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A new American made Bench grinder?

blockhed's picture

Greetings, 


 I need a bench grinder.  Not just some home improvement store special,  a grinder We would all enjoy using.  There are plenty of them out there by established manufacturers, but here's my problem.  As with most readily available power tools, We may buy an established brand at an established brand price, but the truth is, the tool comes from an off brand plant, with the recognizable name stamped on it.  I would prefer a 6" variable speed grinder, which I will use almost exclusively for hollow grinding chisels, plane blades and carving tools. I'm proficient with stones so I don't need a sharpening system, just a good quality, new, made in the USA bench grinder, does anyone have any suggestions?

hdgis1's picture

(post #102001, reply #1 of 32)

http://www.mile-x.com/index.asp?PageAction=VIEWPROD&ProdID=691

Think these are made in America. 6 inches isnt going to do it for hollow grinding. Really need to have minimum of 8 inches. Even a full 1/8 thick blade will have just a sliver at point due to small size of wheel. Dont really think you need variable speed either. Just get slow speed and you should be fine.

joelm's picture

(post #102001, reply #3 of 32)

huh?

a 6" grinder is more than fine for hollow grinding and I prefer it because you get more of a hollow. For turners, who usually want less of a hollow an 8" is more popular.
As my article showed a high speed 6" grinder is also fine and it's the same cost as a lower speed one. Baldor does not make a 6" variable speed grinder. THere are several lines of Baldor but there is a huge price jump between 6" and 8" grinders. Also Baldor makes grinders with sheet metal rests (less expensive)and with rock solid cast iron rest - which I prefer by a lot.

The most important thing is not just the grinder but getting a proper wheel for sharpening without overheating so that needs to be part of your budget no matter what.

joel
( Who liked his Baldor grinder so much he became a Baldor Dealer)

hdgis1's picture

(post #102001, reply #4 of 32)

Joel,

All respect due, but your article doesn't indicate how a 6" grinder is "more than fine" other than to say that it is what you prefer. Given, as you say, that turners prefer the 8", why not just get the 8 and be done with it? It seems rather counter intuitive to me that one would use a high speed 6" inch grinder to sharpen anything they didn't wont to over heat. The smaller that wheel gets (and it will get smaller), particularly the friable wheels you mention, the more pronounced the holow, the thinner the leading edge and the faster one can over heat the tip. While I am no expert on sharpening, if memory serves me correctly both the folks at lee valley and lie nielsen recommend using the largest grinder you can get your hands on. These days, as budget allows, that is usually an 8" grinder. If anyone would like to read a more qualified opinion than mine, i refer you to Leonard Lee's book on sharpening.

Chris

joelm's picture

(post #102001, reply #5 of 32)

Chris,
Once you get the technique down, with the right wheels , properly dressed it is a trivial matter to hollow grind to a wire edge on a 6" or 8" grinder without overheating. So this idea about a thinner edge isn't relevant. That's the whole point of my article grinding fast without burning. Since with a 6" grinder you get a deeper hollow - which lasts longer with repeated honing that's my preference (and I don't turn). As a 6" grinder is a lot less expensive than am 8" grinder (and takes up less space) that's an argument for a 6" grinder too.

I was trained to grind by a professional grinder. I grind things professionally too. That other people recommend other ways of doing it is their opinion and right but I don't agree with their rational or their recommendation.
Joel
www.toolsforworkingwood.com


Edited 7/1/2008 11:14 am ET by joelm

hdgis1's picture

(post #102001, reply #6 of 32)

I guess we will have to agree to disagree. However, of the three blade makers that I spoke with (and I'm sure you can figure those out), not one of them suggests using a 6" slow or high speed grinder. In fact, all of them would do away with hollow grinding! If thats not a "professional" opinion then the world really is worse of than I thought.

Perhaps the emphasis has been misplaced with regards to the wire edge and the heat that is generated there. Perhaps the issue should in fact be, that the thicker that leading edge is the more stable the blade as is cuts.

Chris

joelm's picture

(post #102001, reply #7 of 32)

I think we will have to disagree on this one.

After you grind you need to hone the blade which adds flats which I would suppose adds strength.
Any idea that a deeper hollow weakens the blade compared to a blade with less hollow is a myth and if there is indeed any weakening it is so marginal to be insignificant compared to changes in blade angle etc in the practical world.

