Blade Sharpening, a Professional Approach

[Christine]

Please forgive the ostentatious title, some of you will remember a discussion a while ago regarding tool sharpening and my insistence that sharpening jigs are not needed; well I was asked to write this about how edge tools are sharpened in a professional cabinet making shop. Now please don't try and compare how a jobbing chippy sharpens his or her tools on site that is a different story but cabinetry and Luthiery have a similar need for tools that are precisely sharp as opposed to being sharp enough.

I will honestly say the one machine/power tool I would not do without is a wet grinder, I would rather rip boards up with a ripsaw and plane them flat and to size by hand than do without that and have done in the past. Why you may ask? Well when you are trying to do fine work in wood the single most important thing you need is control and with cutting tools the only way you can get that control is with very sharp tools, not almost sharp or even sharp enough, to get precise cuts first time and every time they need to be sharper than that razor you shave with each morning and kept that way. It is a job that can be tedious if you let it be, the trick is to let it not be and to do that it needs to be quick and easy then it can be seen as a way of releiving your mind from the concentration levels of doing careful work for long periods.

Lets have a look at my sharpening area

 

What you see is a wetstone grinder, a tub of water and two Japanese water stones which a are wedged into wooden blocks to keep them from sliding in use; they are then kept in the tub of water when not being used. Above these I have a variety of gadgets that are associated with sharpening various tools but there is only one of note, the grinding angle gauge

 

 

The wetstone grinder is used to give a hollow grind to the edge on a the cutting tool at a set angle which is determined by a little gauge. Mine is a 25 degree gauge which is a good all round angle for many tools giving a nice balance between durability and sharpness. The blade is clamped into a sliding carriage at the correct angle like this

Then it is simply a matter of switching on and moving the blade from side to side until you have a fully ground hollow edge that is square. I've tried to illustrate that with these photos as best I can

You can just make it out but notice that ragged burr on the edge. All we have done is to prepare our blade for the real sharpening:

In days gone by various types of oilstones were the way to go, when I was an apprentice I had a prized set of Arkansas stones but things thankfully have moved on some since then, we have the waterstones, diamond impregnated tiles, ceramic stones.... My own favourites are the waterstones and I'll explain why. Waterstones are a man made brick for want of a better term, made of precisely graded grits, they are bound together quite loosely so they actually wear quite quickly in comparison to other types but that to me is an advantage. When you sharpen a tool you abbraide it's surface so tiny particles are removed, these can become embedded quite firmly in the stone and cause something called glazing which reduces it's efficiency. Waterstones on the other hand break up very slowly so the particles are freed stopping that glazing. The downside of that of course is that the stone can quickly wear out of true, thankfully it is so easy to flatten unlike the old Arkansas stones that needed taking to a stone mason. To flatten a waterstone just get a strip of 80 grit sandpaper taped to a flat surface and give the stone half a dozen rubs on that and the job is done, easy. Another great advantage is that water is used a s a lubricant so rather than having oily hands after sharpening they are merely wet and the stones can just be put back in the tub with not further cleaning or drying needed.

I have two stones, the large red one which is a 1000 grit stone and the yellow one which is a 6000 grit, I use one at a time, they are both out above just for illustration. I don't have photos of the actual procedure but it is easy to understand. To start sharpening you stand in front of the stone (1000 grit), one foot in front of the other (important). You take the blade in both hands with some fingers from each hand on top of the blade to give it full support. Place the blade on the stone and feel for that hollow grind, there is a point where it sits flat and stable. Now you can either sharpen at that or as I do lift the blade a tiny amount so I only grind the front edge. Lock your elbows tight into your rib cage to lock your arms rigid, then rock backwards using your legs, so weight shifting from the front foot to the back foot, that stops the blade rocking. Do that four times and you should be left with a tiny shiny flat across the whole front edge of your blade. If you look closely mine isn't even, my stone needs flattening (OOPS!) but looking closely notice the burr

Change the stone to the 6000 grit and do the same again, remember this must only be done backwards never forwards, the stones are too soft. So four times then flip the blade over and place it flat on the stone, slide the blade over the stone backwards four times. Repeat that two or three more times until when you examine the edge there is absolutely no sign of any burr and the back face should be almost a mirror finish. That should give you a wholly flat edge, for a bench plane you may want to give that edge a slight curve, to do this I use an extra pass over the 6000 stone with pressure on one outside edge then the other and that will be enough to give you a nice edge for a plane

And that is it, just give the blade a quick dry on a towel along with your hands and back to work but be careful, that blade will be sharp and i mean sharp. The grinding procedure isn't done every time, just when the sharpening procedure starts taking longer as the flats get bigger; typically I sharpen four times then regrind. Even with regrinding a single blade can be processed within a couple of minutes. I keep four to six plane blades above my bench and sharpen all of them at once, that way I am less likely to be tempted to use a dulling iron when it is so easy to quickly change and it is quicker to sharpen six once then one six times.

