Tool rest on 6" grinder

[Batmanacw]

I'm setting up a grinder with white AO wheels to cut hss for lathe tools.

Do you set up your tool rest on center with a 6" grinding wheel or kicked back to create a bit more clearance?

 

[Jake M]

That depends on the size off your wheel, and the size of your turning tools, as the height you're actually looking for is not the rest height, but the height of the top of the tool bit. That's the one that gives you useful geometry. It'll "probably" be on or just a whisker above center, and you can fine tune that to get just the angle that you want, on the HSS blanks that YOU are using. Raising the rest makes more angle, lowering it makes less. Provided it moves parallel. You're really only interested in the theoretical plane of the tool rest, and how that is oriented to the centerline of the grinder spindle. You could have the rest at any height you wanted in theory and it won't matter, so long as it's angled appropriately.

A thought to bear in mind- Food for thought as you move forward. A rest is a wonderful crutch to get started grinding high speed steel blanks, as you figure out how to make it all work quickly and efficiently. You'll soon be wanting different angles on three sides of the tool though, and it's a pain in the tail feathers to have to reset that all the time, test it, verify it, fine tune it, and finally get another angle. Setting it low, and using shims can do that. ("sheet metal" range, not really foil, not really "steel", for hobby sized tools). That's still a pain. In the end, a lot of folks just ditch the rest all together, as freehand is far faster, more flexible, and more efficient. Me, personally.... I'm not that steady, I'm prone to end up launching that tool bit somewhere. So in the end, unless I'm doing something that A, I can "set up", and B, that is worth "setting up", I keep the rest such that it's not so much a tool rest, but a hand rest. I do a lot better at freehand when I have room to move my hand unobstructed for the "sweeping" bits, and can brace my hand against something for the long, (long,... long............) initial grinds on a fresh blank.

 

[DavidR8]

For what's it's worth I have a Wolverine grinding jig. It's not that pricey and super well made. I use it on 6" grinder for my lathe (wood and metal) tools. It's primarily aimed at woodturners but the platform is super solid and easily adjusted.

I keep the rest on wheel centre, and close in for HSS blanks. Wood lathe tools are huge by comparison so doesn't need to be as close.

 

[ChazzC]

I'm setting up a grinder with white AO wheels to cut hss for lathe tools.

Do you set up your tool rest on center with a 6" grinding wheel or kicked back to create a bit more clearance?

The tool rests on my 8” Delta have two adjustments which work together to set height, angle & clearance. The rest should be close to the wheel to prevent your workpiece from being pulled into the gap.

 

[homebrewed]

My approach has been to set the tool rest on my grinder so it will grind about a 10 degree angle. That gives me a reasonable angle for the various reliefs you need. Then all the facets are ground by presenting the bit, sitting flat on the rest, to the wheel. To make it easier to consistently get those angles I set my machinists protractor to the angles I want and use a Sharpie to draw lines on the bit. Then I just grind parallel to the lines until all the facets are where I want. The last step is to lightly grind the end of the tool to put a small radius on it.

This approach is based on a PDF I found on the Little Machine Shop web site. That document also has recommendations for relief angles more appropriate for aluminum and brass; but I've found that 10 degrees works OK for them, too At least for me.

So no frequent angle changes, just set it and forget it. Much of the time, anyway