Thread: Plane sole flattening, again...

Originally Posted by rob streeper

As time permits I plan to continue flattening this plane and see what else I can find out.

Can one of those things be if/how much it actually matters functionally?

The craftsmen of old seemed to get by (read: make incredible pieces) with the tools they had and I can't imagine any of them were even concerned about a couple of thou, let alone a few tenths, much less inclined to try to fix it.

IMHO, it's much like polishing a blade; after a while the difference in using higher grits becomes so little as to be practically meaningless, it's just for bragging rights and personal satisfaction.

Originally Posted by elanjacobs

Can one of those things be if/how much it actually matters functionally?

IMHO, it's much like polishing a blade; after a while the difference in using higher grits becomes so little as to be practically meaningless, it's just for bragging rights and personal satisfaction.

Exactly my point, is plane sole flattening necessary? Does flattening improve the performance of the tool or is it just something to fuel uninformed blather around the Internet? To find out I have to do it and compare. I'm just starting out on this investigation so much is still in the air but if I can I aim to find out and quantitate the result.

Many practices in woodworking are simply accepted without question. I like asking questions and finding answers.

I copied this out from the 'similar threads' box at the bottom of the page here. Seems people have been doing this sole flattening business for some years now, wouldn't it be nice to know if the effort is worth it?

• Flattening the sole on an old Stanley 5 & 1/2
  
  By seanz in forum HAND TOOLS - UNPOWERED
  
  Replies: 9 Last Post: 12th Oct 2013, 08:32 PM
  
  
• Flattening a No.7 sole
  
  By kman-oz in forum HOMEMADE TOOLS AND JIGS ETC.
  
  Replies: 15 Last Post: 28th Jun 2009, 09:03 PM
  
  
• Flattening a sole
  
  By Lignin in forum HAND TOOLS - UNPOWERED
  
  Replies: 3 Last Post: 27th Jun 2009, 11:48 AM
  
  
• flattening a plane sole
  
  By mic-d in forum HAND TOOLS - UNPOWERED
  
  Replies: 35 Last Post: 26th Feb 2009, 04:15 AM
  
  
• Question re flattening plane sole
  
  By JTonks in forum HAND TOOLS - UNPOWERED
  
  Replies: 9 Last Post: 27th Jun 2005, 06:39 AM
  
  
  
  

Hi Rob,

Due of the pertrusion of the blade i wouldn't have thought that being flat across the sole would matter.

Don't Japanese planes have part the sole after the blade very slightly shaved back?

Regards,

Adam

A 100% flat sole in all directions is an artifact of the mechanisation of industrial production. Japanese planes only have 2 points (sometimes 3) of contact the leading ~8mm of the toe and ~8mm ahead of the blade the rest is irrelevant and infact a hinderance increasing friction. I am still learning but the more I do the more I realise the genius of having a sole with hollows. What matters is that key contact points are coplaner.

Flat sole on a jointing or trying plane - yes please - within reason, as these are the planes that get things flat.

Flat sole on a Smoother - less important because it is only to take out marks from previous planing or machining. If the whole surface was flat after jointer/trying (as it should be) then the Smoother will actually make it less flat (most probably) because the whole job won't be planed super-evenly

Flat sole on a Block plane - even less important because they are just for repairing small areas. In fact, I don't think a flat Block plane sole matters a tinker's cusp.

Thinking of some extremes, the Stanley furring plane had contact surfaces only around the mouth and very short violin planes have flat, radiused and compassed bottoms.

I speculate that side to side flatness is likely somewhat more important than is heel to toe flatness because rocking side would produce a more out of flat surface because the width of the plane is typically shorter than length.

Is there an ideal or typical ratio of width to length?

On the subject of Japanese planes, is there a special type of plane for very exacting tasks such as wet-coopering of barrel staves as in European practice?

A proposal for an experiment:

Take an un-flattened plane.

Prepare soft wood test strip 3X the sole length and just as wide as the blade, machine thicknessed and jointed. Place said test piece on surface plate and measure flatness at multiple points over the middle third of the test strip.

Plane with unflattened plane.

Re-measure flattness.

Lap plane sole flat.

Repeat.

Thoughts?

