edge jointing and the mysterious vanishing camber

[PaulO]

My plane is 21 inches, I think. The workpiece is 48 inches. I'm below your limit, at less than 2.5 times plane length.

My guess is that your plane has a bump larger than the shaving you are trying to take

So you're thinking that I may have had a camber a while back, but I removed it by sharpening with too much focus on the center? (This is a possibility, though I don't think I could have gotten a concave edge by sharpening.

Does sound strange, how and when do you flatten your stones?

Is phenolic flat? (My phenolic straight edge seems to be a little dubious.) I thought ebony was a kind of unstable wood, prone to warping and such.

No reason to suggest that phenolic is intrinsically flat, David and I check our references against a small 100mm straight edge, like this:
http://www.****.biz/****/product/707290/detail.jsf

I do this every couple of months and haven't had to replane my block yet. I know David does replane his reference occasionally, but that might be because of abuse by students (to the phenolic, not him :wink: ). This reference is only as long as the blade is wide. Just a softish, dark surface to eyeball camber against

So what about #3. If the shaving is set too small can I get the situation where the plane won't cut? (In other words, it's not just that I'll have to take extra passes?) The shavings were about 0.002" or a bit under.

That sounds like a reasonable working shaving size, so I am guessing your sole isn't that flat.

 

[adrian]

My plane is 21 inches, I think. The workpiece is 48 inches. I'm below your limit, at less than 2.5 times plane length.

My guess is that your plane has a bump larger than the shaving you are trying to take

The bump is definitely larger than the thickness of the shaving. It's probably something like 5-10 shavings thick. Could even be more than that. But I don't mind taking 5-10 shavings.... On previous board I have removed sizeable bumps that took more than 10 passes of the plane to eliminate, so it doesn't seem like this should be a problem.

I know that my planes are not as flat as people here have recommended. I also don't see any reasonable way to get them flatter without laying out an enormous sum of money (to buy a 22 inch long flat reference surface that is too heavy for me to move around by myself), and spending a great deal of time on it, so I figured that I'll just have to do what I can with what I have. And one observation is that flatness doesn't seem to be a decisive limitation because I managed to joint the first 6 boards with the same plane. I didn't drop it on the floor after board #6 so I think it should be just as flat as before.

So you're thinking that I may have had a camber a while back, but I removed it by sharpening with too much focus on the center? (This is a possibility, though I don't think I could have gotten a concave edge by sharpening.

Does sound strange, how and when do you flatten your stones?

I have shapton stones and flatten them on the glass diamond flattening plate that shapton sells. (I previously was flattening on the shapton lapping plate and I discovered that my lapping plate had developed a bump. I managed to get a replacement lapping plate out of them but now I'm scared to use it for anything...)

I [check my ebony reference block] every couple of months and haven't had to replane my block yet. I know David does replane his reference occasionally, but that might be because of abuse by students (to the phenolic, not him :wink: ). This reference is only as long as the blade is wide. Just a softish, dark surface to eyeball camber against

I was trying to think if I have anything on hand that's dark and hard so I could whip out a suitable reference (assuming, of course, that I can get the plane to cut the reference material...) I have some 3/8" thick stuff that's hard and somewhat dark (chechen), and I have some thick stuff (black walnut) that's dark and soft... I assume if the reference is too soft it'll get cut up, so I ought to try to use a wood that's reasonably hard, but if it's thin, it's probably less likely to stay flat, right?

Is phenolic easy to work with hand tools?

How important is it to have the camber in order to get the board to behave along its length? As far as I can tell, the cambering is for getting the board to behave in width (to make it square to the face). In other words, can I blame an inability to cut off the bump on the size of the camber somehow?

 

[Racers]

Hi. Adrian

I flattened my No7 with a sheet of glass and some 60 grit stretched tight on it. it didn't take long.

Pete

 

[adrian]

Hi. Adrian

I flattened my No7 with a sheet of glass and some 60 grit stretched tight on it. it didn't take long.

Pete

I tried that approach with a #5 I got on ebay and the plane got, if anything, less flat as a result of my couple hours of labor over the sheet of glass. So I'm pretty nervous to do it again, particularly on a good plane. As I understand it, that type of approach will tend to give a curved surface, not a flat one. i've also made water stones non-flat by lapping on a sheet of glass. To get a flat surface, as I understand it, I need to get a flat reference (and I've read that glass won't work due to lack of texture to hold the blue) and files or scrapers and remove the high spots. The process sounds like it takes some learning (gee, kind of like trying to make wood flat) and it doesn't sound like it would be particularly fast.

