Bench Grinder Recommendation Wanted

[Jeff Wright]

I am researching bench grinders. I expect to use it for sharpening mostly . . . future lathe tools, chisels and plane blades when needing severe sharpening. I have often read that a 6-inch wheel with a Norton 3x wheel at slow speeds (1750 rpms) is adviseable for sharpening to reduce the likelihood of overheating the steel.

What are your thoughts about the grinders shown here:

http://www.toolbarn.com/category/electric-grinders-bench/

especially the Delta GR275 6" Variable Speed Grinder.

How important is motor size in preventing the wheel from bogging down when sharpening? Woodcraft was selling a 2-speed unit last I was there. Not sure of the brand. I think it was an 8-inch wheel system.

Any thoughts on 6 versus 8-inch wheels?

[Jeff Hallam]

I have read in a few spots that a slow speed (approx 1720 rpm) 8" grinder is recommended since the hollow grind from a 6" is too pronounced. That is, it leaves the cutting edge too thin and fragile.

No affiliation with them, but I have my sights set on the General 8" slow speed. Saving my pennies....

[John Callahan]

I've got the 23-725 and like it, especially for the price. It's no Baldor to be sure but it's hard to stall, seems smooth and well balanced- it spins for a long time after you shut it off and stays put in one spot on a bench when not bolted down. Mine did come through with a bad wheel; bought the grinder locally and they swapped it out. The tool rests are cast iron and seem pretty substantial. I'd buy it again.

[Alex Berkovsky]

I own a Woodcraft slow speed grinder (http://www.woodcraft.com/family.aspx?familyid=4605) and they do go on sale often.


I have often read that a 6-inch wheel with a Norton 3x wheel at slow speeds (1750 rpms) is adviseable for sharpening to reduce the likelihood of overheating the steel.

If you haven't already done so, do pick up and read this month's FWW magazine. There is a great article by Joel Moskowitz on use of bench grinders. Joel states that high-speed 3600 rpm 6" grinder is close to the same surface speed as the slow-speed 8" grinder. FWIW, Joel prefers the 6" grinder.

[Cary Falk]

I have the Woodcraft slow speed grinder also.

[Jeff Wright]

I own a Woodcraft slow speed grinder (http://www.woodcraft.com/family.aspx?familyid=4605) and they do go on sale often.



If you haven't already done so, do pick up and read this month's FWW magazine. There is a great article by Joel Moskowitz on use of bench grinders. Joel states that if high-speed 3600 rpm 6" grinder has the same surface speed as the slow-speed 8" grinder. FWIW, Joel prefers the 6" grinder.

Alex, thanks for correcting my thinking. Yes, I read that FWW article and was taking the author's advice on the 6-inch, but misread it thinking he said SLOW SPEED 6-inch wheel.

Do you have any idea why Delta's variable speed grinders are less costly than the 8-inch slow speed model? It's about half the cost, suggesting less quality.

[Jim Becker]

8" with the Norton 3X wheels (and I also like the OneWay balancing system for even better performance) is the way to go rather. Lower RPM can be helpful, but it does not eliminate the risk of heating on carbon steel used for bench chisels and carving tools. (Most turning tools are HHS and are not very much at risk)

BTW, there is a great article by Joel Moskowitz in the new June 2008 issue of Fine Woodworking on using a grinder for touching up or re-shaping chisels, etc., using a grinder.

[Rod Sheridan]

I have a Lee Valley belt grinder, and a 6 inch grinder with wheels for carbide bits and a Steel City variable speed 8" grinder beside the lathe for turning tools.

I like the hollow grind from the 8" best for turning tools.

I like the belt grinder for chisel and plane blade grinding, knife grinding, as well as the leather belt for knives and carving gouges.

I also use water stones, or abrasives on glass.

Regards, Rod.

[Jeff Wright]

8" with the Norton 3X wheels (and I also like the OneWay balancing system for even better performance) is the way to go rather. Lower RPM can be helpful, but it does not eliminate the risk of heating on carbon steel used for bench chisels and carving tools. (Most turning tools are HHS and are not very much at risk)

BTW, there is a great article by Joel Moskowitz in the new June 2008 issue of Fine Woodworking on using a grinder for touching up or re-shaping chisels, etc., using a grinder.

Jim, yes . . . I read that article as a diehard subscriber to FWW.

