All you might want to know about sole "flatness"

[Arlin Eastman]

Today with the modern machines and so on, I can guarantee that all of the high end planes are surface ground.  The machine my shop has, is in the 60,000 to 75,000 dollar range new and is capable of being straight and true to .0001

General knowledge,  by the end of WW11 the farmer had pretty much switched over from horses to tractors and industry has moved on also. The stuff you see on You tube is for entertainment only and not taken real seriously.

Tom

I was going to mention you name Tom on referbing planes to flat

[Bencuri]

cannot be found here on Woodnet...but it's a place to start..IMO, the two subjects most discussed on Woodnet are No.1.. sharpening and No2..flattening....but so far, no one has been able to define when the pinnacle of each each is achieved.

I did a little Youtubing this morning and found several channels that were very well done. I had an old Stanley catalog with a photo showing a Stanley employee holding a long plane's cast iron sole against a horizontal 12" wide sanding belt. I have not been able to find one showing the plane being ground on a precision machine.. But I was most impressed with one channel showing a very accurate method of "hand scraping" a Stanley #5.. I believe that "accurate scraping" produces the best results but it comes at a very high price in time and material. And if "flatness" is important to you, it may be worth it. Keep in mind tho, that the Japanese woodworker has used planes made out of wood for centuries and the results are amazing...And we know that wood is an actively moving organic material.


Scraping a sole.........

https://www.youtube.com/watch?v=z0ACMMm-ZGc

There are two things I can add to this based on my experiences:

1. Hand scraping: One thing I find as a disadvantage of metal planes are the time and energy needed to correct their sole. I have purchased about 10 pre 1939 Stanleys during the years, but none had acceptably flat soles. And then comes the tiring process to flatten them on sandpaper. Sanding is the process I hate in woodworking: dirty, slow, tiring. So I came up with the idea to scrap the sole of my planes. And I can assure you it is by far not slower than sanding manually. Actually it is pretty easy and fast. Depends on the precision you want to achieve of course, but even with a "fast scarping" method you can achieve higher precision than with sandpaper alone most cases. My method is: I ordered the cheapest scraper that wasn't even machined correctly from ebay.co.uk. Filed it to look precise by eyesight. Then I checked the sole of the plane by a ruler, and marked where the high spots were. Then I started scraping those spots, but did not even follow the classic chequered pattern making method, I was just scraping using the scraper like a pencil when you color something with it. In very reasonable time, the high spots were gone, that would take for hours with sandpaper. Then I removed the scratches resulting from the improper scraping technique by sanding the sole just for a few minutes on 120 grit paper fastened to a cheap granite lapping plate, that was precision ground.

2. It also matters what you are working on. I actually don't go for precision flatness on wooden planes. I rather try to make them convex, not concave, in case I cannot make them precision-flat. This way the surface you are working on will be concave, that is easier to fit together on gluing, unlike convex surfaces, that tend to roll on each other when clamped. 

Japanese planes anyway are not flatt all along the sole. There are only portions that need to be level and flat, that is an easier to achieve thing than flatness all along the sole.

[Patsfan]

I have a plane that Tom flattened
Far from scientific analysis but when sharpened it works as well as any I own

I am the limiting factor not flatness
JMO

[rwe2156]

Can a plane, particularly a jointer plane, get "out of flat"?

I'm wondering b/c I have a plane that used to be perfectly flat but now it isn't.

I've heard when flattening a sole you have to keep an iron and lever cap installed and to the tension is on when you do it.

I've heard of planes sitting around in a barn winter/summer for a few decades and they are actually warped.

Any truth in any of this?

[MarkSLSmith]

Here's my take on the subject.  I'm probably too old to learn to scrape, but I think I understand sandpaper.

https://youtu.be/4__IqvahgNM?si=LJGIaNO-1s5h7mWN

Mark

[EricU]

I have 3 Millers Falls that tablesaw Tom ground.  Beautifully done.  I got the first one for shooting, and then couldn't stop buying more.

[bandit571]

IF a plane is sitting around in the barn, and the barn burns down around it...the heat MIGHT warp the cast iron...

