Official Luthiers Forum!

Hey guys,

I wanted to share a couple (probably obvious) tips on getting better edge life out of the chisels you use for guitar work.

TLDR:
Don't write off the chisels you already have... Often - the tools in hand will do some pretty good work assuming the steel is not junk.. (Sometimes it is.. That's a subject for a different thread...)

If your edges aren't lasting, try running a higher bevel angle on the chisel... Second thing is get them sharper.. While "Sharp fixes most things" - it doesn't fix a bevel angle that's too low and rolls or chips off. You must fix bevel angle problems with bevel angle.....

----------
There is a big chisel "study" going on at one of the woodworking forums...

An interesting thing that turned up in the results is that increasing the bevel angle of a chisel has about the same effect on edge life as making it harder... For most of us - "making it harder" is outside of our consideration... And so the main tool you have is a steeper Bevel angle.. Don't hesitate to grind the bevel of a chisel at 30 degrees or even 35 degrees to get work done.

But another interesting thing came up.... Because the edge life is so much better - it often takes LESS force to cut with a chisel ground with a steeper bevel... That's counterintuitive....

Case in point - we tried 4 1" Orange BORG Buck Bro's chisels... Hardened 2 up to Rc 63. Left 2 at the as-received Rc 56.5 (yes - you read that right.. Rc56).... We then ground 1 hard chisel and 1 standard chisel to 30 degrees and the others to 25 degrees... Sharpened and off we went....

The 2 best performing chisels both had 30 degree bevels.. The standard soft chisel reground to 30 degrees did a lot of good work and still was quite sharp where the soft chisel ground at 25 degrees rolled instantly and failed.... The hard chisels were kinda similar - the 30 degree hard chisel cut best with the lowest cutting forces of these 4 chisels. The edge lasted a long time - and gave nice low cutting forces... The hard 25 degree chisel worked OK till the edge chipped badly....

One very interesting thing that came up was - according to the data - with a proper bevel angle, some of the mid priced and not-super-hard standard western chisels outperformed very expensive premium "boutique" chisels... This was a big surprise to me....

I tried it out.. And on my chisels - the higher 30 degree bevel runs circles around the usual 25 degree bevels I had been using....

This is probably a stupid question but. . . Are we talking about 30 degree secondary bevel or primary bevel. Would one expect the better edge retention at 30 degrees for a secondary bevel or is it even higher (i.e. they reground the primary bevels to 30 and honed in an even steeper secondary)?

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Honestly - this was just a ground and honed bevel to the angle... No Microbevel.

Most of the chisels in the larger test were simply sharpened and honed at whatever angle the factory or the chisel's owner shipped them with.... The thought was that this may be throwing a lot of noise into the test results data - so we cooked up a quick study for hardness and bevel angle holding for the same chisel alloy....

For example - in the larger study - none of the chisels that came ground at or above 30 degrees saw "edge failure"... Where chisels sharpened below 29 degrees (most were 25 degrees or below) only had 2 or 3 of 15 (or so) did NOT see edge failure...

But guess what - nearly every "typical" non-boutique manufacturer ships their chisels ground to 20-25 degrees... And most of those ended up doing very poorly in the testing... Where often the Boutique makers shipped their chisels with higher factory grind bevels (typically around 30 degrees) and most of those did quite well..

I didn't do this testing I am talking about, though I did supply the 4 buck chisels for that trial...

Thanks, that is the info I needed. I will assume that a secondary bevel angel will perform (from an edge retention standpoint) as well as a single bevel of the same angle. I wasn't clear if the effective bevels in your test were higher (30 primary plus secondary of some angel). I usually keep my secondary bevel at 30. I didn't want to bother with all the rigamarole of experimenting with a higher angle out of a misunderstanding. It would be a pain to have to go back down in angle. . .