Is your 8-inch slow speed? Also, what is a OneWay balancing system?

[Tom Godley]

I just bought a Craftsman unit that looks to be the same as the GR450 8" - it does not have the quick change arbor -- On sale with the Craftsman Club discount I think it was less than $90.00.

It is a nice unit -- and I like the VS.

The quick change feature of the Delta may be worth the money to you, and depending on the wheels that come with the Delta that price may be a very good one.

I wanted a 100 3x and a fine white wheel for my lathe tools - the Craftsman came with a rougher wheel and a wire wheel - so I had to replace both.

The oneway system allows you to fine tune the balance of the wheels -- it comes with hardware for two wheels. Packard sells the system.

I went with the 8" because I want to use the Ellsworth jig and it fits that size.

[Jeff Wright]

I went with the 8" because I want to use the Ellsworth jig and it fits that size.

Tom, Do you know whether the Wolverine system will use either the 6 or 8-inch wheels?

[Tom Godley]

Jeff -- without looking into it -- I do not know.

I took David Ellsworth's class a couple of months ago and he has two 8" units - one slow and one fast. David recommended that we purchase the slower speed unit because it is more forgiving and provides and excellent edge.

He uses the wolverine base units with another holder plus his jig to sharpen his style gouge - the 8" wheels providing the proper angle.

With the overall size and price of the units being almost the same -- the longer wearing 8" wheels IMO make it the better buy.

I was surprised by the cost of the VS units -- often lower that the single speed ??

TAG

[Jeff Wright]

Jeff -- without looking into it -- I do not know.

I took David Ellsworth's class a couple of months ago and he has two 8" units - one slow and one fast. David recommended that we purchase the slower speed unit because it is more forgiving and provides and excellent edge.

He uses the wolverine base units with another holder plus his jig to sharpen his style gouge - the 8" wheels providing the proper angle.

With the overall size and price of the units being almost the same -- the longer wearing 8" wheels IMO make it the better buy.

I was surprised by the cost of the VS units -- often lower that the single speed ??

TAG

Thanks Tom.

I did some research on the Baldor grinders and it seems they do not offer a variable speed unit. Wonder if they believe that setup has some drawbacks. Steel City has a variable speed 8-inch recently on special for $129, normally $180. Don't know about its quality. I am pleased with their 17-inch drill press.

[Tom Godley]

Jeff:

I went to Sears to check them out -- the VS model looked to be a normal 3500rpm unit with the electronic speed control added.

This Craftsman must have been made by Delta -- they are identical. For the price of the unit I was quite impressed at the quality.

I ordered the basic wolverine system - I need the bases for the Ellsworth setup - the other parts will get used ???

I have a much larger 220v unit that I use for my metal working hobby - I am setting this up just for my lathe tools.

[Jeff Wright]

Jeff:

I went to Sears to check them out -- the VS model looked to be a normal 3500rpm unit with the electronic speed control added.

This Craftsman must have been made by Delta -- they are identical. For the price of the unit I was quite impressed at the quality.

I ordered the basic wolverine system - I need the bases for the Ellsworth setup - the other parts will get used ???

I have a much larger 220v unit that I use for my metal working hobby - I am setting this up just for my lathe tools.

Tom, I'll check out that Sears Delta knockoff myself. Thanks.

[Tim Malyszko]

I too have the Sears VS 8" model and have owned it for a little over a year. Changing grinding wheels are a bit a pain due to the arbor length, but other than that, its performed well. I replaced the stock stone and wire wheel with Norton stones on it and use it to sharpen mainly turning tools, but use it to sharpen other things (like lawnmower blades) on occassion.

The VS is a nice feature, but the majority of the time, it sits on the lowest setting.

[Bob Willcox]

I own a Woodcraft slow speed grinder (http://www.woodcraft.com/family.aspx?familyid=4605) and they do go on sale often.



If you haven't already done so, do pick up and read this month's FWW magazine. There is a great article by Joel Moskowitz on use of bench grinders. Joel states that if high-speed 3600 rpm 6" grinder has the same surface speed as the slow-speed 8" grinder. FWIW, Joel prefers the 6" grinder.
I must confess that I haven't read the article, but I don't see how that's possible. The math just doesn't seem to workout that they would have the same surface speed, given that the speed is halved with a slow-speed 8" grinder and the 6" has a diameter that is 3/4ths of the 8". Given that the surface speed varies directly with diameter (cir = Pi * dia), I would expect the high-speed 6" grinder to have a surface speed about 50% higher than the low-speed 8" grinder.

