anything other than O1, which is what st james Bay usually cites on their kits, etc.

[Steven Lee, NC]

Thanks. It was just a spur of the moment thing to see if I could straighten a badly twisted board with hand tools. It was quite fun. What do you mean by rank set iron? Getting a lot of golf club info when I google it.

[David Weaver]

Rank set meaning that the curve on it is pretty significant. Not a super tight radius like you would see on a scrub plane, maybe twice the radius, it's hard to know because it's variable based on what you normally do. If you work medium hardwoods and softwoods like most people will end up doing with hand tools (suddenly making lots of things out of hard maple is less attractive when you dimension by hand), that's probably about where my jacks are set (and I say that not because you need multiples, just that I have one each of wood, metal and japanese for entertainment's sake).

But like a lot of things, experience in use will be a very useful guide in determining setup, because you do some lumber preparation on any significant scale with hand tools and your brain automatically tells you (out of our universal laziness gene), "hey, we got this board done with the planes set up like _____ in a lot less time and with less effort".

The best guide in setting up planes for coarse, which you'd inevitably do if you're forgoing power tools for the first few steps, is really sweat and experience. Let your secondary thought processes handle the details, it will happen.

Of course, if you don't want to use the hand tools that much, just steepen the final bevel for now and see how it works - no great reason to set up a jack rank unless you're going to use it that way a lot.

[Steven Lee, NC]

ah ok, not gonna get another blade for my jack plane so I can have one with a curve.

[Adam Cruea]

To mirror what David said, after a scrub, you'd tag the board with a heavy-set jack to flatten things out and knock off the tops of valleys.

When I go for hard dimensions (like I need to take off 1/2" or more), I hit it with my scrub plane, followed by a hogging jack, followed by a thinner jack, followed by a smoother.

The scrub plane takes about 1/16" chips; the hogging jack takes about .014" to .016" shavings, and the minor jack takes down to .002". The smoother is < .001". That's for a board up to about 20 inches long.

When you start getting into super long stock, swap the jacks to fores or jointers to help avoid that hump or dip that will inevitably form.

[David Wong]

Knots are end grain. Something you do not want to take large shaving from. I have softened the knots with camellia oil and taken them down with a chisel, prior to scrubbing. I used a heavily cambered jack plane as a scrub plane, so I could also take light shavings in the knotted area. Nowadays, I use cleaner wood or a powered jointer.