bench grinder recommendations

Hi,

I've got a few blunt chisels, so I'm looking for something to sharpen them. I was thinking of getting a bench grinder.

Can someone tell me if I have understood what I have read here. I think the advice is that wood chisels should be sharpened on a wet stone (whet stone?) or not on a grinder at all (oil stone or diamond thingy).

For cold chisels, bolster chisels, and the like, dry grinding wheels would be ok. There are a lot of models with two wheels: coarse and fine, but at what point do you move the chisel from one to the other?

If I bought a whetstone model, I would lose the fine wheel. Would that be a great loss?

I'm not sure about sds chisels. Some old threads mentioned something about green discs being necessary to sharpen them or have I "misremembered" that? Are they a harder material that needs a special disc?

TIA

Reply to
Fred
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I've got a number of them, but rarely use them. Really only for tools on the metalworking lathe.

The one I do use, and that only for tools for the wood lathe, is a combination with a small fast wheel and a large wet wheel. I only use the wet wheel.

For woodworking tools, I use another grinder a Record / Scan wet wheel grinder with a better stone (Like a Tormek, but cheaper). I might buy another of these, so as to have two stones handy. I use this a lot for resurrecting old and damaged woodworking tools, but my actual sharpening is done by hand on a range of Japanese water stones.

If you want a big cheap wet wheel, get a combination machine. I wouldn't advise a double ender, as it's just not that much use (I prefer an angle grinder).

Broadly yes. If in doubt, get hold of Leonard Lee's book "Sharpening".

They''re OK, but I don't use mine for this, I clamp the chisel in a vice, then take an angle grinder to it. For most purposes with chisels, especially curved gouges, this is easier.

If you have an angle grinder, you already have a grinder. If you don't have an angle grinder, get one first.

Usually by never using the poor quality coarse wheel at all. Cheap grinders have some very nasty wheels on them. Cheap wheels also tend to be "hot" compositions that burn steel. Better grades of wheel run cooler and are much more useful. Look for pink or white wheels.

No - but get one where the dry wheel is usefully fine.

"Green" wheels are needed for carbide tools. It's not often you need to put an edge on a carbide tool, most of the chisels will still run fairly blunt. Many carbide tools that look like they need it are actually damaged beyond repair. You can also sharpen tungsten carbide on a silicon carbide angle grinder flap wheel, although the wear rate is high.

Reply to
Andy Dingley

A useful tool, I only have a cheap double ended coarse/fine one. The only chisels I sharpen on it are cold or bolsters. Wood working chisels are sharpened by hand on an oil stone, they only need grinding if you've taken a great hunk out of the cutting edge by hitting a nail or somthing.

Axes get sharpened on it and other general grinding. Want a scriber, grind a large nail, worn out screwdriver grind it to a bradall, head too large ona screw or bolt grind it smaller.

Reply to
Dave Liquorice

Probably not the answer you are seeking, but it may be worth learning the basics of sharpening before investing in any machinery. There are many items that require sharpening, there are many ways of doing so and many different, and differing, friction materials. After many years I can put a reasonable edge on most common cutting tools, but twist drills still baffle me. Amongst quite a few books I have, I would recommend one by Jim Kingshott ~ 'Sharpening. The complete guide'. ISBN 0946819483 or

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is not complete but gives a good insight and has served me very well. The focus is mainly on woodworking tools. No connection with the author, I just like the book. If/when you get a bench grinder- buy a good one that will suit your needs. Decent quality stones to match your requirements are essential.

HTH Nick.

Reply to
Nick

Wood working

I think you will find this is incorrect. Woodworking tools like chisels or plane blades are ground on a grinder, be it bench, floorstanding, circular or horizontal. A bench stone is then used to hone it to a fine edge. In use, the tool is frequently refreshed on the bench stone. Eventually the tool will lose its edge and regrinding is required. So the circle goes. It pays to ensure that any foreign objects, such as a nail, have been removed prior. I won't even start on about a strop and crocus powder :))

Nick.

Reply to
Nick

What about twist drills? I must admit that I don't sharpen mine all that often...

Reply to
Frank Erskine

Wet stone - (whetstone is a CPU benchmarking program!).

I have a machine like this, and use it for things like cold chisels, SDS chisels, or any other coarse grinding. I would not take wood chisel near unless it was badly out of shape - and even then only vary carefully to save overheating it. So all in all it has its uses, but its not a woodworkers sharpening machine.

Probably not. Depends on what you go for. Things like the Tormek or the Jet have a wet end and a leather stropping wheel on the other. I am tempted by one of these machines myself, but keep reading conflicting arguments as to which are better. There is also a more sensibly priced axminster wet machine, that would probably do - although it lacks the honing wheel.

My Armeg and QDS ones seem to sharpen just fine on the traditional dry grinder.

Reply to
John Rumm

I was taught to *regrind* wood chisels on a dry wheel, and *resharpen* wood chisels on an oilstone.