Someone please correct me if I'm wrong. My math courses were a long time ago and I may have missed something.

[Jim Becker]

Is your 8-inch slow speed? Also, what is a OneWay balancing system?

No, mine is 3500 RPM. The OneWay balancing system is used to make the wheels spin in an absolutely balanced manner...it makes the whole grinder work VERY smoothly.

[Jeff Hallam]

Well, I don't know what version of math or physics the FWW article was using but that just doesn't work out.

the surface speed of a 8" grinding wheel mounted on a slow speed grinder is slower than a 6" wheel on a high speed grinder.

The difference is about 1800 metres per sec = approx 4000 mph

Here is a link for a grinding wheel speed calculator:

http://www.meister-abrasives-usa.com/products/calculators

[Peter Quinn]

I bought a woodcraft slow speed grinder, suits my needs. It was on sale, came with aluminum oxide wheels, spins true enough to be useful and non problematic. The stock tool guide is not exactly a work of art but that is easy enough to over come with a shop made jig or after market guide.

[Howie French]

... I would expect the high-speed 6" grinder to have a surface speed about 50% higher than the low-speed 8" grinder.



Jeff's URL supports you.

Howie

[Jeff Wright]

Nearing a Decision. I am close to going with the Delta 8-inch slow speed grinder, model number 23-725 (http://www.toolbarn.com/product/delta/23-725/) It is pricier than many others - about $180 - but seems like it may be better built than some of the others . . . good bit heavier than others as well. I will plan to replace its wheels with either the Norton 60 grit or maybe a ceramic. Anyone know of some good plans for a base/stand for such a unit? With a small shop, I'd like to store my water stones in the base cabinet and put it on some sturdy wheels. Most everything in my shop is mobile.

[Bruce Wrenn]

Well, I don't know what version of math or physics the FWW article was using but that just doesn't work out.

the surface speed of a 8" grinding wheel mounted on a slow speed grinder is slower than a 6" wheel on a high speed grinder.

The difference is about 1800 metres per sec = approx 4000 mph

Here is a link for a grinding wheel speed calculator:

http://www.meister-abrasives-usa.com/products/calculatorsI think you need to convert your answer to meters per minute. Using 6" = 0.5 feet and 8" = 0.67 feet. 3.14 X 0.5 X 3450 = 5416.5 feet per MINUTE. 3.14 X 0.67 X 1750 = 3681.6 feet per MINUTE. 5416.5 - 3681.6 = 1734.9 FPM. 3681.6 / 5416.5 = 0.679 That is 2/3 of the faster grinder.

[Larry Marley]

I sharpened lathe tools on a high speed 6" grinder for 10 years.
Finally purchased the woodcraft 8" slow speed and it is much easier to sharpen lathe tools without over heating. I never noticed a problem with the 6" dia hollow grind. The slow speed feels safer too. (may be imagined)

My grinder was very smooth out of the box. A friend of mine had one with noticable vibration.

New tools! yea!

[Alex Berkovsky]

I must confess that I haven't read the article, but I don't see how that's possible. The math just doesn't seem to workout that they would have the same surface speed, given that the speed is halved with a slow-speed 8" grinder and the 6" has a diameter that is 3/4ths of the 8". Given that the surface speed varies directly with diameter (cir = Pi * dia), I would expect the high-speed 6" grinder to have a surface speed about 50% higher than the low-speed 8" grinder.

Someone please correct me if I'm wrong. My math courses were a long time ago and I may have missed something.Bob,
I corrected my post to make sure I didn't misquote Joel's statement. Joel said that it is close to the same surface speed. As far as the math is concerned, if it's correct, 50% higher speed I would not consider as being close either.

[Jeff Hallam]

I think you need to convert your answer to meters per minute. Using 6" = 0.5 feet and 8" = 0.67 feet. 3.14 X 0.5 X 3450 = 5416.5 feet per MINUTE. 3.14 X 0.67 X 1750 = 3681.6 feet per MINUTE. 5416.5 - 3681.6 = 1734.9 FPM. 3681.6 / 5416.5 = 0.679 That is 2/3 of the faster grinder.