RMillard's picture

(post #102001, reply #10 of 32)

Joel,


I'm with you. I personally grind my tools with a 5" diameter grinding wheel (it may have started life as a 6" wheel, since it was very old when I got it nearly 30 years ago), the only difference is mine is hand cranked. That has an impact on the heat issue, but the thinness of the edge is really a non-issue.


I use one of those $29.95 Delta wet grinders for carving tools, and its wheel is even smaller, yet I don't have any problems with getting or maintaining an excellent edge.


A few strokes down a coarse stone, and you have a decent flat, that is a strong as one ground on a larger wheel. I'm so lazy, that I grind my tools almost every time they need touched up, just so I don't have to hone as much, so for me the small wheel is actually a plus.


Rob Millard


www.americanfederalperiod.com


 


.


Edited 7/3/2008 4:08 pm ET by RMillard

saschafer's picture

(post #102001, reply #11 of 32)

I think it could be summed up this way:


Q: Since a smaller radius grind leaves less metal behind the cutting edge, does it make the blade weaker?


A: Of course. Less metal means less strength, obviously.


Q: Does it matter?


A: Of course not. In anything remotely resembling normal use, blades never bend or break or otherwise exhibit any weakness in the hollow-ground area behind the blade. Whatever strength you may gain by having more metal behind the cutting edge is completely immaterial.


-Steve


 

joelm's picture

(post #102001, reply #12 of 32)

Steve,
Of course. that's what I said, that's what everyone says in one form or another, just the OP has the minority view.

Jigs-n-fixtures's picture

(post #102001, reply #8 of 32)

Chris, actually the 6-inch wheel will result in a slightly weaker cutting edge than an 8-inch wheel.  But that is only in theory.  The difference is so small it isn't worth considering from a practical stand point. 


With regards to how much belly is left from the grinding:  If I assume the grind is made at 45-degrees to the circumference of the wheel, (which would result in about a 45-degree bevel on the blade), the difference in the depth is only 0.0003-inches for a 1/8-inch thick plane blade, and 0.0013-inches for 1/4-inch thick chisel blade.  Really not much. 


Edited 7/1/2008 3:13 pm ET by Jigs-n-fixtures

chscholz's picture

(post #102001, reply #9 of 32)

In my opinion there is absolutely no substance to the strength argument against hollow grinding.



---

Chris Scholz

Dallas/Fort Worth, TX

Galoot-Tools


Chris Scholz
Dallas/Fort Worth, TX
Galoot-Tools

oldusty's picture

(post #102001, reply #2 of 32)

blockhed ,


           That's a nice Baldor grinder for $ 5-600 bucks delivered but imo you could do just fine by picking up an older 8" grinder at a yard sale or second hand . The cost of U.S. made older models was reasonable even Sears Craftsman brand was good in those days . I would venture to guess that like the majority of new grinders on the market are made in C###a or a neighborhood near by.


  I have an old old Dunlap 6" and a Delta 8" made about 20 years or so ago it is made overseas but in this size motor and the light duty it gets it works just fine , so you may want to look at a new Delta or the equivalent.


             dusty

jquinn's picture

(post #102001, reply #13 of 32)

I bought a Baldor 7" from MSC at least 15 years ago.  It is amazing smooth running.  The 7" wheels are a little hard to find, but there are a few turning supply webstores that sell good wheels.


I'm not aware of any other non-industrial size grinders that are made in the USA by namebrand - MSC or McMasterCarr catalogs would be a good place to start looking for what you want.

oldusty's picture

(post #102001, reply #14 of 32)

  I went to a industrial saw sharpening shop that did work for the mills and such and they gave me a stack of Pink stones wore down to about 7" .


            dusty

philip's picture

(post #102001, reply #15 of 32)

Bloke,
To answer your questions:-
I wouldn't worry where the thing is made or who made it as long as the motor is a smooth vibration free high quality ballbearinged type, preferably slimline .Three phase types will run the smoothest. As important if not more so : the tool rests need to be substantial, fully and easily adjustable and preferably not attached to the guards-which should be easily removable for rapid wheel changing.Sheet metal "tool rests" attached to tin foil wheel guards are a joke, as in those "Elephant" brand grinders....
I have not seen variable speed bench grinders and would suspect that these are non-existent in the serious world. It is better to use the most appropriate wheels for the job which in most cases are required to run at high peripheral speeds, dry, when used on a bench grinder.
I believe that you can find used industrial type grinders at a reasonable price if you are lucky , otherwise virgins cost much more: that Baldor looks almost to fit the bill from what I can see, but ofcourse it is more costly than the ubiquitous diy type grinders which are next to useless unless you are able to re-vamp the tool rests or fit independent tool rests-by which time you might as well have just bought the real thing.You gets what you pays for....

