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View Full Version : Diamonds, best friends etc, part II



Evan
08-15-2006, 12:05 AM
I said in the last thread about that very cool 10" diamond wheel that my wife gave me that I had an idea. Well, it turned out to be one of those projects that makes me want to look over my shoulder for something bad because it went so perfectly. Does anybody remember the Yankee Kahn shaker I posted here a long time ago and again more recently? I have had it for many years and never really use it for anything.

This is it:

http://vts.bc.ca/pics/shaker1.jpg

I took it apart and discovered a really nice drive to a 9 1/8" pulley. The pulley is mounted to the base on a stud and a couple of worn out bearings. The base is a solid steel plate 3/8" thick. It weighs a ton. A little machine work and reboring of the pulley fixed it up nicely. The pulley fit on my lathe with about .020" to spare over the carriage arms. I had to bore it out to fit the 1.250" bore of the wheel. I needed to hold the pulley to face off the top side and discovered that my three jaw will hold a bore from the inside that is no smaller than 1.246". Stuff like this kept happening.

This is what it looks like after a bit of modification.

http://vts.bc.ca/pics/hgrinder2.jpg

Next I needed some sort of bearing to stabilize the pulley and wheel. I remembered a big thrust bearing that I had picked up at a surplus store brand new about 35 years ago, still in the box. Oddly enough I had been cleaning the garage just a few days prior and had come across the bearing and knew exactly where it was. I faced off the underside of the 9" pulley to sit on the bearing. It is preloaded by the stud that holds the entire assembly to the base.

http://vts.bc.ca/pics/hgrinder3.jpg

The 9 1/8" pulley is exactly the right size for the grit on the bottom side to rest on the rim of the pulley and makes it so that there is no need to fasten the wheel because of its weight. It just drops on.

The machine spins at about 150 rpm and the wheel is 80 grit. It works great for roughing accurately to shape. The bits don't even get hot when grinding. I tried it on a piece of C1 carbide and it ate right through it in seconds. C1 is one of the toughest and most abrasion resistant grades.

http://vts.bc.ca/pics/hgrinder1.jpg

Now all I need is another such wheel the same size but fine grit. I mentioned this to my dear wife and she laughed for about two minutes. The wheel she gave me is worth about $1200.00 new.

Oh well, you can't have everything.

sidegrinder
08-15-2006, 12:18 AM
Good job once again Evan. Almost looks like it should be spinning vinyl rather than carbide though ;) I suppose all my old 45's would sound like the chipmunks' greatest hits at 150rpms though...Seriously nice work!

wierdscience
08-15-2006, 12:42 AM
If I were you I would stay out of the shop for awhile,you just shot a weeks worth of luck all to hell:D

A.K. Boomer
08-15-2006, 01:01 AM
Very nice work, some things are meant to be, Can you stand it up sideways? then make a mount to hold an adjustable angle plate,,, that thing would be the cats arss then...

SJorgensen
08-15-2006, 01:16 AM
I think you might be confusing luck with skill. I suspect you've been getting luckier year after year.

Norman Atkinson
08-15-2006, 04:02 AM
Evan,
Actually this is Jacob Holzapffel stuff. It is great to see that you have cleaned it up and brought it into the 21st Century.

In all seriousness, I had been browsing with a diamond wheel which was ex grinding spectacle lenses.Thanks for proving that it can be done.

Any chance of following old Jacob and doing Ornamental Turning?
He had something called a Goniometer to use with his wheel. It's OK, I am quite sober.


Norm

Peter N
08-15-2006, 04:50 AM
Nice one Evan.
That actually looks remarkably similar to the diamond cutting/shaping machines called scaifs(sp?) I think, that I saw on a vist to Amsterdam years ago. Large horizontal diamond impregnated wheel spinning at a relatively low speed. I don't know if was actually cutting or polishing though.

Peter

Evan
08-15-2006, 08:57 AM
There was a lot of luck in this project. Just the fact that I had that old shaker to begin with is unlikely. About the only thing that didn't go exactly as I wished was that I had to nip off the corners of the aluminum plate so it would fit the throat of my bandsaw when sawing the hole for the wheel.

BTW, I didn't show the radial ball bearings that are in the pulley bore which I replaced or the collar I put on the underside of the wheel to keep the thrust bearing centered. I also need to make a simple cover for the thrust bearing circumference to keep the grit out.

The entire wheel runs with virtually no runout and doesn't deflect at all under grinding pressure. It is also very quiet and should present much less than the usual hazard when grinding cobalt cemented carbide as it doesn't give off any dust or heat, just grit from the work that accumulates mainly on the plate around the wheel.

Rustybolt
08-15-2006, 09:02 AM
Some days things just come together. Nice job. Now you have to make a fence and some fixtures to hold the bits and maybe a water cup and a labyrinth to sling the water away from the shiney bits. Etc..........;-)

TGTool
08-15-2006, 09:06 AM
It looks a lot like the wheels gem cutters use. If there's room for a vertical post and swing arm, work can be set for specific angles (as in facet cutting). In India I watched it being done by hand. That is, the wheels were the same but the kids cutting the stones just held them against the wheel, looked at the stone, rotated their fingers and cut another facet. Calibrated eyes, I guess.

JM

A.K. Boomer
08-15-2006, 09:48 AM
Im just curious,,, what did the old can shaker have to shake the cans was it an eccentric if some sorts? also why does that new thrust bearing have grooves in all the individual rollers at different places?

Evan
08-15-2006, 10:47 AM
If you look at the last pic you can see a square frame in the back to the left of the oil can. It has rollers and ran inside the frame surrounding the pulley. It was fastened with an arm to an eccentric mounted bolt in the hub of the pulley. The table was fastened to the square rolling frame.

That thrust bearing is a high load low speed bearing. The rollers aren't tapered and the races are dead flat. That means the rollers will scuff as they roll since the natural tendency is to roll in a straight line. The rollers aren't grooved, they are split into two rollers in each position, one short and one long. This reduces the scuffing action. To equalise the forces that are produced by the scuffing and to prevent wear tracks from forming at the ends of the rollers every other pair of rollers is reversed, long/short, short/long. It's a perfect bearing for this application.

A.K. Boomer
08-15-2006, 11:03 AM
Very Cool --- I always knew rollers of this sort "scuffed" but never seen a solution to the problem, even though they still scuff they dont have as much scuffing to cover, and the staggering is so they dont set up a pattern, Helps them to keep the surface area for high load without paying a high "scuff" price, well discribed Evan.