Advice Request...Converting a Bench Plane to a Scrub Plane ?

[Stew Denton]

Hi All,

I have too many planes, at least for the small space I have. Of those I have two fairly low end smoothing planes. One is a #3 Dunlap, and the other is a #4 Westline.

The #3 is the better of the two, but is nothing to write home about. On both planes, the bedding where the frog and bed meet is cast iron, and un-milled. At least the Dunlap, however, feels pretty solid, and the Westline has two broken spots in the tote.

I am thinking about converting one of them to kind of a scrub plane, in the method that has been discussed on this bulletin board in the past, and that Paul Sellers has a Youtube video on. I am strongly considering converting the #3 because it is the better of the two and also narrower.

If I try to sell one, neither the Dunlap nor Westfield will bring much, if anything, and for a scrub plane the Dunlap may be good enough and might even work well for that. If I tried to sell it, I would not take more than $10 for it, as I don't think it is worth more that that. Even getting $10 might be hard. The Westfield is the same story, or worse.

I am thinking about a 7 1/2" radius, as Sellers recommends.

One other option is a Stanley Bailey #4 type 16 (I think) that has a skeletonized frog. I'm not very fond of it, however, it is a good plane that I am thinking of adding it to my carpenters tool box. I take that box with me on carpentry work but don't a lot of that. It would also be a good loaner. (I like the bedrocks and Bailey types #10 to #15, or so, a lot better for my work at home.)

What do you think, an old Dunlap good enough for a scrub plane?

Stew

[Derek Cohen]

Hi Stew

Paul Sellers has some idiosyncratic views on planes, the reasons I shall not comment about, but it should be noted that he is likely alone in his thoughts in many cases.

The instance of the scrub is a case in point. Firstly, I would not call a plane with a 7 1/2" radius a "scrub plane". It is the camber typical of a jack plane (mine is 8"). However a #3 or #4 is too short for a jack plane, which is typically around 15" long. And here is the second point - Paul Sellers recommends against longer planes, for example would use a #4 as a jointer, and this flies in the face of tradition. Enough of that.

A scrub plane needs a narrow blade with a 3" (approx) radius blade to plough deeply. A 7 1/2" radius blade will struggle to replicate that.

Having stated all this, I rarely use a scrub plane anymore and much prefer a jack plane. This would have a wider range of uses. Better to use a #5 for one.

Regards from Perth

Derek

[David M Anderson]

I have to agree with Derek.

A 5 1/4 is also good for a scrub. Worn down wooden planes where probable the start of the scrub plane.
Stanley I believe just marketed the plane in there line up.

[Nicholas Lawrence]

I have a scrub plane (a number 40, which is significantly narrower then either a #3 or #4) and like it and use it. I think it saves me a lot of time over starting with the jack plane, but if nothing else, it saves the blades on my bench planes from having to deal with dirt and other things that always seems to accumulate on the outside of rough lumber.

I say go for it. If it doesn't work out, you are out a Dunlap that does not presently do useful work, and if it works for you, there is another useful tool in the world.

[steven c newman]

I currently have two scrub planes. Converted a HF Windsor #33 ( $10!) into a 3" radius, #3 sized small scrub plane. The other is a Corsair C-5 Scrub Jack. Frog was made with a single bolt hole! 2" wide iron has an 8-9" radius ground in it. Both are hungry critters. IF your Dunlap has a wide enough mouth to allow the big scoops of wood chips to pass through....go for it. A #3 is about 1-3/4" wide....maybe a 3-4" radius would work well.

[Tom M King]

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Here are some pictures of mine that might be of some use to you. I've never measured the radius on the blade, but it's a lot shorter than 7-1/2". It works great. That's wear at the mouth, not a shadow, but doesn't effect use at all.

[Brian Holcombe]

My only bevel up plane, a #5, is one that I have a heavily radiused edge on for one blade and I use that in the same way one would use a scrub plane. I did so following the guidance of Derek's post on his website and have been very satisfied with the results.

[Prashun Patel]

I don't like using my 3 or 4 for rough scrub work. It's jarring for me to take thicker cuts with them. I appreciate the extra mass of my Bailey jack for this kind of work.

also, unless you have a good eye for flattening in local spots, it is marginally easier to use the jack than the shorter planes. It can be done even by a novice. I have used small planes to scrub, but it's not fun and not efficient for me.

[Stew Denton]

Hi All,

I appreciate all of the advise so far. I do have a #5 that could be used for that service, a 50s Stanley Bailey #5. I don't use it much because of having a few better jack planes than it.

I don't have a Stanley #40, but know that they are a lot narrower than the #3, and as such can take a lot smaller radius on the iron. As such the #3 won't be a true scrub plane because of the greater width of the cut and the lesser depth that can be taken. A true scrub plane can be used to aggressively clean out the back of trim for finish carpentry to clear high spots that the trim needs to fit over, and the #3 can't do that.