Philip Marcou

Philip Marcou
oldusty's picture

(post #102001, reply #16 of 32)

Mook ,


      Sound information from you on this grinder topic , I didn't want to seem ignorant but I too had never heard of variable or two speed grinders either .


     I think the tool rests need to stout enough to do the job and then some .


   And yes used industrial and larger model grinders are always around . What I see a lot of are the mandrels mounted on pillow block set ups that use a separate motor , I suppose if you rigged the tool rests to accommodate , it may work for certain operations .


         dusty, er will be soon

bakesale1's picture

(post #102001, reply #17 of 32)

If you're willing to go secondhand, I see US made grinders all the time on craigslist. This one isn't totally US made but at least you'll never ask if the wheel is big enough: http://sfbay.craigslist.org/nby/tls/735806840.html

blockhed's picture

(post #102001, reply #18 of 32)

Gentlemen, Thank you for your generous responses.  I hope any arguments fueled by this topic can be resolved and there be no love lost between Galoots.  What I have derived from these discussions is that the heart of the grinding operation is in the stone and the tool rest.  The size of the wheel and the motor that spin it, are matters of preference.  I still cannot justify paying good money for an imported machine, but at the same time, my necessity does not warrant the expense of a well built, American made grinder.  It would be an overkill for what I need.  I will have to scour the pages of E-bay and craigs list to find the right machine for me. 


Happy Woodworking


Dan

SteveSchoene's picture

(post #102001, reply #19 of 32)

I've come in a bit late here, but I don't quite see the rationale for avoiding imports?  There are lousy ones, but likely pretty good ones, too.  Seems like a pretty arbitrary limitation.  To me, specifications matter a lot more than geography.  But we have to make our own choices.   


Edited 7/8/2008 9:45 pm ET by SteveSchoene

Test your finish on scrap, FIRST, or risk having to scrap your finish.

AdamCherubini's picture

(post #102001, reply #20 of 32)

I have questions and a few observations:

What does variable speed do to the torque of a motor? If you turn the speed down, do you lose a disproportionate amount of torque?

About low speed 8" grinders: I think Joel mentioned this configuration doesn't reduce surface speed that much because the wheel is bigger. This is not so. The motor speed is half standard and the wheel is only a third larger. So here's the answer in surface feet per second:

6" wheel running at 3600rpm = 94 ft/s
8" wheel running at 1800rpm = 63 ft/s

The reduction in speed is 32%. That's not inconsiderable.

Regarding edge strength and hollow grinding:
There's no question that scooping material out of a bevel weakens an edge. But weakening is really not a concern we have. Hollow ground chisels don't break more readily than flat ground chisels. But the hollow ground chisel is softer, i.e. more prone to deflection. And increased deflection will degrade your edge. Also, the hollow ground shape lends itself to stress concentrations at the edge. This also effects edge retention.

I think a lot of woodworkers who hollow grind, end up honing large flats, such that the effect of the hollow grind is diminished to insignificance. But if you are hollow grinding then honing a tiny bevel, that's really not great. And you have two things working against you- you have the thin cross section that's more prone to deformation, and you have the intersection between the rough ground hollow and the small honed area as a stress riser, i.e. a corner the stress must take (stress doesn't like going around corners).

In terms of edge retention, it would be better to shape your edges like an airplane wing. Additionally, the stress risers due to the gross shape also apply on the microscopic level to scratches. For this reason you should: hone front to back to put scratches in the direction of the load. Reduce scratches by polishing.

You may find, as many woodworker have in the past, that your edge retention is fine and you like to grind and hone the way do currently do it. Of course that's fine. But if you are looking to increase the performance of your edge tools, things you can do are:
-grind less hollow or hone it out
-grind low and hone high to make a more elliptical cross sectional shape (I think this is what guys did before synthetic grind stones were invented)
-hone front to back
-polish your edge to a mirror shine.

