Micro Back Bevels

Seems that somehow became the thing to do, so I started trying the little steel rule thing to do a micro bevel on the back of plane and chisel blades.

now, I'm not a top flight woodworker by any stretch of the imagination, but I reckon that ends up ruining the plane of the back of chisels. Trying to pare down an end grain on a box joint, the chisel just doesn't get down far enough (compared to a chisel without the microbevel my fingers can actually feel the difference, and they're old fingers), but then it sure makes getting a keen edge easier, so i thought.....

(yeah, I know; don't strain yourself Bob. Did it hurt? all that :) )

My solution is a simple strip of electrical tape stuck to the chisel back exactly 2 inches from the end.

1. precision, the micro bevel is ALWAYS exact

2. the micro bevel is now so tiny that in working with the chisel you honestly can't notice it.

3. Easy to do. no slipping of that stupid ruler on the stone.

I only use it on the last grit of course, a 6000 water stone, and it slides well and doesn't seem to affect the stone at all.

So for what it's worth guys, maybe give that a try.

BB, am I correct in understanding that you are back bevelling a bench chisel? If so, this is highly not recommended. You lose coplanar, even though the amount is tiny.

Only about 1/2" - 1" begind the bevel needs to be flat and polished. That is not hard to do, and it is much easier to sharpen. Another problem with using a backbevel on a chisel is that you cannot strop the edge freehand, which I like to do to keep the edge going.

Regards from Perth

Derek

Yes Derek, I think i was taking too much notice of the 'YouTube Experts' :)

I do find it particularly helpful sharpening the plane blades; it's very quick to give a few swipes of that small back bevel on the last stone. With the chisels, I kind of agree with you, but the refined and much smaller back bevel with the electrical tape seems to work fine. The one with the ruler? No good at all.

I'm a sucker for every new idea on YouTube, might need to go into detox I think :)

Quote:

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Originally Posted by derekcohen

BB, am I correct in understanding that you are back bevelling a bench chisel? If so, this is highly not recommended. You lose coplanar, even though the amount is tiny.

Only about 1/2" - 1" begind the bevel needs to be flat and polished. That is not hard to do, and it is much easier to sharpen. Another problem with using a backbevel on a chisel is that you cannot strop the edge freehand, which I like to do to keep the edge going.

Regards from Perth

Derek

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:whs:

Quote:

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Originally Posted by Bendigo Bob

Seems that somehow became the thing to do, so I started trying the little steel rule thing to do a micro bevel on the back of ... chisel blades.

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Hi Bob
do you recall where you got this advice from?

The "ruler trick" has been popularised by David Charlesworth, but David has always, always stressed that it only be used in plane blades, never on chisels.
Is there a youtube charlatan out there who needs some re-education?

No, wasn't him. I don't think I can track it down now either. Wasn't Rob Cosman, I know he uses it on plane blades. Oh dear, so many YouTube subscriptions in my list. I think i need radical help :)

Anyway, i reckon the electrical tape is better even on the plane blades, far more consistent, simple and no fuss.

Got to break myself away form the infernal computer now and actually go out and do something. :cool:

Electrical tape is about 100 micron thick or. 0.1mm. According to BB, he placed it 50mm from the edge, or a back bevel of 1 in 500. Now I guess the 6000 water stone has a grit size of about 5 micron give or take. Assuming that 10 micron of material is removed by honing, and based on the gradient of 1 in 500, the back bevel is only extended to approx 5mm from the edge. I don't think it makes any difference to the coplaner issue with a gradient of one tenth of a degree. If you only hone the last 1/2" of the back of the chisel and remove the same amount of material, say 10 micron, you will have a 10 micon step from say 12mm back and if it doesn't matter to the coplaner issue. Using BB's method wouldn't not change the issue of flatness at all. The only caution I would make is that it is easier to remove more material than is necessary.

On the other hand the ruler is about 1mm thick, you definitely wouldn't want to use it on a chisel.
I reckon the electrical tape is a goer. take a bow BB, well done.
Aluminium tape could be more rigid than electrical tape, but also slightly thicker.

Those calculations sound correct to me (but I'm no maths head :-). Nevertheless, I will not support this method for chisels. It is just too easy to instead flatten the immediate back of the bevel than to run the risk of damaging the chisel (and its use). What are the risks? .. that the angle will increase over time, that the back of the blade will need to be restored by grinding away the area affected. A lower ledge (steel ruler or tape) lengthens the backbevel, which affects more of the back, placing it increasingly out-of-flat each time it is renewed when sharpened. All-in-all, it is so much safer to hone with better technique based upon a flat chisel back and a single or double bevel.

Regards from Perth

Derek

Good advice all round there fellows, thanks.

I'll keep it for the plane blades, but also maybe for one chisel to pare off those box joint highs, seems to work nice for that, less risk of scoring into the face of the sides.

Have tried a few times to freehand, but I think I lack the patience :)