I hadn't thought about a #5, because the camber of a jack used for a fore plane, as Derek pointed out above, matches what I am talking about for a #3 or #4.

At this point I don't know how a #3, with the iron sharpened like a fore plane, would work and how useful it would be. Right now I have that Dunlap that does me no good at all, and I was thinking about what I could do to make it useful.

I am very much appreciating the comments, both positive and negative to the idea.

Stew

[ian maybury]

Hi Stew. I have a Veritas scrub plane, have used it once or twice so far (so i'm a big time expert) and been amazed at how it peels off sizeable amounts of wood for minimal effort - so the principle seems to work. Against that I'm not sure how much use it's going to get since I'm set up to machine my stock - except in the case of specific situations where bringing the plane to the work is necessary. I can't yet say if the strategy was a good call or not, but this means too that my other planes are set with moderate camber.

I guess the call on how to set a jack and a scrub up is determined ultimately by our total 'wood removal' strategy. If working entirely by hand the story would likely be different.

Speaking from an engineering perspective my preliminary insincts on some of the critical features that enable scrubs to work would (subject to correction by those with greater experience of setting them up) be roughly as follows:

1. Narrow body/iron - reduces what could be a very high force required to push one.

2. No chip breaker - again plays a big part in reducing the required force.

3. Open mouth - permits thick chips to pass through without problems.

4. Thick iron, well bedded in a decently robust body - reduces the possibility of chatter.

5. Heavily cambered iron permits a deep cut, but if required over a relatively narrow width - again provides the option to reduce the cutting force if required by retracting the iron while still cutting quite deeply. (but over less width)

There's no doubt subtleties that i've not figured out, but my instincts if thinking of converting another plane for the task would so far as i could be to choose a victim that permitted me to as far as possible mimic the layout of a dedicated scrub plane. Better still, find somebody who has done it already (the same conversion) if possible, and try to find how it worked for them and what issues arose. Why change what works? Too much width in the iron/body seems like it could definitely lead to problems (?)

[Richard Line]

I use a 5 for my scrub work, and I'm happy with that choice. Its blade has about an 8 in. camber. But some other thoughts on the choice of plane for scrub type work.

A few years back I heard & saw Chris Schwartz give a talk on fore planes. His main point was a fore plane was the first plane to touch the wood, and that meant bringing it to near final thickness. He said a jack plane was a reasonable choice, with a highly cambered blade. But he used a wooden plane, about the size of a no. 4. If I remember correctly it had about a 3 or 4 in. radius camber. He said you would probably want at least an 8 in. camber. The choice of camber tied in to how much wood you typically were going to remove. He didn't same much about the length of the plane to be used, but I did note that his demo was using pieces about 8 in. by 16 in. (with no knots or reversing grain) and he was taking off 1/4 in. or more during the demo. But then he commented that pieces of wood he was provided were too well prepared for what he was doing.

When I use my scrub/jack, I'm typically taking off less than a 1/4, but also trying to correct cupping and twist. For that work I think the longer length of the jack (15 in.) helps in truing the board and being ready for the jointer.

I also think Prashun has a good observation.

[Reinis Kanders]

No.3 is hard to hold properly for scrub type work, I have good size hands and even with some No.4 planes I do not have enough space. Cambered No.5 works well for me as initial scrub/jack. I also like horn type German planes that are about 9 inces long and are cheap when bought used. I got one with lignum sole and 50 degree bed, with cambered blade one can really remove some material fast and there is a bit less of a tearout. Woodie also better works with wood that has been rived and is nowhere near flat.

[Jim Koepke]

Interesting read on what folks find to work well as a scrub plane in their use.

Depending on the work to be done, the individual's strength and hand size anything from a #3 through #6 can be used for the job.

It might be interesting for those of us with calipers to measure our typical shaving thickness when using a scrub plane or a bench plane set up for scrub work. This could then be matched with the plane size and a description of the camber.

FWIW, the camber on the two planes that are used for my scrub needs is not really known. It is just kind of random curvature on a #5-1/4 blade.

jtk

[john zulu]

I have the Veritas Scrub plane. I have used it a few times. But I was glad I had it as it was the only plane to scrub hardwood which includes resak and chengal. As Derek mentioned the 3" blade radius is an important part of the scrub plane.

To convert the #4 to a scrub plane is very possible but it is not the best configuration. One can create a similiar radius to 3" but the weight of the plane is far heavier compared to the scrub plane. With all the chipbreaker, cap lever and frog it adds a lot of weight to the plane. A dedicated scrub plane works well at what it does. A jack plane can be used as a scrub plane with a modified radius. Derek has proven that in his writings.

