If I can only buy 1 CBN grinding wheel, is 180 grit aggressive enough? [Archive]

Kees Heiden

03-09-2016, 8:34 AM

Half a cm is a lot indeed, but I regularly grind them down almost that much. It's a lot quicker then trying to remove pitting like that on a lap. I've also ground back edges of blades, next steel project is going from a 54 to a 52 mm blade (somehow I am postponing that one...) That's a lot of steel too. It is no problem with a Norton 3X, 46 grit wheel, just a little dusty. Of course I cool the steel often in a bucket of water. It's been a long time since I overheated a blade.

I wonder if a CBN wheel is usable for work like that, and if 180 grit would be too slow.

george wilson

03-09-2016, 9:53 AM

I can easily grind away MANY TIMES that amount on my Square Wheel belt grinder. When the cutting edge gets thin,I dip in water. I use 36 grit blue zirconia belts for big stock removal,finer belts for finishing,followed by hand polishing for a mirror finish. Much cooler grinding than a wheel because the belt is 72" long,and doesn't stay hot due to its length,plus the 36 grit is much more aggressive. Sometimes i "sharpen" used belts by dragging a single point diamond dresser across them at full speed. This works to some extent,but the belts are not as good as new,but good for some extra use,at least. Only works on coarse belts that are thickly coated enough to not have their cloth backing cut by the diamond.

I grind out whole knives with my belt grinder,starting from bar stock. These grinders are pretty expensive,but you can get a serviceable belt grinder from Grizzly. BE SURE to use a DEDICATED vacuum (NO WOOD DUST!!!!),right under the place where you do the grinding. That means right under the tool rest,or else the point where you grind freehand. You don't want to go breathing steel dust OR ceramic dust(EVEN WORSE!!) from the belt. It never goes away in your lungs. I have enough COPD already.

If you want significant stock removal,get a belt grinder and use the blue zirconia belts. You can buy the belts cheapest on Ebay.

However,1/2 cm. is not what I'd even consider a significant amount to grind,anyway. Just grind a few seconds and dip in water. The whole operation won't really take very long.

The 6" Bowie knife I made was completely ground on a belt grinder,as was the 8" amputating knife for the museum . Both were ground from 1/4" tool steel. I probably easily ground away at least 1/2 of the steel in the sawn out blank with the belt grinder. And,I used VERY TOUGH types of tool steel on each,because they were air hardening,the safest types of steel to use if you don't want distortion or cracking when you quench. These just harden in air without a quench. The amputating knife has a cross section that looks like a straight razor. A lot of steel was ground away.

Go buy a belt grinder. The Grizzly isn't any more expensive than a GOOD bench (wheel type) grinder(last time I checked). The difference between a belt SANDER and belt GRINDER is the belt grinder runs at least twice the speed of a belt sander. A belt grinder will burn wood,it is so fast. Plus,the belts are usually a lot narrower,like 2" wide,for example. The foot per minute surface speed for a belt grinder is on the order of 4200 sfpm or more. Can be twice that on really powerful industrial units.

Patrick Chase

03-09-2016, 10:44 AM

This is a question I am interested in too. Say, I have an old woody iron with pitting near the edge. I grind it back, half a cm or so, and grind a new bevel. Would that be a doable job on the 180 CBN? I guess it would take a little longer then 3 seconds...

I have both 80 and 180 CBN wheels, and use them on a 1700 rpm grinder (the 1 hp Rikon).

You can certainly do everything you describe on the 180. The thing to keep in mind is that the 180 heats the workpiece at about the same rate as the 80, but removes material ~half as fast. If you impose grinding time limits between rests/quenches then everything will be fine. Also it's CBN, so the heating rates are relatively low to begin with.

Patrick Chase

03-09-2016, 10:58 AM

I can easily grind away MANY TIMES that amount on my Square Wheel belt grinder. When the cutting edge gets thin,I dip in water. I use 36 grit blue zirconia belts for big stock removal,finer belts for finishing,followed by hand polishing for a mirror finish. Much cooler grinding than a wheel because the belt is 72" long,and doesn't stay hot due to its length,plus the 36 grit is much more aggressive. Sometimes i "sharpen" used belts by dragging a single point diamond dresser across them at full speed. This works to some extent,but the belts are not as good as new,but good for some extra use,at least. Only works on coarse belts that are thickly coated enough to not have their cloth backing cut by the diamond.

