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grinding a camber, anyone?

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grinding a camber, anyone?

#1

grinding a camber, anyone?

frank shic (walnut ck, ca)

>guys, in my quest to retool a former wooden rabbet plane into a dovetail plane, i purchased a slow speed grinder from woodcraft which did the job quite admirably. however, i've been thinking about regrinding all of my former plane blades and chisels because the reflection does not exactly DROP OFF on the bevelled edges and because i'm an OBSESSIVE COMPULSIVE FREAK! anyways, i'm wondering how many of you GRIND a camber into your plane blades to minimize plane tracks. i'd use the 120 grit wheel to do it and i promise not to let the edge turn BLUE!

Re: grinding a camber, anyone?

#2

Re: grinding a camber, anyone?

Danford C. Jennings

>Frank,

I simply round off the corners. There's a couple of "schools of thought" on cambered edges.

My belief is that the irons of smoothers were never intentionally cambered in the days of yore, I think they were honed on stones that were "dished" from use and not flattened.

David Charlesworth does recommend, however, a cambered bezel on jointer planes. His argument is that it's easier to joint an edge because each "swipe" can be seen and with three strokes you end up with a flat edge. I actually tried this technique and went back to a straight bezel...FWIW.

Dano

Re: grinding a camber, anyone?

#3

Add on

Danford C. Jennings

>...Should've mentioned that I do have a cambered bezel on one of my jacks that I use after my #40, 'bout 3/32nds of a crown. I did this by hand; don't like hollow ground edges.

Dano

Re: grinding a camber, anyone?

#4

As said by Mr. Jennings...

Scott Burr in really rainy Ben Lomond,CA

>If we're talking smoothers just round off the corners. It's not that hard you...OBSESSIVE COMPULSIVE FREAK! Don't get obessive over the little poo Frank. After all it's NOT rocket....ya know...

Re: grinding a camber, anyone?

#5

Re: grinding a camber, anyone?

ThomD

>There is ample evidence that craftsmen intentionally ground camber in, camber varies across the set of planes, and so no one set of stones would produce the ideal result for every blade. And also the individual stones hollowed at different rates so there wouldn't be any consistency moving between grits. We also have living traditions like in Japan where this skill is observed and passed down, even in the absence of monthly magazine deadlines to meet with new insight.

Any historical craftsman who could keep molding planes, gouges etc... in fighting form wouldn't have blanched that much over cambering cutters. Odate recently complained that he found it nearly impossible to do. But his tradition includes hyper polishing stones. There it does get tricky, because maintaining a camber with extremely fine grits, without perfect stone to tool fit gets pretty hairy. But with fast cutting stones it isn't too bad.

Frank, I'm sure you will manage fine. Don't go overboard with the grinding at first, the plane will tell you how far you need go, and whether it is a regrind job, or something you can do on your whetstones.

Blue is way to far on some tools, though not on all, try to keep any discoloration completely at bay. Blue past most hard tools, with good edge holding, unless HSS.

Any time you want to really reshape an edge it is safer to grind the new profile blunt, then grind in the bevel. This means the edge spends much less time at the fine point while grinding, and heat doesn't concentrate.

Re: grinding a camber, anyone?

#6

Re: grinding a camber, anyone?

Derek Cohen (in Perth, Australia)

>Hi Frank

There are two basic types of cambers on blades, and these must be dealt with in completely different ways.

Firstly, there is the camber that is associated with scrub blades, and here we are talking about very noticable cambers, with the typical scrub blade ground around a radius of 3". To do this one either draws the curve and then grinds it out freehand, or you can do so with a template (I wrote an article on this and you can access it in the Article section here).

The second type of camber is used on a smoother to prevent train tracks (when edges of blades dig into the wood surface). This is not ground on a grinder! Think of it this way - let us assume that the average smoother takes a shaving of between .002" and .001". Therefore, this is the amount that should be removed from the ends of the blade to avoid the edges digging in. This is a very, very small amount. Can you do this on a grinder?! I sincerely doubt it. So, instead, it is part of the honing process on the media of your choice (waterstones, sandpaper, etc). Basically, just lean on that corner as you hone and you will eventually remove this amount. David Charlesworth demonstrates this very well in his DVDs.

