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View Full Version : General musings on grinding wheels...



alanganes
10-22-2011, 10:40 AM
Just thinking on this stuff lately. I am just putting some finishing touches on a Darex M4/5 drill grinder that I managed to piece together from various sources. The grinder that I mounted it to was a "Central machinery" 6" bench grinder that I have had for lots of years. Long enough that it was made in Taiwan rather than China. Anyhow, it of course had those nasty too-hard grey grinding wheels on it that had to go before I do much drill grinding.

I had a 6" Al Oxide 60 grit K wheel laying around that I put in place on the drill point grinding side of the machine. I dressed it and it works great. That Darex is a way cool machine, BTW. My wheel is 1/2" wide as opposed to the 3/4" that was on there, but it has not seemed to matter much. I still need a decent wheel for the point splitter, so I started looking at all of the usual on-line tool and industrial suppliers.

What I find is that there seems little available in good wheels in the 6" size, and almost nothing in the 3/4" wide style. Am I just looking in the wrong places? Even the industrial supply places like MSC, McMaster, and the like seem to have a very limited selection in those sizes, and none seem to have any decent softer wheels that one would use for any sort of careful grinding.

And what is with the typical wheels that come on most grinders? Does ANYONE find those things very useful? I know that most industrial users go with 8" or larger grinders, but with the number of 6" grinders that are out loose in the world, one would think that the wheel manufacturers would make at least a few decent wheels for them.

Am I the only one with this problem?

RWO
10-22-2011, 01:22 PM
I have the same set up as you except it's mounted on a Sears grinder. I was using the white ALOX tool grinding wheel supplied by Darex on the left side for years and it's OK except it did require truing/dressing fairly often. I finally got the point splitting attachment on eBay a year ago and it was immediately apparent that an ALOX wheel would not do because it has to have a durable edge to make the 90 point splitting cut. If you tried to do it, you would be redressing the wheel to square it up every time you made a cut.

Now I know why Darex recommended CBN wheels for the M5. I got one from Darex and put it on the point splitter and it was a revelation. Runs perfectly true and since it is a plated metal wheel, it does not wear away like an ALOX wheel. I liked it so well I got another one for the left side. Drill point grinds are much smoother, cutting edges are sharper because the CBN wheel is 120 grit. It's drill sharpening heaven, but cost like hell to get there. But I wouldn't go back.

I have a couple of original Darex 6" ALOX wheels you can have if you want to pay the shipping. Drill grind wheel is 3/4". Point splitter wheel is 5/8". I don't recommend them.

RWO

alanganes
10-22-2011, 07:22 PM
Thanks for the info, it all makes sense. I would like to take you up on the offer for the ALOX wheels, I'll gladly pick up shipping cost. They may at least hold me on the point grinder side until I can scape up the free cash for the official CBN wheels.

It is interesting to me that the CBN wheels I have seen seem to cost more than equivalent diamond wheels.

If you PM me with cost and how you would like payment, I'll get that on it's way to you.

Thanks,
Al

Ian B
10-23-2011, 04:11 AM
If you're looking for a 6" x 3/4" wide CBN wheel, how about this:

http://www.ebay.com/itm/Resin-CBN-grinding-wheel-plain-18x150mm-New-/170709061411?pt=LH_DefaultDomain_0&hash=item27bf0d8f23

The only snag that I can find with the CBN wheels (never having used one) is the speed that they should be run at - I'm seeing figures of 60 to 120 m/s quoted, which would mean running a 6" wheel at about 14,000 rpm...

Ian

RussZHC
10-23-2011, 07:39 AM
Alan: no you are not, IMO this is not a problem of yours or my perception either...actual supply of said sizes can sometimes increase if you go looking more to those who supply woodworkers [have grinders but esp in HS situations very less likely to have eight inch "metal" working ones]

But even if you look at mfg catalogs, there does not appear to be much choice of any type...well there is if you add up all possible variations of grit, bond, width and arbor hole size but realistically, not much...to me, other than catalog search, the proof is going to EBay, start with a simple/general search and then narrow it down to what you are after (6" variable in particular) and you will be left with surprisingly few results

I found Lee Valley to have more of what I need (for grinding lathe tool bits) as they have both cooler running AlOx type wheels as well as some higher tech Norton wheels ("3X")

alanganes
10-23-2011, 08:10 AM
Russ - Thanks. Indeed, Lee Valley does seem to have more of what I would be looking for. I know of Lee Valley, it just never occured to me to look there. Glad I asked!

