Plane Blade Camber

[adrian]

As a data point, I asked Lee Valley how flat their "glass lapping plate" is and they say it's flat to 0.01". That would seem to suggest that it's worthless for this application. But granite surface plates that are 25" long are rather expensive. (Heavy too, I'll bet.)

 

[tnimble]

This assumes implicitly a reference surface as long as the plane. If the plane is longer than the reference, it would be necessary to do one end at a time. Would that procedure be ok?

Due to the gap you replace the large reference needed with technique. Technique being remeasuremnt and stopping when you are about to reach the desired shape.

Hm,

This setup will produce a convexe sole if one doesn't stop at the right moment.

Indeed, that the goal, replace the very long flat rerference that one doesn't have with technique. And the warning that its only to be used for concave planes.

And the convexity might be bigger than the former concavity. I wouldn't do it. I would lap the whole sole, i.e. put wet and dry under the whole length of the sole. The high spots are at both ends. These touch the wet and dry first. You can mark with a felt pen. The markings at both ends will disappear first. Only when the spot ahead of the mouth wears no felt marking anymore the sole should be flat enough.

Only if one has a flat reference of at least a third to double the length of the plane that is flatter along that length than the accuracy of flatness to be accomplished.

I had a low angle jack plane with a convexe sole. It was very awkward to plane with it . It was not possible to take a consistent shaving over the whole length of a board. I tried to remedy and flatten the sole but I gave up. The belly was too big. What I want to say is, if the convexity is too bad, it will become a tedious job to put it right again. Pushing downwards at the same spot in the centre without rubbing the ends on the sheet is highly exhausting.

With a slight convexity or only convexity at the tops of the toe and or heel this problem is non-existent. Taking out a convexity on a flat surfae is not possible. The same as with any plane when taking only trough shavings will always end up with a convex board.

This is how Lee Valley....

It appears that you have this backwards:...

A concavely iin the sole is not a problem as long as its not in front of the blade ie the mouth. Japanese planes have multiple concavelies along the length. Having concavely is different from being concave. I shall try to put up a few drawings.

As a data point, I asked Lee Valley how flat their "glass lapping plate" is and they say it's flat to 0.01". That would seem to suggest that it's worthless for this application. But granite surface plates that are 25" long are rather expensive. (Heavy too, I'll bet.)

Its very useable for the right tsks and with correct technique. not even The perfect flat reference (if that would exist) would be 'fools proof' of producing an flat plane sole.

 

[tnimble]

Concave

The above two planes would not be able to make fine shavings (up to an extend depending on the amount of concavity) The wood fibres are not supported and pushed down.

Many Japanese planes have a sole like this (but a completely different body and could have a bamboo or brass spring in front and or back of the blade) Since the concavities are not within a reasonable distance away from the mouth the plane can make very fine shavings. The concavities reduce friction and help to speed up flattening a board.

Convex

This plane would be very difficult to operate. When the plane is set to a fine shaving the plane does only make shavings at a specific balanse point. If one shifts the downward preasure slightly the plane stops making shavings.

When the plane is set to make thicker shavings the plane does a fine job when either pressing down on the toe or on the heel. If one shifts this presure to the middle the plane digs into the wood.

This plane would do a wonderful job on making fine shavings just as good as a perfectly flat plane (which does not exists) that is a bit less longer in length.

 

[David C]

Hooray,

The last picture represents 90% of the planes in my workshop. They work very well indeed.

This shape is inevitable when lapping on abrasive paper on a flatish surface.

(Bugbear's spot filing etc will get them flatter).

No1 is how many production planes arrive from the manufacturer and they do not work well at all. Try planing a straight edge with a fine shaving.......................................................... :-(

3 is also very good.

David C

 

[pam niedermayer]

Here's the main fettling page I saved from Jeff's site:

<i>To Be or Not to be A Flat Soler?
Do I need a truly flat-soled plane? If you are involved in fine woodworking that requires a tear-free finish, it is important that the front lip of the mouth can effectively press down any fibres that might tend to lift, split ahead of the cutter and tear themselves from the body of the wood before the cutter can cleanly shear them off. Close Your Mouth

If the sole is concave, or (as seems to be quite common) there is a bump just behind the mouth, obviously this cannot happen.

If the plane is required to plane straight edges, as when joining pieces to make up a panel, the sole will need to be straight from end to end.

If your plane is just for trueing the edges of doors and suchlike, you can probably manage quite well with the one you've got

Note: For a good finish, a very fine shaving aperture is also essential, but that is another story.

How to check A heavy-section, purpose-made straightedge is best, but failing this, a good quality steel rule, preferably marked British Standard 4372, is essential.

Check the edges for slight damage. Without touching the original machined edge, use a fine abrasive to remove any small nicks acquired during general use.

A pitfall Rules are likely to become somewhat bowed in their thickness. This means that unless held at right-angles to the surface under test, they will give either a false concave or convex reading, depending on the inclination away from, or towards the user. The "blade" part of a good quality combination square, which will be thicker than a normal bench rule, is less likely to have this fault. (Avoid very cheap versions, I found one to have a 0·13 mm (5 thou) error along its edge.)