You are correct Bruce, I misread the output units of that calculator. But I stand by the fact that (as supported by your calculation) the slow speed grinder gives *gasp* the slower speed.

[John Callahan]

Jeff, No experience with it but if you have a Steel City dealer nearby, their 15400 might be worth a look- it appears to be almost identical to the Delta 23-725.

[Tim Sgrazzutti]

I've been going through the same decision making process about these the last few days also. I did the math myself on the surface speeds, and came up with the following, all in feet per second:

6" @ 3450 = 92
6" @ 1725 = 46

8" @ 3450 = 120
8" @ 1725 = 60

So, a high speed 6" is 50% faster than a slow speed 8", and 25% slower than a high speed 8".

I think you need to weigh the pros and cons of each. I drew out the 3" and 4" radii of each size very close to each other, and while you can see a difference between the two, it isn't much over the distance the wheel would contact a bevel, so it's not an issue for me. 8" wheels cost more, and can have larger balancing issues than 6 inchers. This has me leaning toward the Delta 6" variable speed, which is around $85 at Lowes. One of the wheels on it is a friable white wheel already, so if I replaced the gray one with a blue Norton, I'd be all set up for around $120. I think the Delta you linked to is really nice, but when you add up the price of it with shipping, plus two 8" blue wheels, that puts the total package around $300.

I should also mention that I currently have a high speed 8" with two gray wheels, which is great for lawnmower blades and metalworking, but useless for edge tools.

Good luck with your decision

[Randal Stevenson]

I just bought a Craftsman unit that looks to be the same as the GR450 8" - it does not have the quick change arbor -- On sale with the Craftsman Club discount I think it was less than $90.00.

It is a nice unit -- and I like the VS.

tools - the Craftsman came with a rougher wheel and a wire wheel - so I had to replace both.



Jeff:

I went to Sears to check them out -- the VS model looked to be a normal 3500rpm unit with the electronic speed control added.

This Craftsman must have been made by Delta -- they are identical. For the price of the unit I was quite impressed at the quality.




Tom, I'll check out that Sears Delta knockoff myself. Thanks.

List the prefix code of the Sears one! Sears has two variable speed 8" grinders. One goes down to 1725 and is made by the same company as the Steel City Grinders (not Delta), the other I don't know about.
I have an earlier one (Sears doesn't carry it now) that is also made by the Steel City manufacturers, but isn't slow speed.
(not at home) I will check later today and get the prefix code of mine.

[Jeff Wright]

List the prefix code of the Sears one! Sears has two variable speed 8" grinders. One goes down to 1725 and is made by the same company as the Steel City Grinders (not Delta), the other I don't know about.
I have an earlier one (Sears doesn't carry it now) that is also made by the Steel City manufacturers, but isn't slow speed.
(not at home) I will check later today and get the prefix code of mine.

I went to Sears yesterday and saw the 8-inch variable. The clerk said the unit was manufactured by Ryobi. I think I will go with the Delta 23-725, a slow speed 8-inch WITHOUT variable speed. It has a 3/4HP motor and weighs in at about 90 pounds. Cost is about $180. I suspect this unit is a more industrial version and, hopefully, higher quality. I will get the OneWay balancing device to dress the Norton 60 grit 3x wheels that I plan to get. I understand a balanced wheel will not only result in better sharpening but also longer bearing life. Not sure that's true, but it sounds good nonetheless. :D

[Randal Stevenson]

I went to Sears yesterday and saw the 8-inch variable. The clerk said the unit was manufactured by Ryobi.


Ryobi's prefix is 315. (rest of model number here)

[Greg Narozniak]

I bought a woodcraft slow speed grinder, suits my needs. It was on sale, came with aluminum oxide wheels, spins true enough to be useful and non problematic. The stock tool guide is not exactly a work of art but that is easy enough to over come with a shop made jig or after market guide.

I did the same as peter and added the PSI sharpening system (Wolverine clone) and I an no expert on sharpening by any means and I was able to sharpen up all my gouges to almost like new. I am happy with my purchase.

[Jules Dominguez]

I read and enjoyed Joel's article also, but his arithmetic's not good. The rim speed of a 6" grinder at 3600 rpm would be half again as fast as an 8" grinder at 1800 rpm.
I thought his idea of putting a crown on the edge of the wheel made sense, and plan to try it.

