Heat damage to blades when grinding...

[ian maybury]

This is to respond to several posts at once. This isn't meant in a combative sense, but it's all very well to talk about over thinking, and once a person has a simple method that works for their purposes it's got to be very temping to fly that particular kite. The fact is though that almost everybody here talks of working through potentially quite a long evolution of methods to get to what now is 'obvious', but which in retrospect wasn't obvious at all. Not only that - if it's so obviously the 'right' way to do a job, why is it that so many don't necessarily agree? (there's lots of reasons many of which don't hold water and some which do, but the end result is a cacophony of competing recommendations)

I guess it'd certainly help a lot if there were 'certified' solutions out there. It equally though ought to be possible to table problems and/or possible development directions on a forum.

One complicating factor in all of this is not everybody has the same set of requirements - because their situation or tool is different enough to matter. I keep on banging the drum on this, but grinding a new bevel angle on a thick BU plane iron is a very different ball game to just grinding off the honing bevel on a relatively much thinner BD iron for example.

The other issue is prior investment. So a soft bond wheel on a low speed grinder is the greatest? Wonderful, but what if you have already invested to head down a different road which has some strengths too. Do you change tack buy a new grinder and soft wheels, only for example to find that as a method this contains shortcomings too? That doesn't mean that it's not the right thing to do, but for sure you're going to seek ways to get your current investment working better before dumping it...

That's been my situation, and I'd so far rather stick with flat bevels. Be that as it may it's become clear that the classic bench grinder is a highly cost effective solution. Minimum parts count, simple fixtures, minimum cost, good access to the wheels for changing angles etc. Add variable/low speed and low heat wheels and it takes another step forward. A belt type grinder has some potential advantages - but it's for example instantly a more complex and more expensive piece of kit - a fact reflected in the relatively higher cost of decent quality linishers etc. Plus it seems that there's little available with the variable speed etc that would be ideal.

That sander Derek is sold in the UK under the Clarke (a moderate cost eastern) brand. This guy might be a prospect too, but it's going to be a bit more expensive, and would ideally need variable speed: http://www.vansantdistributing.com/M...nt_p/mt364.htm Quick belt changes between a wide variety of grits is an advantage.

Thanks for the input on the 120 waterstones Noah. I actually have a 120 grit Shapton professional, but have been quite disappointed by it. I'm even suspicious that it may be a bad example - it had three relatively significantly harder granules at one end for quite a long time. They have by now ground away, but it begs the question of whether or not it's a good example of the type. It cuts at nothing remotely near the speed of 80 grit Al oxide paper on a 1,420 rpm disc sander (and is multiples slower than the WorkSharp too on the same grit) - but the sander is running at about 3,500 ft/min or about x4 the surface speed of a WorkSharp which must go a long way to explaining both the high metal removal rate and the heating the former produces.

[David Weaver]

This is to respond to several posts at once. This isn't meant in a combative sense, but it's all very well to talk about over thinking, and once a person has a simple method that works for their purposes it's got to be very temping to fly that particular kite. The fact is though that almost everybody here talks of working through potentially quite a long evolution of methods to get to what now is 'obvious', but which in retrospect wasn't obvious at all.

Many of us, myself included, don't like to settle on someone else's knowledge all the time. And the trouble with that is it costs us a great deal of expense to fiddle around with everything. I was lucky to get a tormek used, but I bought some accessories for it. I sent them to george. I'm down $500 on that. Waste.

I then bought a version of the viel grinder and blew up the motor on it. I still have the grinder parts in my shelving in the garage, I've got to find someone who has a motor and wants a grinder, and who will pay enough to make it worth putting in a box (which isn't much).

And then I had either an 80 or 100 grit wheel on a ryobi grinder, white wheel - that's what rockler had in stock here. Bad choice. Maybe good for HSS, bad for other stuff.

I tried using a belt sander of the style derek shows, but a bit smaller. It wasn't as precise as a belt grinder, and I replaced the viel with a small kalamazoo grinder (nice machine for the price).

And before that, I went back to the gray wheel on my ryobi grinder and used the grader every time I ground something (the gray wheel that came with it was 46 grit). That was the end of it. Even the gray wheel didn't burn things that easily, the grit size is the key. And I splurged and bought a baldor.

Most of us want to do this kind of stuff, fiddle. I have four wheels for my baldor grinder. Two brown gemini wheels, a white H hardness wheel and a pink surface grinder wheel, and now a fifth - the CBN wheel coming.

