Plane Blade Camber

[Joe]

I'm going bananas trying to put a slight camber on my No.6 plane blade - no matter how hard I try I always end up with a concave profile. I am using waterstones a little wider than the blade (which I flatten frequently on a Norton flattening stone) and a Veritas Mk2 Jig with camber roller. My only thought is that I'm wearing the the surface of the stones into a convex profile. If anyone can offer any advice on this matter I'd be very grateful.

 

[George_N]

It sounds like you are "dubbing" the edges of your water stone as you attempt to keep it flat, creating a convex surface. How flat is your flattening stone?

 

[matthewwh]

Hi Joe,

Welcome to the forum.

I'm sure Mr Charlesworth will wade in shortly -and what he doesn't know about cambered plane irons probably isn't worth knowing. If you can still find a copy of this November's F&C there is a fantastic article about this very subject. But in the meantime here's my fourpennerth.

Installing a slight camber is actually qute a big metal removal job in waterstone terms but it can be done. From your description and symptoms it sounds as though you are using honing techniques and materials to do a grinding job. If it's any consolation I did exactly the same when I first started using waterstones, lots of mess, lots of furrowed brows and pipper all progress! Once you take a step back you realise what you are doing it all becomes clear; you wouldn't want shorten a board by four feet with a shooting board and a block plane, but (if I'm right) that is the equivalent of what you are doing.

First off I would highly recommend using some sort of grinder for this operation, be it a water cooled grinding wheel like the Tormek, or a belt based system like the Sorby Pro-Edge. If you have a friend who has one of these machines and can install a camber for you in 10 minutes it's well worth the postage back and forth and a couple of pints for all the effort it will save you. People describe waterstones as being 'fast' which can be confusing if taken out of context. An olympic sprinter is 'fast', but if you want to run a marathon, then the best tool for the job is a motorbike.

If you do want to do it by hand, go for a very coarse stone 240 - 250 grit and work one side of the blade at a time along the centre of the stone. If you use the honing guide the blade will naturally follow an arc giving you a wear pattern like this )( on the surface of the stone. If you do it freehand, try to keep the wear pattern straight ll.

Once you have two well established triangular facets on either side, you need to straighten up the groove in your waterstone (if necessary) so that it looks like this l l rather than this )( A large cardboard mailing tube with some 80 grit wrapped around it is your best friend for this job. Now work the blade straight along the groove, using lots of pressure and firm positive pull strokes - avoid the urge to scrub back and forth like a washerwoman as this will give you a bevel that is rounded in both planes. Waterstones are all about slow, intentional, considered strokes.

Once the facets have melted into each other and you have a smooth continuous curve, carefully remove the burr, don't use the coarse stone for this, try drawing the upturned blade onto a piece of scrap hardwood to bend back the burr without scratching the polised back of the blade. You can now go back to your honing setup and polish a microbevel on the edge.

 

[David C]

Joe,

Are you trying to work with a single bevel? I e. do you have separate grinding and honing angles.

What grade of waterstone are you using?

A strip of plastic file material along one edge of the stone. will prevent honing on that side and ensure that the blade is tilted. swap sides later and do the same to other edge.

David

 

[woodbloke]

I'm going bananas trying to put a slight camber on my No.6 plane blade - no matter how hard I try I always end up with a concave profile. I am using waterstones a little wider than the blade (which I flatten frequently on a Norton flattening stone) and a Veritas Mk2 Jig with camber roller. My only thought is that I'm wearing the the surface of the stones into a convex profile. If anyone can offer any advice on this matter I'd be very grateful.

Joe - welcome to the forum, here's my input on this one tho' you'll receive a lot of conflicting advice on this topic. I gave up using waterstones long ago simply because they go out of shape at the drop of a hat unless you are super-regimented in your stone flattening procedures. I now use the DMT stones which remain flat and hence are much easier (and far less messy) to use. I also use a MrC modified Eclipse clone honing guide which is very simple to use (simple is always good IMO) and which has a narrow roller. This makes it very easy indeed to put a slight camber on the blade by simply altering the pressure on your forefingers as you hone...press down on one side and then the other. The cambered bevel is honed at 33deg on the green DMT and then a micro bevel at 35deg is honed using a Spyderco 10000g ceramic stone, which will also stay flat. Mr C's ruler trick is used at both stages to refine the back of the blade. A cambered edge is not difficult to achieve but I would have thought well nigh impossible with a concave waterstone - Rob

 

[bugbear]

I'm going bananas trying to put a slight camber on my No.6 plane blade - no matter how hard I try I always end up with a concave profile. I am using waterstones a little wider than the blade (which I flatten frequently on a Norton flattening stone) and a Veritas Mk2 Jig with camber roller. My only thought is that I'm wearing the the surface of the stones into a convex profile. If anyone can offer any advice on this matter I'd be very grateful.

