Plane fettling

[Jacob]

Well, what do you know? I am an engineer. Trust me, I do this for a living, I'm not dazzled by accuracy specs.

I do/did woodwork for a living and `I was not dazzled by accuracy specs either.
Usually work to the tape measure i.e. to 1mm, or often check thickness with a basic vernier calliper, to 0.1mm if necessary , but 0.5mm good enough for woodwork - it's more about making things fit together nicely, once you've got them sorted to 0.5mm etc.
Some of us live in the real world!

 

[steve355]

So, it's a lost cause then? I have to hire a machinist or buy the equipment and learn how to scrape a surface?

I use a straight edge and sandpaper on a block of wood. It gets my planes flat enough.

I think that as long as you use a flat-ish piece of plywood or mdf, you’ll be fine. That’s how it’s been done forever and very few woodworkers or even machinists have much experience in scraping. It’s an extremely laborious process. To apply it to hand planes you’d need a lot of time on your hands and you’d definitely start from where you left off with the sandpaper.

Just to illustrate the process (in case anyone‘s interested, and I’ve had a go at it) here are a few pics of the column of my surface grinder when I was refurbing it.

Basically you rub the item you want to flatten on a surface plate (known to be flat to <0.0001”) covered in blue dye, and scrape off the high spots. Eventually you even it all out and it slowly gets flatter and flatter.

See wear (gaps) at points that the knee of the grinder attached to the column. Surface plate in background.

Getting flatter.. still low spots on the right hand side, so all of the rest of the surface need to be scraped down to match.

Arguably good enough.

With the high spots all in a physical plane around a few ten-thousandths of an inch thick, this is way OTT for any hand plane. In fact I’d think that bluing up a hand plane might be counter productive as it would lead you to believe it’s not flat, when in fact it’s perfectly flat enough for the job.

However now I have one I find all kinds of uses for the surface plate, e.g. checking straightness and flatness of all kinds of things, gluing sandpaper to it for flattening chisel backs etc. and these days accurately marking up plane blades for cutting.

Steve

See below an Eclipse scraper.

Surface Grinder back together

Checking a Toolstation square to see if it is square…

 

[Jameshow]

I think that as long as you use a flat-ish piece of plywood or mdf, you’ll be fine. That’s how it’s been done forever and very few woodworkers or even machinists have much experience in scraping. It’s an extremely laborious process. To apply it to hand planes you’d need a lot of time on your hands and you’d definitely start from where you left off with the sandpaper.

Just to illustrate the process (in case anyone‘s interested, and I’ve had a go at it) here are a few pics of the column of my surface grinder when I was refurbing it.

Basically you rub the item you want to flatten on a surface plate (known to be flat to <0.0001”) covered in blue dye, and scrape off the high spots. Eventually you even it all out and it slowly gets flatter and flatter.

See wear (gaps) at points that the knee of the grinder attached to the column. Surface plate in background.
View attachment 161002

Getting flatter.. still low spots on the right hand side, so all of the rest of the surface need to be scraped down to match.

View attachment 161003
View attachment 161004Arguably good enough.

With the high spots all in a physical plane around a few ten-thousandths of an inch thick, this is way OTT for any hand plane. In fact I’d think that bluing up a hand plane might be counter productive as it would lead you to believe it’s not flat, when in fact it’s perfectly flat enough for the job.

However now I have one I find all kinds of uses for the surface plate, e.g. checking straightness and flatness of all kinds of things, gluing sandpaper to it for flattening chisel backs etc. and these days accurately marking up plane blades for cutting.

Steve

See below an Eclipse scraper.
View attachment 161005

Surface Grinder back together

View attachment 161008

Checking a Toolstation square to see if it is square…

View attachment 161007

Where do I sent my bandsaw?!

 

[paulrbarnard]

In fact I’d think that bluing up a hand plane might be counter productive as it would lead you to believe it’s not flat, when in fact it’s perfectly flat enough for the

Anyone with tendencies to OCD should avoid it at all costs.

 

[CliveB]

I thought that scraping doesn't actually provide a smooth surface, for a machine tool slideway this is an advantage because it traps oil for lubrication. When I tried to scrape a plane body a while ago I just ended up with a rougher surface which provided much more friction than the original state. Just as well it was only a cheapo handyman plane. Admittedly I am no expert at scraping, but I learned that it takes an awfully long time.

Clive

 

[steve355]

I thought that scraping doesn't actually provide a smooth surface, for a machine tool slideway this is an advantage because it traps oil for lubrication. When I tried to scrape a plane body a while ago I just ended up with a rougher surface which provided much more friction than the original state. Just as well it was only a cheapo handyman plane. Admittedly I am no expert at scraping, but I learned that it takes an awfully long time.

Clive

That’s broadly correct, it does trap oil, and thats part of the point of it. Smooth is all down to your definition of smooth.

The difference between the high spots (blue) and the low spots is probably about 0.0005” at most. This is imperceptibly smooth to the touch. It is however enough for light to reflect differently so it can be seen as the scraping pattern.