 

[Mr Ed]

I think theres a number of issues here;

1. When edge planing for joining boards the primary objective is to get a perfect fit to the other board. I use straight edges to make sure I'm heading in the right direction, but the final checking tool for each edge is the board its joining to. The pursuit of the perfect edge can become a bit esoteric; perfect in what context? The only true measure of the perfect edge here is if it fits the one on the other side.

2.In edge jointing the cambered blade is only going to help you across the width of the edge. In the convexity or concavity of the edge along its length (which I think is your issue if I understand correctly) its irrelevant.

3.If you have a gradual bump in centre of the length of the edge its quite possible you could plane up one side of it over the crown and down the other side. I would think you would notice transition from one slope to the other, but maybe not. As others have said, the way to deal with this is to work in the middle first. If the plane won't cut due to length you can skew it to effectively shorten it, so the sole is hanging over both sides of the board.

4. It would be surprising, but not impossible, if either of the planes you have would be out of flatness to such an extent that it causes the problem you are having.

Hope something here helps.

Cheers, Ed

 

[Paul Chapman]

If, as you say, you have planed several pieces without any problem and it's only this one board which is causing you problems, then I wouldn't start worrying about flattening soles and other drastic things. I'd look for a simpler explanation.

Have you tried turning the board around and planing it in the opposite direction?

Have you tried another board and still had the same problem?

Cheers :wink:

Paul

 

[adrian]

Because I was stuck on this for a while, it becomes hazy what exactly I tried or didn't try. I did turn the board around. That didn't seem to help. I think I tried a shorter plane, but now as I think back I'm not sure. (I have the shorter plane set to a really heavy shaving and have been using it as the first plane on the edge, the remove the saw marks. If I tried the short plane, I didn't reset it for a thin shaving.) I did not try a different board.

If I have a list of things to try when I return to the shop that will be good.
So far those things are: take shorter cuts around the bump, use shorter plane/skew the plane, try a different board. Did I miss anything?

 

[PaulO]

I was trying to think if I have anything on hand that's dark and hard so I could whip out a suitable reference (assuming, of course, that I can get the plane to cut the reference material...) I have some 3/8" thick stuff that's hard and somewhat dark (chechen), and I have some thick stuff (black walnut) that's dark and soft... I assume if the reference is too soft it'll get cut up, so I ought to try to use a wood that's reasonably hard, but if it's thin, it's probably less likely to stay flat, right?
Is phenolic easy to work with hand tools?

Phenolic is easy to work with hand tools. I wouldn't worry too much about the softness, as you only place the blade lightly on the reference. I chose ebony because it was dark and tight grained, and I didn't have any phenolic lying around

But as Ed said, the camber of the blade isn't the source of this problem, as you have worked out. But the camber does help you get the edge square.

How about ripping a clean edge and trying again? You obviously have the bump / slope / convexity in some strange configuration that means the blade misses the bump for your plane / shaving combination. For example if the convexity in the edge of your board over the length of the plane is greater than the height of your bump + shaving.

 

[adrian]

But as Ed said, the camber of the blade isn't the source of this problem, as you have worked out. But the camber does help you get the edge square.

Right. But even if it's not directly connected to this particular problem, if I don't get my cambering worked out properly at some point I'll have trouble getting the edge square if not now, then later.

How about ripping a clean edge and trying again? You obviously have the bump / slope / convexity in some strange configuration that means the blade misses the bump for your plane / shaving combination. For example if the convexity in the edge of your board over the length of the plane is greater than the height of your bump + shaving.

I suppose I could try this, though my ripped edges (by bandsaw) tend to be kind of wavy and, as I'm nervous about having enough width, I'd rather not cut it off unnecessarily at this stage. I guess it seems like a reasonable thing to try if nothing seems to work on this board, but if I go on to another board and everything works fine.

 

[newt]

I am not sure if you said what type of wood you are using, not that I think that is an issue, just interested. The first thing I would do would be to try a shorter plane in the middle. You said that you had the shorter plane set for a thick shaving it gave me the impression that you did not want to adjust it for a fine shaving if that is the case why not. If the shorter plane does not cut and the blade is sharp and it is definitely convex in the middle then it may be something very strange about the wood. You could just check that it cuts ok in the middle with a chisel. If that does not work I would assume all your planes soles have suddenly become concave. Even is this was the case increasing the depth of cut would eventually produce a shaving.

 

[adrian]

I am not sure if you said what type of wood you are using, not that I think that is an issue, just interested. The first thing I would do would be to try a shorter plane in the middle. You said that you had the shorter plane set for a thick shaving it gave me the impression that you did not want to adjust it for a fine shaving if that is the case why not.