I hope you can see the logic in that method, every cabinet shop I have been into uses that exact method so I assume that it is probably the best and easiest way of doing it, being quick and easy you are more likely to want to do it and the more likely your work will improve.

One last thing and this is actually the very first thing with any flat blade. The back face of a cutting tool needs to be flat, when you buy it it won't be, not even close. The first job with any new chisel or plane blade is to flatten it; how depends on how bad it is. Sometimes 10 minutes on a 1000 grit stone will do it flattening the stone a couple of times, if it is really bad then some 80 grit carborundum powder and a piece of glass it the way to go. Once it's flat then it will stay flat as long as you keep your stones flat but that back face MUST be flat to get the best out of your tools. Very briefly the reason why: A chisel is used mostly but supporting the back edge on work that has previously been cut, either to the side or behind the cutting edge. The back of the chisel is used as a rest and as a guide for progression, if your blade isn't flat then it will either dig in (blade concave) or ride up (blade convex) and that will never ever let you produce good work. Plane blades Other than you wont be able to sharpen properly a bade that is hollow along it's length one of the most important pasts of a bench plane is the cap iron, unless that is in intimate contact with the blade face it will clog up and even with the sharpest blade in the world that plane will not work or certainly won't be capable of quality work but more on that again.

 

[Andyjr1515]

I'm going to set some time aside to read this properly!

Hmmm...whetstone grinder...not got one...always wondered...

[Jimothey]

After reading your earlier post I dug out my whetstone grinder (but I had lost my clamp bar when I moved so I had to make a new one) my version has got the leather linisher on it to polish the blade up afterwards the only difference I do to you is use and 1000grit oilstone

Very informative and a great guide for people who don't have that much experience in sharpening!! 😀

Have you ever tried the Scary Sharp system as one of my mate swears by it and it does live up to the name!! 

[LukeFRC]

thanks Christine. This should be pinned

[Christine]

16 hours ago, Jimothey said:

After reading your earlier post I dug out my whetstone grinder (but I had lost my clamp bar when I moved so I had to make a new one) my version has got the leather linisher on it to polish the blade up afterwards the only difference I do to you is use and 1000grit oilstone

Very informative and a great guide for people who don't have that much experience in sharpening!! 😀

Have you ever tried the Scary Sharp system as one of my mate swears by it and it does live up to the name!! 

No I haven't, I've just had a look, it probably does work but it looks a bit of a faff, just too many stages to be convenient but if it works for your friend I wouldn't dream of trying to stop him, the important thing is sharp tools

I have a leather wheel on mine too. I do use it occasionally for things like carving gouges or a quick fresh up of a scalpel blade. \the trouble with those is they can put a slight rounding to the edge, whilst it is still sharp it takes more time next time to hone the edge flat again, also if you use it on the back of a plane iron then it takes the vital flatness away. That probably sounds daft in isolation, I'm going to do something similar for plane set up or how to turn your cheapo Record or Stanley plane into a thing of wonder, it will become clear then why that flatness is so important not just a load of pretentious crap because i have shares in Japanese water stones

[Christine]

1 hour ago, LukeFRC said:

thanks Christine. This should be pinned

Thank you

I can't stress enough how important sharp tools are. Yes there are loads of different ways to get them sharp but the easier it is, the more likely it is you will sharpen them regularly. As an example, when I make drawers, I will cut the dovetails with a dovetail saw, then I will used a jewellers saw to remove the waste, finally I will use a chisel to pare down the the gauge mark, just a few light cuts along the whole drawer side but I am likely to sharpen that chisel twice on each side and at least twice on every socket on a drawer front

[LukeFRC]

1 hour ago, Christine said:

No I haven't, I've just had a look, it probably does work but it looks a bit of a faff, just too many stages to be convenient but if it works for your friend I wouldn't dream of trying to stop him, the important thing is sharp tools

I have a leather wheel on mine too. I do use it occasionally for things like carving gouges or a quick fresh up of a scalpel blade. \the trouble with those is they can put a slight rounding to the edge, whilst it is still sharp it takes more time next time to hone the edge flat again, also if you use it on the back of a plane iron then it takes the vital flatness away. That probably sounds daft in isolation, I'm going to do something similar for plane set up or how to turn your cheapo Record or Stanley plane into a thing of wonder, it will become clear then why that flatness is so important not just a load of pretentious crap because i have shares in Japanese water stones

The plane thing would be good - own one but it’s so merging I haven’t worked out yet. I say that s as someone who can turn my hand and pick up most everything to a mediocre level ... but this plane evades me!

