No they don't, as I keep patiently explaining. How could they possibly, with such different shapes and sizes of blade?
My narrow but deep cutting ECE scrub cuts through the surface gunge on old timber, or paint, into the clean wood underneath.
Deep is the operative word. DEEP
If you do the same with a jack it can't cut as deep because of the width of the blade and the effort requires and hence it cuts into the surface gunge or paint, getting blunt very quickly.
The scrub also removes more material more quickly but very roughly. If the surface is already rough a jack can only skim the high points.
You can get a similar scrub effect with a power thicknesser - if you try to skim a painted surface you will blunt a blade very quickly. If you do a deeper cut into the cleaner wood it will last longer and you remove more material. Not advisable in either case as you don't what pins and bits of grit are hidden beneath the paint.
Not sure if I can be bothered to explain it all over again, again!
Andy Kev and other people seem to use different "scrub" planes differently.
Good luck to them, and happy new year!
Jacob, I have no idea why you think you can't put a significant radius on a jack plane. Most people seem to believe this is also the case, that the smoother is flat, the jointer has a tiny bit of camber and a fore or jack has just a little bit more taking near full width strokes. They don't do that - in wood that's suitable to be planed like that, there's no need to use even a jack.
If you get obsessed with super narrow and deep, you end up suffering serious accuracy issues with flatness and taking a shaving that's not more volume than a jack shaving, but is harder to overlap.
if you knew what you were talking about here, Nicholson would've written about it. I don't need you to keep explaining it, you're prescribing gentleman's modern woodworking and accusing other folks who are doing more accurate work just as fast as showing gentleman woodworking. If you're talking about just roughing up reclaimed fir and soft redwood beams, nobody here is likely to be doing anything of the sort.
What's far more likely is facing and then perhaps thicknessing up to a quarter of an inch off of a rough board. Again, done more slowly with a scrub, with more damage, and needing subsequent assistance. The part which seems to be flying completely over your head is that at one point, with dry wood, this was something of a subsistence issue for a worker. If it was easy enough to just gimmick a narrow plane to save time and make more money, it would've been common. I haven't got a clue what the history of the euro bismarck is here and many probably don't, but I would suggest it's more likely that such a plane was used with wet lumber or for sizing small bits like shoe blanks.
Not only did nicholson not write about a scrub, but he clearly said that the radius of the jack is to be set as needed for the material being worked. You set it at whatever works fastest rather than stopping at an arbitrary point and saying "more coarse would be a scrub". It turns out that something less drastic than the often quoted 3" scrub radius is the most productive in volume planed for a given level of effort, not to mention the improved follow up condition, but this is the case even for thicknessing, especially if you have to hit a mark and volume and accuracy count at the same time.
You have yet to address how tens or hundreds of thousands of woodworkers did something different for a living working far harder than you, but somehow missed the gimmick that only became widespread for construction work after rough work was completed with power tools.
Which leads back to the topic of the thread - a scrub plane is not essential, and you'll do faster and better work if you set up a jack plane properly and keep a scrub plane out of the shop. How do I know? I've used several patterns of scrub planes and now have none because I started to count time and effort so that I could work entirely by hand and not ruin stock or waste time stabbing around breaking wood out. The precise problem with a scrub plane is that it's narrow and short, and doesn't ensure very good flatness by itself, and even at its best possible setup, it may be equal to a rank set jack plane.
Just how easy is this to see? set two jack planes, one intentionally rank as one of mine is, and another with something far more drastic in curvature than someone like schwarz or sellers would demonstrate, but that can be driven to within a 16th or so of a mark without concern. The former will end up collecting dust, just as mine does.
If the generation of living tradesmen and their fathers hadn't come about in a period of time where hand tools were just spot work and play, we'd never be stuck with this kind of goofy talk.
I do get that refitting an older wooden jack plane with a double iron can be a bit tricky, but I can't do anything about that for people in the UK other than make a video showing how to address feed and fit issues in a double iron plane. In the states, I just refit planes for anyone who asks and is willing to send their plane.
When I do make jack planes for people here (which I don't do for pay, but I will if someone has something that's interesting to me), I know better than to set their planes up as a jack plane save one person (brian holcombe, a professional woodworker - I knew he'd use a jack plane like a jack plane), and instead send a jack plane set up like a smoother, but with the capability to work in either context (no tight mouth or any other such nonsense).
There are generations of long gone workers who set the standard for this, and revisionist gentlemen tool catalogue advice or construction site advice isn't going to be useful unless someone is working on a construction site.
(I checked with brian a month or so after I shipped him a plane, as he was using planes at that time for paying work dressing rough lumber, and he said something along the lines of "I haven't had to adjust the radius, and to be honest, I don't know If I've sharpened the plane". That's a separate issue, not noticing a jack getting dull, and I'm sure once he resharpened the first time, subsequent sharpenings were more often. brian was the last person I knew making an actual living doing work - furniture and cabinets - with only hand tools full time, but his order list has gotten larger and larger, and he's moved to power tools for the work.
When I say he was working full time, that means self employed and at the time deriving no other income from teaching classes or having an hourly wage job.
There are so many people giving advice about this stuff and so few who do it that this scrub nonsense lives on. Everyone I know who has done significant work by hand only to a standard uses two wooden planes (jack/try or long plane) and a metal smoother.
back to what I mentioned earlier - if this is just being done for play, then people can leave their jack planes with little camber for fear of not being able to use them for smoothers. If they want to master this stuff and move on, they'll follow what nicholson prescribes or what's shown in the seaton chest as far as tools go. It may be boring at first, but the efficiency and quality of the work in combination of using the correct tools makes that go away.