How long do you use each belt in total? I'm asking because the one big advantage that conventional grinding wheels have is friability, wherein they sacrifice abrasive from the surface as it begins to dull. In the absence of your "diamond sharpening trick" a belt dulls exactly like a non-friable wheel of the same abrasive and grit. My own experience with belt grinders is that they work great at first but then start to run hot. I still use them for plenty of stuff though.

Also, bulk belt/wheel temp isn't an issue with either. If you quickly stop a grinding wheel after heavy work you'll notice that it's pretty cool, mostly likely due to the fact that it has high thermal mass and was spinning around really quickly in air. The heating we need to worry about is of the localized sort.

The 6" Bowie knife I made was completely ground on a belt grinder,as was the 8" amputating knife for the museum . Both were ground from 1/4" tool steel. I probably easily ground away at least 1/2 of the steel in the sawn out blank with the belt grinder. And,I used VERY TOUGH types of tool steel on each,because they were air hardening,the safest types of steel to use if you don't want distortion or cracking when you quench. These just harden in air without a quench. The amputating knife has a cross section that looks like a straight razor. A lot of steel was ground away.

Did you grind those out of annealed bars and then heat-treat, or did you actually shape them at full hardness? If the former then that isn't really relevant to Kees' question - Just about *any* grinding method is effective on annealed tool steel (annealed A2 is Rc 32 or so), and as a bonus you don't have to worry about de-tempering.

george wilson

03-09-2016, 11:08 AM

What I wrote was exactly the correct information. I have spent hundreds of hours grinding. More like thousands of hours. No time now for more talk.

O.K.,I'm back. But for a short time.

The knives were ground from annealed tool steel,A2 and D2,then hardened.

It is EXTREMELY incorrect to say that "any grinding method" is as effective as any other on annealed tool steel. D2 steel has about 12% CHROME,which makes it hard to grind in any condition. Even on MILD STEEL,a belt grinder will grind circles around a bench grinder. I don't have the most powerful unit. Mine runs about 4200 SFPM. Some high powered units run more like 8000 sfpm. I have seen a high powered unit grind a 45º angle FROM THE SQUARE END OF THE ANGLE IRON in about 5 SECONDS. The angle iron was heavy gauge,with walls 1/4" thick. Try that on your bench grinder.

I have a Wilton Square wheel grinder,and I guarantee that it will remove steel many,many times faster than a wheel of ANY KIND.

You WILL NOT FIND any knife maker out there who uses a wheel type grinder. They all use belt grinders,unless they just cannot afford better. Go to youtube and find some knife makers grinding. Unless they are total amateurs,they will be using belt grinders,because they can't afford to work for .25 cents an hour.

Yes,belts cost money,but if you are working for a living,like I was doing as toolmaker,the cost of a belt or 2 is a LOT LESS than what your time is worth. I think I paid $2.50 per belt from Barbkat on Ebay. I can't tell you how long they last as I seldom used one till it was worn out at one sitting. But,I could spend several hours grinding on one blue belt. Brown aluminum oxide belts are cheaper,and do not last as long,or grind as cool.

Belts grind cooler,period. The belts are long,so each part of a belt stays in contact with the steel a much shorter time. This is not up for argument.

Kees Heiden

03-09-2016, 11:33 AM

I can see a belt grinder in my future. But not now, little low on money at the moment. So no CBN wheel either. The question was mostly out of curiosity.

george wilson

03-09-2016, 11:55 AM

Very sensible,Kees.

paul cottingham

03-09-2016, 4:10 PM

george wilson

03-09-2016, 4:27 PM

Paul,if you find the little 1x42" belt grinder to be useful,you will think you have died and gone to Heaven when you get a 2"x72" high speed (4200SFPM) belt grinder. I really think the Grizzly model would be fine. The Wilton is made in Taiwan,and I think they are just riding the Wilton name a bit. i do like the Wilton's enclosed belt,though. Some dust does get carried past the dust collector nozzle. I'd made a plywood enclosure,at least. My dust collector "nozzle" is a 12" x 12" black plastic "scoop. We had a metal nozzle at work,but the plastic one shows no sign of melting,etc.. I put a coarse screen over the hole at the bottom of the scoop to catch whatever I might drop. Better than taking the hose loose.

