Scrub planes

[tvrgeek]

As I have "discovered" scrub planes and turns out it is one of my most useful tools, I now need to prefect sharpening them. Being a roughout tool, they take a bit if a beating.
OK, I seem to do pretty well grinding just pivoting around my thumb through the slot. Not that great on honing. I thought about using the old Eclipse jig but it can't rock far enough.
FWIW, I have been primary grinding @ 30, 3 1/2" radius. They seem to hog out stock pretty well at only 1200 hone but upping it a bit when my new plates get here. Not sure it matters as a few swipes and they are probably back to 1200 or so.

I have an idea for a way to pivot around a peg in the grinder stage so that will make it easier, but the honing is still a question. Anyone made a clever jig? Thinking about a stick that mounts through the slot to a height reference stick back behind the stone.

On a side note, I have been learning the hard way about the difference in flatness of a stone vs diamond plate. Just the tiniest dish, one or two strokes, is enough to back bevel a couple mm, so flattening back to dead level is quite a chore. Leather strops and even the give in paper for Scary seem to be enough to cause me a headache. ( arm ache) Can't really use the ruler trick on a scrub plane.

 

[pop-pop]

I’ll suggest the 11th commandment -“Thou shalt not sweat it”

A scrub plane by design produces tear-out and thus doesn’t need to be super sharp. Sharpening by free hand rocking does just fine for me.

 

[creasman]

I have a No 3 that I use for this purpose. It has a large mouth and can eat some wood. I use it cross grain mostly to take the warp out of a board on one side before running it through the planer. I don't worry about getting it super sharp like I might if it were the iron of a smoothing plane. Often the irons on scrub planes are slightly rounded so they can "scoop" out the wood.

 

[Scott H]

I made one that looks sort of like this for sharpening my scrub plane blade and it works well. The fact it rides on a single point means you can rock it enough to reach all of the blade. I forget if there was any math involved to the design but it's not too complex. I used through bolts and wing nuts not screws.

Single Point Honing Jig

Honing guide I designed.

www.mwells.org

Update: Added some photos.

 

[Mike Davis]

My scrub plane is a #6 with an 8 inch camber. I used blue dye and a divider to mark the grind line. Grind freehand and hone freehand. As has been indicated already this is a roughing tool. I hone on a 600 grit diamond stone to a slight convex. Works fine and holds well.

 

[tvrgeek]

I made one that looks sort of like this for sharpening my scrub plane blade and it works well. The fact it rides on a single point means you can rock it enough to reach all of the blade. I forget if there was any math involved to the design but it's not too complex. I used through bolts and wing nuts not screws.

Single Point Honing Jig

Honing guide I designed.

www.mwells.org

Update: Added some photos.

Single point was what I had in mind. Going to build something tomorrow.
Mine is a old Handyman #4 modified by Chris Black. It does hog come wood! Like Jim, it is much easier to take an ugly board ready to send through the jointer or planer. My DW 735 does not like big humps. Smoothness of cut is not an issue, how hard to push/pull as is tearout.

My goal is to make it easier and so quicker as I suggested, being rough, it gets beat up pretty easily.

 

[tvrgeek]

I like the idea of a #5 rather than a #4. When I upgrade my #5, maybe I'll convert my old one.

 

[tvrgeek]

OK, scrubbed up my scrub. ( #4 Handyman)
Pictured is the gig for honing. Blue tape is for the current grind. Regrind, just move the tape. Micro bevel, just slide it back a hair. Primary is 25 degrees. Not sure if that is optimal for a scrub, but that is how it was presented to me.

By a small filing on the frog, I was able to rotate the adjuster lever clear of the top face. Took the lateral adjuster off as who cares, it is a scrub plane. This allowed me to flatten the frog with 150 on a plate. It was really bad. Flattened the base and honed the ways in the sole. Still a pain to adjust the frog, but it really only has to be done once. At least it moves without catching or rocking.

I still want to make a fixed pivot for grinding.

 

[Hmerkle]

As the scrub is a roughing tool, I will argue that this tool can be treated differently than nearly all the other planes we use on the bench...
1. The back does not need to be flat, (like a chisel or "normal" plane blade...but the bevel and the back need to meet at the same plane along the blade's radius to create the cutting edge (no burrs, no pits on the back of the blade at the cutting edge, or cup / warp of the blade)
2. The plane does not need to be "scary sharp" since it is "hogging-out" chunks of wood
3. I am now questioning if it needs to be honed... would a grund edge function just as well as a ground honed edge (sounds like a cool test...)