[lowell holmes]

I'm amazed that people are still firing at Paul Sellers. They obviously have never seen him work in person.

My definition of a scrub plane is a plane with a narrow, iron that has a sever camber sharpened into the iron.

I have a #3 that is normally a straight forward #3. It is my favorite bench plane.

I purchased narrow replacement iron at one of the box stores and ground a severe camber in it. When I need a scrub plane, the narrow, highly cambered blade goes in it, and Voila!, it becomes an aggressive scrub plane.

Try it before you permanently butcher a plane. It works.

[Derek Cohen]

Lowell

Anything can be made to work.

The issue is whether it is an efficient tool, or not. And if not, what is better?

Regards from Perth

Derek

[Allan Speers]

I have a #3 that is normally a straight forward #3. It is my favorite bench plane.

I purchased narrow replacement iron at one of the box stores and ground a severe camber in it. When I need a scrub plane, the narrow, highly cambered blade goes in it, and Voila!, it becomes an aggressive scrub plane. .

This is a good idea, since the OP will not likely use a scrub much. Who does?

Everyone covered it, a narrow, highly cambered blade with an open mouth is the whole point. - but I'll add one more thing about usage:

The typical use for a scrub is when prepping raw lumber, or when taking down a lot of width in a completely non-powered shop. thus, the blade projects a significant amount and one hogs off large strips. For that, I prefer a plane that has a front handle which can be PULLED, such as the Swedish types. (ECE, Ulmia) - And these also have the advantage of being light weight.

However, a converted plane can work great for prepping tough lumber, such as figured hard maple & some burls, before the final planing. For this, you keep the blade VERY shallow, and make a series of light passes in all directions. Even with this job, you want a very narrow blade and a very high camber. However, a slightly longer body & more weight can actually be helpful.

[Michael Ray Smith]

Hi All,

At this point I don't know how a #3, with the iron sharpened like a fore plane, would work and how useful it would be. Right now I have that Dunlap that does me no good at all, and I was thinking about what I could do to make it useful.

Stew

I converted a No. 5 1/4 to a scrub plane. The 5 1/4 is the same width as a No. 3, and I wouldn't want anything wider than that.

As for the radius on the blade, I think you want something that's not as tight as the radius on a No. 40 just because your blade is wider than a No. 40, but I could be wrong about that. I honestly have no idea what radius I used on mine. I simply started out with something that looked about right, erring on the side of something that was too wide, tested it out, and then adjusted it a time or two until I was happy with it.

After you're happy with what you have, if Paul Sellars or anyone else tells you you're not doing it right, tell them to take a hike. Well, unless it's George. If George tells you you're not doing it right, give serious consideration to the possibility you're not. And then if you still think what you're doing is okay, stick with it.

[steven c newman]

Working down some rough pine planks I had glued up
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Plane is a Corsair C-5. 14" long scrub jack. Iron is at about 8-9" radius. Trying to flatten a wavy top. Lots of scallops. Have had this plane for quite a while, might have had to sharpen it once....

[steven c newman]

Have a Harbor Freight Windsor #33, converted into a #3 sized scrub plane
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Radius is about 3", hungry little beasty
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BIG thick shavings. As for that Corsair C-5 Scrub jack?
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may it is by Great Neck, and maybe it was designed with a single bolt to hold the frog in place. But, grind a 8-9" radius on the edge of the iron, and we have a fairly decent wide mouthed scrub plane. Might have sharpened both of these once in the last year or so.
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Had just cleaned and candle-waxed the sole today, even...

[Tom M King]

I don't know that a scrub plane is any faster at removing stock than a Jack is. We use a scrub plane for scrubbing old beams and boards before putting a good iron in the wood. Look at the picture I posted that shows the iron edge. It's dull as can be, but was still working at the end of that day. I never understood why people started using a scrub plane on clean lumber. An 8" radius Jack iron might not take as deep a bite, but the width probably takes about the same amount of wood. If I'm knocking a high corner off a board to save time before running it over the jointer, I almost always reach for the Jack. An sharp iron is always easier to use, but the scrub iron doesn't stay sharp long cutting dirt and grit.

[Barry Dima]

Thanks all for this conversation. I've been kicking around the same idea—and with the same plane—as OP. The pictures are especially helpful; I have 0 idea what I'm doing, so the visual references are really helpful. Dang, those open mouths. Although the opening isn't as important as a rigid chipbreaker or wedge—albeit one not bedded too closely to the end of the iron, yea?

[steven c newman]

To quote Herr Schwarz....you want to be able to see the corners of the iron.

Just keep it close to the corners of the cambered itons. Close as in maybe 1/32" or so back