Grinders....making the "switch".

[odie]

After having used my 6", 3350rpm grinder for a quarter of a century.......this week, I purchased a Delta 1725rpm, 8" grinder. I have a couple of SG wheels on the way......

I spent the morning and afternoon making the switch in my shop......and did some shaping on a hard maple bowl. The complex curve shape was a good test of tool sharpness.

So far, so good.......but, I'm not detecting any dramatic improvements in sharpening ability. The only thing that looks like an improvement, is it appears as if I can slow down the arc at which the tool moves during sharpening......but, the final results seem to be not much different.

The Delta is a much nicer, and better made grinder......but, I wouldn't purchase one for that reason alone. The 6" grinder always did a very good job of sharpening. The difference in fpm on the surface of a 6" wheel @3350rpm isn't as much of a jump as you'd think, over 8" @1725rpm......so, with that in mind, it's all a matter of technique, in my humble opinion.

Here's my question: Am I missing something here? After all this time about hearing about how good a slow speed grinder is, this is an anti-climax for me.

otis of cologne

(Go Giants!)

Here's before/after pics:

 

[MichaelMouse]

High speed is less forgiving. You can make a dig in half the time on a 3450. If you're good, machts nichts.

If you use the slow thing long enough, it will probably end up prolonging the life of your tools, because you'll take off less steel in the same time. Almost like a power hone versus a grinder.

 

[odie]

High speed is less forgiving. You can make a dig in half the time on a 3450. If you're good, machts nichts.

If you use the slow thing long enough, it will probably end up prolonging the life of your tools, because you'll take off less steel in the same time. Almost like a power hone versus a grinder.

If it helps prolong my tool life, the new grinder will pay for itself......only time will tell, but I'm one that sharpens a lot! For this reason alone, the new grinder will likely be a good investment.

Not familiar with the term "dig".......what is meant by that?

otis of cologne

 

[georgetroy]

High speed is less forgiving. You can make a dig in half the time on a 3450. If you're good, machts nichts.

If you use the slow thing long enough, it will probably end up prolonging the life of your tools, because you'll take off less steel in the same time. Almost like a power hone versus a grinder.

Yes, my digs are side ways slips off the wheels. I also have two grinders my old 3/4 hp high speed Sears that's 25 years old and my Delta 8" which is about 5 years old. I have 4 different wheels. I will also mount a rubberized wheel on the shopsmith sometimes to hone. The Oneway holders are on the 7 and the 8" has the Kelton.

 

[odie]

Ok, with the help of georgetroy's post, I understand now.

I haven't had very many "digs" in recent years. Certainly, they are annoying when it happens, but learning tool control on the grinder is just as important as on the lathe....:cool2:

It just might be possible that my learning experience with sharpening on a 6" grinder made me better overall.......because I had to learn to do it faster.....and smoother!

otis of cologne

 

[john lucas]

In my experience there is very little difference in a sharpening on a 6" 3450 grinder and an 8" 1725 grinder as far as sharpening quality. I now have one of the Woodcraft 2 speed 8" grinders and have been switching back and forth between 1725 and 3450. There is a noticeable difference in these two because the surface speed is doubled. The biggest difference is how fast you move the tool. I have to move it much quicker to keep from over grinding certain areas of the tool. The 6" High speed grinder is only about 1/3 or so faster surface speed than 8" slow speed which is why I didn't notice much difference in cutting action.
I like the slower speed because it just feels safer. I also like the larger curve of the wheel. It doesn't make as deep of a concave surface but I really can't tell the difference in actual use between this and my 6" grinder. On hand chisels which have a much longer bevel it does make difference.
I like 8" because you can get 1" wide wheels for it. You can use a lot more stone before you have to toss them, and the 8" grinders are physically heavier which reduces vibration.(assuming of course you have a decent enough grinder not to vibrate in the first place.)

 

[robert davis]

my 7" sg wheels are belt driven and run 1380 rpm. as john says slow gives one easier control. you will like the sg wheels

 

[Mark Mandell]

SG Wheels

I presume these are Nortons.

What you guys don't say is what grit your have and who you got'em from.

I've been watching for a 120 grit SG wheel for my 6"grinder to work my higher alloy tools , but so far haven't seen them. So . . . . .

Who's got sg wheels in what sizes and grits??

 

[odie]

I presume these are Nortons.

What you guys don't say is what grit your have and who you got'em from.

I've been watching for a 120 grit SG wheel for my 6"grinder to work my higher alloy tools , but so far haven't seen them. So . . . . .

Who's got sg wheels in what sizes and grits??