IF a scrub blade DOES need to be honed, and you have created an 8 inch radius on the blade, only a small portion of that radius will "function" or "see" wood so about an inch-wide section in the center of that blade needs to be sharp and or honed... allowing you a much smaller space to concentrate on when you are working on the stone...

 

[jlimey]

OK, scrubbed up my scrub. ( #4 Handyman)
Pictured is the gig for honing. Blue tape is for the current grind. Regrind, just move the tape. Micro bevel, just slide it back a hair. Primary is 25 degrees. Not sure if that is optimal for a scrub, but that is how it was presented to me.

By a small filing on the frog, I was able to rotate the adjuster lever clear of the top face. Took the lateral adjuster off as who cares, it is a scrub plane. This allowed me to flatten the frog with 150 on a plate. It was really bad. Flattened the base and honed the ways in the sole. Still a pain to adjust the frog, but it really only has to be done once. At least it moves without catching or rocking.

I still want to make a fixed pivot for grinding.

Hi Scott,

Next time you need to grind, I would suggest a larger bevel angle. Might as well have an edge that can withstand the force of using a scrub plane a little better.

 

[tvrgeek]

After a couple of jobs, I noticed it was harder to push. Honed again ( 1200 broken in diamond) it returned to it's previous ability to make wood disappear. Yea, only about an inch does the work. I flattened the iron only to 1200. The sole is smooth, but not honed flat and the sides are not square, but it is not for shooting. Fixing up the frog and ways was to make adjustment easier. No effect on cutting.

Playing with my shooting board. I like my Lyon trimmer, but it can't take the hair off a plane can. Too much play in the ways. I find my #5 to be awkward and baulky, where my new #4 is easier. I have not pulled the blades out of the Lyon to hone them to scary which would be very worthwhile.

Bought some 3/4 box and rod to make a tool rest for the Wolverine jig. The stages are too deep for bench chisels. A button that clamps on the scrub iron would then work. Basically just a horizontal rod.

 

[tvrgeek]

Hi Scott,

Next time you need to grind, I would suggest a larger bevel angle. Might as well have an edge that can withstand the force of using a scrub plane a little better.

Thought about that. 25 is what Chris supplied, but thinking almost 35 might be smarter. Might see if I have any salvageable old irons to grind away with. Always handy to have one ready anyway.

 

[tvrgeek]

Watching Sellers. He suggests a much larger radius. 7 inches or so. Mine is 3. Again, guess I need to grind one and test. Maybe a short radius for really fast, larger for closer.

 

[Mike Davis]

Like I said, mine is 8 inches. That is what Chris Schwarz recommended.

 

[tvrgeek]

Lie Neilson says theirs are a 3 inch radius. Several say 25 primary and 30 secondary. I do steeper primary and tiny secondary so I may try a steeper grind. Bet I can find a few chip breakers on e-bay and have several blades as the job needs. I bet it is like the universal consultant answer: "It depends"

 

[mdbuntyn]

Lie Neilson says theirs are a 3 inch radius.

That's on a 1½" wide iron, in a plane with a much larger mouth and no adjustment mechanism. The 2" roughing blades that they used to sell had a 8" radius

 

[tvrgeek]

Regardless of the iron width, we only use about the center inch. So, it would be the same narrow or wide. It comes down to how aggressive we want it and how hard it is to use. I will be testing.

 

[Gofor]

To rough mine out, I used a long carriage bolt, a couple nuts and a couple flat washers. I sandwiched the blade between the nuts, washers (i.e. nut, washer, blade, washer, nut). By adjusting up and down, as well as forward and back on the blade slot, I was able to get the bevel right as well as the arc. The pivot was the head of the carriage bolt. This was before I bought the DiaSharp plates and Mark II guide, and I started with 80 grit cloth. The rounded head of the carriage bolt allowed me to move back and forth as well as swinging it side to side when using cloth or wet/dry paper on a granite slab (scary sharp method).

I do have a Lee Valley scrub plane, that has a thick iron and is close to the 3.5 - 4" radius, However, I have found that an old #5 with the 8" radius is easier to use, and thus quicker. The Lee Valley works good in soft wood if you have a very large amount to scrub off, but the #5 works better in oak and walnut.
IIRC, you bought the Veritas Mark II guide with the camber roller. It works well for a #5 iron.

The drawback to the #5 is getting the mouth open enough if you have too much radius on the iron. Not too much problem with the 8" radius, but quickly goes down hill as you reduce it.

 

[tvrgeek]

If I talk myself into a WoodRiver #5, I'll convert my old Bailey. Rib sole so it is a great candidate.

Honestly, I have not tried the camber roller yet as I am so used to just a slight rock for the corners. I have two more #4 irons I can play with before I try it on my "good" ones.