[Daz39]

Most insightful and informative. I can barely cut MDF into a shelf, but am still fascinated by the skills behind the art.

@LukeFRC is right, this ought to be pinned - perhaps there should be a section in the build diaries forum for skills, techniques etc. There are a growing number of highly skilled craftspeople here and I'm sure the budding and newbie self-builders would love an easily accessible set of guides for things like this.

 

[SpondonBassed]

Many thanks.

[Si600]

Do I flatten the back of my no-name B&Q DIY chisel before I try and sharpen it?  I've got access to a bench grinder and an oil stone, but haven't got one.  (The revered parent, who's grinder it is also made a tool and cutter grinder. http://www.lathes.co.uk/quorn/).  The last time either of my chisels went anywhere near a grinder we set it up wrong last time and ground the chisel to an angle.  Whoops.  It was OK to hack out a door latch hole, which is it's usual habitat.

[Christine]

2 hours ago, Si600 said:

Do I flatten the back of my no-name B&Q DIY chisel before I try and sharpen it?  I've got access to a bench grinder and an oil stone, but haven't got one.  (The revered parent, who's grinder it is also made a tool and cutter grinder. http://www.lathes.co.uk/quorn/).  The last time either of my chisels went anywhere near a grinder we set it up wrong last time and ground the chisel to an angle.  Whoops.  It was OK to hack out a door latch hole, which is it's usual habitat.

If you're going to do accurate work with it yes, it has to be flat. If you just want to chop out lock mortices on a door then there probably isn't a need. Be very careful with a grinder, they can overheat the tool steel before you know it. The steel only needs to get to a straw colour and it is only fit for opening tins of paint

[Owen]

On 28/08/2018 at 11:11, Christine said:

 

Lovely!

[honza992]

Stupid question. When you say to flatten the rear face of the blade, do you mean the whole thing or just a few millimetres next to the cutting edge are flat? 

[Christine]

Just now, honza992 said:

Stupid question. When you say to flatten the rear face of the blade, do you mean the whole thing or just a few millimetres next to the cutting edge are flat? 

Good question!

Chisels need the lot doing.

Start off doing the whole of the front of the blade on a plane iron, after a short while you will see a change in colour where the usable steel is, once you see that stick to just that bit, then when you sharpen the blade keep doing the lot and it will always stay flat

[samhay]

Thanks for taking the time to write this all down. The only pulling backwards on the stones techniques is bringing back distant memories. Must give it a try.

Do you ever use honing compound at the end?

[Christine]

20 minutes ago, samhay said:

Thanks for taking the time to write this all down. The only pulling backwards on the stones techniques is bringing back distant memories. Must give it a try.

Do you ever use honing compound at the end?

No, never, any type of stropping causes rounding even if only microscopic which seems to make sharpening more difficult next time. The edge off a 6000 grit waterstone is as sharp as you'll ever need.

The idea of pulling the blade backwards is for two reasons, the most important being that you polish the burr off rather than break it off and also so you don't dig into the stone damaging it as well as your blade

[Jimothey]

8 hours ago, Christine said:

No, never, any type of stropping causes rounding even if only microscopic which seems to make sharpening more difficult next time. The edge off a 6000 grit waterstone is as sharp as you'll ever need.

The idea of pulling the blade backwards is for two reasons, the most important being that you polish the burr off rather than break it off and also so you don't dig into the stone damaging it as well as your blade

I must be a bit weird as I always take the burr off by slapping the chisel at an angle on my hand then the other way (it's a bit difficult to describe??) or by running the chisel edge downwards on the corner of a scrap bit of timber, well that's how I was taught by an old cabinet maker and to never go straight when sharpening always do a figure of 8 so to wear the stone evenly

As far as honing compound you wouldn't use that at the end as honing is getting the chisel/blade to the correct angle or free from chips/dents before you sharpen it well that's what I've always thought anyway?? The compound I've used at the end is more to polish and stop the blade from getting too hot than a cutting compound?? 😀

Edited September 1, 2018 by Jimothey

[alyctes]

That's a really useful read

Pin, please, mods

[Christine]

