Chisels

[jaco]

Chisels
From Plansnow.com


Getting a chisel to work properly starts with using the best blade angle for the type of cut you want to make. If you don't get this right, you'll end up breaking the blade or dulling the edge too fast. Below are three common types of chisels and blade angles for cutting wood efficiently and safely.

Paring Chisel – 15 degrees is perfect for removing very thin layers of wood. The low angle provides less resistance, making it easy to push through wood without having to use a mallet.

Bench Chisel – 25 degrees makes a good general purpose chisel for removing both thin and thick layers of wood.

Mortising Chisel – 30 degrees adds more metal behind the cutting edge...that means more power for cutting deep into wood without breaking or getting dull. Mortising chisels come with reinforced handles for use with mallets.

[Alf]

Less "without having to use a mallet" and rather more "for the love of Norm, don't use a mallet" I'd have thought. My initial reaction was I'd stick another 5° on all those recommendations; what do other people favour? I think the blasted A2 steel in the LNs may be skewing my thinking on the bench chisels, but 15° seems a little too fine for the parers...?

Cheers, Alf

[davidc]

Alf,

Yes indeed, I would like to see someone paring end grain Partridge Wood with a 15 degree bevel.......

I think these generalisations are fairly meaningless without reference to the hardness of timber being used.

Best wishes,
David

[engineerone]

and also in my limited experience some of the chisels will break out even in soft wood if the angles are not somewhat higher.

paul

[argus]

.

I experimented with a 15 degree angle some years ago for paring into tight corners and found the resultant edge far too delicate - the first hard knot (I was using well-dried Oak, admittedly) gave it a nice serration, which was not what I wanted!

It may work better on the more expensive qualities of laminated steel with a reinforces back, but I used a bog-standard European chisel and quickly reverted to a steeper angle.

I didn't work for me, but might be fine in very soft stock.

.

[evergreen]

I'm doing mainly DIY jobs with softwoods, MDF and chipboard these days and I hone my chisels (some very old, some early 70s) at about 30 degrees, whatever the job. This angle seems to be a good compromise.

Regards.

[matthewwh]

First of all, hello everyone! My name is Matthew and I run a small business selling hand tools and occasionally get to spend a few hours in the workshop enjoying my own woodworking.

For me one of the most important steps in tuning a new chisel is establishing the shallowest honing angle that the steel will tolerate, given the timber and techniques used. If you use hard timbers and do a lot of chopping, the microbevel will naturally need to be steeper, but every extra degree reduces the cutting efficiency of the chisel slightly, so how much is too much?

I use a technique called bracketing, adapted from a method used to lay artillery onto targets in the minimum number of shots. I begin with the angle the chisel was supplied with, which can vary enormously from Robert Sorby bevel edge at 20+5 degrees to LN bevel edge at 30+5.

When the first resharpening comes around, I examine the edge and if it has become rounded through abrasion but has not actually failed (either by bending or chipping depending on the heat treatment) I can afford to go shallower with the microbevel. Conversely, if the edge shows signs of steel failure then I need to make the angle steeper. The first time around I will adjust in the appropriate direction by 4 degrees and make a note of the new honing angle. The process is repeated at the second resharpening but this time the adjustment is only two degrees.

By the third time you sharpen the chisel and make a one degree adjustment you will know that you are within a degree of the shallowest suitable angle for that tool given your particular methods and materials. By making a note of it and always honing your chisel at, or slightly above this angle, you will minimise the possibility of edge failure and subsequent regrinding whilst enjoying as much performance from the tool as possible.

Cheers,


Matthew

[paulchapman]

Hi Matthew,

Welcome to the forum.

Cheers

Paul

[engineerone]

yes, welcome and thanks for the interesting idea.

paul

[dom]

Welcome Matthew, good to have you here.

Dom

[argus]

Excellent, Matthew. It makes perfect sense.

[mrgrimsdale]

Makes "sense" but is a difference of 1 deg at all meaningful?
Mine are all about 30 give or take a few degrees.
15 too tight for anything I wudda thought. I reserve sharper angles for some larger chisels: too fine an angle on e.g. a 1/4 bevel edge makes it too weak - corners go first.
Forgive me if I'm wrong but I often wonder how enthusiastic sharpeners find time to make anything.

cheers
Jacob

[Alf]

Welcome, Matthew.

I can only conclude either a) you don't have enough chisels, or b) you're much more organised than I am. 'Course it might be c) both! ;D

Cheers, Alf

[matthewwh]

Thanks for your welcomes guys (and lady).

Jacob - Its not so much a question of honing accurately to one degree every time, as recognising that here is a specific angle at which steel failure stops happening and that this is influenced in part by the way that you work so it cannot be pre-set by the manufacturer.

It's really just a refinement of 'if it chips or bends - go a bit steeper, if it doesn't go a bit shallower'. Once you know the angle it doesn't matter whether you are using a jig and measuring it every time or freehanding curved bevels and just develop a 'feel' for where it is. Either way, if you are only sweetening up a worn edge and not having to remove dings every time, you will be saving time and preserving more of the blade.

Al - I'm struggling to get my head around the concept of anyone having enough chisels!

Cheers,

Matthew

[Alf]

matthewwh said:

Al - I'm struggling to get my head around the concept of anyone having enough chisels!

Fair point.

Usually it's either not enough or too many... ;D

Cheers, Alf