Lathe tool bit grinding attachment

Hi All,

Does anyone have any experience or feedback on using this Boyar Shultz tool grinding attachment:

Single Function Tools - Model G Boyar-Schultz SMT

Any advice or help would be appreciated

As you probably know from the link, those attachments are commonly used to grind HSS tool bits for box tools that are used with turret lathes. I have one of them along with the "manual" which is essentially a blueprint of the Model G with some basic instructions on the diagrams. I can try and scan that (in pieces) and send you a PDF if you are interested. If you want a full size copy and are willing to pay the cost I can see if a local FedEx or Office Max can make a digital copy in this size. Either option would take me a few days. PM me with an email address if you are interested.

Thanks Mike, pm sent


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jeffers said:

Does anyone have any experience or feedback on using this Boyar Shultz tool grinding attachment

Click to expand...

I've used one. I have to say it's a neat gizmo, but it really is single-purpose and doesn't work that much faster than a 3-axis toolmaker's vise. It's not totally idiot-proof in operation, and if you pre-computed the necessary vise axis angles and wrote them on a Post-It note (or job ticket) the equivalently trained operator could totally duplicate the "repeatable box tool grind" with a UniVise or anything similar.

If you're buying a used one, make sure the internal gearing works properly, or there's no point to it..

sfriedberg said:

I've used one. I have to say it's a neat gizmo, but it really is single-purpose and doesn't work that much faster than a 3-axis toolmaker's vise. It's not totally idiot-proof in operation, and if you pre-computed the necessary vise axis angles and wrote them on a Post-It note (or job ticket) the equivalently trained operator could totally duplicate the "repeatable box tool grind" with a UniVise or anything similar.

If you're buying a used one, make sure the internal gearing works properly, or there's no point to it..

Click to expand...

I want to use it to grind conventional has lathe tools, the gearing appears to work correctly, Mile has kindly offered to send me a scan of his manual for it


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Well, for conventional lathe bits (non box-tool) I'm not sure it adds much value. In fact, if you just ground a slot and put a clamping screw in a mild steel block with bottom and side faces at the right angles (think of the ubiquitous endmill sharpening fixture for surface grinder), you'd probably crank out your repeatable conventional tools with less fuss than using the Model G at some thing other than its sole purpose.

That would be an option but I would have to make several blocks to cover the permutations rather than just dial in the requirement. I grind my tools freehand at the moment without too many issues but the attraction of this attachment is to add a chip breaker accurately, I machine mostly 316 stainless and the “birds nests” that form are quite dangerous. I figured if it will grind box tools then it will grind lathe tools by maybe turning the attachment by 90 degrees? After all the only difference is that the tool cuts in a holder that is on an axis at 90 degrees to the toolpost?


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It's not my intention to discourage anybody from thinking outside the box, or doing things creatively. But I really think you'd happier in your stated task using a 3-axis toolmaker's vise (for experimenting with angles) or a dedicated tool block (when you settle on angles you like). The Model G does a good job at one thing, and is not real helpful at anything else.

When I sharpen a conventional lathe bit, I have six angles that define three surfaces meeting at a point. A chipbreaker groove or nose radius is in addition to those three surfaces. The Model G grinds one surface plus a chipbreaker; the other two surfaces are sides of the square tool bit blank. Plus, the one main face you grind on a Model G is oriented about 90 degrees off from the corresponding top face on a conventional lathe bit. This is because (generally speaking) the shanks of box tool bits are held tangentially to the work, rather than radially as with a conventional lathe bit.