11 hours ago, Jimothey said:

I must be a bit weird as I always take the burr off by slapping the chisel at an angle on my hand then the other way (it's a bit difficult to describe??) or by running the chisel edge downwards on the corner of a scrap bit of timber, well that's how I was taught by an old cabinet maker and to never go straight when sharpening always do a figure of 8 so to wear the stone evenly

As far as honing compound you wouldn't use that at the end as honing is getting the chisel/blade to the correct angle or free from chips/dents before you sharpen it well that's what I've always thought anyway?? The compound I've used at the end is more to polish and stop the blade from getting too hot than a cutting compound?? 😀

The figure of eight technique was used with Arkansas stones and carborundum that were very hard. Being so hard the tool was near impossibly to gouge into it and getting even wear was important because you needed to take them to a stone mason to get flattened if they got dished. Waterstones being soft will let the tool dig in but also can the flattened on a piece of sandpaper in a few seconds. Pulling the blade backwards is also better because the burr gets polished off, pushing tends to break it off which can fool you into thinking the blade is sharp. The other reason we pull backwards is it is easy to maintain the tool angle by rocking from one foot to the other with our elbows locked into our ribs, the old figure of eight methods usually ended up with a rounded bevel that needed to become progressively steeper or to hone for longer

There really is no need to use honing compounds, a 6000 grit stone will finish your tools to a mirror finish and more than sharp enough even for planing Satinwood or Snakewood. There is no need to worry about overheating with waterstones, using them is a wet process and self cooling.

[SpondonBassed]

On 28/08/2018 at 09:51, LukeFRC said:

thanks Christine. This should be pinned

 

9 hours ago, alyctes said:

That's a really useful read

Pin, please, mods

Third time's a charm...

@Dad3353, Any chance of getting this pinned please?

[Jimothey]

I meant re the blade overheating when linishing not sharpening

Good to know that I've been doing it wrong for almost 20 years!! 🙄

Edited September 2, 2018 by Jimothey

[Dad3353]

1 hour ago, SpondonBassed said:

...Any chance of getting this pinned please?

The general policy is to let nature take its course, and have topics 'sink or swim' depending on the  frequency of posts added. Any subject not attracting replies would then, naturally, sink down (but would still be found by searching, of course...). Some topics, such as warnings about Paypal scams, are of permanent interest, and would normally not, in themselves, solicit replies; hence the pinning. It's also true that, when pinned, topics tend to become 'part of the furniture', and no longer receive any visits at all, because they're pinned..!
Having said all that, and recognising the quality and value of the OP, I'll pin this, as it's in the proper section for those interested. On my head be it, then; let the pinning commence..!

[Christine]

54 minutes ago, Jimothey said:

I meant re the blade overheating when linishing not sharpening

Good to know that I've been doing it wrong for almost 20 years!! 🙄

It's not wrong as long as the blade is sharp and the back is flat, this is only intended as a quick and easy method of getting a blade sharp of course there are other methods. Linishing is just another step, more time and valid when using other types of stone I suppose when they aren't able to produce a result straight from it. The only time I use any form of strop of compound is when sharpening carving gouges as it isn't something I can do well enough and with a carving gouge the flat back isn't critical. usually

[Jimothey]

14 minutes ago, Christine said:

It's not wrong as long as the blade is sharp and the back is flat, this is only intended as a quick and easy method of getting a blade sharp of course there are other methods. Linishing is just another step, more time and valid when using other types of stone I suppose when they aren't able to produce a result straight from it. The only time I use any form of strop of compound is when sharpening carving gouges as it isn't something I can do well enough and with a carving gouge the flat back isn't critical. usually

I hope you don't think I was being funny with my last comment, I just meant what you said makes perfect sense and that I've been doing it a certain way for all these years which I thought was the right way to do it but you've opened my eyes to another method of sharpening 😀

[Dad3353]

Our Eldest is interested in these methods, as he's started making his own guitars; I'll see if I can acquire a wet grinding wheel for modest expense. My own personal requirements are for sharpening to surgical degree my modelling blades (mostly X-Acto n°11 or similar...). Whilst not needing the same 'elbows dug into ribs' technique, there must be a better way than my present system, consisting of leather stropping, using green paste/wax stuff. Sometimes I get a good cut, but it's hit'n'miss. The blades, even from new, are not apt for cutting the balsa woods I use, and they dull all too quickly, resulting in torn wood if they're not changed. Anyone got any tips, then, for keeping these types of blades at their finest..? Thanks in advance...