Quick question for you hollow grinders...

[bob blakeborough]

I just picked up a deal on an 8" variable speed grinder and am wanting to experiment with hollow grinding, and while I know I can probably get away with the stock grey wheels, my Blue Spruce chisels are pretty dear to me for personal reasons above just the cost of them, so I do not mind investing in a white wheel simply to be extra cautious and give myself just a bit less of a chance of accidently frying an edge...

My question is one of grit size. Should I optimally use the 80 grit or 120 grit? I will be doing lathe tool and carving tools as well as the usual bench chisels and plane blades if it would make a difference on a recommendation...

Thoughts?

[Mike Henderson]

I'll give my opinion and that's that it's very easy to overheat an edge, especially the corners, of a chisel on a 1725RPM grinder, no matter what wheel you use. My recommendation would be to get a real slow speed device, such as the WorkSharp, the LV equivalent of the WS, or even a Tormek (although I'm not a fan of the Tormek). Grind your primary bevel to something like 25 degrees and then put a secondary bevel at whatever you want on water stones.

Some people can use a 1725RPM grinder - or claim they can - but it's very easy to overheat the edge. And when you overheat the edge, you soften the steel, which means you really need to grind back to remove the soft steel.

This is not true for high speed steel (HSS) versions of turning tools. They can tolerate being overheated. But regular carbon steel cannot tolerate being overheated.

My opinion - Leave a 1725RPM grinder to your turning tools and for rough grinding in the shop (like sharpening your lawn mover blades) and use other tools for sharpening your high quality chisels and plane blades.

Mike

[And you ABSOLUTELY do not want to put carving tools to a 1725RPM grinder.]

[Steve Voigt]

Bob,
If I were you, I would have at least one of my wheels coarser, like 60 or even 36 grit. I suggest you experiment with the grey wheels if they are already on the grinder. If you opt to go with the white wheels, I would still make sure one is coarser, 60 or below. If you are doing lathe tools and going straight to the lathe from the grinder, you may want a finer grit for that. But for planes, chisels, etc, coarser is better.
By the way, I totally disagree (big surprise) with the comment that an 8" 1725 grinder is somehow "dangerous" or only for rough tools. Nonsense. The sfm on that grinder is actually a little lower than on a standard 6" (3450) grinder, and I (and many others here) have used that for years without a problem.

[Doug Trembath]

Really, Bob, it isn't that easy to damage an edge, if you simply let your fingers do the walkin'... to borrow a phrase. If your fingers get uncomfortably warm when you touch the edge, dunk it in a container of water. It isn't rocket science here, just be sensible, keep the temperature below the top level of the comfort zone, and grind away...

It really is as simple as that. Too much is made about heat control, IMHO... It ain't that difficult. Your fingers will tell you WAY before you hurt something, if you simply test the metal as you grind. If you are really worried, take quick passes on the grinder, and dunk it after every pass. No worries then, unless you keep the metal on the grinder until it overheats and the color changes. If you do this, you will probably only do it once...

There is a lot of metallurgy info on the web, and you can find it easily, but in reality, you simply need to keep the heat that grinding generates down to a comfortable level...

You can do a LOT of grinding, with any wheel you already have, if you can touch the metal without flinching from the heat, and to be absolutely honest, you would have a LONG way to go before you damage anything at that point. Most of us cannot hold an item at 160 degrees, That is a long way from the temp it would take to thermally damage any tool steel you are likely to encounter in woodworking. Just don't overheat the metal!

Grind away, and find your own comfort level.


Simple, huh?

Grinding really is that easy, no matter the grit, the speed, or the size of the wheel. Just be careful.

Doug Trembath

[David Weaver]

Bob, I'd put a 120 grit white wheel on one side for turning tools and a 46 grit wheel for chisels and plane blades on the other side where type of wheel is based on what you're willing to pay.

I'd keep the carving tools away from power tools except for a compound loaded buff.

[george wilson]

I dunk the edge into water and grind very briefly till the water sizzles,then instantly dunk again. The thinner you grind the edge,the less time you can spend grinding. I grind about 2 seconds on a COARSE wheel,then the water sizzles and I dunk and repeat.

Some like to keep their fingers very near the cutting edge while grinding,but I prefer to just keep an eye on the water that clings to the end of the chisel while grinding.

I mostly use my belt grinder with blue,coarse belts,like 36 grit these days,but they are very expensive(for the Wilton Square Wheel grinder,needlessly expensive,I think. They are Taiwan made). But I do much enjoy the Tormek that David very generously sent me. It never will heat an edge as it runs in water,and,being a fine wheel,leaves a nice smooth surface.

You could get a cheaper version,the Delta grinder that has one wide,white wheel that runs in water,I think. The other wheel is a normal speed bench grinder wheel. I haven'd had one,I THINK the wide wheel runs in water.

I used a normal 6" bench grinder most of my earlier years,with as coarse a NORTON white wheel as I could find. So much better than the old gray wheels. Miles better. I still have it,but use it mostly to touch up metal lathe cutting tools as I don't have to turn on the dust collector(I do with the belt grinder). The HSS lathe tools are not affected by burning blue,though I still don't want them to get blue just as a matter of personal preference.

Mike Henderson above MUST be referring to HSS wood lathe tools,not just tool steel turning tools. All cutting tools are tool steel,but that name is very broad,and refers to anything from carbon steel to HSS and even powdered metal.

[Mel Fulks]

George, I know from your posts you prefer the faster bench grinders over the 1725 rpm so I can't help but wonder what
types of work the Tormek is used on. Unusually small things that burn fast ,or just more as a hone?

[Mike Henderson]

Mike Henderson above MUST be referring to HSS wood lathe tools,not just tool steel turning tools. All cutting tools are tool steel,but that name is very broad,and refers to anything from carbon steel to HSS and even powdered metal.