I have nothing against adjusting the shorter plane for a thinner shaving. I wrote that it was set for a thick shaving in the context of trying to recall what I did, and one thing I know I did NOT do was adjust it for a thin shaving.

The wood is quarter sawn American cherry. It's a fairly soft hardwood, easy to work. I was having a bit of trouble with tearout on the face of the boards, but the edges are planing smooth like glass (and it seems like I can plane either direction).

 

[newt]

Adrian, When you say you cannot remove the hump in the middle, do you mean the plane does not remove any shavings or you produce shavings but the hump remains.

 

[ivan]

David Charlesworth's 3 books have all the DVD info and a lot more, cheap on Amazon's Marketplace etc. When I began woodworking I had a devil of a problem with a Record #6, which when I knew more, turned out to be 25 thou hollow. You can imagine the problems that caused. But you can't flatten without a flat plane, sound as if yours is 5 or 10 thou hollow. Books above have info on flattening, you can use float glass of 1/2" or so - must be thick - maybe scounge an offcut. Chinese granite plates are not too dear if you also do a bit of metalwork.

When your plane is really flat, you can plane with stop shavings till it doesn't cut, and then give 1 or 2 through shavings; at this point you can test 1 board against the other by pushing each end and seeing where it pivots (the other end if both slightly hollow) I think this is also covered in DC's books.

 

[Racers]

Hi,

You can get a plane sole flat on glass, but you must either stick the sandpaper down or stretch it tight its the little ripple that forms as you push the plane forwards and backwards that causes the sole to go convex.

Pete

 

[adrian]

My planes have hollows that are around 2-3 thou, as I recall. I didn't test them recently.

I've also read in the messages about plane flattening that glass can flex. So if I wanted to risk a plane with the sandpaper approach I need a piece of glass that is very flat and is 1/2 inch thick and at least 2.5 feet long so I have room to move the plane on the sand paper? (Is all glass flat to .0001" or something?) I guess part of the problem here seems like the target tolerance. If I wanted to make it flat to 10 thou or 5 thou it wouldn't seem like that difficult, but to be flat to 1 thou or less seems like a major challenge. Ivan suggested that Chinese granite plates might be affordable. I can get a small 12"x18" granite plate without spending too much, but at 85 lbs I don't think I could move it around without help, and that's not big enough for a 21" long plane. Actually looking around I see some bigger ones that appear affordable (though I expect that the cost of delivery is about 3 times the cost of the product, so maybe not as affordable as they appear). But nobody seems to sell 36" x 6 inch granite plates.

I cut some lines in a piece of MDF to test my 2 ft starrett straight edge. The results of this test are that it is perfect. I'm not sure what the accuracy limit on this test is. (I doubt it would detect a 2 thou deviation, for example--the knife would follow the previous line.) It appears that Starrett claims this item is flat to 0.0004", though I suspect the layer of wax I put on it varies in thickness by more than that...

The behavior that I observed was that there is a substantial bump on the wood but the plane won't cut at all. So it wasn't that it was cutting and cutting and the bump remained.

Is it possible that the ability to cut a bump could depend on the twist along the edge? If the edge isn't square to the face but instead twists across the length could a plane trying to make a centered cut ride the twist somehow and be unable to cut? Like if the bump is in the middle but the twist gives a high spot at both ends of the plane that hold it above the bump? (If this were happening I assume that a shorter plane would have a better chance of cutting, and presumably the best thing to do would be to remove the twist first.)

I have read all of the Charlesworth books as well. In fact, I strongly prefer books to DVDs both as a general personal preference (I read a lot) and because it's much easier to refer to them in times of need. But for some reason, I seem to find the Charlesworth books difficult to learn from. I'm not sure why. I read them all but somehow the DVD was still a revelation. But for example, I wonder if it's worth getting the DVD on shooting boards. I already improved my shooting board technique based on what he said in the book....

So I snuck down to the shop last night and tried to do some planing with the sharpened Clifton #7 and found that, lo and behold, it is now taking off the bump. I'm not sure why.

Of course, I discovered a different problem, namely that I seem to having a much harder time that before getting and staying square to the face. Before it seemed like I could just drift the plane a bit here and there and the edge would come to square and then it would stay square while I worked on the lengthwise condition of the surface.

