Burr on plane blade

[J4m3sg]

hi all,

First post so apologies for the noddy topic. I've had a good root around the forums but can't find an answer to my question.

I've just started woodworking, and one of my first tasks have been to sharpen my tools. I've got some Aldi chisels I've had for a while and I've managed to get them to a point where they'll slice through paper. I've used a honing guide with the Paul sellers wet and dry paper method (240/600/1200 grits, then leather).

So I know this way of sharpening works for me. Problem is when I do the same on my plane blade, I can get it even close to sharp, and I've been at it for literally hrs. I can't get a burr on the edge at 240 grit, and I believe there's no point going to higher grits without a burr.

I must admit I inherited this plane from my dad and it had some pretty nasty dinks in it which I removed by spending some ( a lot) of time with the blade on some 80 grit paper.

I'm at the point where I'm considering getting a new plane, but I'd really rather try and figure out why this one won't sharpen. Anyone have any bright ideas, or have I knackered it?!?

Thanks
Jim

 

[Bod]

How old is the plane blade?
Is there a makers stamp on the blade?

Bod

 

[J4m3sg]

Hi bod,

Couldn't tell you exactly how old, would guess it's from the 60s. Plane is a Stanley no4, blade is also Staney and is original to the best of my knowledge

Jim

 

[Billy Flitch]

Hi Jim, just a thought is the jig a old eclipse I think there are two different settings for chisels and plane iron its written on the side of the jig.

 

[Mike.S]

May be worthwhile to colour the blades bevel (a black 'sharpie' pen or similar) to give yourself a clear visual indicator of whether the sharpening extends to the edge. If it does and you're still not getting a burr that suggests the blade may be one of those rare manufacturing failings where the steel's crumbling at the edge and you'll never get it sharp enough.

What angle are you sharpening at - c.25 degrees is normal?

 

[rafezetter]

I would echo the above about possibly bad steel and just as a side note about using a honing guide - regularly check that the protrusion length (which gives you the angle required) is what it's supposed to be - as you are removing metal, especially if it's a lot to remove chips, the blade protrusion is getting shorter so the angle is changing thus making the cutting edge that much thicker.

A half decent replacement plane blade costs very little - and you might even be able to get one for free if you ask as many forum members seem to have drawers full of them!

 

[Woody2Shoes]

It's worth checking also that the back of the iron is flat - not flat all over, as many irons are deliberately not flat all over (perhaps as a fortunate side-effect of the manufacturing process) - just flat across the width in the area within a few mm of the cutting edge.

Assuming that the steel is OK (ignoring a manufacturing defect, perhaps it could have lost its temper if someone overdid grinding with an abrasive wheel in the past), then as has been said, I'd check that the angle is correct and that it is steep enough to abrade the steel actually at the cutting edge (rather than a gnats' body part behind the edge, as is possibly happening) - as others say, you can use felt-tip markers, and a good magnifying lens plus good light, to analyse your progress.

Cheers, W2S

 

[custard]

Mike S has given you the right advice. Get a black felt pen and blacken the entire bevel area, let it dry a moment and then give it one or two strokes at your previous setting. A pound to a penny you'll see that metal is only being removed at the "heel" of the bevel and you're not yet down to the actual cutting edge.

Good luck!

 

[J4m3sg]

Thanks fellas, all good advice. I was sharpening at 30degs rather than 25 as that had worked for my chisels. I'll have another go and report back...

 

[Eric The Viking]

Give it one more, systematic go, then consider changing the plane iron (blade).

You've been given excellent advice above. I have one more suggestion that helped me:

Get a good quality magnifying glass, or old camera lens (50mm, used backwards), or jeweller's eyeglass (strong magnification, say 4x), or a head-worn magnifier. Have a good strong desk lamp or other worklight near where you are sharpening.

Look at the edge of the blade often during sharpening: as you go down through the grits you'll see one set of scratches replaced by progressively finer ones, each time you change grits. You can also see any burr as a jagged edge (microscopically).

Sharpness is the most sharply-defined angle you can get between the honed bevel and the back of the plane (not the most acute angle!). The cleaner and sharper the angle, the sharper the plane. The more ragged it looks (lots of torn steel, microscopically speaking), the more it's rounded over or rough, the less well it will cut.

You can see how well you are doing and when to change grits - the moment when when the new finer scratches you've been making completely replace the ones from the earlier grit. You can also see how important it is to have a really flat and very smooth back to the plane iron - if that is rough and serrated (microscopically) you can never get the two faces to meet in one smooth, sharp angle along the edge of the blade (wot you want!).

Flattening the back is the most tedious and time-consuming thing to do, but you only need to do it once (usually). The flattest, smoothest, shiny-est you can get will give you the best edge in the end.

After a while, you'll feel when you reach the point to change grits. The one you're presently using will stop cutting and the iron will slide over it. You can feel this change with a little experience - magnifying the edge will help you recognise when you are close to that, but after a while you won't need to keep stopping and looking.

Hope that helps,

E.

PS: when we sharpen kitchen knives on a steel, we're actually making a saw, at a microscopic level. If you look at the edge of a common-or-garden kitchen knife with a lens, it looks really ragged. Those ragged bits tear through animal and plant fibres, which is why they cut well, for a while. Woodworking edge tools (ironically, even saw teeth!) don't work that way - they cut rather than tear, or they should. That's why we go to all the fuss that knife grinders tend not to!

PPS: If I don't say this quickly, someone else will: Japanese kitchen knives are a quite different matter, working much more like woodworking tools (here I gladly defer to Pete Maddex!).