For a quick first check If you are limited to only using a rule for testing, it is usually better to work by feel rather than try to lift and hold a heavy plane to the light. Grip the rule about its mid-point. On a convex surface it will swivel freely. The ends will tend to grip a concave surface and the middle part can be made to flex. (You might also find this advice of useful when preparing face sides, etc, on your wood).

More careful checking To overcome the effects of bow, hold the face dead upright against something machined 'square' such as the side of an engineer's square or accurately planed piece of wood.

In various places along the plane use feeler gauges to check for gaps between the sole and the rule.

It would be much better, however, to use a surface plate. You can improvise one.

This will be essential if the sole is to be finished by scraping. Scraping: The abrasive approach - first, and maybe the last, stage

If you decide that your plane would justify some extra work, whether you decide to go the whole hog and scrape or not, you'll first need to abrade the sole (unless you have access to a surface grinder, of course).</i>

Pam

 

[newt]

The longer your reference surface is the faster you can flatten the sole of the plane.

However a perfect flat surface is not needed as long as that surface has no twist / wind.

When your not sure about the surface and you have a convex plane use two sheet of sand paper with about 1 to 2 third the length of the plane between them.

Then take a number of passes and remeasure the hollow in the sole of the plane. Make a guesstimate on how long you should continue this.

Remeasre the plane. If the hollow in the plane gets less but moves to the toe or the heal of the plane move presure or remove one of the sheets for a while.

Your reference to using two sheets of sandpaper for a convex sole should surely be for a concave sole. Your third picture which David C says is good, and I agree, however reducing the area does not directly reduce friction. Fiction = Coefficient of friction (the material) * mass.

 

[tnimble]

Your third picture which David C says is good, and I agree, however reducing the area does not directly reduce friction. Fiction = Coefficient of friction (the material) * mass.

The coefficient of friction (COF) between to objects is depends on temperature, speed, atmosphere, as well as on the geometric properties of the interface between the materials.

Besides the kenetic and static friction the 'resistence' you encounter when moving two object along each other also depends on the molecular adhesive attraction. For materials that have a rough interface between them this force is neglectable. For materials that have a perfectly flat interface between them this force can be as high as the tensile strength.

 

[bugbear]

Here's the main fettling page I saved from Jeff's site:

I think Jeff took those pages down due to issues of copyright. You might respect his decision in that regard.

BugBear

 

[bugbear]

Due to the gap you replace the large reference needed with technique. Technique being remeasurement and stopping when you are about to reach the desired shape.

In this case, your measuring straight edge is the reference, and indeed, must be (nearly) as long as your plane.

In my case the distinction between "reference" and "metal remover" is a little more obvious.

BugBear

 

[bugbear]

Concave
(pictures removed)

Thanks for doing that work; it may well help some jargon ambiguity, especilly since convex versus concave depends which way up you're thinking of the plane.

BugBear

 

[newt]

Tnimble, I accept what you say about friction, but don't you think the reason there are concave areas on the planes sole is to make it easier to flatten, just like the Japanese chisels.

 

[tnimble]

Tnimble, I accept what you say about friction, but don't you think the reason there are concave areas on the planes sole is to make it easier to flatten, just like the Japanese chisels.

A good Japanese plane is delivered completely flat by its maker. If one would want to reflatten the plane after a while one has the tedious job of removing the spring(s), flattening the plane, reinserting, refitting and tensioning the spring(s). Probably a job left to done again by the plane maker, who might just make a new body to match the plane blade.

For cheaper more factory made Japanese style planes it would indeed ease flattening. But this has little to no benefit if one would flatten a wooden plane using a power jointer.

 

[ivan]

LV glass flat to 0.01"? must be a misprint surely? Would look like handblown! Plate glass is virtually optically flat (or it would distort like a lens) orders of magnitude flater than a plane. We used to bed plate glass onto blobs of car body filler to support* it, then we splashed out on a 600mm chinese granite plate in a sale.

*we used a concrete slab (not bendy ply)

 

[bugbear]

We used to bed plate glass onto blobs of car body filler to support* it,

*we used a concrete slab (not bendy ply)

Yes; glass should be supported as much as possible without introducing distortion; I've seen thick pile carpet and various rubbers (e.g. router mat, car underlay) recommended.

When supporting using blobs, you have to be sure that the blobs don't shrink or move when drying/setting (or use bouncy blobs)

And, yes in the modern era, granite surface plates are (IMHO) cheap enough that all this becomes unneccesary.

BTW, for planes up to 22" (#7) I will point out that the DIAGONAL of a 12x18 surface plate is a rather helpful 21.6 inches.

BugBear

 

[adrian]

Lee Valley doesn't have any published specs for the glass plate. I inquired by email and they wrote back that it was 0.01". I asked again and got this reply:

Thank you for your reply. The 1/100" mentioned would be a maximum, the plate is designed to be flat as possible as you stated.