Lastly, to answer the original question, I have an 8" slow speed grinder from Woodcraft. The tool rests are cast and need to be ground or machined to be square with the wheels. The collars on the wheels are neither flat nor have they parallel sides. This makes truing the wheels difficult. I like the grinder, but these components are junk. I'd like to see someone making upgrade parts for this grinder. I can't afford an 8" baldor slow speed grinder.

Adam

joelm's picture

(post #102001, reply #21 of 32)

Adam,
Talk about myths. there is no difference in edge retention between grinders because as you hone you end up with a flat at the edge. In the beginning a tiny flat, later less flat. And difference in flexibility is very marginal and far less than a difference in flexibility you would get by changing the bevel angle. (a hollow to the very edge would simply perform like a slightly shallower angle - this isn't magic) Since I use a microbevel (not a secondary bevel) I am getting far far stronger edges anyway. Not an issue.

Even Moxon recommends hollow grinding - although on a larger wheel.

and 8" slow speed grinder does go a little slower than a 6" high speed grinder but if you want to do turning tools too it's a good compromise.

I would rather own a 6" top quality grinder that I can afford then not have any good grinder because of some myth that I am doing something wrong with the smaller grinder.

I get perfectly fine edge retention as least I don't seem to be having any problems. your method of an "elliptical" section does the same thing as a secondary bevel but in neither case do you get the performance benefit of a micro-bevel. It also takes longer to do.

My article on grinding was mostly about grinding technique, not which grinder to buy. The wheel and the dresser is a lot more important than the grinder. I'm probably just as guilty as the next poster on tool obsession but I think all this endless postulating on making things so complicated is really discouraging for a beginner who can feel that getting started to do anything right is way too complicated to even start.

AdamCherubini's picture

(post #102001, reply #22 of 32)

The equation for stiffness is EI. E is the Modulus of Elasticity and is dependent on the steel. I, or Moment of Inertia is the width of the chisel times the thickness to the third power. So thickness of the edge highly influences the stiffness. Even tiny deflections of the edge can work harden or initiate micro cracking which leads to the loss of the edge.

So that's the physics. I don't know how to slice it any other way. There may be someone with a better understanding of this that can correct me. From where I sit right now, hollow ground edges are weaker, and will lead to premature edge break down.

Now, knowing the physics here, experience tells me the real world somehow behaves differently. I think with small thin chisels, this may not matter or be detectable. So it may be worthwhile to continue hollow grinding. But if you want more edge holding performance from the chisels you have, I've given some suggestions that should help.

If you are grinding a mortise chisel, I would most definitely discourage folks from hollow grinding. The physics aren't different for a mortiser. We pry a little with all of our chisels. It's inescapable.

As to your article, I thought it was great. I bought your wheel, your dresser, and your rounded wheel shape, and love all three. Only thing I didn't expect was the shower of particles. A full face shield would be a good idea and I don't have one.

Adam

joelm's picture

(post #102001, reply #23 of 32)

Adam,
I took the same engineering courses you did. Your math is right. but your second paragraph says it all:

"experience tells me the real world somehow behaves differently. I think with small thin chisels, this may not matter or be detectable. So it may be worthwhile to continue hollow grinding"

Practically hollow grinding saves lots of time, saves wear and tear on the stones, and doesn't noticeably effect anything adversely.

If I did notice anything I would just increase the grind angle a few degrees.

I do hollow grind mortise chisels if I have too - and as long as you have a proper secondary bevel on them there is no adverse effect.

ps - I am glad you liked the article and we sell facemasks too (not on website yet) - although the guards on my grinder take care of most of it and I don't wear a full mask.

chscholz's picture

(post #102001, reply #24 of 32)

Adam,



I applaud your attempt to bring some sound engineering concepts into the discussion. However I strongly disagree with your conclusions (i.e. hollow grinding with a ≥6" diameter wheel appreciably weakens the tip of a woodworking tool and leads to premature localized failure of the cutting edge).

Edge failure is a microscopic phenomenon that depends on local angle, surface roughness, distribution of dislocations, plasticity, micro-cracks, material, material processing, heat treatment, grain size, etc. As long as you do not use a outrageously small wheel (hard to quantify what outrageous means, I would guess that you'll be ok down to ∼2") hollow grinding will not effect edge retention in any measurable way.


Here is a bit more detail on the subject of edge retention in the context of the perennial A2 vs 01 discussion.