So to a photon, it’s probably pretty rough. But to the human touch it is very smooth, running a fingernail over it you can just perceive the scraping marks.

 

[paulrbarnard]

I thought that scraping doesn't actually provide a smooth surface, for a machine tool slideway this is an advantage because it traps oil for lubrication. When I tried to scrape a plane body a while ago I just ended up with a rougher surface which provided much more friction than the original state. Just as well it was only a cheapo handyman plane. Admittedly I am no expert at scraping, but I learned that it takes an awfully long time.

Clive

There is a subtle difference between smooth and flat. Flat defines the collinearity of the high spots. Smooth defines the difference between the highs and lows. Something can be very smooth but completely un flat (think of a ball bearing) and conversely something can be very flat but completely not smooth. Consider here a plane with a ridged sole.

 

[raffo]

I think that as long as you use a flat-ish piece of plywood or mdf, you’ll be fine. That’s how it’s been done forever and very few woodworkers or even machinists have much experience in scraping. It’s an extremely laborious process. To apply it to hand planes you’d need a lot of time on your hands and you’d definitely start from where you left off with the sandpaper.

I think I'm being misunderstood, despite reiterating the question multiple times. I'm not really asking how to get a surface flat or what method is best. I can figure that out on my own.

Is the flatness of the sole of a plane important, then why?

Many of the responses have been "technique is more important", "flat sighting down the work is good enough", "a block plane can do it", "flattening is for OCDs", etc. Many here state that they plane flat and straight and have been doing it for a living for a long time. Well, good for them, but I didn't ask them that. I would like to know the reasons they're able to do it? Do they have a flat plane? convex? concave? For all we know they have really flat planes and they just don't know it because they've never bothered to measure it.

A response on a related thread the other day stated that sprung edge jointing was a centuries old technique. In page 162 of Mechanical Exercises by Peter Nicholson, there is a procedure for joining two boards. The procedure doesn't call for planing the edges with a hollow. In fact, given that this book was published in 1812, this task would have been done with wooden planes. How flat can you get a wooden plane? There is a procedure on page 159 on how to make a straight edge which would precede joining two boards.

https://archive.org/details/PeterNicholson1812/page/n239/mode/1up
Is Nicholson wrong? are the procedures described in the book obsolete?

Rafael

 

[Jacob]

....

Is Nicholson wrong? are the procedures described in the book obsolete?

Rafael

If they work for you then they are right. Or vice versa. Have you tried them?
You have to remember that Moxon, Nicholson et al were not the text books of the day, read in the modern way by apprentices as part of their training, not least because most of them could not read.
They were the first DIY guides for the gentleman amateur, written by amateurs themselves, trying their best to describe the trade, but also slipping in their own ideas, some possibly misunderstandings.
If in doubt try it out; have a go at that planing two boards together trick and let us know how you get on.
PS I don't think Moxon or Nicholson say anything about flattening plane soles. Obvious really - they have to be as flat as you can conveniently make them - nobody needs that explaining!

 

[paulrbarnard]

I think I'm being misunderstood, despite reiterating the question multiple times. I'm not really asking how to get a surface flat or what method is best. I can figure that out on my own.

Is the flatness of the sole of a plane important, then why?

Many of the responses have been "technique is more important", "flat sighting down the work is good enough", "a block plane can do it", "flattening is for OCDs", etc. Many here state that they plane flat and straight and have been doing it for a living for a long time. Well, good for them, but I didn't ask them that. I would like to know the reasons they're able to do it? Do they have a flat plane? convex? concave? For all we know they have really flat planes and they just don't know it because they've never bothered to measure it.

A response on a related thread the other day stated that sprung edge jointing was a centuries old technique. In page 162 of Mechanical Exercises by Peter Nicholson, there is a procedure for joining two boards. The procedure doesn't call for planing the edges with a hollow. In fact, given that this book was published in 1812, this task would have been done with wooden planes. How flat can you get a wooden plane? There is a procedure on page 159 on how to make a straight edge which would precede joining two boards.

https://archive.org/details/PeterNicholson1812/page/n239/mode/1up
Is Nicholson wrong? are the procedures described in the book obsolete?

Rafael

Shame all the answers and comments have not addressed your exact requirements.

There is no definitive right or wrong answer as you can probably see. What works for one might not work for another. What is flat for one is bowed for another. Some have amazing hand eye coordination others don’t. Peoples tolerance to tolerances are different.

If you want an absolute yes/no binary solution buy a CNC system.

 

[CliveB]

Shame all the answers and comments have not addressed your exact requirements.

There is no definitive right or wrong answer as you can probably see. What works for one might not work for another. What is flat for one is bowed for another. Some have amazing hand eye coordination others don’t. Peoples tolerance to tolerances are different.

If you want an absolute yes/no binary solution buy a CNC system.