I've done enough tinkering that if george tells me something now, I'm willing to believe it. You can go and spend all the money you want, and you can discount what we have concluded (many of us who have thought the same thoughts you're thinking before - none of us is as unique or cunning as we like to think we are, someone else has thought the same things, and recently.). Just don't be surprised if you either:
* don't conclude the same things we have, and find yourself never quite satisfied with the method you choose
* do conclude the same thing and find yourself quite satisfied and realize this was all a waste of time, and has stunted you from thinking about things that will really matter in the shop, most notably training your eye

[David Weaver]

I wish i would have read this thread a few days ago. I bought an 80 grit grade k stone and it is not much better than the gray wheel. Despite the claims that i will never blue a tool; on thin bevels it gets hot in seconds and the grinder is only foot powered. It is a neat feeling how the hollow ground bevel registers on the stone though.

You can obviously avoid bluing things with a wheel that fine, but it takes willpower to keep the touch light, especially when you have that last little corner that's left with more on than you want, etc.

A 46 grit wheel will solve your issues.

80 and 100 grit white wheels create a lot of heat, even when just resetting a bevel.

[David Weaver]

I happened across an Australian forum where Stu Tierney wrote that a Sigma 120 is about as fast as a powered grinder. I do not know if your Shapton is a glass stone but he also wrote that that stone (the 120) is rubbish. i would think Crystolon stones need to be very friable as they are silicon carbide. The sigma apparently does not wear yet maintains speed.

Crystolon stones are a great bevel grinding stones. I know stu's stones had loading problems initially, but that's probably because they're harder than crystolon stones, and also because they're not using the right fluid to carry away coarse swarf. Coarse swarf needs a thicker fluid.

A coarse crystolon is probably the best bevel work stone I know of, though I haven't used stu's sigma stone (which is some type of silicon carbide like a crystolon stone). I'd personally rather have a medium crystolon, though, and use it a little bit more often.

I don't know of any stone that works as well as a grinder when the grinder is properly set up. I'd imagine it's less than 30 seconds of actual grind time for me to remove 4 or 5 honings worth of wear and stop right at the edge.

[Derek Cohen]

it's all very well to talk about over thinking, and once a person has a simple method that works for their purposes it's got to be very temping to fly that particular kite. The fact is though that almost everybody here talks of working through potentially quite a long evolution of methods to get to what now is 'obvious', but which in retrospect wasn't obvious at all.

Hi Ian

That is a fair comment. Sharpening is one of those skills that everyone needs and most can do well enough to get by .. and therefore there are lots of opinions .. probably more posts on sharpening than anything else. Not all of it is helpful to someone that has moved past the beginner stage and has begun recognising their own special needs, and questioning the advice given. There are too many variations possible to prevent this being anything but a minefield for the intermediate sharpener. One of the other issues that goes with this is that our direction in woodworking can change as well, and with this our methods.Some of us here have been around long enough to know what we want, and have spend time (and money) learning what works for us. At times we forget that we have differences of need and personality, and advice can sound quite black-and-white.

One complicating factor in all of this is not everybody has the same set of requirements - because their situation or tool is different enough to matter. I keep on banging the drum on this, but grinding a new bevel angle on a thick BU plane iron is a very different ball game to just grinding off the honing bevel on a relatively much thinner BD iron for example.

I assume that you are using 25 degree primary bevels and adding a secondary micro bevel on your BU irons? If not, read this article I wrote some years ago: http://www.inthewoodshop.com/WoodworkTechniques/TheSecretToCamberinBUPlaneBlades.html

Whether you prefer a belt sander or a wheel grinder to create a primary bevel here, the aim is simply to create that primary bevel, and not to "sharpen" the blade, er se. I tried that and gave it up many years ago. I still have belts for the belt sander that will take the edge to about 10000 grit! It is just too much work and too slow. A secondary microbevel is much quicker. This is best done with a honing guide (not freehand - save that for BD planes and chisels) to achieve the angles needed. This said, the grit needed for a belt/wheel is best as coarse as possible to keep down the heat.

This is the direction I took.

Regards from Perth

Derek

[Steve Voigt]

I wish i would have read this thread a few days ago. I bought an 80 grit grade k stone and it is not much better than the gray wheel. Despite the claims that i will never blue a tool; on thin bevels it gets hot in seconds and the grinder is only foot powered. It is a neat feeling how the hollow ground bevel registers on the stone though.

Hey Noah,
This is a little OT, but…I'd love to see some pics of your pedal-powered grinder. That sounds really cool. Did you build it yourself, or is it a vintage grinder?

[ian maybury]

Think I should have said as well that another factor in the scenario is misleading marketing by those selling the sharpening hardware. That becomes a major issue when you live a long distance from stockists, and it's not possible to inspect stuff before purchasing.

Have to say that your circuitous path to Nirvana makes me feel OK David. Truth be told i think we're screwed once we stop taking responsibility for ourselves/listening to our own insight (that doesn't mean ignoring external input - but there has to be a filter) - so maybe it's inevitable that we each have a path to follow. There's a Buddhist saying on what is perhaps the broader reality of stuff like this that approximates to: 'the cows all take different paths to the barn, but they get there just the same'.