Thanks for doing that work; it may well help some jargon ambiguity, especilly since convex versus concave depends which way up you're thinking of the plane.

Actually "concave" and "convex" are independent of orientation. (But it's still nice to have those pictures.)

Why can't plane #2 make a fine shaving, as long as you keep the toe down on the work and don't let it tip back when you get to the hollow?

Does rubbing a plane on sandpaper on a flat surface plane #5 rather than plane #4? You would get a long flat region in the center?

 

[pam niedermayer]

I think Jeff took those pages down due to issues of copyright. You might respect his decision in that regard.

BugBear

You know, I kept visiting the new, reformed site looking for an explanation/reason as to why Jeff removed 90% or so of his pages. From the moment Netscape/Mozilla/Firefox was able to save complete pages with some reasonable retrievability, I've been saving pages that were very important. I can't think of another site that's had more of an influence on the development of my woodworking skills than Jeff's. And while I think I understand his reasons for doing such and such a thing, I don't have a lifetime to rewrite them, draw new pictures, and the like.

I also think it's unreasonable to withhold this information from other woodworkers. So, can you please give me some accessible place to point to that has said information without copyright issues? And what's the situation vis a vis UK copyrights in the US?

Pam, who as a software developer for 34 years is a true copyright warrior and disdains people who plagiarize and/or steal music, software, and other intellectual material

 

[pam niedermayer]

Tnimble, I accept what you say about friction, but don't you think the reason there are concave areas on the planes sole is to make it easier to flatten, just like the Japanese chisels.

A good Japanese plane is delivered completely flat by its maker. If one would want to reflatten the plane after a while one has the tedious job of removing the spring(s), flattening the plane, reinserting, refitting and tensioning the spring(s). Probably a job left to done again by the plane maker, who might just make a new body to match the plane blade.

For cheaper more factory made Japanese style planes it would indeed ease flattening. But this has little to no benefit if one would flatten a wooden plane using a power jointer.

Springs? What springs? The only spring I know of vis a vis Japanese planes involves the blade and its relationship to the bedding.

And generally one doesn't want to reflatten Japanese planes. Perhaps only tune what's worn through use. Of course, horribly abused planes would be the exception. As to replacing the dai, making them isn't rocket science; but it is much more involved than most think. The complexities are subtle.

As to shipping flat dai, some do, some don't, depends on the daiya and whether he's (yeah, afaik there are no Japanese female daiya) knows the ultimate customer.

Pam

 

[Paul Kierstead]

As to shipping flat dai, some do, some don't, depends on the daiya and whether he's (yeah, afaik there are no Japanese female daiya) knows the ultimate customer.

As a curiosity, if he knew the ultimate customer, and the customer consider himself (or was considered to be) a craftsman, would the plane be flattened or not? It seems that it might be an insult to assume the craftsman would not be flattening the plane to his own satisfaction, OTOH sending an "incomplete" plane could be considered poor form. Japanese etiquette can be complex...

 

[pam niedermayer]

As a curiosity, if he knew the ultimate customer, and the customer consider himself (or was considered to be) a craftsman, would the plane be flattened or not? It seems that it might be an insult to assume the craftsman would not be flattening the plane to his own satisfaction, OTOH sending an "incomplete" plane could be considered poor form. Japanese etiquette can be complex...

I don't know all that much about Japanese eitquette either. I suspect it's up to the customer to specify what's desired, but few planes are sold directly from daiya to customer. Generally it's no big deal. I've been making dai for several years now, but also buying complete planes from places like Iida-san's when he has a good deal available (as in it's cheaper to buy the finished kit than the blade(s) alone). It never occurred to me to ask for a fully configured plane. I always have to fit the blade(s) and scrape the sole to suit, which suits me fine.

However, I'd also have no compunction about buying a plane directly from Inamoto-san and asking him to configure the sole, since I know he'd do a top notch job. The first plane I bought (from Misugi) had the sole configured. This was before I knew how to make dai, and was the impetus to learn how. When I saw the recessed areas in the sole and started fitting the blades, I knew I was out of my depth, so I set the plane aside and took a dai making course from Inamoto-san.

Pam

 

[bugbear]

I think Jeff took those pages down due to issues of copyright. You might respect his decision in that regard.

BugBear

You know, I kept visiting the new, reformed site looking for an explanation/reason as to why Jeff removed 90% or so of his pages. From the moment Netscape/Mozilla/Firefox was able to save complete pages with some reasonable retrievability, I've been saving pages that were very important. I can't think of another site that's had more of an influence on the development of my woodworking skills than Jeff's. And while I think I understand his reasons for doing such and such a thing, I don't have a lifetime to rewrite them, draw new pictures, and the like.

I don't think that effects Jeff's right to withdraw them.

I also think it's unreasonable to withhold this information from other woodworkers.

Jeff decision, not yours.

So, can you please give me some accessible place to point to that has said information without copyright issues?

On which subject? Flattening by scraping is on my website

And what's the situation vis a vis UK copyrights in the US?

Are you asking legally or morally?

BugBear