The belt grinder at work got used so much,the black,wire enforced hose got full of holes. I got a high temperature SILICONE RUBBER hose with spiral wire in it. It never got holes in it. You'd have to get that from a rubber supply place.

You will get the benefit of an 8" wheel,plus the flat platen. On my Wilton,they also offer very small wheels,but they are easy to wear out the small bearings on. I also made a curved platen that clamps to the flat platen. It gives the effect of a much larger grinding wheel,like those of the 18th. and 19th. C.. The Bowie and the amputation knife were both hollow ground with the curved platen. The belt just runs right over it,no moving parts.

I also got tired of having to re machine the cast iron platen from grooves getting worn on it. I made a FULLY HARDENED A2 steel platen surface that has a countersunk flat head screw in each corner. Countersunk on both sides so I can turn it over. But,the fully hardened A2 platen has lasted many years by now. MUCH better than running on the soft cast iron platen. Really good grinders have a sheet of carbide,like those for contour grinding windows for cars. But,the carbide has to be custom made. Big bucks probably. A2 works fine. D2 would be even better. But,I used what I had on hand.

Patrick Chase

03-09-2016, 4:37 PM

I use a small Viel 42" belt grinder for sharpening (don't judge me George!) and I would never go back. If I had the money, I would buy a proper 72" 2" wide grinder in a heart beat. As it is, my budget will likely lead me to buying another 42" Viel rigged for stropping.

that being said, if I bought a CBN, it would be the finer one.

For the record I also have a 1x42 (of the Taiwan-made clone variety) and a full selection of belts ranging from coarse Zirconia-Alumina ceramic to 2000# Trizact. It's good for some things, not as good for others. I personally don't see the claimed "coolness of cutting" benefit except with a perfectly pristine and sharp belt. Once those abrasive particles start to wear down it's just as bad as any non-friable "grey" grinding wheel.

In either case (wheel or belt) the basic physics are the same: Abrasive particles of type W and sharpness X moving past the tool at speed Y with pressure Z. For any combination of W, X, Y, and Z the results will be approximately the same, period. Belt sanders have no intrinsic advantage for W, Y, or Z, and most of them have an intrinsic *disadvantage* for X because they don't shed worn abrasive (exception: A sharding ceramic like Regalite). George noted that he uses "Zirconia" belts - If that's a Zirconia-Alumina ceramic like Norzon then those will probably be a bit better than the SG ceramics in a blue "3X" wheel, though again with the disadvantage that (unlike the wheel) they don't shed and expose new particles.

All of the hand-waving about the belt "cooling down" because of it's length is just that: Hand waving. For the way we grind tool steels (pressure, duty cycle, etc) wheels actually run cool, too, and this is easy to see/test even without an IR camera (though I have access to one like most mechanical engineers, so I'm quite sure). Even if the wheel got hot I doubt it would matter, because conductive transfer from abrasive->tool is unlikely to be a dominant heating mode, though I admittedly haven't done the math for this one. I would bet the drink of anybody's choice that almost all of the heat dissipated into the tool comes from friction and material dislocation, and those are governed by the parameters (W, X, Y, Z) above.

george wilson

03-09-2016, 4:56 PM

Patrick Chase

03-09-2016, 5:09 PM

Just because you don't see it doesn't mean it doesn't exist,Patrick. Yes,belts do wear out and they cost a little money. But,wheels wear down too. And they cost a lot more. Sharp belts are best,yes. Anyone would know that. But,if your experience is limited to 1x42" belts,you can't judge a 72" belt so easily. Frankly,I don't bother with 1x42" belt grinders. I bought one for my wife,but neither of us ever use it. It doesn't make it compared to the larger machine.

George, you just keep making assertions ("X is better") but can't provide a plausible explanation as to why that is consistent with the laws of the physical world. Can you please explain why you think a 70% increase in belt length would cause a huge change in performance?

It's not merely a question of what I "see" (I've long since learned to distrust that unless backed up by sound analysis, and you would do well to do the same), it's a question of what's physically possible. We're in "Unicorn" territory right now.