 

[custard]

I was sharpening at 30degs rather than 25

There you go, I told you Mike S had it right with the Sharpie trick!

No need to hand over any money to the tool dealers, the blade you've got together with your Aldi chisels is all you need for a long while yet.

Start swapping out the blade and you can end up with a load of further expense. Before you know it you'll need to change the yoke to make it fit, and you'll have to buy a file to file out the mouth, plus grinding a thicker blade is a nightmare on an oil stone so you'll be wanting a diamond stone (and then a second diamond stone when the first isn't course enough), then you'll abandon that for a wheel grinder, which will mean an aftermarket tool rest and new grinding wheels...

Don't bother, just work with the tools at hand and overcome the obstacles one at a time.

Good luck!

 

[Eric The Viking]

@custard:

You, sir are a tonic!

 

[Jacob]

Agree with the above. Unlikely that the blade is the problem - even if it was made of plastic you would get a burr if you were doing it right. So it's technique.
If you don't get a burr it means the actual edge isn't coming into contact with the stone - you are removing metal from behind the edge instead. If you keep doing it at roughly the same angle you will get down to the edge in time. Or of you lift to a slightly higher angle you may get a burr straightaway.
But the main thing is to look closely at whats going on - magnifying glass even, and hold it up to catch the light so you can see where you have been.
If you are using a jig you might have to remove a lot of metal before the whole edge engages with the stone, especially if it is cambered or was freehand sharpened before. So dump the jig, it will probably be easier without it.
Jigs themselves are a big cause of sharpening difficulties especially for beginners.

 

[J4m3sg]

Yup, got it. Think it was just perseverance with the 80 grit. Next to reattach to the plane and see if works!

Thanks everyone. The magnifying glass idea is a good one.

 

[JakeS]

PPS: If I don't say this quickly, someone else will: Japanese kitchen knives are a quite different matter, working much more like woodworking tools (here I gladly defer to Pete Maddex!).

Off-topic, but strictly speaking I think it's simply that you make a choice: you either sharpen your knives to be a long, continuous edge or you steel them and have the ragged saw-effect edge. It doesn't matter whether they're Japanese or not! The ease with which a sharp chisel or plane (or planer, if you're clumsy installing them) blade cuts your fingers demonstrates that a continuous edge is quite sufficient for meat. However, if you use a steel and sharpen to a continuous edge alternately, you'll be removing much more material than necessary each sharpening and the knife will disappear faster.

We sharpen ours and never let a steel or those horrible paired-ceramic-disc things near them - evil destructive things! The only problem I've ever had is that butter and cheese stick like anything to the side of the blade 'cause without the micro-serrations there's no air between the cheese and the steel!

 

[bugbear]

Yup, got it. Think it was just perseverance with the 80 grit. Next to reattach to the plane and see if works!

Thanks everyone. The magnifying glass idea is a good one.

Sounds like it was badly honed/ground by the previous owner, and you just had to work (all the way) though it. Well done!

BugBear

 

[J4m3sg]

Last couple of points on this from me, this has been really useful already:

1. I'm guessing then that the point of sharpening is to get the two surfaces to meet (thus generating a burr) then to progressively hone those 2 edges to remove any microscopic defects to get the best cutting edge?

2. WRT jigs, if I put my plane blade back in my jig again in a few weeks, surely unless I set it the exact same distance in the jig, I'll be sharpening/polishing one end of my edge more than the other? Given that we're talking about removing microscopic defects the tolerances seem to be pretty small, so I guess even a mm one way or the other will generate this effect? Does this mean I have to re grind the edge each time?!?

Jim

 

[Droogs]

No, as long as you make sure you have the blade set in the jug at the same angle (use a protactor/guide block etc) and you make sure it is square so that the full edge is on the stones surface you will get an acurate honing.
this is what happens with freehand sharpening too, the more you do it the more the muscles remember how they were and how to hold the blade and you get a good edge.

 

[Jacob]

Yup, got it. Think it was just perseverance with the 80 grit. Next to reattach to the plane and see if works!

Thanks everyone. The magnifying glass idea is a good one.

Sounds like it was badly honed/ground by the previous owner, and you just had to work (all the way) though it. Well done!

BugBear

Not necessarily badly ground - just differently ground.

 

[Jacob]

.....
2. WRT jigs, if I put my plane blade back in my jig again in a few weeks, surely unless I set it the exact same distance in the jig, I'll be sharpening/polishing one end of my edge more than the other? Given that we're talking about removing microscopic defects the tolerances seem to be pretty small, so I guess even a mm one way or the other will generate this effect? Does this mean I have to re grind the edge each time?!?

Jim

Well yes this is the basic problem of the jig. OK you've worked away and got a sharp edge, but next time, unless you can get an exactly identical setting on a dead flat stone, you'll have to work away again to bring it level. Hence all the stuff about flattening stones, glass plates, granite slabs etc.
Not a problem with freehand sharpening.
NB if you were doing a lot of handwork it wouldn't be a few weeks it'd be hours or less - even with one of the magic wonder steels from the planet tharg.

PS I was grating an apple this morning - you get something similar to a burr as the skin folds up and doesn't get grated off. Trouble with steel edges is that the burr needs only be tiny and you can only tell it's there by feel. And you MUST have a burr over the whole width especially the middle to be sure you are sharpening - blades tend to wear in the middle and that is the last bit where the burr will start to show and which it's easy to neglect.