There's no question of trying to sharpen off a grinder Derek - i've been getting great edges off Shapton waterstones. The WorkSharp was bought solely to grind flat bevels and backs. Trouble is its turned out (inevitable i suppose given its DIY/price point led and pretty minimalist spec) to deliver relatively low rates of metal removal (pretty much inevitable on single speed given that it has to handle chisels too) and to eat (over here) very expensive consumables. On the positive side it does a great job when the area/thickness of metal to be removed is minimal - but no more. Plus I'm a bit wary about longevity. The Tormek is a legacy from years and years ago bought primarily to sharpen power planer knives. It proved dog slow on the stock wheel for that, the jig wasn't great and (so far) not wanting hollow ground bevels I've avoided using it for hand tools. It does lots of odd jobs though.

Your site actually switched me on to using 25 deg BU blades for everything, and honing camber and micro bevels as required by the job. Trouble is that previously (some years ago) I unthinkingly bought a few BU planes and some spare blades in various bevel angles from Lee Valley, and wasn't going to throw them out. (it's not cost effective to bring over small lots of stuff, and it's much more expensive here) I got them re-angled very nicely using the previously described 80 grit disc sander - but it's a very touchy job given how much heat it produces at its high surface speed and I'd prefer something a little more forgiving of a minor slip.

Hence as before the continuing search for a one stop flat bevel grinding solution - which is proving rather more difficult than expected given some additional requirements.

It's very helpful to be able to grind using a honing guide to set the angle as it means the Japanese chisels subsequently sharpen single bevel very easily on the waterstones. It means though that the any flat grinding solution with this requirement in mind must if lots of remedial waterstone work is to be avoided (a) have a platform that can be accurately adjusted level and absolutely flush with the working surface of the disc/belt, (b) grind accurately flat surfaces (bevels and backs - and belt sanders don't seem necessarily to do this), (c ) be capable of running at low WorkSharp like surface speeds/metal removal and heating rates for small area/finer work (e.g. chisels etc), and (d) be capable of being adjusted to cut much faster for the occasional heavy job that comes up like the re-angling of the plane blades. (which probably suggests a requirement for variable speed)

David and others will by now be having fits, but right now i'm thinking seriously of sticking a small VFD on the disc sander which is already set up with a work platform. It's advantage is a dead flat aluminium backed surface, the disadvantage is that changing the self adhesive sanding discs requires use of a heat gun and is a bit of a job compared to throwing a new belt on a belt sander...

[David Weaver]

You'd be far ahead with a belt grinder with a VFD and hard and soft platens (if that's the route you want to go). Sooner or later you'll get a catch on a disc sander with an aluminum backing (most of which do have some flutter) and when you do, catastrophic things can happen - like irons bouncing across the shop.

A disc sander is a widely available but not very good option. You have to create some kind of fixture that will keep your iron from grinding out of square, too. (well, you don't, you can just use a fixture that gets the iron close and then allows you to use touch to correct small squareness issues.

[ian maybury]

That seems to be about the choice David - with biting the bullet on hollow ground bevels and reverting to a bench grinder based solution as the other feasible route. Perhaps i've been lucky, but the sanding disc in this case (an old 90s Record) is dead flat.

The Lee Valley mk2 honing guide with the full width cylindrical roller does a good job of holding a plane blade square - although it needed some dialling in first (by filing the mounting surface on the roller assembly bracket) as the roller wasn't as delivered quite in the same plane as the blade clamp.

I did one blade using the cambered roller in the guide, and relying on my eye-balling the squareness. It worked, but it's very touchy. Even a small amount of extra pressure applied to one or other side of the blade will cause it to tilt out of square as a result of extra metal being ground off from that side. Worse still - do it on the other side as well and you would end up with a humped bevel which would greatly increase the amount of honing subsequently requiring to be removed on the waterstones to create a full width micro bevel….

[David Weaver]

These are things you would completely avoid with a hollow grind. there are times I've noticed irons or chisels getting slightly out of square, but never close to outside of the adjustability of a plane or outside the envelope of easy use with a chisel.

When you notice something a tiny bit out of square with a hollow grind, you just favor that side of the tool when sharpening for a grind or two and it's out.

I'm going to send subliminal messages in type and say I'll see you back here in this thread next year when you have glowing thoughts about a dry grinder.

(my CBN wheel arrives today, I might make a random comment about it if I get a chance to use it tonight. I'm curious as to whether or not it may actually be cooler than a coarse pink wheel).

[ian maybury]

It's very possible David. (the glowing comments)

The CBN looks very interesting. The big question for me presuming it does the business is the life - it's expensive enough at around €180 per wheel.