EDIT: You're absolutely right that wheels wear down, but when they do they EXPOSE FRESH ABRASIVE. Over, and over, and over, and over again. Belts don't. That's sort of a key concept here. Obviously that's not the case with electroplated CBN or diamond, so in that specific case a (hypothetical) electroplated CBN/diamond belt would be on equal footing with the wheel (though real-world CBN/diamond belts are resin-backed IIRC)...

george wilson

03-09-2016, 5:53 PM

Patrick,I have a lifetime of experience to back up what I know. I was a Master Craftsman in Williamsburg for 40 years. I was hired as such in 1970. Before that,I had to have already become equal to that task,or I'd have only been hired as an apprentice,or as a journeyman. My needed "Sound analysis" was accomplished by many years of working and experimenting. So,please do not be lecturing me about this. I am 75 now.

Do you really think that I don't know from many decades ago,that friable grinding wheels wear and expose fresh,sharp grit?

BTW,don't forget the 100% increase in belt WIDTH on a 2" wide belt. All that extra abrasive area adds up. So does the use of cubic zirconia.

I haven't even seen a scrap of your work,though I have asked several times to see some. The people who have been here for a length of time know who I am and something of what I can do. What you can actually do is still an unknown.

I know what works for me and in the case of belt grinders,what works for ALL of the competent knife makers. But I am certain that no one will be able to change your mind. They even use belt grinders on that silly TV show "Forged in Fire". They furnish what knife makers use on that show. Unfortunately,all I saw were duds,though,so I quit watching it VERY soon!:)

You have stated that a CNC machine can equal anything a hand carver can do. That is simply not true. I can tell you that. But,I am sure you will not believe it. go to the carving section,and see if your CNC machine can duplicate the "Old Money" carving. And,I would not even say that that carving is the best one there. It has a lot of very deep undercutting that no CNC is going to do.

I don't intend to spend a lot of time arguing about these things with you. It is necessary to be nice here.

Patrick Chase

03-09-2016, 6:14 PM

Patrick,I have a lifetime of experience to back up what I know. I was a master Craftsman in Williamsburg for 40 years.

I haven't even seen a scrap of your work,though I have asked several times to see some. I don't know much about you. The people who have been here for a length of time know who I am and something of what I can do.

I know what works for me and in the case of belt grinders,what works for all of the competent knife makers.

I know that belts work. I understand that belts work for you. I would never (and didn't) question that level of experience.

Where you went off the rails is with your insistence that belts are unquestionably better for everybody, and your refusal to accept grinding wheels as a worthwhile solution. You then went further off the rails when you gave all sort of physically impossible explanations for why that's so.

Like most engineers I've come across more people like you (deeply experienced tradespeople with funny ideas about the world) than I can count. All I can say is, we take the good (your unquestioned experience and skills, and resulting ability to deliver stuff we could never dream of achieving) with the bad (superstition about how you do it).

EDIT: My woodworking is at what I consider the "infantile babbling" level. I'd prefer not to show it just yet.

EDIT 2: The beauty of physics is that in the final analysis it's self justifying. My level of experience and work don't matter. Either the analysis is correct or it is not. Everything else is hand-waving. That's frankly how the backs of the medieval guilds (bastions of superstition all) were finally broken.

george wilson

03-09-2016, 6:50 PM

Tom M King

03-09-2016, 7:09 PM

When the company that Don White worked for as a club grinder for 38 years sold out to Golfsmith, Scratch Golf hired him. He bought the 1944 machine he'd worked on all those years. Scratch had to take down a wall to get the machine in their place. Fast forward to 1:34 in this video, and you will see Don turning the machine on, and then grinding on it. I kind of remember someone saying it's a Burr King, but not sure at all that is correct. He said it was made in 1944. Don White is known as Da'Man when it comes to grinding golf clubs.

https://www.youtube.com/watch?v=yTX03sUyAlE

george wilson

03-09-2016, 7:14 PM

Yabbut,he's just another of those old tradesmen with funny ideas!:)

Patrick Chase

03-09-2016, 7:16 PM

O.K.,O.K.. You work at an "Infantile babbling level" in woodworking. You list your occupation as a "software hack". But,you call yourself an "engineer" here.:)

Now,I'm not being mean here. These things are what you wrote. And,your level of experience DOES MATTER.