By the way, Young's modulus (modulus of elasticity), E-modulus, or whatever you want to call it) is ∼210 GPa (using archaic units). The modulus of elasticity is pretty much the same for all ferrous materials (steel, cast iron and such), so your reasoning would boil down to a purely geometric argument. In my opinion your argument is based on linear elastic behavior of materials and not valid for the the case of edge failure.





---

Chris Scholz

Dallas/Fort Worth, TX

Galoot-Tools


Chris Scholz
Dallas/Fort Worth, TX
Galoot-Tools

derekcohen's picture

(post #102001, reply #25 of 32)

hollow grinding will not effect edge retention in any measurable way


Hi Chris


I have a related question, that is, the effect of hollow grinding laminated blades. Perhaps you will comment on the following.


With the exception of David Charlesworth, I have not heard others supporting the hollow grinding of (usually) Japanese laminated blades. OK, he is using a Tormek, and the 10" wheel creates a flatter hollow than a 6" or 8" grinder.


I hear the theoretical arguments against this practice, but I believe that this is another one of those situations where the Real World presents a different view.


I received one of your Economy Series  Chinese-made laminated plane blades from Steve Knight. I hollow ground it on the Tormek and used it in a HNT Gordon smoother. For those unfamiliar with the blade, it is 2" wide and 1/4" thick. This is a very nice blade indeed! It got very sharp and held its edge for a long time (at some stage I will compare it with my original O1 HNT Gordon blade). At no time was I concerned about the edge failing for any reason other than normal wear. I should point out the the secondary bevel in this case is a true microbevel (courtesy of the Tormek grinding so cool), so there was the minimum amount of steel backing the edge.


Your thoughts about the Tormek and also higher speed and smaller wheels on laminated blades?


Regards from Perth


Derek


 


Edited 7/11/2008 1:57 am ET by derekcohen

chscholz's picture

(post #102001, reply #26 of 32)

Hi Derek,



I look forward to the report.



Feel free to hollow grind laminated blades. As long as the laminations are done well (and you don't overheat the blade), there will there is no appreciable difference between laminated blades and blades made of sheet metal with respect to grinding. The reason is that both E-modulus and thermal expansion coefficient is about the same for all ferrous materials. This is a matter of geometry and for the purpose of grinding there is no appreciable difference between both types of blades.


The advantage of laminated blades is better dampening properties. By the way, damping has no direct correlation with the elastic modulus. But of course the dynamic properties of the blade depend on geometry, elasticity and damping coefficient


There are other reasons why manufacturers and users of Japanese blades in general discourage hollow grinding. It is hard to draw the temper on a bench stone, users who hand sharpen might be in general be more respectful to their tools, hand grinding wastes less material and probably many other reasons. Our customers tend to be advanced woodworkers so we don't have many of the problems other manufacturers face.



---

Chris Scholz

Dallas/Fort Worth, TX

Galoot-Tools


Chris Scholz
Dallas/Fort Worth, TX
Galoot-Tools

RMillard's picture

(post #102001, reply #27 of 32)

Derek,


For what it is worth, I grind my Japanese chisels on a 5" wheel, and they hold up very well;I have pounded them into everything from aspen to zebrawood.


Rob Millard


www.americanfederalperiod.com

derekcohen's picture

(post #102001, reply #28 of 32)

Thanks Rob. I am going to hollow grind a couple of slicks and try them that way.


Regards from Perth


Derek

derekcohen's picture

(post #102001, reply #30 of 32)

Hi Joel


I am interested in getting a Norton 3X wheel from you. This question may interest others, which is why I ask here.


The 3X is to suit a 8" wheel. Do I get a 46 grit (which would be my choice if this was a white wheel) or do I get a 60 grit? I understand that the latter will not run as cool as the 46, but have the "rules" changed with this new composition?


Linked to this, would there be a difference in choice if the machine was a half speed or a full (high) speed machine? Note that in Oz our high speed machines run at 2800 rpm and the half-speed at 1400/1450 rpm. My thought would be that it is possible to go for a smoother 60 if the speed is reduced .. otherswise stick with the rougher but cooler 46 for faster grinding ... ?


Regards from Perth


Derek

joelm's picture

(post #102001, reply #31 of 32)

Derek,
the 46 grit wheel will run cooler than the 60. on a 2800 rpm 8" grinder I would recommend the 46 grit but you should certainly be able to use ( control ) the 60 grit also. Get the "I" grade. for turners I would go with the higher grits.