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

What it comes out to is that if you feel like you are having edge issues - often you can chase the cutting edge bevel (or microbevel if you use one) up a degree or 2 at a time until your edge holds up.... This pushes you away from edge failure modes of chipping or rolling to plain, regular wear... And then the edges "last" 10 or 100x longer....

For example - with the Orange BORG Buck chisel at Rc 56 (which is really soft) - moving from 25 degrees to 30 degrees resulted in a cutting edge that held up around 100x longer because it didn't fold over in the first 3" of the cut...

I'm a little perplexed by all the chisel talk. I work on furniture, 2 large wooden boats, and guitars. Try chopping with a chisel on purpleheart, greenheart, jatoba, osage orange, and oak and you will learn about edges! A chisel gets more use chopping one mortice than on an entire guitar. I use mostly 2 chisels when I make guitars, a 3/4" and a 3/8". I occasionally pick up a 1/4" or an 1/8". They are between 25 and 30° on the "entry" bevel, but I don't find it critical. I sharpen to 2000 grit emory paper on glass for guitars, and I might re-hone on a piece of pine with green crayon halfway through, but If I don't get 2 or 3 guitars out a sharpening I would be surprised - I never build 2 or 3 straight so I will never know. My main chisels are a nice set of Marples with boxwood handles I got for my first wedding anniversary in 1972, with vintage additions to fill in. Might be that I am lucky to have good chisels to start with, and if that is the case, that makes an argument for spending a few bucks to get a good one or two, or spend some time at fleas and garage sails hunting a couple of good vintage tools.

"There is a big chisel "study" going on at one of the woodworking forums."

I would be curious to know which forum, and what their testing methods were.Quite a few years ago Fine Woodworking did a comparison of bench chisels. Their method seemed to be; to pound the chisel into a piece of wood and see how the edge held up. The Robert Sorby chisels made a poor showing IIRC. But it struck me at the time that they weren't using the chisels as bench chisels but more as mortising chisels and abusing them at that.
My thinking is that if you want a chisel to "shave" sharpen it more like a razor and if you want it to "chop" sharpen it like an axe (obviously not to either extreme).

Just a quick note, seeing as I've written on chisels before: I've pretty much always sharpened chisels to 30 degree micro-bevel, and for a long time now have sharpened everything but low angle plane irons to 35 degrees micro-bevel. For the low angle planes I use 30 degrees micro-bevel. Going to 35 degree on plane irons was a big step up in longevity. FWIW.

_________________
Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

We usually grind at 25 degrees and hone at 30 degrees, with no micro-bevel. Easy enough to go to 35 degrees, such as we found useful for bloodwood bindings.

_________________
For the times they are a changin'

- Bob Dylan

25 deg primary 35 secondary chisels and plane blades, and i have a bad case of TAS , tool aquisition syndrome .Where I can never find the right chisel/ plane for the job at hand

Ernie my friend - I am in the same boat with TAS... That's why I tried to keep this post on the topic of experimenting with higher bevel angles for better edge life rather instead of trying to "Buy success". And it's why I am trying not to talk brands....

As I circle back around on this - most BORG chisels including the $11 Buck chisels will do a pretty good job when honed at 30 or 35 degrees.... And most very expensive chisels perform miserably at 25...

I just picked up a 3/4” chisel from Lee Valley:

http://www.leevalley.com/us/Wood/page.a ... at=1,41504

It comes from them at 25 degrees, there is a micro bevel, I’m guessing maybe 27? Anyway, I should hone this thing at 30 instead?

Brad


Sent from my iPhone using Tapatalk

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

Try it out and see how it does. If it holds up well - keep whatever it has if that makes you happy... If the standard angle doesn't hold up - increase it a bit at a time until it does.

I have reground some chisels to do 1 task only, they are used junk store or yard sale castoffs, some are ground at 22 deg to act as a paring chisel in hdwd and a lower bevel one at 17 to 20 degrees for pairing softwoods these also have a slight belly on top due to needing frequent sharpening on a dedicated buffing wheel run at 1700 rpm on a 6in cotton buffs 1 side is red rouge an the other is charged with green rouge from lee valley. These same buffs are also used on my carving tools, which have similar bevels.