I will suggest that you start listening to these old tradesmen with "funny ideas" Like I DID,if you want to improve your work and experience. When I was young,if I found an old geezer with a lifetime of experience,I was all ears for what I could learn from them. Good craftsmen like them were way too few and far between.

My undergraduate degree is in Mechanical Engineering. I worked as a product designer for Hewlett-Packard for about a decade before going back to grad school in computer science. I then worked for another decade+, again in HP, as a systems engineer and Master Architect (my official title). I've designed HW, SW, and parts of ASIC in my career. I currently work as a Senior Software Engineer.

I don't like to puff out my chest about my work experience, which is why I prefer the relatively low-key "software hack". I prefer to let my arguments do the talking.

Believe it or not, I *do* listen to my elders. I've just learned to be really careful about which parts represent their empirical experience ("belt grinders work for P, D, and Q and here's my work to prove it") and which parts are conjecture and superstition ("belt grinders are inherently superior because of X, Y, and Z", where X, Y, and Z happen to be physically impossible).

george wilson

03-09-2016, 8:04 PM

Well,I GAVE work pictures to prove it,didn't I? Two of many knives I've ground from the solid. Freehand ground,by the way.

I never said I NEVER use bench grinders. I use one when I am putting the final grind,before honing,on a lathe bit. A wheel will leave a straight,smooth surface. A belt,no matter how tight it is,always leaves a slightly rounded surface where the top surface of the side is held against the wheel. The belt always "bags" a little bit,even tight as can be before the joint gives way. And,a mylar joint can get very tight. BUT,I am not about to take a 1/2" square HSS lathe tool and grind it into a threading tool on my bench grinder. I can do that in 10X less time on a belt grinder.

I use a bench grinder to grind drill tips. I can also use a belt grinder if I need to on larger drills. And touch up the edges with the wheel,and hone.

But,the OP's question was about taking 1/2 CM. off the end of a plane iron. A belt grinder will do that much faster than a wheel,too.

As for CBN wheels,I have none. I use diamond wheels. CBN is NOTHING compared to the hardness of a diamond. It is just the hardest thing man came up with,BEFORE he started making synthetic diamonds. However,CBN wheels seem to cost MORE than diamond wheels. I use a 200 RPM vertical/horizontal diamond grinder to touch up carbide,sometimes HSS bits(I have grits MUCH finer than my white wheel bench grinder.). And,I pay only $9.00 per 6" disc.I get them down to 3000 grit. And,I have diamond compound much,much finer than that. I use the diamond grinder to sharpen up ceramic kitchen knives,too. Most people haven't the capacity to do that.

My lathe toolpost grinder uses wheels.

The quality of my work does not reflect anything about superstition or conjecture. I doubt you have seen much of it. Or,if you have,you do not comprehend it.How much do I have to know about art history,for example,to correctly do the decorative work on the 17th. C. Italian style marquetry guitar. And,how much about drawing to draw it in the first place? That was all freehand pencil work. No computer help at all. I did not know how to turn a computer on when I made that guitar.

This is a true statement,not meant to be an insult. Don't take it as such: When you said that your lack of experience did not matter,that was a very extraordinary thing to say. Because,you have to understand,when you are a beginner at something,you do not know how much you do not know. And,the more you learn,the more you will discover that you STILL do not know. The sooner you understand this,the better off you will be when it comes to learning woodworking.

Frederick Skelly

03-09-2016, 9:44 PM

I don't like to puff out my chest about my work experience, which is why I prefer the relatively low-key "software hack". I prefer to let my arguments do the talking.

I don't doubt that you are very skilled in your professional life my friend. But you described your woodworking skills as being "at the infantile babbling level". Please let up on George, a demonstrated Master, and he'll help ALL of us get better at this stuff.
Fred

Stewie Simpson

03-09-2016, 10:14 PM

The discussion on prac vs theory reminds me of another current topic on fleam angles. If you search the internet you will come across suggested fleam angles up to 25*. imo, That's fine if your restricting that advise to handsaws with a tpi below 10 tpi. But the practical benefits of applying these extreme fleam angles on backsaws with smaller sized teeth in my view is extremely questionable. One should also bear in mind the benefits gained from less resistance within the sawn kerf from using thinner backsaw gauge saw plates of 0.015, 0.020, and 0.025 ".