Funny thing is that you would think more metal working types would be looking for this sort of wheel for sharpening HSS lathe tooling, not just drill bits.

As to the general variety you are correct, but even looking in the larger tool/industrial supply catalogs, if you are looking for a 7" or 8" wheel there are vastly more choices than in the 6" size. There is often only one or even nothing outside of what looks to be the same overly hard grey wheels that the grinder came with in the first place. I know the 7" ones are generally surface grinder wheels with a 1.25" arbor hole, but we are a bunch of machinists, after all...

Ian - Thanks, I had looked at a few similar and wondered how the resin bond wheels hold up for this sort of use, as opposed to the metal electroplated ones like Darex sells. Have you ever tried them? For under 60 bucks total it may be worth a try, they could always be useful on the T&C grinder for other stuff I suppose.

Ian B
10-23-2011, 09:02 AM
Alan,

No, I haven't tried any of the CBN wheels. I need to make a planer blade resharpener, and was looking at a 6" CBN cup wheel. The resin bonded ones seem cheap enough, it's just the high recommended spindle speeds that are putting me off. From what I read, running the wheels too slow results in rapid wear and overheating of the work - sounds counterintuitive.

Ian

PixMan
10-23-2011, 09:37 AM
I picked-up a couple of those Norton "3X" blue seeded gel ceramic wheels at Norton's charity-benefit yard sale last year. I put one on dad's old Craftsman 6" bench grinder, and I just can't believe how cool it runs and how it refuses to break down. It's really quite amazing.

I have a similar 5SG46-KVS 8 x 1/2 x 1-1/4" wheel in the surface grinder 90% of the time, and it just loves to be abused. These wheels are to an old 25A grade wheel what coated carbide is to HSS.

I had no real choice for a wheel on the BW2 Black Diamond drill grinder, as it has dual grit and a special shape notch on the corner. Using it requires stepping into the WayBack machine, and it's painful. We get a nice grind on drills, but I am looking for a 5SG wheel that I can dress into the shape needed for the Black Diamond grinder.

alanganes
10-23-2011, 01:21 PM
Thanks for that Pix, I love getting that sort of first-hand info. If they work that well that may be a good cost/performance compromise for the drill grinder, at least until I find a bunch-O-cash for the fancy Darex-type ones. And if those ever show up here the 3X wheels could move over to the T&C grinder. And it is not like I do that much drill grinding, being just a hobbyist shop. I may never feel the need to graduate to the top shelf stuff. It's just that I've always sort of wanted a Daerx, and when a few extra bucks collided with the opportunity to by most of one, I did it.

I had no idea that Norton held a charity benefit yard sale. Do they still do that? What sort of stuff shows up there? If there is much that would interest an HSM type, it would be worth the ride out. It's not so far from here after all.

BTW, I still plan to have you stop in some time when you are up this way to mess with the KO Lee I picked up a while back. I'm still tweaking a few things on it to get it in full operating trim, mostly cleaning off some of the scales, and replacing crusty dried out wiring. Gotta clean enough of the shop so that two of us can stand near the machine at the same time, too...

Ian- You are right, low speed = more wear does sound pretty counter intuitive. Still looks like it may be worthy of an experiment.
Edit: Just saw this: http://www.graffdiamond.com/products/RB_GrindWheels_pg7.html
These speeds seem a bit more typical. Anyone else have experience with these resin wheels?

Thanks again to all for taking the time to reply.
-Al

PixMan
10-23-2011, 05:07 PM
I had no idea that Norton held a charity benefit yard sale. Do they still do that? What sort of stuff shows up there? If there is much that would interest an HSM type, it would be worth the ride out. It's not so far from here after all.


Last year was the first time in over 100 years of doing business that they did anything like that. I made out pretty good, getting the bench grinder wheels, an armful of sharpening/honing stones, microfiber cloth samples, some bonded abrasives (a.k.a. sandpaper/emery cloth) and many other things I now forget. It was a fund-raiser for the United Way.

They just held it again this year on Saturday Oct, 8th. I couldn't make it (plus I already have WAY too much stuff) so I don't know how different Year 2 might have been. I'll keep my eyes open for it next year and let people here know if y'all are interested.