Having read the other responses, I have a question.

How much (in whatever terms you're happy with) of a camber do you want?

The "normal" range goes from "enough that shavings don't leave ridges when smoothing" though "enough to make corrections when edge jointing" up to "I want to hack furrows out of stock when thicknessing".

BugBear

 

[Paul Chapman]

Hi Joe,

I second what Woodbloke says. Diamond stone (with oil not water), Eclipse-style honing guide and slight pressure on each side of the blade will give you the slight camber you are after. I also use the Veritas Mk2 with cambered roller but only for scrub plane blades which have a far more pronounced camber - which is not what I think you are after.

I finish my blades on a leather strop for a super-polished finish although Rob reckons the ceramic stone is even better.......

Cheers :wink:

Paul

PS If you also have the straight roller with your Veritas honing guide, I'd be inclined to try that, but putting pressure on the blade each side near the cutting edge with your finger. It's easier with the Eclipse-style jig and its narrower roller, but should still be possible with the Veritas.

 

[tnimble]

With the Veritas MKII camber roller it is possible to control the amount of camber placed on the blade from a very slight camber to a to a camber for hogging wood with your fore plane.

To only create or maintain a slight camber on the blade gently press just off centre on both sides.

The further you press away from the centre of the blade (along with more grinding time) the more aggressive camber can be created.

To create a nice camber start grinding on dead centre till at least establish a good bevel in the middle. Then repeatedly start working your way outwards using an increased amount of strokes on the stone. See it as a set of grindings just like a set of shavings explained in David C's DVD on planing boards wider then the planes blade.

 

[Derek Cohen (Perth Oz)]

Joe

BB's question is very pertinent - if you are wishing to turn the plane into a scrub, then I would use a template to mark out the camber and grind it first on a belt sander or bench grinder. If you are seeking a slight camber ala a smoother, then you are only going to remove a shaving's worth at the corners. The latter can be easily done on waterstones. I am going to assume that you seek to do the latter.

For bevel down blades I will hollow grind first and then freehand this on my (hard) Shaptons. I do not see any problem using the softer Kings, which I also own. If you prefer to use a honing guide, try either the Eclipse or the LV Mk II with the camber wheel.

I follow a similar, but simplified, version of David Charlesworth's "cambering by numbers" (which is my name for it).

Simply put, start with a wire edge on a straight bevel using a lowish grit, say King 800 waterstone or Shapton 1000. Then remove the wire edge on your finish stone (say 8000 grit). It is important to remove the wire edge after each 'stone. This gives you a better idea of what the blade is doing.

Now focus on one outer corner (place pressure directly over this area and off the other side) and count the number of strokes it takes to get a wire edge there. The thickness of the wire edge will help you decide how much you have bevel you have removed. Now do the same on the other corner, using the same number of strokes. Remove the wire edge on your finish stone.

Now you go to your next stone. If I was using Shaptons I'd go 1000/5000/8000/12000 or Kings at 800/1200/8000.

On the next 'stone hone the centre section of the blade and count how many strokes it takes to get a fine wire edge. Then use the same number of strokes at each corner. Remove the wire edge after each stone.

Proceed to next stone, etc.

I usually finish on a leather strop.

Regards from Perth

Derek

 

[Joe]

Thank you to everyone for so much interesting, detailed and useful advice. First off, in response to George, it transpires that my "flattening" stone has a concave surface. Obviously this isn't helpful. In reply to David's question, I am honing a secondary bevel of 30 degrees followed by a slightly higher-angled micro bevel using the Veritas jig's facility for doing this. I am using 800, 1000 and 4000 grit stones followed by a leather strop.

I am not an experienced wood worker, I am an artist making wooden patterns for casting into plaster in order to make wall mounted reliefs (although I'm thinking of getting into box making). This involves dimensioning timber initially with a bandsaw before final dimensioning and squaring with my plane (I don't have a planer/thicknesser) either on my bench top or on a shooting board. I need a fine surface finish because the moulds I make will replicate any defects. My wish to camber my plane blade comes from trying to learn the techniques demonstrated in David's DVD about preparing stock - so the answer to Bugbear's question would be ""enough to make corrections when edge jointing" I guess.