My apologies to Fred for moving outside the primary topic of dicussion.

Stewie;

Curt Putnam

03-09-2016, 11:15 PM

George,

I have a Delta 1 x 42" grinder. I absolutely love the machine for working on knives, but that is about all I can do with it. Do you have any advice about using it to grind chisel or plane blade edges? I've not been able to figure out how to fixture it those kinds of edges and I don't have the skill to do it by hand. TIA

Curt

Bruce Haugen

03-09-2016, 11:47 PM

A lot of people , machinists, woodworkers, luthiers (Frank Ford) have 1X42 strip sanders. They will work well for woodworking, grinding lawnmower blades and small stuff, but not for the kind of grinding that George cites.. Your grinder is meant for smaller jobs, which it excels at, but not for hogging or for thicker stock. I ground a Bowie blade (5160 steel) on a belt sander like yours it took forever. It would have been a snap on a Burr King or Bader grinder. I don't know how to fixture or jig either one; you need to do that stuff freehand.

The skill that George shows in the folder he made for Jon is incredible. You have no idea... Sometime, check out some of the professional machinist forums to see the kind of respect that his work commands. Those guys work to tolerances that are simply impossible with wood.

Steve Voigt

03-10-2016, 12:51 AM

Like most engineers I've come across more people like you (deeply experienced tradespeople with funny ideas about the world) than I can count. All I can say is, we take the good (your unquestioned experience and skills, and resulting ability to deliver stuff we could never dream of achieving) with the bad (superstition about how you do it).

Maybe you don't realize how patronizing this sounds. It sounds like something out of Victorian England, with you, the enlightened engineer, benevolently explaining the world to the poor, ignorant, and superstitious tradespeople. Fortunately we don't actually live in Victorian times, and lots of "tradespeople" are also highly educated. I've spent much of my life working in various trades, despite having advanced degrees, and I'm hardly unique.

My woodworking is at what I consider the "infantile babbling" level. I'd prefer not to show it just yet.

There's no shame in that. But it's surprising, to say the least, that you would feel confident about lecturing to George, Derek, and others who have demonstrated prodigious skill…

The beauty of physics is that in the final analysis it's self justifying. My level of experience and work don't matter. Either the analysis is correct or it is not. Everything else is hand-waving. That's frankly how the backs of the medieval guilds (bastions of superstition all) were finally broken.

As George said, this is an extraordinary statement. Extraordinarily convenient, too, in that it makes your engineering education worth so much more than the actual hands-on experience of those superstitious tradespeople.

It's obviously wrong, too. It's like a high school kid who confidently solves an algebraic equation and arrives at a ridiculous answer, because he/she made an incorrect assumption or faulty calculation along the way. Without reality to act as a check, you could arrive at an absurd conclusion and never know it. I have seen lots of people here at SMC use math and physics to make claims that were frankly ridiculous, because they didn't have the practical experience to know better. You are no different. I was going to provide some examples, but it's frankly not worth the effort.

Patrick Chase

03-10-2016, 2:33 AM

I don't doubt that you are very skilled in your professional life my friend. But you described your woodworking skills as being "at the infantile babbling level". Please let up on George, a demonstrated Master, and he'll help ALL of us get better at this stuff.
Fred

Fair enough. I would note that *nothing* I've said or claimed in this thread has anything to do with woodworking, though. Abrasives and thermodynamics are completely unrelated to the working of wood...

Kees Heiden

03-10-2016, 2:46 AM

I have been searching around, and 1x42 or 2x72 or something similar just doesn't seem to be available overhere. I see these quite a bit, at 100x1220, it is twice as wide as the 2" belt, but a bit shorter then 72". https://www.hbm-machines.com/producten/metaalbewerking/schuurmachinesmetaal/schuurmachinemetaal/hbm-100x1220-bandschuurmachine

Another affordable type of machine are those small bench grinders with a belt attachment on one side. The belt is usually something like 2" x 32". Those are more like toys I guess.