Regrinding happens infrequently, and with great care not to overheat and detemper the steel (by dipping in water frequently and checking the steel temperature with your fingers).

Regrinding gets the basic 25 degree angle on the tip, i.e. you're just getting the basic shape there.

A toolrest set to the correct angle helps a lot. Ensure the chisel is square to the wheel, and touch to the wheel for a few seconds only, inspect, repeat as necessary.

With care, any chisel can be brought back to life, whatever the shape of the tip - by carefully regrinding that bevel-shape on it.

Once that's done - then move to the oilstone. Squirt a bit of light machine oil (e.g. 3in1) onto the stone. (This acts as a cutting fluid to float away the abraded metal)

First flatten the *back* of the chisel (i.e. the non-bevel side is flat onto the stone. Slide back and forth, until it takes on an all- over matt appearance for the last 40mm or so - i.e. you're removing the imperfections from casting, usually a slight hollowness). You're aiming to produce a perfectly flat surface to meet up with the bevel.

Second, turn the chisel over and work on the bevel. This is done by pressing the bevel flat to the stone, left hand index finger near the tip, right hand around the handle, then lift the handle very slightly

- so only the very front edge of the bevel is in contact with the stone. Now slide back and forth, so you're just sharpening the very front edge of the bevel.

The idea is the chisel is *ground* with a 25 degree bevel on the wheel, then you flattened the back face, then you sharpened the front face of the bevel at a 30 degree angle - bringing the 2 **PERFECTLY FLAT** faces of the bevel to a *perfectly* sharp edge.

Finally you remove any microscopic burrs by sliding the tip of the now sharp chisel sideways through some wood a few times.

Now use your now-sharp chisel again and again on whatever you're making, until its starts to loose its edge.

Once it's beginning to dull, just repeat the sharpening steps. Flat the back very slightly on the oilstone (you only have to do this throughly on a new chisel), then repeat the technique of pressing the bevel flat and lifting the handle slightly to get that 30 degree angle on the bevel.

Each time you resharpen, you're working a slightly larger area of that

25 degree bevel you ground on the tip. So each resharpening takes slightly longer than the previous one. Eventually you would be trying to remove metal from all over the bevel at a 30 degree angle.

So - before then - once it's getting hard work to sharpen the bevel on the oilstone - you go back to the grinding wheel and reproduce the original 25 degree shape.

Typically you might get to resharpen a dozen times on the oilstone, before you have to return to the wheel.

With practice, each little resharpen will probably only take 30 seconds, with slightly longer when you have to reshape again. And, no matter if you even take a chip out of the tip of the chisel (typically by dropping it, or hitting a hidden nail) - you can always regrind the bevel, and start again.

Exactly the same technique is used on plane irons, except that because these are often wider than the grinding wheel or oilstone, you have to gently drift from side to side across the wheel, or drift side to side as well as the back and forth motion on the oilstone. On plane irons, flatting the back of the iron on the oilstone is crucial, rather than merely a good practice as it is with chisels.

This method of sharpening does demand some skill - i.e on your very first chisel you might spend an hour mastering it - but ever after it probably takes less than a minute (unless rescuing a seriously abused chisel).

Because the above demands some skill, and because some people like woodturners need to resharpen very often, there are now great tools that turn the whole thing into a less-skilled process - I think the Tormek system is probably the best regarded. It costs considerably more, and probably takes longer because of mounting chisels in tool holders - I don't know, I have no experience of them.

There are also gadgets to de-skill using an oilstone - little clamps on a wheel to hold that 30 degree bevel angle for you. I've never used one - it must be slower, but deskills the process.

The only place I've needed a sharpening gadget, is spokeshave blades - just too small to hold in your fingers and get the angle right on the oilstone.

The method I was taught is probably old-fashioned compared to the array of modern sharpening systems. It does cost a fair amount of dosh to tool-up for the Tormek system though. The results I believe are excellent, at the cost of slower resharpens.

Finally I'll mention diamond-stone replacements for oilstones. Bloody excellent. They consist of a resin moulding, with a collander-like appearance on the face - the metal "collander" has diamonds embedded in it - the "holes" are slight depressions where you can see through to resin moulding - that's so the microscopic metal particles you grind off your chisel have somewhere to go.

Expensive for a good one (e.g DMT brand). You use water in place of oil as the cutting fluid - and it's essential to dry the stone and not leave water on it - although that just means wiping the water off on your overalls. The advantages are they will always stay perfectly flat, and cut very fast due to the diamonds.

The cutting power of diamond stones is so good, you can almost get away from using a wheel, in all but the most serious regrind-the-bevel jobs. You would need to purchase more than one though - they're colour- coded - black for coarse, then blue, red. green (I think) for finer stones.