Thanks again

Joel

 

[Joe]

Sorry, I meant to say I'm using 800, 1200 and 4000 grit.

 

[Joe]

I really shouldn't try and post whilst cooking the kids' supper. They're 800, 1200 and 6000 stones!

 

[tnimble]

O that case a very light camber is enough. Use the method of putting on a straight wire edge,, remove the edge on a fine stone. Then move to pressure on ne side, and count the passed need to create a wire edge. Do this again for the other side. Move to a finer stone repeat the same thing.


I'm interested in your work with the moulds you make. Any change on some piccys and work in progress?

 

[Joe]

Ta, I've not tried removing the wire edge between stones. I'll give that a go.

If you want to see some pictures you can visit my pages at the axis artists website
http://www.axisweb.org/artist/joelmarshall

 

[David C]

I have never found the Japanese stone flattening stones to be remotely flat.

The Norton one can be flattened fairly easily but does not stay flat for long. Flattening on wet & dry on glass is a good method which leaves the waterstones minutely convex. Convex is infinitely preferable to concave.

My other advice is to keep the 800 grit bevel as narrow as possible by frequent regrinding (which I like to do at 23 or 25 degrees. The grinding does not reach the edge but leaves a minute sliver of the 800 grit bevel.

When 800 bevel is narrow it is easy to shape for small camber. Wide 800g bevels are much more difficult to reshape.

David

 

[bugbear]

I really shouldn't try and post whilst cooking the kids' supper. They're 800, 1200 and 6000 stones!

Psst; try the "edit" button for small changes to posts.

BugBear

 

[adrian]

I'm also interested in cambering my blade enough to use the techniques described in Charlesworth's book and DVD for face and edge preparation. A few messages up someone said that for this a "very light" camber would suffice. However, in the book, Charlesworth recommends that the edge of the blade be 0.25 mm below the center. I'm having a really tough time measuring the camber on my blade, but I have a feeling that 0.25 mm (0.01 inch) is bigger than "very light".

I worked my blade until I could see a gap between the edge and a straight edge. This didn't take a particularly long time on the shapton #1000 with a 1mm bevel. I don't know how big that gap is, however; I'm pretty sure it's a lot smaller than 0.25 mm. And when I took an edge shaving on a piece of scrap it appeared to be the same thickness across its width. And I can't seem to get the plane (Veritas #5 1/4) adjusted so that it cuts in the center and doesn't cut at the edge. All of these things have lead me to suspect that my very light camber is insufficient.

So how much camber is actually necessary for different tasks assuming a plane with a 45 degree bedding angle? How do you tell when the required camber has been achieved?

Why also is it better for the stones to be convex than concave? I sharpened for years with concave stones and my blades came out cambered without all this effort. (I didn't know what was going on. Perhaps the resulting convex backs weren't ideal. :? ) In fact, you can even buy a set of concave diamond plates to use for shaping a camber (promoted by Toshio Odate) along with a convex plate to use for making your waterstones concave. Odate apparently prefers a smaller camber as these plates are only concave to 0.0025 in = 0.06 mm over their 3 inch width.

 

[tnimble]

A very light camber is indeed somewhere in the range of a quarter of a mm. A heavy camber for instance required for a bevel up jack is more in the range of to a centimetre difference between sides and centre.

 

[adrian]

It looks like the lower end of your recommended camber range was missing from your post. A centimetre camber sounds like the shape suggested for scrub planes. If I wanted to use my bevel up jack plane for final flattening and edge jointing I expect I'd want the camber to be about 3.5 times the camber for a bevel down plane (based on the bedding angle of 12 degrees instead of 45 degrees). It would probably take quite a while to establish a 0.85 mm camber with the 1000 grit stone.

 

[Paul Chapman]

I'm having a really tough time measuring the camber on my blade

Do people really try to measure this :? :?

Just sight along the sole as you lower the blade and, if it has a camber, you will see the centre project before the egdes do. If you lower the blade so that just the centre projects, you will find that just the centre of the blade cuts (ie very fine shavings). However, if you lower the blade far enough so that the edges of the blade project as well, you will get full width, quite thick, shavings.

For a normal, bevel-down plane you need only a very slight camber - far less than I would attempt to measure (not that I've ever attempted to measure the camber on a blade).

Cheers :wink:

Paul