Different types of grinders are usually aimed at the professional market and very expensive.

Maybe it comes down to making one myself. Someday, when I have loads of time available...

george wilson

03-10-2016, 8:32 AM

Fair enough. I would note that *nothing* I've said or claimed in this thread has anything to do with woodworking, though. Abrasives and thermodynamics are completely unrelated to the working of wood...

Sorry,wrong again. Abrasives are VERY related to woodworking. There are endless discussions here about what abrasives to use for grinding and sharpening tools for wood working. This has been only one of them . There ought to also be more discussions about available sand papers as well.

I would not consider the heating of metal during grinding to be very deeply involved in thermodynamics. Just another big word (which we all know) to impress,metal tool heating is a simple process experienced by anyone who ever ground a tool. I wonder if Chippendale or Grinlin Gibbons ever thought about thermodynamics.

Kees,I forget how much the Grizzly knife grinding outfit is. But,it certainly is affordable. I don't know about the shipping to Europe! A friend has one,and it hogs off metal just fine. And,even the Burr King grinders have un inclosed belts. I don't know why,though.This is why I prefer the ugly,but very adaptable Wilton Square Wheel belt grinder. You don't want to breathe stray fine metal and abrasive dust. Earlier in my life I could not afford a dust collector,or a paint spray booth. Now I have enough COPD,I get short of breath going to the mail box and back. And,there is no cure.

I beg ALL of you to get a dust collector for your high speed belt grinder. I just have an old Delta,the type that has the motor and impeller mounted above the large drum. I got it used for $150.00. I also have an exhaust fan behind the collector that gets the "fly stuff" which manages to get through the cloth bag. I have a large plastic 12x12" scoop just under where you grind,and a simple 4" spiral wire clear plastic hose going to the collector. Not the World's greatest system,but it works fine. No wood dust is ever allowed to get into the drum. I can see through the clear hose that the largest spray of sparks that I can make are extinguished by the time they get 3 feet down the hose.

Failing this,AT LEAST get an appropriate dust mask. And certainly get a CORRECT dust mask with changeable filters for spraying. I got pyelonephritis in my kidneys back about 1964. I was very active and was spraying lacquer every week or two. Fever of 104. Be careful of messing up your kidneys as well as your lungs. I still have no where to put up a spray booth. But I certainly do wear the mask. I think it was about $40.00. Cheap insurance for your VERY critical internal organs!!

Brian Holcombe

03-10-2016, 8:54 AM

I made knives as a hobby in my youth and came to the same conclusion as George, ultimately building myself a variable speed belt grinder. I ground blades out of ATS-34, D2, BG-42 and 440C. When using highly alloyed steels, you find out very quickly what kind of grinding belts do the work quickly.

I don't use it on my woodworking tools because I have not built a dust collection system for it.

george wilson

03-10-2016, 9:33 AM

Kees,the Grizzly is $651.00 on Amazon. They say FREE shipping,but obviously that does not apply to the Netherlands!!:)

The reviews are mostly good. Some report tracking problems. But,they seem to have solved that by buying good belts. I have NEVER had a tracking problem,and use the $2.50 belts I get off of Ebay. My cheap belts never wobble(from being joined together crooked). So,I'm not sure where they are coming from.

Some claim not enough power,but the Grizzly and my Wilton came with a 1 H.P. motor. I find my Wilton plenty powerful enough. But,I am not ham handed. Maybe a beginner is. I made my Wilton variable speed with a 1 1/4 H.P. DC motor and control from Surplus Sales. You will not be able to do this,unfortunately. Having a variable speed motor really helps when putting the finishing touches on a knife,and you don't want to put a dollop in it from a fast moving belt. Take heart,though. None of the knives I have posted were made with a variable speed belt grinder. It was upgraded only lately.

You might want to get a thicker piece of steel to make a more substantial tool rest.

One said the motor gets in the way. That probably refers to grinding very long knives. I think it will be just fine for woodworking tools. I like my 1963 Craftsman bench grinder (but not its cheap looks!) because it has a flat front motor,and did not get in the way when I was grinding things like a draw knife,back when I had nothing else to use.

