Surface Grinding

[Conrad_R_Hoffman]

Sometimes I feel hexed too! They have lots of good PR on the 5SG wheels, but I have to question the heavy cuts recommendation for most of us. IMO, the typical 612 size surface grinder doesn't have the power or rigidity to be taking more than a couple thou. And, IMO again, you'd never want to be taking heavy cuts with the finer wheels. If anybody is being more aggressive, I'd like to hear about it.

[pete]

I hope no one minds if I back track a bit as I'm way late to this thread. But I thought I'd throw in some information about VFD's that I haven't seen anyone mention yet since there was some concern about there use on a surface grinder. I have zero idea about how the offshore VFD's are set up so they could be a whole lot different than the Baldor I bought. On it there's dozens of parameters and presets that can be user selected and adjusted. One is the maximum hertz, it easy to set it so it's at the normal 60 hertz and the motor can't go above that during a normal start. After starting I can still manualy run the motor up on the speed past the preset simply by using the up arrow until I reach whatever rpm I want while overspeeding the motor. But the VFD still holds that preprogrammed 60 hertz in it's memory. Any motor restart after that and using that same program list the motor will still only go to that maximum 60 hz every time it starts, so to get more rpm I again would have to manualy adjust the motor speeds above that preset limit. At least for the VFD I'm using I wouldn't think twice about using it on a surface grinder if I had one. But I'd make real sure I didn't add any speed presets for any reason into the program that pushed the motor up past that 60 hz limit. There is multiple buttons that can be set to start and run to far more or far less than the 60 Hz if you did want that on a lathe or mill and I do use them on my mill. They wouldn't be of any use on a surface grinder. Mines also somewhat idiot proof if you disengage the idiot part while setting it up for the machine it's being used on. When you did want more speed while using a smaller wheel you'd always have to make a decision to do so and manualy make the VFD do it. Anything electrical and especialy programable can of course fail at any time, ignoring those possible failures then fwiw any VFD that's set up to operate like mine does should be safe enough on a SG.

[earlgo]

Here is the pic of the end of my single diamond dresser. I'm glad this subject has been brought up as I'd never have looked else. It would appear that it is near the end of its life.

diamond

I think the diamond remnant is inside the red box as that is the place that glints when the light is right.
It still dresses the wheel as it should, though. It is held at a 15°angle to the wheel periphery.
--earlgo

[GlennW]

The entire gray area is the diamond as they are a tetrahedron shape bedded into the shank.

The area you refer to is just an inclusion.

It's seen better days, though!

[Conrad_R_Hoffman]

Good info on the VFDs. I love mine. Something else they do is ramp the speed up and down at a programmable rate. That prevents any shock to the system and, IMO, results in more predictable grinding. The person who sold me my grinder complained that every time he shut it down and powered it up, he had to redress the wheel. He had regular 3-phase from the pole. With my VFD I've never noticed anything like that. Wheel shift if not tight enough?

[Harold_V]

Wheel shift if not tight enough?

In my opinion, yes. The wheel should be tight enough to withstand startup without shifting.

H

[earlgo]

I did not know diamonds had inclusions, but maybe industrial diamonds do. In any case it appears it is getting to be time to retire this one.
--earlgo

[John Hasler]

That's one of the things that makes them "industrial".

[Cary Stewart]

Don't give up on that rock yet. Diamonds are mounted with something called spelter. It can be melted and the diamond turned to a new point. Might be worth a try. However, I can't remember any details about the spelter and what temp. it requires. Do some research. You didn't say what carat size the stone is. If less than a 1/4 carat it may not be worth the effort.
Cary

[Harold_V]

I did not know diamonds had inclusions, but maybe industrial diamonds do.

Inclusions are very much a part of diamonds. The lack of them, along with color and cut, make them all the more desirable.
Take a look at a reasonably sized diamond (in a ring) using a loupe (10 power or a little greater). You'll most likely see an inclusion or two. You have to train your eye to look in the diamond, not on the diamond.

When I refined, I dismounted a tiny one that was faceted single cut, maybe two or three points, that had a black inclusion roughly in the center. It was quite an ugly stone as a result.

H

[earlgo]

Cary: This was bought so long ago that I don't remember what fraction of a carat it is. Maybe I'll just use it until it no longer works. Only time will tell. But thanks for the information.

--earlgo

[Harold_V]

Often the diamond size is noted on the shank. Might help to examine it closely to see if you can find any numbers.

H