The so-called "warp" some claim to find...is do to the plane being USED for a few decades..and wears.    Any "warp" happened right at the Factory where they were made...on a Friday near Quitting Time.....

Wood bodied planes will warp and wear...cast iron is NOT wood.  

Leave the dang feeler gauges in the drawer with the rest of the Ignition Tools....where they belong...

[Nordic]

There are possibly(?) internal stresses that can warp cast iron over a long period of time. Heat, especially if unevenly applied can warp.  Happens once in a while with cast iron pans.  I suppose its possible over decades if a plane went through many seasonal cycles, where the temperature was uneven throughout the body of the plane somehow.  I very much doubt it would be much for either, but I’m not qualified enough to say.

Cast iron will also wear under heavy use..  That would be a lot of use, I think.

Most likely I would say that it came warped from the factory.  Not all working folks are as discerning about it, and many woods its simply not an issue for.   Also…. some planes are junk and just plain suck.  Just because most from a manufacturer are flat doesn’t mean it’s universal.

Chris Schwarz has reported that a warp of greater than .005” can cause a plane to start misbehaving…. I don’t doubt it.  It doesn’t take much to bring up some chatter, when you think on it.  Some sawdust under the blade, not enough tension on the cap iron, etc.

Before flattening a sole, though, I might first look at the cap iron, blade, even the frog to make sure everything is seating properly and of decent quality, that that there are no cracks anywhere, and that the blade is properly sharpened, of course.

I am certainly not against trying to make a misbehaving tool proper though…. I’ve also mentioned it’s interesting to see a machinist’s take on it.  There is a point of diminishing returns one should take into account for most of us - however I do so hate seeing the old quality tools tossed, too.

[AHill]

Excellent video. The degree to which that plane's sole was out of flat is a good indication of how poor the manufacturing process was when it was made. My father had a No. 4 made in the 80's and you couldn't get a decent shaving out of it to save your life because the sole was so far out of flat.

He covers a lot of important things about getting a plane sole flat like making sure the frog is installed. One might ask why not just use sandpaper on a flat surface? It's very easy to put uneven pressure if lapping on sandpaper to the point where you do more damage than help. The technique of continually checking progress helps to mitigate over lapping (or scraping in his case).

Interestingly enough, I use a carbide scraper to sharpen my pruning tools. It's much more convenient for curved surfaces.

[bandit571]

Couple of items:

First off...there are 3 areas on the sole that MUST be coplanar with each other....toe, both sides of the mouth opening, and the heel...IF the sole has a "hollow in-between any of these areas, LEAVE IT BE.   IF there is a high spot between the areas, THEN bring it down to match the main 3 areas. 

Secondly...Imagine a tool in use for over 80 years....which is a lot of the older, "Vintage" planes....they were not meant to be posing on a shelf, looking pretty, they were to work, and help a workman make his wages.   To have a plane that makes nothing but see-through shavings, does NOT fill a Workman's Purse....He needed to get a job DONE as fast as he could.  

Finally..I have a very simple test for "Warped" soles.   I use both index fingers, one on each end of the plane's sole, with the plane sitting on a flat surface. 1st, set them in the centerline...press one then the other finger down...any movement?   No?    Then the fingers go to the diagonals, repeat the pressing down...any movement?  No?  Put the plane to work.  ( Note: Iron is retracted and out of the way for the test.)

I will sand the soles, but only to clean them up, as some can be very nasty looking.  In the 40+ YEARS of doing Plane Rehabs..have seen a lot of plane soles go by.   I just MIGHT have learned a few things along the way. 


Have noticed on a few soles, that right at the leading edge of the toe gets worn down, almost ramp-like.   This comes from the Workman dragging the plane back by raising up the heel...not a biggie, usually not enough to affect anything. 

Yes, my own shop has a LOT of handplanes..and they all get used when they fit the size of the job being done.  

Yeah, let the Machinists out there talk about a "Perfectly Flat Sole" all they want...they work with metal.....I work with wood using metal soled planes.

When you do happen to send a sole out for "flattening" because the plane isn't working for you...keep it's iron with you.   When the plane comes back, re-install the iron, chipbreaker as you usually do..and see IF there is any difference....No?   Then it wasn't the plane's sole's Fault....