That pretty much sums up why I started using a dry grinder. I can grind back a secondary bevel in a seconds or change the primary or radius in a couple minutes.
Originally Posted by David Weaver
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That pretty much sums up why I started using a dry grinder. I can grind back a secondary bevel in a seconds or change the primary or radius in a couple minutes.
-- Dan Rode
"We are what we repeatedly do. Excellence, then, is not an act, but a habit." - Aristotle
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I've read something some time ago about this, so I don't remember exactly. These sparks are something burning, a carbide or an oxide, don't know exactly. But they need ignition heat, and that comes from the rubbing of the steel against the wheel. They measured temperatures up to 600 degrees in a microlayer in the steel.
Sorry to be so vague. I really think it doesn't matter though. The overheated crystals are being removed when you hone the edge. And even when you accidentilly blue the steel a little bit, it isn't the end of that chisel. It is suboptimal, but it will be removed in the next sharpenings. There is no need to be anxious about grinding.
[OP]
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Guess i can accept that minor heat effects are (probably - i'd love to see objective/microscopic proof of this) relatively easily honed off, but i'm not as relaxed as some seem to be about the risk of burning an edge. It isn't just a matter of skill/practice and good technique - not at least when the full range of grinding tasks is considered.
It's also a lot to do with matching the abrasive, surface speed, pressure and time between coolings to the actual job. i.e. it's necessary to have the right equipment setup (one that gives good control) as well as the right technique. Most woodworkers seem to do little except grind the honing bevel off on existing tools, and with a set up optimised for this it's not hard to get right - but it becomes a different ball game when the full range of possible jobs is considered.
Volume and area of metal to be removed are huge factors in choice of setup because pressure and speed are important variables so far as heating effect and metal removal rate are concerned. A set up that's fast enough to grind a new primary bevel on say a narrow chisel is going to be dog slow when it comes as I said a while ago to removing amounts of metal measured in mm grinding a new bevel on a 4mm thick + BU plane iron. The set up that does the plane iron in decent time will burn a narrow chisel in moments.
I'm as before influenced by having recently had to re-angle a lot of bevels and then sharpen the tools - everything from regrinding narrow chisels to re-angling the above plane irons. I have to say that I ended up frustrated as hell at not having a good one stop grinding solution to cover this full range.
I did my best. I have a Tormek and all the bits bought about 10 years ago, but while the water cooling is great it only grinds hollow and proved dog slow on the stock wheel on heavy jobs. (wonder if there is a coarse wheel available that significantly speeds it up?) I have a WorkSharp and it does a great job of producing flat bevels on smaller work off the top platform with a honing guide - but it's again dog slow on heavy jobs, eats expensive consumables like there is no tomorrow and isn't all that robust. Then I set up a disc sander based grinder like the WorkSharp for heavier jobs, and it can certainly shift lots of metal. Lots of care is needed though to avoid overheating once the bevel starts to thin a little - it runs at about double the surface speed of the WorkSharp, and it's too aggressive for light work. Plus it needs frequent abrasive changes.
So the one stop (flat bevel grinding) solution remains elusive, and doesn't seem to exist on the market. This thread has confirmed the thought that belt sanders have promise because because they run fairly cool, because there's a good range of abrasive types available, and because variable speed can easily be added. Low heat wheels on variable/low speed grinders ditto, but they grind hollow. Coarse waterstones are slow - hand techniques don't seem to cut it unless perhaps some of the Japanese lapping techniques can hack it? Then there's the CBN wheels Derek has just put up. They seem to run cool, they don't wear, they hopefully given the price last almost indefinitely, they are accurate, and they hopefully don't generate boron dust as it's very dangerous indeed from a health and safety point of view.
Wonder if there's a flat CBN grinding disc done that would fit a (maybe DIY) heavy duty variant of a WorkSharp equipped with variable speed?
Last edited by ian maybury; 10-24-2014 at 6:18 PM.
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Ian, you're way over thinking this, there is no point where you'll have any practical problem with a dry grinder unless all get and swarf must be captured.
You don't need to hone off any appreciable amount with the stones, either. I don't, and I grind right to the edge and did when I used a cheap gray wheel. It just needs to be coarse and dressed. I don't even keep water at my grinder.
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+1 to that. I have to admit I'm bemused by this whole thread. I tend to think that threads like this arise from thinking abstractly about sharpening, and reading internet threads about sharpening, rather than actually sharpening.
No, that is simply not correct. It is a matter of "skill/practice and good technique." The order is reversed, though. Read up on the technique first, practice the technique, and once you've practiced enough, you will have acquired the skill. Just like any other woodworking skill. There's nothing magical about it.
