Sign in to follow this  
Dave Slight

Plane sole vs straight edge

Recommended Posts

I'm not sure the craftsmen of old were overly obsessed with accuracy. They more than likely just learned to accommodate the  shortcomings of their cutting and measuring tools.

What has become one of my favorite quotes that keeps cropping up time after time in my daily work is this:

It is the mark of an educated mind to rest satisfied with the degree of precision which the nature of the subject admits and not to seek exactness where only an approximation is possible. - Aristotle

I think he was a pretty astute, wise individual in his time, and all ages up to the present.

 

Share this post


Link to post
Share on other sites
33 minutes ago, Bill Yacey said:

I'm not sure the craftsmen of old were overly obsessed with accuracy. They more than likely just learned to accommodate the  shortcomings of their cutting and measuring tools.

What has become one of my favorite quotes that keeps cropping up time after time in my daily work is this:

It is the mark of an educated mind to rest satisfied with the degree of precision which the nature of the subject admits and not to seek exactness where only an approximation is possible. - Aristotle

I think he was a pretty astute, wise individual in his time, and all ages up to the present.

 

I like this approach. I've got an old #6 that's not really that flat. In fact I don't think it's ever been lapped, but I still get nice center joints with it without much fuss. 

Share this post


Link to post
Share on other sites
32 minutes ago, Bill Yacey said:

I'm not sure the craftsmen of old were overly obsessed with accuracy. They more than likely just learned to accommodate the  shortcomings of their cutting and measuring tools.

What has become one of my favorite quotes that keeps cropping up time after time in my daily work is this:

It is the mark of an educated mind to rest satisfied with the degree of precision which the nature of the subject admits and not to seek exactness where only an approximation is possible. - Aristotle

I think he was a pretty astute, wise individual in his time, and all ages up to the present.

 

I've seen modern versions of that quote, not knowing the original.  Also a favorite of mine. One of my little hobbies is learning the origin of sayings or quotes.  Thanks. :)

-Jim

Share this post


Link to post
Share on other sites
23 minutes ago, Bill Yacey said:

It is the mark of an educated mind to rest satisfied with the degree of precision which the nature of the subject admits and not to seek exactness where only an approximation is possible. - Aristotle

The problem is that today with all the technology and tools we have, you can get to incredible levels of exactness if you feel so motivated.  It is more complicated to decide what level of exactness is appropriate when the possibilities are endless.

Glue joints are one thing I think should be relatively precise, at least to the level of preventing glue gaps and weak spots.  I'd say within .002" or .05 mm is safe and not too difficult to achieve (with good tools). Arching and graduations and taptones, not so much.

Share this post


Link to post
Share on other sites
8 hours ago, zdalton13 said:

Checkout the video in my thread. I'm no expert by a long shot, but Rob Cosman, who has been doing woodworking for decades, mentions that a hand plane will naturally produce a convex surface.

That is exactly my experience. You do not need a straight edge to test that. If the two planed edges spin when placed together they are longitudinally domed. I've used a straight edge to test for flatness when planing wedges held in the vice and when using the plane held in the vice and they were invariably slightly convex. I probably had the same result using a shooting board, but I can't remember.

It would not surprise me if the opposite was true when planing lengths much longer than violin wedges. Maybe you would have to worry about planing concavity when dealing with cello wedges.

If you have a good plane it will do what it is going to do, it has nothing to do with experience. If the result is not flat it is easy to make it flat.

Trying to flatten plane soles by hand is not practical. I've tried it on all my old planes and even the ones only slightly out of flat would take forever to flatten properly. I only use them for rough work. But some are beautiful tools and worth taking to a machinist.

 

Share this post


Link to post
Share on other sites
2 hours ago, Bill Yacey said:

It is the mark of an educated mind to rest satisfied with the degree of precision which the nature of the subject admits and not to seek exactness where only an approximation is possible. - Aristotle

 

 

I like to convert this to modern speak: Don't bother chasing rainbows, because you'll never reach them.