If it gave a long life it'd be dead interesting for doing flat bevels if there was a fully coated disc available - even a disc that fitted the WorkSharp.

It's possible as well to grind a flat bevel off a wheel (whether CBN or something else) by feeding the item in the direction of the plane of the disc too...

[dan sherman]

I'll add my two cents.





A six or eight inch dry grinder with an appropriate wheel is probably the cheapest powered way of quickly removing material from the edge of a tool. In my opinion the number one thing people screw up, is getting the appropriate wheel. Usually then end up with a high grit hard wheel that's designed more for touching up hss turning tools than sharpening a tool steel plane or chisel.

If you turn to the abrasive section of just about any industrial wholesalers catalog, you will find a chart like this that explains how to decipher a girding wheels information code.
5-9.jpg

Another good source of information is the actual wheels manufacture. Take a look at what Norton recommends.
http://www.nortonindustrial.com/uplo...references.pdf


For reference this is what I have on my 6" grinder. It does an excellent job at removing stock quickly and not producing a lot of heat.
http://www.use-enco.com/CGI/INSRIT?P...PMPXNO=3507702


For flattening the back of a plane or chisel, a work sharp is probably the cheapest powered option. The best option is probably a variable speed 2x72 belt grinder with a glass planten.

[Bruce Mack]

I think, therefore I dither. Confession: at home sharpening aids include Worksharp (acquired at low cost), King stones, Naniwa stone, Shapton stones, Veritas plates with oil soluble diamond paste, granite plate for scary sharp, Diasharp coarse for flattening Shaptons, Spyderco stones (given to friend), Eze Lap coarse and fine on order, Eclipse, Kell and 2 Veritas jigs, crystalon stone, steel plate and silicon grit for flattening same. Haven't yet gotten a grinding wheel or Lap Sharp. Are my blades sharp? Yes. Thing is I like to mess around in the shop, sometimes more than working wood. In my other life I was disciplined and productive. Here I'm a happy advocate of Brownian movement. Sorry to hiccup the thread.

[Noah Wagener]

A coarse crystolon is probably the best bevel work stone I know of, though I haven't used stu's sigma stone (which is some type of silicon carbide like a crystolon stone). I'd personally rather have a medium crystolon, though, and use it a little bit more often.

That is surprising that the Sigma is a silicon carbide stone. I thought silicon stones had to be soft because the abrasive is so hard and brittle and breaks down. All the talk about it was how hard it was and difficult to lap. I have used loose, coarse SiC and it breaks down to polishing in under ten seconds. I would not want that securely bonded on a coarse stone. I bought an old Crystolon by accident and it slurries fast. Well most of the time. It is quite a vexing stone as sometimes it is obnoxiously loud and fast and other times it seems to not work at all. It is at its worst after lapping it and seems to harden up. sometimes the spent slurry smears into the stone and i cant rinse or work it out. I am using it on backs though and i recall you seeing it does not work well on them.

Ian, chefkivestogo also has some uber coarse bench stones for flat bevels. By Nubatamo or something. Like 24 grit. It did not seem to slurry in the video. It looked almost like it was the texture of it that was grinding.

Steve, i did not so much make the grinder as assemble it. According to Carl Sagan everything is like that. "If you want to bake a pie from scratch, you need to create a universe." It is not cool at all. They are all kinds of neato multitask machines powered by bike. I have one of those grinders with a pulley in the middle and i just put a belt around an old bmx bike wheel as a fly wheel. The chain is attached to a treadle that is returned by a bungee (it is a freewheel hub [correct term?]). I also have one of the big sandstone wheels but it just throws water from the trough all over and empties it. It is too cold here as well to have a water cooled grinder. It is pretty slow as well yet puts some random deep scratches in.I happen to have some pics for craig'slist on hand.

sawmillcreek 233.jpgsawmillcreek 234.jpgsawmillcreek 111.jpgsawmillcreek 217.jpgsawmillcreek 216.jpg

[dan sherman]

That is surprising that the Sigma is a silicon carbide stone. I thought silicon stones had to be soft because the abrasive is so hard and brittle and breaks down. All the talk about it was how hard it was and difficult to lap. I have used loose, coarse SiC and it breaks down to polishing in under ten seconds. I would not want that securely bonded on a coarse stone. I bought an old Crystolon by accident and it slurries fast. Well most of the time. It is quite a vexing stone as sometimes it is obnoxiously loud and fast and other times it seems to not work at all. It is at its worst after lapping it and seems to harden up. sometimes the spent slurry smears into the stone and i cant rinse or work it out. I am using it on backs though and i recall you seeing it does not work well on them.

The Sigma Select II are silicon carbide, but I don't think the other lines are. If memory serves, The Select II's are sintered silicon carbide, and thus 100% abrasive. So, when it breaks down all it does is expose new fresh abrasive.