Ian, I'm reading your posts and seeing you talk about Tormeks, Worksharps, CBN wheels, belt sanders, etc. All of these are expensive solutions to a non-problem. As has already been suggested by David, Kees, Dan, and others, not to mention folks like Joel Moskowitz and Larry Williams, the simplest solution is a dry grinder. Sell the Worksharp, Tormek, and all the other junk, buy a dry grinder, and you'll have enough $$ left over to buy some nice boards and a six pack.
Last edited by Steve Voigt; 10-24-2014 at 11:23 PM.
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Ditto that, the real problem is that all of those other things were bought before a dry grinder. That was my problem, too (though I had a cheap dry grinder, early on before this was a topic on the forums, I had a 100 grit white wheel, which was not an insurmountable problem, but it wasn't a coarse wheel).
I've never once missed the tormek.
There is no "level of damage" on the edge of an iron or chisel, that kind of supposition has sold a lot of tormeks, but it has no practical place in a discussion with someone who has refreshed the grind on a couple of dozen irons (or fewer).
And bloggers and magazines have written about the "dangers of burning an edge" at length, which is hocum. Sure, you can do that if you do it wrong. You can also make miscuts on a dovetail if you don't use a router jig.
Last edited by David Weaver; 10-24-2014 at 11:49 PM.
[OP]
Member
One problem is that we really only find out the capability of the various methods when we try them - despite many being pushed as universal sharpening solutions.
The focus here is to sort out a good grinding solution, but we're maybe going to have to agree to differ on that one. The thread follows directly from my experience in the past couple of months in setting up a bunch of chisels and BU planes - using what I happened to have available.
It's not even a subtle issue - it's that a method that shifts steel fast enough to be efficient on a job like re-angling the bevel on a heavy plane blade is far too aggressive for safe (for the tool) back flattening and bevel grinding on a chisel. Or vice versa - that a WorkSharp (bought to put flat bevels on Japanese chisels, and doing that and flattening backs on them very nicely) simply hasn't got the clout for jobs like the heavy reworking of a plane blade described. As it happens I got by on the plane blades using the adapted disc sander described before, but it produces a hell of a lot of heat and forced dropping back to the WorkSharp to finish stuff once the bevel started to significantly thin.
Presuming that it occupies the magic minimal heat/high metal removal rate space (something I'm happy to accept) I'd happily use a coarse white wheel or even CBN on a dry grinder - but neither does the flat bevels I'd prefer to stick with, there doesn't seem to be a variety in either case that uses the flat side of the wheel (please say otherwise if this isn't the case), and anyway I don't have a tool grinder.
I've got this far, and can continue with what I have since it's going to be mostly about relatively light duty re-grinding of bevels to eliminate the honing bevel from here on - but I'm left looking at what is an unsatisfactory mish mash of solutions. There has to be scope for a one size fits all flat grinding solution. e.g. a belt grinder with variable speed that at one end of the scale cuts at about the rate of the WorkSharp, but that at the other can shift a lot more metal and not cost an arm and a leg for consumables.
There's no fundamental issue in that there's something that I need to sharpen that I can't - but my instincts very much suggest that there has to be a single/one stop/much more elegant solution possible that would allow the offloading of all of the half and high risk solutions….
Last edited by ian maybury; 10-25-2014 at 10:46 AM.
Contributor
Why did I go down the Tormek wet grinder route, then (several years later) purchase a CBN wheel for a dry grinder?
First off, I am not trying to send a message that says "this is the best and this is what everyone should also get". Everyone must do what they feel suits them best.
All I seek from a sharpening system is one that is efficient and leads to sharp edges with the minimum of fuss. However, what works for me does not necessarily work for others. Follow my lead at your own risk.
Is it cost effective? Does it cost too much? Frankly, that is of little importance to me. I can afford what I have purchased. It is not up to others to decide what I can afford. Decide for yourself what you can afford. There are lots of ways to spend money on sharpening systems, some of them in my opinion are a waste of time and money, and some of mine are no doubt for others a waste of time and money!
On average I can grind a blade and hone it in just a few minutes. Resharpening takes under one minute. CBN wheel for grinding - to the edge of the blade. It is warmer than a Tormek, but much much faster. The final hollow is slightly deeper. It will last slightly longer. It is important that the edge is smooth and the hollow grind is straight. This means much less work to do in terms of preparing the edge with a coarse stone.
I freehand on the hollow and, after the CBN, shape in a camber on a broken-in Eze-lap Fine grit. I've had this stone over 10 years now. Magic! This is followed by a Medium Spyderco, which raises a very fine microbevel in about 8 strokes. On a PM-Vll blade it is so small that one must look carefully to see it. Five strokes on a Ultra Fine Spyderco, and I could call it done. A few strokes on either Veritas green compound on planed hardwood or the 0.5 micron diamond mesh, and the blade is very, very sharp.