Now I found that when the bump was gone, the edge was out of square. And I tried to adjust the plane, because it appeared that maybe it wasn't cutting in the center and so I wasn't doing what I thought I was doing, but making this adjustment seems to be difficult, but because I don't have a clear way to tell when I'm off by just a little bit, and because the adjustment lever makes small adjustments difficult. I tried the method of running a little scrap over the blade and looking for the little shavings in the plane. And that worked to a point, for getting me into the right neighborhood, but not for the final adjustment.

After a great deal of fussing and frustration I eventually got an edge that appears square and that stayed square when I turned my attention to the lengthwise direction. And I was able to remove the bump. So I don't know what was going wrong before.

We'll see how things proceed with the next board.

One thing I did notice is that the method of swiveling one end of the straight edge sometimes gives a puzzling result. There seem to be three outcomes. One outcome is that the straight edge spins freely on a point somewhere in the middle. Clearly there is a bump. The straight edge will rock. Another outcome is that the straight edge pivots on the fixed end. Clearly the surface is concave. The third outcome is that the edge pivots on a point about an inch from the other end. So if I shift the right end of the straight edge, it pivots on a point an inch in on the left. Is there a small bump at the left end? Well, if I shift the left end then the straight edge pivots on a point an inch in from the right end of the straight edge. In this case the straight edge will not rock perceptibly. Could this indicate that the surface is flat relative to the straight edge?

 

[Paul Chapman]

So I snuck down to the shop last night and tried to do some planing with the sharpened Clifton #7 and found that, lo and behold, it is now taking off the bump. I'm not sure why.

Maybe the problem all along was the (lack of) sharpness of the blade. That seems to be the only thing that changed.

Cheers :wink:

Paul

 

[dunbarhamlin]

Good stuff, glad it seems sorted, Adrian. I find sometimes I just have accept that something I did worked - and hope either there isn't a next time, or that I'll notice what does it when it does recur.

The straight edge check is indeed just as good as the eye can see ( I have thread counters in various sizes to help see detail)

Easier adjustment is I think one of the benefits of a significantly cambered blade.
For my straight blades, I've taken to using a small plane hammer for fine adjustment (toffee hammer would do as well) - didn't get raised eyebrows from Rob when I mentioned it the other week, so guessing this is OK, and it's certainly quicker than fiddling with the lateral adjuster.

Cheers
Steve

 

[Racers]

Hi,

The glass can't flex if it is on a hard surface like your bench ot a lenght of MDF. My sheet is only 6mm thick but my bench is flat. I clamp a block of wood at each end to hold the abrasive and them use clamps to pull the blocks apart too tension the sandpaper, giving me a 3 foot clear run to flatten planes on.

Pete

 

[adrian]

Maybe the problem all along was the (lack of) sharpness of the blade. That seems to be the only thing that changed.

It's possible that the profile of the blade changed, as I tried to establish the camber when I sharpened. (Recall that the blade edge appeared to be concave before sharpening.) This might have thwarted my efforts to get a square edge. If a non-square edge presents problems it could have played a role. I have yet to attempt to make a dark wooden reference for checking camber.

I did also try sharpening my LV bevel up jointer and trying it, but it doesn't seem to cut as well as the clifton for some reason. I'm not sure why that should be---I think the cutting angles are the nearly the same (45 for the clifton and 12 deg bed+32 deg bevel = 44 for the LV). It also had a jerky cutting pattern, as if the wood was going up and down a lot, so it would cut for a moment, and then cut for another moment, and so on. And each place it cut it would tend to leave a sort of gouge line. When I returned to the Clifton it cut in different places, and was generally more smooth.

My bench isn't flat. I have some MDF lying around. Is it flat to 0.0001"? (I actually got it to try to use it as a router guide for jointing edges when I couldn't get the planes to work....and I found the edge to be inadequately smooth.) I could lay some glass on top of the MDF which is resting on my non-flat bench with shims to support it, I suppose, and blocks to keep the MDF from moving.

Pete, I don't understand your description of how you attach the abrasive. Can you elaborate?

Regarding the lateral adjustment, you just tap the iron itself with a small hammer? Does this approach work regardless of the type of lateral adjustment mechanism the plane has? I think I had two issues with lateral adjustment. One is figuring out when it is properly adjusted. The second was making adjustments. The first was a bigger problem than the second---I couldn't tell if it was wrong and what needed to change. The second was problematic because I couldn't tell for sure if I was making a change and I had a poor sense of how much change I was making. But if I had a solid grasp of the first then the problems with the second would be less of a problem.

 

[dunbarhamlin]

Yep, just little taps. Don't know about LV LA adjusters, but it does the trick on my Bailey style planes (Cliftons and a Record) and on a modern Stanley block I was using the other week with the useless little pressed yoke type lateral adjuster.