I asked around locally, and couldn't find anyone who could supply the Norton SG wheels. They didn't even have them listed in the dealer's catalogues.

I've been using the Norton 80gt SG wheels on the 6" grinder, and I really like them. I ordered a set of 80gt 8" SG wheels from CSUSA, but haven't arrived yet. Be warned, they are expensive. Through them, only 6" and 8" diameters, 46gt and 80gt are available. I'm providing a link at the bottom of this post for your convenience.

I use two of the 80gt wheels on my Wolverine jig. I have other cheaper wheels of coarser grit, when I need to do some basic shaping of lathe tools, but the SG wheels are used far more often, so they are the ones that stay mounted most of the time.

otis of cologne

click:
http://www.woodturnerscatalog.com/s...___Wheels___Norton_SG_Wheel___norton_sg?Args=

 

[Mark Mandell]

Thaks, Odie,

I can get the 80 grit SG wheels a number of places, it's the 120 that I use to put an edge back on the tool that I haven't snagged yet. Norton's site says they make them in 6x1, but I've yet to find a retailer.

mm

 

[mo' wood]

more grinder tips

Hi Folks,
I agree with John about the speed not being as much of a factor in sharpening as the grit and condition of the wheel. Spend the money on a good diamond dresser, and be sure to steady it on the tool rest rather then free hand it, which over time results in the wheel getting out of round if the dresser ‘hops’.

One other suggestion is to get a simple foot switch that you plug the grinder into- one that shut off when you take your foot off of it. It turns any grinder into a variable speed grinder- just ‘goose’it and let it coast when sharpening smaller tools or any edge that doesn’t have much contact area on the wheel. In addition to being less aggressive, it also makes it much easier to sharpen small tools that may not fit a vari-grind jig or sit flat on the angled panel tool rest. You can position the bevel on the wheel using both hands, then turn the grinder on with the footswitch while maintaining the proper angle. I think it gives you much more control.

Just remember free advice is worth about as much as you pay for it.

 

[robert davis]

I presume these are Nortons.

What you guys don't say is what grit your have and who you got'em from.

I've been watching for a 120 grit SG wheel for my 6"grinder to work my higher alloy tools , but so far haven't seen them. So . . . . .

Who's got sg wheels in what sizes and grits??

my 7" 80 and 100 are from packard.

 

[Steve Worcester]

Personally I am a big fan of the Oneway wheels. They are available in different compositions for the grinder speeds and in 6",7" and 8"

http://www.oneway.ca/sharpening/wheels.htm

 

[Mark Mandell]

In case anyone's interested . . .

I contacted Norton about their SG wheels in finer (120+) grits which they list in their catalogue, and asked for retailers. The reply e-mail told me to contact Woodcraft. But woodcraft doesn't carry them and can't order specially Samo with the industrial tool suppliers I use.

I then contacted an outfit in New York that carries the courser grit sg's and was informed that while Norton lists the wheels, they are not actually making them (which is wierd). They said they would try to place an order for the 120 grit 6x3/4" wheels and will let me know in a few weeks.

I'll report back with a link so that anyone else wanting a 6" 120 grit SG wheel for refreshing a tool's edge can place an order as well.

mm

 

[Dann Chapman]

where to get Norton wheels

I found mine at sharpeningsupplies.com before they were available in the other usual catalogs. Found them to be an excellent outfit to work with.

DTC

 

[Mark Mandell]

I found mine at sharpeningsupplies.com before they were available in the other usual catalogs. Found them to be an excellent outfit to work with.

DTC

Thanks Dann, but they only have grits up to 100. I'm trying to get the 120. I use a AO 120 now, however the wheel is getting worn (too quickly - now less than 5") sharpening the powdered and vanadium higher alloy steels in my turning tools.

From a 120 wheel I get a very nice edge and smaller wire edge burr that slips right off with a couple of passes of the hard arkansas in the flute.

mm

 

[Dave Roller]

I have a 6" Rockwell Delta grinder (3425 rpm) and a Woodcraft 8" (1750 rpm).

When I want a variable speed (mentioned above), I use MDF covered with sandpaper or emory cloth. On occasion I have mounted a grinding wheel backed with plywood on a morse taper and used the side of the wheel. These are mounted on the lathe and work very well for skews.

 

[KurtB]

Sale on Woodcraft 8" Grinders

Just noticed this, Woodcraft is currently selling the 8" 1725 rpm grinders for $79.99 through the end of February. If anyone was thinking of upgrading their grinder, this is the time! Check it out!
KurtB