Diamond disappointment

I have asked in the past what the correct way to to true/dress a diamond wheel and never have gotten an answer that gave me the warm and fuzzy.

I asked about truing a metal matrix diamond wheel back in November 2004 and got this reply.

"Hi. I owned a grinding shop for years and had 12 to 20 machines running diamond wheels. First (blue the wheel), typically on a surface grinder, to true the wheel we bought silicon or boron carbide blocks and just ran the machine over the block - dry cut, about .001 in to the block and dust collector on... After the wheel looked cleaned up we repeated this with a .0002 or 3 cut... Secondly, after you true the wheel, sharpen it. We generally found the mold makers polishing sticks, 220 grit or so held against the wheel, wet, would sharpen the diamonds a bit and clean out the excessive brass thus giving the effect of sharpening.

Finally we never removed the wheel from it's hub as that's expensive, requires re truing etc."

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This is a significant reason why I use HSS instead of carbide, as I have diamond cup and disk wheels but only the one original spindle adapter for my surface grinder, and Sopko adapters cost several times what the grinder is worth. Attempts to turn the correct inside taper to make more haven't been encouraging. I did use a 1/8" carbide end mill the other day to modify grey Anderson SB50 housings to fit yellow ones.

I know what you're saying but at least you can buy them new, maybe you'll be lucky and score a 2nd hand one sometime. I have an Exe surface grinder

and the company closed less than a decade ago but a former employee taught a young engineer he knew how to rebuild and service them so there's some support and he bought all the remaining spares and technical details as I understand it. He had a spare NOS wheel arbor on ebay at a quite reasonable price so I had that so I have 2 to play with. I've turned internal tapers in the past with good success to match an existing arbor so may have a go at making another sometime. Last internal taper I turned was 1MT to take out the bulk of the metal with a reamer to finish the last couple of thousandths, judging by the amount of material removed by the reamer the taper was a few  0.001" small at the small end which I was happy with. I hadn't tried to clock the compound precisely to the correct angle as I had the reamer.

I have a cheap (relatively) Grizzly 6x12 surface grinder. It was actually cheaper if you count the stand/cabinet than the Enco (yes MSC still had some last I looked) than anything else I found at the time. I was hoping to be able to buy multiple arbors since it was a brand new machine (a few years ago), but they do not sell an arbor as an assembly. They do sell all the individual pieces, but by the time you add the cost of every little screw, weight, etc its pretty darn expensive. For now I just have a white wheel on the surface grinder, and I have used it on carbide. There are a fair number of carbide mills in holders that it ground flats on for a set screw. I don't typically use it on carbide, but I have. It works. Just not great. After I got the TC grinder I haven't used the surface grinder much. Mostly because it is not setup with coolant. I do plan to try it with mist to see if it keeps parts cool enough to prevent heat warping, but if not I'll eventually set it up for flood cooling.

Anyway, my plan originally was to have a hard wheel, a soft wheel, and a diamond wheel for it each on their own arbor. If I do that in the future I'll probably make arbors. I have multiple lathes mills. Balancing isn't that hard, and you have to rebalance after you mount a wheel anyway. You have to nail one taper modestly well and get it concentric. If you do most of the work in one setup or turn between centers I think you will likely scrap or have to recut one shaft before you get it. If you are making a few for different wheels it shouldn't bet that super critical. If you do think it should be that critical... well didn't you want to make a small cylinder grinding setup for your surface grinder anyway?

Recent epiphany... sorta. Sometime back I asked similar questions about dressing and truing diamond wheels. I did get some responses, but there wasn't really an easy answer. Not like dressing an aluminum oxide wheel with a diamond nib.

The other day I was making the 18 degree chamfer mill (D-drill), and I came up with a good way to find my zero on the base round carbide blank (broken end mill). I took a very light pass on one side, bumped the tool head around, and took another pass repeating until I had a visibly uniform width flat the length of the cut. While I know its not perfect I am sure its "pretty good." The reason I "know" this is that significantly less than the line width of the degree mark on the head made a significant visible difference in the line width from end to end of the flat. Am I going to be making custom production tooling in some big shop? No. Of course not. Will I get this job done? I'll let you know when I stop being afraid of it and just do it.

I have no idea how flat the flat face of the diamond wheel is, but if I set the head to zero, and run the tool across it I get a uniform flat cut. If I just feed the tool into the face of the wheel, maybe not so much.

I just did a CAD model to find the zero point I want to use on this tool yesterday. I might work up the nerve to run it today.

Standing at the machine with your hand hovering over the e-stop button ? I ended up shimming the mandrel at the "low" spot , runout is less than a thou now . But the next time I need to cut a gear I'll be making a new mandrel to mount the cutters . I ain't takin' that wheel off that mandrel unless I'm forced to .

Recent epiphany... sorta. Sometime back I asked similar questions about dressing and truing diamond wheels. I did get some responses, but there wasn't really an easy answer. Not like dressing an aluminum oxide wheel with a diamond nib.

The other day I was making the 18 degree chamfer mill (D-drill), and I came up with a good way to find my zero on the base round carbide blank (broken end mill). I took a very light pass on one side, bumped the tool head around, and took another pass repeating until I had a visibly uniform width flat the length of the cut. While I know its not perfect I am sure its "pretty good." The reason I "know" this is that significantly less than the line width of the degree mark on the head made a significant visible difference in the line width from end to end of the flat. Am I going to be making custom production tooling in some big shop? No. Of course not. Will I get this job done? I'll let you know when I stop being afraid of it and just do it.

I have no idea how flat the flat face of the diamond wheel is, but if I set the head to zero, and run the tool across it I get a uniform flat cut. If I just feed the tool into the face of the wheel, maybe not so much.

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Are you saying you got good results by grinding slowly with only the highest area on the undressed diamond wheel?

That's exactly what was happening with mine . Maybe a quarter of the wheel was actually cutting , but it left a very nice surface . I can't complain , I've salvaged several end mills that were otherwise headed for the scrap pile .

No I was very aggressive. I have neither the time nor the patience to take off a tenth at a time.

I was only gentle to find my zero, and for the finish passes.