I'll comment on where flatness matters:
* on a plane where the mouth is below the heel and toe - not that much. You can work with a plane like that, and plane a board flat or hollow
* on a plane where the mouth is above the heel and toe - you will have constant problems. Even a few thousandths (like a sheet of paper) will cause problems if you are jointing boards. A plane sole will flex some, but not enough to make up for that.
* twist, it depends on what you're doing and how finely

I have flattened plane soles by hand to less than 1 1/2 thousandth end to end. It's not a lapping process that will allow you to do that, it's a progressive process of filing the center of the plane out with a flexible file and lapping until you can uniformly lap the plane surface. Is it better than just lapping? probably not in the hand of an experienced user

I generally hand lap all of my planes so that the toe and heel are just slightly proud. If you do a good job hand lapping, that's what you'll end up with. Several thousandths to perhaps something slightly under a hundredth on a very long plane. That's a bias in favor of an experienced plane user.

never let someone tell you that plane soles never need work, just the same as you wouldn't allow someone to tell you that they always do in every case.

The tradesmen who used planes for fine work were probably long dead when the "old timers" working in the early-mid 1900s were riding the declining standards due to economic necessity.

(I only do the hollowing and lapping exercise to get a truly flat sole on infill planes - it just seems fitting that when I make one, I should take an hour or two to make it very flat. I would never send a plane out to someone to mill it, but some would. I think that's a waste of money and it robs you of your ability to learn to do something that you may need to do when you encounter a plane with a high mouth).

Rob

An interesting proposition and I appreciate you are not attempting to to see how flat you can make a sole but indeed whether it is worth the effort. I will stay tuned.

One question comes to mind: A corollary if you like: How are you going to restore your hands to their former colour?

Regards
Paul

Originally Posted by Bushmiller

Rob

One question comes to mind: A corollary if you like: How are you going to restore your hands to their former colour?

I use a Scotchbrite pad and a mechanics hand soap containing pumice and orange oil. If it's really bad a fine wire brush helps things along.

Rob,

An excellent study matter an this will bring out some fire and brimstone for sure.
I can sense it’s already happening, but I must say [emoji6] we haven’t seen or heard from you around this neck of the woods for what seems forever and then you just reappear with this.

Talk about walking on stage with the full school band playing behind you.
No just slipping back in through the side door.

Hope to see this thread get completely out of hand the forum needs a little fire put back into it.

Cheers Matt
Will promise to try to have something more contrastive to say next time.[emoji849][emoji849]
Welcome back.

Rob, I applaud your commitment, and I'm gobsmacked by the precision of your lapping, but I very much doubt you are going to settle the question of how flat a plane sole needs to be! Mainly because of the breadth of opinion, which as any politician knows, isn't too heavily influenced by facts. But besides sole flatness, there are just so many other variables to control, and how will you decide on the criteria for judging the results of your labours?

I've got an old home-made plane of my dad's that was cobbled up from a chunk of channel iron in the depression era. It's rougher than burlap underwear, with a mouth that would intimidate a bull terrier and a sole whose flatness you would measure in mm, not fractions of a thousandth of an inch. But he'd sharpen it up & make a pile of shavings with it whenever the need arose. The surface it left wasn't exactly ready to French polish, but it served his purposes adequately.

I went down the rabbit-hole of plane sole flatness back in the 80s when it surfaced for the first time that I became aware of (& as you point out, it keeps coming round cyclically). I soon learnt that bits of sandpaper stretched over a tablesaw top didn't get me remotely near the realm of your figures. Admittedly, most of the planes I tried were not seriously out of whack when I started - just a glimpse of light between sole & straightedge here or there. After I 'flattened' them, none showed the slightest difference in use, at least nothing that I could detect. Some were still dogs, but it had little to do with their soles, there were other issues like blade bedding & cap-iron fit that had a larger effect - things I learnt to recognise & deal with over time.

I decided to leave soles alone after that, unless they were clearly convex or concave from toe to heel - I think both can be detrimental to function depending on what the plane is expected to do. These days I'm happy if the toe, at least a few mm in front of the mouth, & the heel, are all co-planar & the bits in between aren't more than a very faint slit of daylight lower.

I'm not obsessed about having surfaces ready to polish off-plane. I aim for a very good finish but I don't mind using a card scraper or a lick of fine paper to ensure a surface is glass-smooth. So a super-performing plane would most likely be wasted on me.

Anyway, curiosity is a good thing, imo, go for it, & tell us about what you discover...

Cheers,

I got off duty at 2:30 today and in the remaining hours of daylight I made up a precision dimensioned test block of No. 2 pine and set up a surface plate dial indicator rig and started working on it. I have yet to process the data but it's possible lapping may help. More later.

plane testing rig 050719a.jpg

plane testing rig 050719b.jpg