[Cary Swoveland]

...8" wheels cost more...
Just a darned minute, Tom. Shouldn't an 8" wheel last 77% longer than a 6" wheel? [ (4/3)^2 = 1.77 ]

Cary

[Tim Sgrazzutti]

Yes Cary, and 8" should last longer than a 6", but it also depends on how much wear you consider to be acceptable before replacement. By my figuring, 1" of wear on the radius works out to 15.7 cubic inches of material gone on a 6", and 22 cubic inches of material on an 8". By this, the 8" takes 1.4 times as long as the 6" to wear 1". The 8" is 1.3 times as expensive as the 6", so I guess there is a slight advantage.

The thing I didn't consider before, is that the hollow created by the 6" when new is O.K., but when it's worn to 4", the hollow is more extreme. Also, the balance issues with 8" wheels will not be as bad on a slow speed machine, and the extra inertia of the 8's would probably be a good thing at slow speeds. Considering all this, maybe I'll just wait 'till the 8" Woodcraft is on sale.

[Randal Stevenson]

My model, that they now carry the variable speed version, is 152.xxxxxx. It is made by Orion (same as Steel City).

[Paul Gatti]

I got the GR450 for Christmas this year and I have to say that I'm not all that impressed with it. I use the grinder primary for sharpening. The biggest problem has been trying to get the grinding wheels to spin true and balanced. I replaced one of the wheels with a Norton 60 grit and I'm still having balancing issues. Part of the problem appears to be with the quick release nuts and the end plate that goes on the arbor and butts up against the outside of each wheel. Both seem to add instability and wobble to the wheel because of the poor machining quality (the arbor holes aren't drilled dead center) .

In addition, the supplied tool rests are junk. If you what to use the grinder for sharpening, I suggest getting a Veritas Grinding Jig (http://www.leevalley.com/wood/page.aspx?c=2&p=45938&cat=1,43072).

I ended up bolting my grinder to a piece of 3/4" plywood and then I bolted that to the surface of my worktable. This helped add some stability, but it didn't completely solve the balance issue.

Eventually I will get a dedicated sharping system and keep the delta for rough buffing and grinding.

[Tom Esh]

...I ended up bolting my grinder to a piece of 3/4" plywood and then I bolted that to the surface of my worktable. This helped add some stability, but it didn't completely solve the balance issue.
...

Been there. The thing either wanted to walk off the bench or take the bench with it. I'd been contemplating the OneWay blancing system and finally pulled the trigger. Wow! What a difference. I can now run up to the full 3600 rpm smooth as glass without a clamp in sight. With some creative shimming, I even managed to get a wire wheel balanced on the other side. FWIW even my brand new Norton 3x required a significant weight shift to balance. I didn't run it before, but my guess is things would have been rattling at 3600.

[Tim Sgrazzutti]

Interesting, my approx. 8 year old cman industrial 8" 3450rpm grinder is a 152.211080. It looks identical to the SC 15420, with the exception of the variable speed. So apparently Orion, and sears using them as a supplier, predates steel city.

[Raymond Fries]

I have the same grinder as Alex and have been real happy with it so far.

There are a lot of good choices.

Good Luck finding what fits you.

[Tom Godley]

It does look like the VS Craftsman is the same unit as the Steel City. But I am only looking at a picture of it on the SC web site

When I was looking at them in the Sears store they had a Delta unit sitting next to it - it was not VS -- but it was the same exact unit without the VS parts.

I am not using the tool rests or guides - I am placing it on its on cabinet to be used strictly to sharpen my lathe tool using the worlverine system/ Ellsworth jig.

I was going to buy the low speed unit -- until I noticed this VS.

I put two new Norton wheels on it and it is quite nice.

[Johnny Kleso]

If your talking about the artical by Joel in FWW this month Joel is in ERROR....

I think he said a high speed (3600 rpm) 6" grinder has a slow surface speed than a slow speed 8" slow grinder.. I just did the math and here is what I get

3600 6" SFPM =5654
1750 8" SFPM =3665
1750 10" SFPM =4581

So the 8" slow speed is closer to 1/2 as fast than it is to faster as Joel said..

The 6" is so fast it it is still faster than a 10" slow speed grinder.. I have a 10" HF grinder I got on sale for $72 and love it, I bought all my replacement wheels off eBay for a song, it leaves a small raidus (hollow) on chisels and blades and is 2HP if I remember right..

I have read a lot of good things about the WC grinder as well like others said..