After reading various chisel conversations, I bought a set of Aldi chisel, sure were cheap enough... Any idea of the angle they're ground to? Same questions about the blue-handled Marples chisels Santa bought me from Amazon?

Thanks!

_________________
Peter Havriluk

Both my Aldi and recent production Marples were ground a hair under 25... Neither of them hold up for me at that angle. 30 will probably be good on the Marples for most things. The Aldi will probably need at least that if they are like my Aldi chisels - especially if you want to do any chopping with them...

One weird thing with Marples - give them a night in your deep freezer... They often come back out more uniform hardness and often a bit harder...

A 30° edge has the bevel twice as long as the thickness

To avoid confusion with micro-bevels, secondary bevels, etc., we use the term 'ground bevel' and the 'honed bevel' in the shop, with the ground usually being 5 degrees less than the honed. The reason is that - assuming the ground bevel is flat - honing the entire bevel does not really have much value beyond the cutting edge, while working the narrower slightly steeper honed bevel takes a lot less time. We regrind to 25 degrees on most blades when the honed (polished) bevel extends halfway up the ground bevel.

With new tools like the Aldis ground to 25 degrees, it's a case of flattening and polishing the back, then establishing the honed bevel at 5 or 10 degrees higher angle...for most work, 5 degrees works, but mortising chisels and work in abrasives seem to work better with the steeper 35 degree honed bevels.

Interesting that my kitchen knives are happiest at 40 degrees for the German blades and about 30 degrees for the Shun and Miyabi Japanese chef and santuku blades. I may sacrifice one of my old bargain brand blades and grind to 20/hone to 25 to see if there is actually more in the way of bending and chipping below 30 degrees on a kitchen blade.

_________________
For the times they are a changin'

- Bob Dylan

Pete .I have2 setsof aldi chisels, flattten the backs first I use 360 to 2k diamond stones or sandpaper from 180 to 1200 to flatten the backs,on my granite surface plate Then a 25 deg primary bevel followed by a 35 deg secondary bevel for the aldi chisels, Hard to beat for the price. I also have a set of blue handled marples straight chisels bought in 1977, they are worn , but very useful for grunt tasks around the shop.

Thanks! Would've been good if l remembered my high-school geometry.

Meawhile, this conversation has given me an awful lot of information.

Much obliged.

_________________
Peter Havriluk

PS FWIW I used to guess at the 35 deg secondary bevel , as I was using a 40 yroldeclipse honing guide . Last year I bought a L/n sharpening jig and a 13 k ceramic sharpening stone . It was a big improvement I got a shinier secondary bevel , and the 35 deg bevel lasts much longer even on Aldi chisels bought last sept.

Yeah - I suppose that 35 on Aldi chisels does hold up a lot better than 30.. But even then I have trouble with them rolling edges when chopping.... What I ended up doing to get Aldi chisels to hold up under the mallet was to simply give it a whack, polish the rolled burr off the back on my finishing stone, touch up the bevel on the strop - then give it another whack.... Repeat till the edge stabilizes.... And then they can do quite a bit of work... I haven't encountered this with Stanley's or Two Cherries chisels...

John , I have 1 older 1/4in badly abused marples blue handled square chisel. Going to try your idea of a 24 hr freeze , the edge retention on it sucks

Thanks for the info John! I'm going to try some steeper angles.

Where any of the chisels in the study 01 or PM-V11?

Sent from my SM-N910T using Tapatalk

_________________
Pat

I'm interested to hear more about this freezer trick. How is this effecting the steel? I have a limited understanding of what is going on with annealing, hardening(quenching) and tempering, but I don't understand what freezing would do. How cold are we talking about a regular freezer around -20 C (-4 F) or colder (I have a -80 C [-112 F]) freezer.

_________________
Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.