Share this post


Link to post
Share on other sites

If planing can be said to have a "natural" effect, in my experience it is to be hollow in the middle with a bump towards each end, as the sole starts to lose contact  with with the wood and the blade is no longer fully gauged by full length of the base Someone will have to explain to me how, properly handled, a bump in the middle can result.

Share this post


Link to post
Share on other sites
59 minutes ago, Michael Darnton said:

If planing can be said to have a "natural" effect, in my experience it is to be hollow in the middle with a bump towards each end, as the sole starts to lose contact  with with the wood and the blade is no longer fully gauged by full length of the base Someone will have to explain to me how, properly handled, a bump in the middle can result.

I suspect that it comes from not knowing how to reposition the downforce on the plane at the beginning and end of the cut. But that wouldn't be "proper handling", of course.

Share this post


Link to post
Share on other sites
19 hours ago, zdalton13 said:

Checkout the video in my thread. I'm no expert by a long shot, but Rob Cosman, who has been doing woodworking for decades, mentions that a hand plane will naturally produce a convex surface.

That suggests that Rob Cosman would not be a good person to learn planing technique from. He seems to do alright with a table saw though. :lol:

Share this post


Link to post
Share on other sites
21 hours ago, Carl Stross said:

Thanks for the post. The print is fine so I will have to print it out. There are a lot of stresses in cast metals from the solidification process. I guess the study the Navy did looked at this for cast gray iron which the body of planes would be made of. The study was done in 1955 and many of the references go back to the early 20th cent. That does not mean it is not correct. If there is some kind of thermal cycling going on, like a car engine heating up and cooling off that will provide the necessary added strain/stress to caused internal relaxing of stress from casting. A high temp anneal will solve the problem. If planes are flattened when new to a reasonable value where does all the distortion come from In older plane bottoms? Does the added stress during use cause the yield stress to be reached locally within the plane. Seems like every plane I see is not close to being flat. I wii read the report, thanks. I have to print it out.

Share this post


Link to post
Share on other sites
27 minutes ago, Greg Sigworth said:

Thanks for the post. The print is fine so I will have to print it out. There are a lot of stresses in cast metals from the solidification process. I guess the study the Navy did looked at this for cast gray iron which the body of planes would be made of. The study was done in 1955 and many of the references go back to the early 20th cent. That does not mean it is not correct. If there is some kind of thermal cycling going on, like a car engine heating up and cooling off that will provide the necessary added strain/stress to caused internal relaxing of stress from casting. A high temp anneal will solve the problem.

1. If planes are flattened when new to a reasonable value where does all the distortion come from In older plane bottoms?

2. Does the added stress during use cause the yield stress to be reached locally within the plane.

3. Seems like every plane I see is not close to being flat. I wii read the report, thanks. I have to print it out.

1. If they were properly annealed, from shocks. I doubt any planes are properly annealed. Never seen a straight one.

2. Sharp shocks will do that. Precision straight edges ( camel backs etc ) can not take any sharp shocks. The most common way a camel back gets out of straight is by dropping it by mistake during a print.

3. I have a couple of planes from Veritas and Lee Nielsen and none of them is flat. Years ago I bought for little money a 580mm plane - made in India. Badly off. I faced the sole ( the right way, on a shaper ) and I tried to scrape it but it kept moving so much that I called it quits after 2-3 hours. I have no reason to believe Veritas castings are much better. I guess that if you like planes ( I do :) ) the best option is to make yourself one from Durabar and buy a Lie Nielsen frog for it.

 

 

Share this post


Link to post
Share on other sites
12 hours ago, Michael Darnton said:

If planing can be said to have a "natural" effect, in my experience it is to be hollow in the middle with a bump towards each end, as the sole starts to lose contact  with with the wood and the blade is no longer fully gauged by full length of the base Someone will have to explain to me how, properly handled, a bump in the middle can result.

I do see the logic with that explanation. But my planes will produce a bowed convex surface if I just push the tool across without using any downforce or shifting my weight. Perhaps it may have something to do with the innate geometry of my tool or something.

