Grinder Speeds

[Dave Wimmer]

I have always read and been told that a slow speed grinder was better for sharpening lathe tools, that the high speed grinder would cause too much heat. The instruction manual for the Oneway Wolverine system says to use a high speed grinder. They recommend an 8 inch grinder @ 3450 rpm. They say surface speed should be between 6000 and 8000 fps. 8"@3450rpm=7225fpd. 8"@1725=3612fps
Wasupwidat?

[Bernie Weishapl]

Dave I use a 8" high speed grinder and have had no problems sharpening. You just have to be careful not to leave them in one spot or press hard and you will be ok. I almost bought a slow speed when I called oneway and they told me it doesn't make any difference and they wouldn't wasted the money if I already had the HS one. If you watch their video on their site it is a high speed that they use. Just my $1.298

[John Hart]

Dave, I've seen a dozen or more arguments for and against...all seeming valid. I have both a low speed wet and high speed dry. I prefer the high speed dry. But then, I'm still learning so maybe I should just shut up.:o :) :D

[Andy Hoyt]

Dave - Over the years I've discovered numerous conflicts within Oneway's literature, and have pretty much learned to expect it. Machinery gets updated constantly yet the attendant documentation seriously lags far behind. Of course, that's true with a lot of stuff these days.

If you visit their page about wheels http://www.oneway.on.ca/sharpening/wheels.htm you'll see that they offer wheels designed for either 1750 or 3400 rpms; and do not recommend one over the other.

Slower speed grinders are great for carbon steel tooling or HSS; and the faster grinders are fine for just HSS tooling. Why? Faster speed equates to more heat which, in turn, is bad for carbon steel. Something to do with tempering and annealing - two subjects I'm mostly ignorant about.

If I were gonna buy a new grinder, I'd opt for the slower speed so I could feel safe knowing that I wouldn't ruin whatever I was sharpening. And I'd go with an 8" unit - less friction hence less heat; and it produces a shallower concavity on the tool than would a 6" wheel.

[Gary Max]

Lets see--- I have three grinders---450rpms/wet stone---1750rpms dry and 3450dry.
My thought is ---it depends on what I am wanting to get done and what size of tool I am working it.
If I only had one of these grinder to choose from it would be my 8 inch 1750 because I have my wolverine jig set up on it.

[Jim Becker]

You can use either for HHS. Both of my grinders are 34xx rpm. The slower speed grinders are more forgiving for beginners, but obviously, it takes more time to complete the task. Sharpening should be done with a light touch so the speed is less of a concern in the long run...with HHS. The good news is that about the best value on the market is the slow speed unit from Woodcraft that includes the white AO wheels....and AO wheels are absolutely necessary for this task.

[Keith Burns]

My vote would be the slow speed. How much time is a high speed going to save when grinding a gouge ? I got the woodcraft unit a year or two ago and have had no problems.

[Randy Meijer]

You can ruin a lathe tool with either type......it just takes a little more effort with the SS version. If you are getting this machine to use solely as a sharpener, the SS unit will give you a little extra margin against making a mistake. If you intend to use the machine as a grinder as well as a sharpener, the HS version will save you time a good deal of time. Note that by grind, I mean tasks that involve removing metal from items other than cutting edges.......like bevelling edges of metal stock for welding.

[Dennis Peacock]

Well, here's my vote on this.

I vote for the slow speed grinder.
1. It is a little more forgiving than the high speed version.
2. It takes a little longer to build heat at the tool edge than with a high speed grinder.
3. Starting out? You'll feel more comfortable using a slow speed grinder. With this in mind, you'll tend to be more relaxed at the grinder and you'll achieve a better grind on your tools because you are more relaxed.
4. Use light pressure on the grinding wheels. Most times, just the weight of the turing tool itsself is plenty of pressure for putting the edge back on the tool.

If you get the slow speed from Woodcraft? It should arrive with an 80 grit on the left side and a 100 or 120 grit on the right side. I use the 80 grit to "grind" my tool edges to shape and then put a final edge on them at the 120 grit wheel.

So....that's my 2¢ on this subject. All this and $1 will get you a cup of coffee at the local McDonalds.:)

[Bob Noles]

Dennis,

Thanks for posting the info on the WC as they did not bother telling which wheel was on which side. I had to just guess and looks like I guessed right :)

[Dennis Peacock]

Dennis,

Thanks for posting the info on the WC as they did not bother telling which wheel was on which side. I had to just guess and looks like I guessed right :)

Then I'd say you did "good". ;)
So how you like the grinder?

[Rich Stewart]

I got the two speed grinder from PSI. 1750 low speed and 3500 high speed. 120 AO wheel and a 80 grey wheel. 1750 sounds like a freaking jet engine. Haven't even hit high speed yet. Can't imagine anybody needing more than 1700 rpm's

[Bob Noles]

Then I'd say you did "good". ;)
So how you like the grinder?

Dennis,

I like the grinder a lot and think it is a great value for the money. It does a good job with the Wolverine. My dream though is to get one of those Tormeks like you have :D

[Carole Valentine]

I have always read and been told that a slow speed grinder was better for sharpening lathe tools, that the high speed grinder would cause too much heat. The instruction manual for the Oneway Wolverine system says to use a high speed grinder. They recommend an 8 inch grinder @ 3450 rpm. They say surface speed should be between 6000 and 8000 fps. 8"@3450rpm=7225fpd. 8"@1725=3612fps
Wasupwidat?

Dave, if I didn't have a grinder at all, I would go for the slow speed one. If I already had a high speed grinder I would use it. My theory: The Wolverine folks are in the business of selling. Since the majority of grinders currently in shops are high speed and most turning tools are HSS (which is far less likely to be harmed by high speeds), they can sell more jigs if they assure folks they don't have to buy a new grinder to go with their jigs. A slow speed grinder works great ( I use one) and has the added advantage of letting you use it on carbon steel tools without generating as much damaging heat (still have to be careful though). JMHO