There is a third camber, one inbetween these two, there one that DC advocates for the jointer plane. This is a variation of the second camber type, but do not ask me how much you need to remove since I do not use this method. Others will no doubt offer their knowledge here.

Regards from Perth

Derek

Re: grinding a camber, anyone?

#7

Re: grinding a camber, anyone?

Alice Frampton, UK

>His argument is that it's easier to joint an edge because each "swipe" can be seen and with three strokes you end up with a flat edge.

That's interesting; I didn't think that was DC's argument at all. The idea is that rather than tilting either the plane or the blade, you just move the track of the plane laterally across the work so the lowest cutting point of the blade is over the highest point of the edge - et voil�! A square edge.

Cheers, Alf

Re: grinding a camber, anyone?

#8

Re: grinding a camber, anyone?

Alice Frampton, UK

>Frank,

"Plane tracks" sounds like the smoother blade is the issue. In which case, as others have mentioned, it's such a slight camber you're best off working it on your finer honing media. The easiest way to decide when to do one or the other is just to think what the grinder's there for - to do the big metal removal work. So the more extreme cambers such as the scrub and roughing jack are best ground, because otherwise you'd be at your stones all day. For the gentle camber of the smoother or jointer you'd likely do more damage on the grinder by removing material too quickly, so the stones make more sense.

But fwiw, as Thom says, first grinding the profile "blunt" with the blade horizontal to the stone reduces the risk of drawing the temper. Then grind up the bevel just shy of that edge, which also helps to prevent overheating.

Cheers, Alf

Re: grinding a camber, anyone?

#9

Re: Cambered iron's multipurpose

Marc in Luxembourg

>That's how I understood it too. It works great. Generally I use it with #6 fore plane as I lower mentioned.

I grinded on the waterstones. It takes a while, but the camber is going to be pretty exact, just the way you want it to have.

Marc

Re: grinding a camber, anyone?

#10

TOUCHE!

frank shic (walnut ck, ca)

>

Re: grinding a camber, anyone?

#11

it's all your fault! :)

frank shic (walnut ck, ca)

>derek, i was hoping for your response - after all, you're the one who got me into this MESS by refitting that wooden rabbet plane. BTW, i just need to add the fence to mine and i'll have saved myself $100 in the process!

your second response is the answer i was looking for. i think that i will regrind my chisels and plane irons blunt and HONE a camber into the jack, smoother and jointer irons.

after i got this grinder i just couldn't stop thinking of other potential uses for it besides the aforementioned dovetail plane construction. it's easy to get carried away, isn't it?

Re: grinding a camber, anyone?

#12

thanks ALF

frank shic (walnut ck, ca)

>when i first received my jack plane off of ebay i did notice that there was a noticeable camber that would have taken me DAYS - ok i exagerrate, right? - to achieve with my sand paper. i would like to try a very teensy tiny camber on the grinder.

Re: grinding a camber, anyone?

#13

gotcha

frank shic (walnut ck, ca)

>edge shaping and then bezel/bevel (which one is it thom?) afterwards.

Re: grinding a camber, anyone?

#14

interesting...

frank shic (walnut ck, ca)

>would have NEVER thought that the camber was due to improper flattening of the sharpening surface!

Re: grinding a camber, anyone?

#15

Re: thanks ALF

Dean J in MN

>

when i first received my jack plane off of ebay i did notice that there was a noticeable camber that would have taken me DAYS - ok i exagerrate, right? - to achieve with my sand paper. i would like to try a very teensy tiny camber on the grinder.

Frank --

As to camber on blades in general -- I am of the school of thought that all planes other than joint making planes have camber. The fore plane (jack) has a lot, as you noticed on your ebay jack plane, a try plane less and a smoother even less, as was mentioned.

But, a jointer has none. I think folks are refering to the jointer by its length, not its purpose/blade shape. A jointer is used to make a joint (edge to edge) whereas a try plane is used to both surface and correct an unsqaure edge. DC's use of a curved blade makes it that plane try plane, not a jointer. My try plane is nearly as long as my jointer, so length is not the only way to group/name planes, I'd say it is a poor way to group planes in fact.