Share this post


Link to post
Share on other sites
30 minutes ago, Nick Allen said:

I do see the logic with that explanation. But my planes will produce a bowed convex surface if I just push the tool across without using any downforce or shifting my weight. Perhaps it may have something to do with the innate geometry of my tool or something.

There needs to be a bit of scientific rigour applied to this subject. How many people responding to this subject have taken the time to examine what happens when they plane a violin wedge. How flat is their plane? How do they test the surface of the planed edge without using a straight edge to see what is happening?

I have spent the time and that has proven to me beyond doubt that using a flat plane, large or small, produces a slightly convex shape in the planing process. If your plane has a flat sole the idea that exerting more pressure to the front or back during the stroke can somehow modify the result is fantasy. When a plane with a flat sole and a sharp blade engages the wood at the beginning of the stroke it will cut at the full depth for the full length of the stroke. Why it produces a domed cut is debatable. But is seems to cut deeper at the end of the stroke.  If the blade is blunt or the plane sole high at the mouth anything can happen. 

I don't know who Rob Cosman is but on this subject he certainly knows what he is talking about. And so does Nick Allen.

 

Share this post


Link to post
Share on other sites
49 minutes ago, Dennis J said:

If your plane has a flat sole the idea that exerting more pressure to the front or back during the stroke can somehow modify the result is fantasy. 

I’m happy to report that my fantasies are repeatable.

At least some of them...

Share this post


Link to post
Share on other sites

So how do you manage to make a straight joint, since y'all's planes can't do the job? Mine can do a good joint with just a bit of spring the middle.

 

Maybe you need to send your planes for lessons. Gotta say, I call a concave line a normal one, followng the geometry of the plane, and a convex joint an incompetent one.

Share this post


Link to post
Share on other sites
4 minutes ago, Michael Darnton said:

So how do you manage to make a straight joint, since y'all's planes can't do the job? Mine can do a good joint with just a bit of spring the middle.

 

Maybe you need to send your planes for lessons. Gotta say, I call a concave line a normal one, followng the geometry of the plane, and a convex joint an incompetent one.

Mine still do a good job. And I agree that a convex surface is unacceptable, as that's violin making 101. Just saying what my personal tools tend to do with minimal intervention.

Share this post


Link to post
Share on other sites

Cabinetmakers use planes with convex and concave soles to plane convex and concave surfaces. Plane manufacturers make planes with flat soles to plane flat surfaces. I find, as do others apparently, that flat planes seem to take more off at the end of the stroke, possibly when the toe of the plane passes over the end of the board. Not a major problem, easy to compensate for. It's as simple as that.

If you are happy gluing edges together necessitating the use of clamps good luck to you. I prefer gluing flat matching surfaces when joining any two pieces of wood. No clamps needed. And the integrity of the joint made with matching surfaces must be as strong or probably stronger than any other joint. That's just plain common sense.

 

 

 

Share this post


Link to post
Share on other sites
5 hours ago, Melvin Goldsmith said:

It's an elementary piece of woodwork..Joining two pieces.....If you can't do it or need to theorize it you are fired!

Damn... still can't find my like button!  :) 

 

Share this post


Link to post
Share on other sites
On 4/30/2020 at 2:41 PM, Michael Darnton said:

Dave, I assume you are judging by holding up to the light and looking through the gap to see how much light comes through? Take your two best straightedges, then put a small slip of paper between them and check again. Drive a truck through the gap. .003" inches looks huge with light pouring through. Maybe the situation's not as bad as you think?

Hello Michael,

Yes, the light method is the one I have been using, and I think for my purposes the straight edges are straight enough.
It was interesting to me that we assume these things are perfect, but in reality this is never the case.
It was a surprise to find an expensive meter rule was nowhere near straight, according to my best straight edge, and this got me wondering if others were checking things with something they assumed was straight, but was actually less accurate than expected.

 

The thread has taken a bit of a turn now on the use of planes, but a lot of interesting thoughts from all the contributors. Thanks to those who participated.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.