Kees Heiden

03-10-2016, 9:45 AM

Well, it certainly isn't going to happen on the short term, but I have some more metal working projects on my list. Not sure yet what I like more, blacksmithing, filing, handwork, stuff like that or more in the machining direction.

michael langman

03-10-2016, 12:34 PM

I find this conversation bringing back to me the age old proverbial quotation, "You can make an engineer out of a machinist, but you cannot make a machinist out of an engineer".

I have been following SMC in the back ground for 5 years or more now, and have only responded if I felt I was able to help someone in some small way. The knowledge on this site has helped me tremendously.

Being a highly skilled tool and die maker, machinery repairman, machinist, and having the to work with some very good engineers, I have learned much in my life.

Using the Machinery's Handbook as a guide, and spending many years on the bench making and building all kinds of tooling, and some dies, and applying them to the manufacturing needed at the time, I can honestly say that, " Not all things in engineering and physics is as straight forward as, coming up with an idea, designing that idea, and applying it to the real world."

All of the most successful mechanical engineers have listened to their toolmakers respectfully, with an open mind, simply because they know that what can be worked out on paper, does not always happen in the real world of making and developing things.

Anybody can have a fine mind and learn how to do an equation or remember Pi = 3.14157...,
but from Experience comes Knowledge.

If I have learned anything this has been the most important.

michael langman

03-10-2016, 12:53 PM

I made a mistake in the above statement, From Experience comes Knowledge, what I should have said is that ,"From Experience comes Wisdom."

Knowledge comes from books.
My apologies.

Pat Barry

03-10-2016, 1:06 PM

Anybody can have a fine mind and learn how to do an equation or remember Pi = 3.14157...
See, right there is what separates a machinist from us engineers. Us engineers think of Pi as 3.1415926535. We wouldn't round that to 3.14157!

Otherwise I agree with your sentiments

george wilson

03-10-2016, 4:06 PM

Why stop at 35,Pi goes on forever.

Brian Thornock

03-10-2016, 4:34 PM

I find this discussion fascinating. I am a physicist and see no issue with what George is saying. There are many variables at play with a belt grinder. Just because one does not elaborate them in a discussion does not mean they don't exist. Off the top of my head, other factors at play between belt grinders and wheel grinders are things like grit size, how that grit is distributed and exposed, SFPM, amount of pressure that can be applied to the grinding medium, and on. I build a lot of guitars and many people try to describe all the variables at play in the system. It never works out because there are so many that escape one's notice. Just because they aren't listed does not mean they don't come in to play.

Getting more back to topic, I would like a CBN wheel, but I think that is just the tool acquisition side kicking in. I probably wouldn't get great use out of one, but they just seem so cool!

Matt Owen

03-10-2016, 5:29 PM

I find this conversation bringing back to me the age old proverbial quotation, "You can make an engineer out of a machinist, but you cannot make a machinist out of an engineer".

Add this to the list of ridiculous statements. It's a complete over generalization on both sides. Can't we all just get along. :D

Niels Cosman

03-11-2016, 11:54 AM

This is a true statement,not meant to be an insult. Don't take it as such: When you said that your lack of experience did not matter,that was a very extraordinary thing to say. Because,you have to understand,when you are a beginner at something,you do not know how much you do not know. And,the more you learn,the more you will discover that you STILL do not know. The sooner you understand this,the better off you will be when it comes to learning woodworking.
^^^^^^
This is the biggest take away from this thread. This applies to any type of learning, which if done properly, is a lifelong pursuit.

James Waldron

03-12-2016, 12:43 PM

{snip}
I also got tired of having to re machine the cast iron platen from grooves getting worn on it. I made a FULLY HARDENED A2 steel platen surface that has a countersunk flat head screw in each corner. Countersunk on both sides so I can turn it over. But,the fully hardened A2 platen has lasted many years by now. MUCH better than running on the soft cast iron platen. Really good grinders have a sheet of carbide,like those for contour grinding windows for cars. But,the carbide has to be custom made. Big bucks probably. A2 works fine. D2 would be even better. But,I used what I had on hand.
I"m a little late here, but maybe it will help someone.
It ain't free, but small amounts of D2 are available as flat plates, square stock and drill rod at onlinemetals*com as are O1, A2, and W1. I've had very good service from them over time.