You're right, George. I went back and edited my post to make that specific. Thanks for pointing that out.

Mike

[bob blakeborough]

Thanks guys... I have a few cheaper chisels I am going to practice a bit with before attacking the special ones, but I think am going to attempt the stock wheels first. I am assuming I should use the wheel dressing tool on the new wheels first go hey?

[Jim Koepke]

I have a few cheaper chisels I am going to practice a bit with before attacking the special ones

Always a good idea.

jtk

[Mike Cherry]

Maybe I missed it, but what grinder did you get? I was looking at the Rikon woodcraft has on sale right now.

[bob blakeborough]

Maybe I missed it, but what grinder did you get? I was looking at the Rikon woodcraft has on sale right now.

my local Lowes had a clearance on the Porter Cable 8"variable speed for $103.00 (cdn money so like $85 ish USD)...They do not get that cheap often up here in the great white north...

[Winton Applegate]

Delta grinder that has one wide,white wheel that runs in water,I think. The other wheel is a normal speed bench grinder wheel. I haven'd had one,I THINK the wide wheel runs in water.

I think George is talking about this dude.

Looks like it is out of stock but I got mine, I think, at WoodCraft. They may still stock them or your general power tools store. Where they have metal cutting bandsaws, next to table saws, next to diamond core bit turning drills, next to sheet rock screw guns. You know a pro power tools store, not Home Depot.

I don't think much of mine. The big wheel turns too slow. Yes it runs in a water. I recommend dumping the water out if you are not going to use it for a few days. I forget all the reasons but trust me on that one.

Also you need a good back to do this because it is HEAVY even without any water in it and awkward to dump and clean. It gets a fair amount of white grit in the bottom fairly fast. When I use it a lot I like to keep this cleared out.

Hey ALL the reasons I just use a coarse 120 grit flat stone and my jig is all coming back to me now. I got tired of spending all that effort "saving time" with the wet grinder so I let it alone.

By the way I bought mine to use on my metal cutting tool bits. If I did it again I think I would go with something else. Maybe even the ones with the multiple disks each with a different diamond grit that you drop in place. This is more for carbides though. I use HSS bits for the most part.

I haven't used my Delta (on the wet) for probably a year. I do use the small white wheel which turns fast and goes to town.
The tool rest for the small wheel is dog doo doo.
Plan on coming up with your own design and build for a new one there.
When I was using the wet side a fair amount I was in the habit of taking the small wheel off which turns all the time and causes some noise and vibration I could do without. I had to modify the shaft to get tools on it to make the job tolerable.

Nah over all it is an almost tool that they just didn't follow through on.
the good news is it is practically free. I think I paid like $169 for mine a decade ago.

THE BIG WHITE WHEEL ON MINE IS ALSO DOG DOO DOO.
It has a hard spot in it that doesn't wear at the same rate as the rest of the wheel so you get this grind thunk, grind thunk sensation every revolution.
If I liked the grinder more over all I would invest in another wheel.
It is a crap shoot whether it would be any better. I have had people here and other chat rooms tell me there were at least two good wheels out there (they each had a good wheel).

I think I would second Davids very coarse (white ?) (or pink ?) wheel (46) recommendation on a faster dry grinder then use water stones.

PS: ooorrrrr (sorry David) a Washita stone.

[george wilson]

Thanks for the evaluation,Winton. One of the shops in Wmsbg. had one similar to that one,and I never heard any complaints. Cheaper than a Tormek,though.

You need to empty the water(the Tormek has a lightweight plastic tray that lifts out),because if you leave it submerged,that part of the wheel will be softer,and will wear faster,leaving you with a wheel that isn't round. Same thing applies to natural sandstone wheels. Apparently it also applies to the man made white wheel.

Sounds like the thing to do with the Delta would be to drill and tap a 1/8" pipe tap at the bottom of the tray,and screw in a plug or a spigot. Surprising to hear about a hard spot. I hadn't heard about that. Hopefully it's a rare occurrence.

Anyway,I was thinking the Delta would be a cheaper alternative to the Tormek. I guess you get what you pay for.

I formerly had a Jet wet wheel grinder. Stay away from them: They quit working,often right out of the box,say the dealers. The reason,I found out,is the beer can thickness push on wire connectors(NOT AN EXAGGERATION,they are REALLY beer can thin),are so thin they crack from being pushed on. I just soldered my cracked connector to get the unit working. Then,it quit again. Another cracked one. I should have soldered ALL of them when I had the circuit board out.I haven't opened it up again because I got the Tormek. I'll probably use the wheel off of it on the Tormek when it becomes necessary.

[Derek Cohen]

I just picked up a deal on an 8" variable speed grinder and am wanting to experiment with hollow grinding, and while I know I can probably get away with the stock grey wheels, my Blue Spruce chisels are pretty dear to me for personal reasons above just the cost of them, so I do not mind investing in a white wheel simply to be extra cautious and give myself just a bit less of a chance of accidently frying an edge...

My question is one of grit size. Should I optimally use the 80 grit or 120 grit? I will be doing lathe tool and carving tools as well as the usual bench chisels and plane blades if it would make a difference on a recommendation...

Thoughts?

Hi Bob

I have a white Norton 46 grit on one side and a 46 grit Norton blue 3X on the other. The 3x has hardly had any use in about 4 or 5 years. It's a great wheel if you want cool grinding, but it is messy. Obviously my skills have improved over this period as I obtain a cool grind from the white. The basic element is to keep the surface clean and use a light touch. If you wish an even cooler grind, go for a white 36 grit. I've not used the pink wheels, so cannot comment on them.

Regards from Perth

Derek