As someone who has spent a few hours flattening my 5 1/2 plane to less than +/-0.75 thou, and not really seeing an advantage in actual practice, could someone explain to me what happens if you have a truly flat plane sole and then you have a cutter which protrudes more than a few thou beyond that flat surface. How does that work?
Clive

 

[Woody Alan]

"How does that work?
I can't answer the question but agree you have a point in that it doesn't completely. If I plane an edge on a board and continue to plane without taking the effect from cutter position into account I'll never get a flat edge it will always bow down at the ends because the support of the sole for and aft of the cutter is lost at the ends. Hence checking for flatness and planing only the middle section to achieve flatness or an elusive shallow curve to give slight spring when joining boards.

 

[raffo]

As someone who has spent a few hours flattening my 5 1/2 plane to less than +/-0.75 thou, and not really seeing an advantage in actual practice, could someone explain to me what happens if you have a truly flat plane sole and then you have a cutter which protrudes more than a few thou beyond that flat surface. How does that work?

Edge planing would be a good starting point.

Plane a board with your 5 1/2, plane a differnet board with another plane. Place one over the other. Are they well matched? is there a gap?

See the Nicholson reference above regarding edge joining.

 

[Ed Weber]

I’m puzzled by the opinion that a laser flat sole is the meal ticket to fine work. Wouldn’t skill building count for something? I would also bet that novices many times do more damage than good to plane soles.

opinions?

I think the entire subject is overblown.
While we all want our straight tools to be straight and our flat tools to be flat, etc, obsessing over the perfect at the expense of the good (above necessary tolerances) is a waste of time.

A laser flat sole is of no use if the operator doesn't know how to use the tool, Skill building counts for a lot more than something.
A poor craftsman may only gain a slight improvement with top of the line laser perfect tools.
While an experienced craftsman can use any level of tool and maintain a high quality.
A .001 discrepancy in the flatness of the sole of the plane, will not be seen in the final product, nor will it make the construction more difficult.

 

[raffo]

If they work for you then they are right. Or vice versa. Have you tried them?

The edge jointing and testing of the joint as described in the text, I have tried and have had good results with that. I think having the metal plane that I use flat helped in not getting a convex edge. I was able to take full shavings even after taking my hand off the front of the plane. I did not use the sprung edge method.

You have to remember that Moxon, Nicholson et al were not the text books of the day, read in the modern way by apprentices as part of their training, not least because most of them could not read.
They were the first DIY guides for the gentleman amateur, written by amateurs themselves, trying their best to describe the trade, but also slipping in their own ideas, some possibly misunderstandings.
If in doubt try it out; have a go at that planing two boards together trick and let us know how you get on.
PS I don't think Moxon or Nicholson say anything about flattening plane soles. Obvious really - they have to be as flat as you can conveniently make them - nobody needs that explaining!

I don't take the books as gospel. I do not know if the purpose of the books were to serve as a DYI text for affluent hobbyists or a genuine desire to document a trade. Other books have come later, they have similar prescriptive procedures on how to use the tools. I give them more credence than contemporary publications which are usually marketing vehicles rather than objective sources.

I've been reading books on traditional varnishes, some dating back to 1688. They give enough detail for one to cook you own copal varnishes. They don't seem like amateur work.

Thanks for the response.

 

[pe2dave]

Does the phrase 'flat enough' sum up this thread?
... for the owner being the postscript.

 

[CliveB]

Following on from my comment about the cutter protruding from a very flat sole, I've exaggerated the cutting depth in the attached diagram hugely but in the middle of a board (on edge and narrower than the cutter) wouldn't the geometry look like this with the plane sole making contact with the wood at two points only - see the arrows.

Of course at the start and finish of the cut the geometry would change.

 

[raffo]

Following on from my comment about the cutter protruding from a very flat sole, I've exaggerated the cutting depth in the attached diagram hugely but in the middle of a board (on edge and narrower than the cutter) wouldn't the geometry look like this with the plane sole making contact with the wood at two points only - see the arrows.

That's what seems like, two points. However, the heel is not making contact until after the planes has been pushed its whole length. How much flatness can we allow between the cutter and the heel of the plane? A very slightly convex plane would still work since it would effectively be a shorter plane. If concave, the bigger the concavity, at some point the plane will not stay in the cut, and round the edge of the board, assuming we focus on edge planing in this discussion.

I wan't remind to those that are assuming I'm trying to get or propose some concrete flatness number or that I'm arguing that we should all flatten a plane to within 10 microns. For the umpteenth time, no. I just want to understand how much flat is flat enough to make a plane work. I know one needs to know how to use the plane. When people say "technique is everything", "0.001 in out of flat is fine", etc. That's all just opinion, without knowing if your plane is flat or not, all those statements are just guesses.

 

[Ed Weber]

You're complaining about guesses and opinions while simultaneously saying you don't want a concrete number.
Members are trying to answer your question but you don't seem to know what you're looking for.

It would seem obvious that there is no one single answer but a range of answers, as there is a range of planes that all perform the same task.
Not so convex that it won't stay stable, Not so concave that the blade lifts out of the cut. The range in between is your ansewr and it varies.

 

[Jacob]

...... I just want to understand how much flat is flat enough to make a plane work.....

Depends on who is cracking the whip! If it's desperate you will find a way however cra p the plane.
Seriously though, I'd guess it needs to be not obviously concave. Flat to convex should be OK?