As others have said, you'll find you only need to grind your fore plane camber, the other surface planes camer is small enough to shape with your stones.

-Dean

Re: grinding a camber, anyone?

#16

Re: grinding a camber, anyone?

Danford C. Jennings

>I was referring to the "why" not the "how"...

About five years ago on another forum, I participated in a discussion similar to this one. Mr. Charlesworth also was a participant.

Dano

Re: grinding a camber, anyone?

#17

Ha! Don't forget to post a few pics when it's done

Derek Cohen (in Perth Australia)

>

Re: grinding a camber, anyone?

#18

Re: thanks ALF

Warren in Lancaster, PA

>Dean

I also use the slight curve on the jointer to correct wind or slight out of square. I usually glue up without flattening the face side, then use the trying plane on the face only after glue up.

The method you use- putting the boards face to face and planing together does avoid problems of wind etc., but you must plane each board's face flat first and then plane the whole again after glue up. That's three times trying the face. This takes more time and I doubt it is a historical method.

I know that there are many books that say the jointer is always sharpened straight across, but some of these authors haven't made joints like this more than a handful of times.

Re: grinding a camber, anyone?

#19

Re: grinding a camber, anyone?

Alice Frampton, UK

>Seems to me the "why" and the "how" end up being pretty much the same thing, however, evidentally I'm not fully grasping what you meant by 'each "swipe" can be seen and with three strokes you end up with a flat edge'. Any chance of some clarification, 'cos I can do the "how" just fine, but this "why" is a closed book to me at the moment.

Cheers, Alf

Re: grinding a camber, anyone?

#20

Re: thanks ALF

Alice Frampton, UK

>I think folks are refering to the jointer by its length, not its purpose/blade shape.

Not I. Edge to edge jointing for gluing up boards into larger panels and such? Slightly cambered blade in a #7 or similar. Ergo jointer plane. I think. At least if I've read what you wrote aright.

Cheers, Alf

Re: grinding a camber, anyone?

#21

Re: grinding a camber, anyone?

Danford C. Jennings

>Alf,

Probably a matter of semantics; I see tecnhique as the "how", the "why" would relate to the reason one technique is used over another.

As I recollect the discussion, Mr. Charlesworth explained that one pass is done on each side with the plane offset from the center. The resultant "hump" in the center of the edge is easily seen for the final stroke down the center. Thereby leaving, a flat edge, as I believe someone pointed out here.

The gist of which, is the "why" he uses this technique....

Dano

Re: grinding a camber, anyone?

#22

Re: thanks ALF

ThomD

>My jointers are sharpened straight across, but if they were wider, I would clip the edges slightly. Best of both worlds.

One doesn't need to flatten the faces if one doesn't want to one simple needs to present the part in the relationship one untimately wants them to be in.

Re: grinding a camber, anyone?

#23

Re: grinding a camber, anyone?

Alice Frampton, UK

>Ah, I see. I hadn't heard that specific way of using the camber before, not that I recall anyway. A different "why" too, fwiw ;~)

Cheers, Alf

Re: grinding a camber, anyone?

#24

Re: grinding a camber, anyone?

ThomD

>I agree about tracks. I don't like tracks with any planes because they seem to required greater efort tearing the corners through, even if they get planed over later.

I doubt one can effective grind very subtle surface of a few thou. But one can swing a shallow radius cut, and then bang it back with a flat cut across everything except the very edges. That will get you somewhere for all but polishing if you want flat with softened edges.

Re: grinding a camber, anyone?

#25

Re: grinding a camber, anyone?

ThomD

>"you just move the track of the plane laterally across the work so the lowest cutting point of the blade is over the highest point of the edge - et voil�! A square edge."

Of course that tends to happen anyway. If a person shot the edge a degree or two off with a perfectly squared up plane centered on the wood, then just moving the plane to the high side tends to off-ballance the plane and correct the cut. There are about 10 ways of getting back to square so one of them is bound to work. And I wasn't even aware of this method. I must say if a person can't square up an edge with a straight blade I doubt their ability to hold the exact ofsett the full length of the board! But still the more options the better I guess. Thanks for the explanation, ALf.

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