No water. No mess. I can focus on the important part of woodworking - working the wood.
The irony is that the CBN wheel creates a perfect hollow and the Spydercos remove so little steel that the hollow looks like it will last a long time ... and grinding will be done so infrequently!
Here are images of the edges created on a 1" PM-Vll chisel blade. Firstly off the 180 grit CBN wheel ...
Secondly, the Medium Spyderco ...
Then the Ultra Fine Spyderco ...
Finally, a few strokes on a 0.5 diamond mesh to add a final polish and ensure the wire edge is gone. And demonstrating that edge on soft Radiata Pine ...
The stones: Medium, Ultra Fine Spydercos, Diamond mesh (on perspex on hardwood), and Fine Eze-lap.
Regards from Perth
Derek
Last edited by Derek Cohen; 10-25-2014 at 2:21 PM.
Contributor
Have not used the pm 11 but have been reading the good reveiws. I'm surprised at how ragged the newly ground edge is
in that photo. Was it ground without moving the chisel side to side, or is that just the nature of that steel?
My problem with a grinder has been concern over the refuse they throw in the air more than the heat issue. My allergy issues create a level of caution beyond what most people would be concerned with. I picked up a Delta 8", variable speed grinder yesterday when I was at Lowes. The low speed is 2000 instead of the more typical 1750 or 1800 low speed on more expensive grinders. The top speed is 3400. I am not sure I need the speed adjustment anyway but it might come in handy. Any reason this specific grinder might not handle typical grinding chores?
I have a 8" CBN wheel with rounded edges, hopefully shipped. I am wondering what to do with the other side of the grinder. I would like something that would provide more grinding help, maybe Dave's 80 grit CBN wheel. I don't plan to order another expensive CBN wheel though until I try out the 180 grit I ordered. I was also wondering about a leather or felt wheel for buffing. The Tormek has a leather wheel I can use but it will remain in another room, the rotation speed is quite slow and I might sell it or trade it off. I wonder if a buffing wheel of some type moving between 2000 and 3400 rpm might be useful? I don't think most buffing wheels throw off much in the way or airborne refuse. I plan to do the major part of my touch up sharpening on my Spyderco stones, but a little buffing might help too? I am also considering a stone/ceramic wheel if I can find something that does not toss up too much dust. I do have dust masks, although I don't particularly like wearing one. They tend to fog my glasses among other things.
Last edited by Mike Holbrook; 10-25-2014 at 11:26 AM.
Contributor
Hi Mel
I thought that someone would comment on that. It is not typically ragged like that off the Tormek. It may be that the CBN wheel is new and still wearing in. It may also be (more likely) that I ground a little further than I would usually as the wheel on the dry grinder is set up fractionally off the line of the Tormek, and it was necessary to grind fractionally further to square the edge.
The final edge was smooth.
Regards from Perth
Derek
Member
I hate to keep saying this, but the above (at least the part about bevels) is simply not true and just reflects a lack of practical experience with dry grinders. I have used a cheap 6" grinder to grind 1/8" chisels, and I have used it to put a 20° skew on a 2 1/2" plane iron and then regrind a whole new primary. The dry grinder is perfectly fine for both tasks--the difference is simply a matter of touch. Use a delicate touch for small things, be more aggressive with larger objects. That's it, that's all there is to it, other than practice.
In my old machine shop, where time was money, we used dry grinders for virtually all rough sharpening tasks. The only exception was really large lathe drills. If I needed to sharpen a 3" diameter drill, I'd do it freehand on a belt or disc sander. But that is a scale of metal removal that the hobbyist woodworker is unlikely to encounter.
For flattening backs, the dry grinder is obviously no help. But that is a completely different task from grinding a bevel, and it seems rather quixotic to expect one device to be able to do all things equally well. A tablesaw is great for all sorts of things, but I don't expect it to cut curves.
Member
For me that optimal setup is a dry grinder, 2 stones and a strop. It does require a minimum skill level with the grinder, so there is an investment of time and a few practice pieces, but the payback in time saved down the road is pretty good.
Derek, thanks for the additional pictures and report. It sounds/looks like grinding nirvana to me.
From what I understood from Dave concerning the longevity of his CBN wheels, I suspect this solution will turn out to be very cost effective over time as well. Maybe, including the spyderco ceramics and a couple diamond plates, we have a complete system that will be very fast and likely outlast us. Will be nice to get back to working wood with sharp tools vs worrying with sharpening issues so much of the time.
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V11 holds on to its wire edge pretty stiffly, so you're not going to get a clean toothy edge like you'd get from hard water hardening steel. If you thin it, it comes off fine, though, especially if you strop or use a really fine stone (as in the edge is still smooth).
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