I suspect part of the choice of sharpening methods is about what you want to *do* with the chisels. Crude approaches with angle grinders - just for carpentry - is probably ok. The above method is more suited to fine joinery, with straight bladed chisels - it will enable you to cut see-through slivers of wood from a dovetail joint. But if you're woodturning or woodcarving, particularly with gouges and other non- flat chisel shapes, a sharpening system may be best.

Reply to
dom

Which comes from a term for a sharpening stone. Sharpening is whetting. (To whet one's appetite is to sharpen it). So what the OP wants is a wet whetstone.

Reply to
Jón Fairbairn

A tricky one this, you need to know the geometry at the tip. There are two cutting edges, each with a flute in front to clear swarf. the angle between is 120 degrees from memory. BUT you must not sharpen like a "cone", this prevents penetration into work, just rubbing/friction. Now think in direction you push drill...Cutting angle is needed, this is provided by flute in front of cutting edge. Then clearance angle is needed, this is provided by face following cutting edge, it must "fall away". ie. the leading edge of face(cutting edge) is closer to workpiece than trailing edge. You can sharpen by lining up twist drill with wheel (30 degrees off centre), cutting edge touching wheel, push in gently whilst rotating clockwise, AND with slightly increasing pressure. Takes some practice. Too much pressure will produce lop sided angle. You do need to see what you are producing, so drills smaller than 5mm I chuck when blunt!

Reply to
Olav M

When was that, and what were these chisels made out of?

If you look at a modern "typical" quality plane (i.e. Stanley) you'll see that the plane iron is proudly stamped "Chrome Vanadium steel" or similar. Yet this is a poor steel for making plane irons from and refuses to take a good edge. Its one virtue is that it can be ground rapidly in production factories on an air-blast dry wheel without risk of overheating and drawing the temper. This is an irrelevance for sharpening, or even regrinding, in later service. You're not in a production timescale, nor do you have an air blast wheel. Grinding on an uncooled dry wheel is still a risk of overheating and drawing the temper, albeit less than a plain carbon steel.

In the 1950s and 1960s, the great woodworking drought when cabinetry skills vanished, it was fairly common practice to make chisels and plane irons from these modern steels (assume anything with a plastic handle) and not to care about the performance of the final edge. This myth that dry wheels were appropriate for sharpening spread. Incidentally, if you can't handle the heat from minor sharpening, how are you going to cope with the bulk of shaping or grinding?

If you use power for woodworking tools, use a wet wheel. Unless you're serious though, there's little need for a powered wheel at all. A coarse waterstone (250 grit) is cheaper and cuts as quickly.

Reply to
Andy Dingley

Totally agree about modern Stanley planes. Best place for them is the bin (or leave in the shop). I bought my (second) plane from an antique shop - typically about 20 quid for a good condition No:4, i.e half the price of a new one, for twice the quality. (That said, I haven't tried "posh modern" like Lie Nielsen - but prices are more like 100-200 quid)

Worst "modern" I bought was a spokshave. I ended up buying an old one just for the blade. I couldn't believe Stanley was actually selling a completely useless product - the original blade behaved more like monkey metal.

There are some quite reasonable modern chisels about though (and a lot of dreadful ones). Mine are Bahco and take as good an edge as old ones. (Or buy old-but-good ones piecemeal)

However it's quite possible to regrind on a dry wheel without hurting the temper - just go gently and dip in water when it feels warm. The only times its tricky is removing a damaged portion, or straightening up a rather skewed bevel (I was taught to flip the chisel onto its back, and square off a bit of the bevel, then flip back to grinding the bevel back in - that's when you're in danger of burning it).

Reply to
dom

N20 !

but also a sharpening stone and a stone circle amongst other things

Reply to
geoff

N20 in the winter

Reply to
geoff

I have a Martek drill sharpener thingy... bought a long time ago well before I got a bench grinder. Not sure I'd want to attempt to sharpen a drill on the bench grinder but pretty much any new drill will be sharpened before use. 'Cause out of the packet they ain't sharp, I was quite surprised how much sharper my ordinary HSS drills were after a trip through the Martek.

Reply to
Dave Liquorice

Thanks for the informative post. Are all sds chisels carbide, even the cheap ones?

Reply to
Fred

Thanks. I will look into this and the book that Andy recommended too.

Reply to
Fred

Thanks for such a long and informative reply. It's been very useful.

Reply to
Fred

Pretty much all SDS drill bits, but not the chisels.

Reply to
Andy Dingley

As it happens, it was the axminster I was looking at. They sell this one:

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is ten pounds cheaper than the one at machine mart and they seem so similar in spec that I wonder whether it is the same machine painted in a different colour:

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mart put the "h" in wet, which is why I wasn't sure of the spelling.

Axminster also sell this one:

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I think is the same model but with a clamp to hold your chisel at the right angle, which sounds a good idea but it adds a lot to the price.

I have heard great things about axminster here but never bought from them before.

I have looked into the two books mentioned in earlier replies but both seem out of print but are available second hand.

Thanks to everyone who has replied so far.

Reply to
Fred

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