Thread: Grinding Box Tool Edge

Hi All,

Learning some machining doing projects on a screw machine. Any good tutorials on grinding box tool bits. See attached photo. The guy that explained to me (once) said to use 13 degree angle, but I'm more asking about the relief and the best way to grind that. The angles and point on the edge are where I need to understand a bit more.

Thanks,

Tom

We need more information, like what make and model of box tool,....... there are many variations and a lot of different angles, then you add in the material being cut.

Yes, the picture shows a correct grind for steel. Brass would be different. I have a fixture specially made for that job, but have not ground a box tool in about 28 years, so i am a bit rusty. It should be done on a surface or cutter grinder with a sharp cornered wheel.

I never made brass parts on my turret lathes, but the grind is just a flat end. A new HSS tool bit has about the right grind for brass right out of the box, no chipbreaker groove or sharp back rake needed.

Larry

Originally Posted by Limy Sami

We need more information, like what make and model of box tool,....... there are many variations and a lot of different angles, then you add in the material being cut.

Sorry. This is for 304 stainless on a B&S screw machine regular box tool for shaping bar stock.

Thanks. I have a surface grinder and a fixture. I'll take some additional pictures and post them. Just trying to figure out the details.

Boyar-Shultz makes a grinding fixture specifically for grinding box tools called the Model-G that you use in a surface grinder.

Accessories

I grind the top of the tool with the fixture set @ 6 degrees. Then once that's done set the fixture at 35 degrees and grind the "chip breaker" into the bit trying to leave roughly .003-.005 land.

Depending on how many parts you are running its probably worth it to pick up a Micro100 Brazed Carbide bit. The "BT" series.

http://www.micro100.com/inch/inch_catalog.html

http://www.micro100.com/

Originally Posted by L Vanice

Yes, the picture shows a correct grind for steel. Brass would be different.
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Thanks for helping out Larry.


FWIW & IME, Roller boxes and short chipping brass are not a good idea, the tiny chips get under the rollers and cause dimension problems etc etc

Use solid back rests.

I recently offered all the info. you need for screw machine tooling, this info is now on PM. Look for B & S screw m/c booklets. Enjoy your time on these machines, I surely did

Okay, here are some pictures. The first is the box tool with the cutter in it and the rest are various fixtures that I have around the surface grinder. Which one is the correct one to use?

Thanks,

Tom

Picture 1 shows your box tool is missing one of the roller assemblies, probably needed for close tolerance work with good surface finish.

You don't seem to have either the Boyar-Schultz model G fixture or a Delta Omnivise, either of which are good for holding the bit at the correct angles under the surface grinder wheel.

Larry

Originally Posted by L Vanice

You don't seem to have either the Boyar-Schultz model G fixture of a Delta Omnivise, either of which are good for holding the bit at the correct angles under the surface grinder wheel.

Larry

Any idea of the price on the Model G and are they easy to find? Let me check ebay

Hmmm, only one there is $500. Wow.

I found this by the grinder, it looks kind of similar, but uses a collet.

You have a Simco Microgrind that uses 5C collets. It is not for box tools.

You can ask the current B-S company for the new price of the Model G. They look expensive. Note the picture on the Model G page is wrong, but the text is correct.

Model G

I only see one on eBay today, but the picture is good.

Larry

It took me a while to find it, but this thread on another forum shows that you don't need a Model G or Univise to do a nice job grinding box tools. Nice photo showing a very simple shopmade fixture.

The downside of the shopmade fixture is a fixed grind. The main distinction of the Model G is its internal gearing to generate a family of useful grinds. The Univise, well, ... it's up to you to figure out how you want to set it, but you can set it to anything.

Thank you, that thread is very helpful. There is a fixture in this shop for grinding these as I watched the previous owner do it before. I'll keep looking for an inexpensive Model G as well as practice with what I have for now.

I picked up one of those Model G grinding fixtures a few years back and it came with instructions on a single, large, blue-print page. Does anyone have a copy of the instructions in PDF form that they would be willing to share?

Mike

Originally Posted by B&SDude

Depending on how many parts you are running its probably worth it to pick up a Micro100 Brazed Carbide bit. The "BT" series.

Many thanks for that. I had no idea these were available.

FYI

Roller boxes with replacable inserts, self retracting too.

Roller Box Tooling Products | High Quality Rollerboxes | CNC Lathes

There are probably others.

We ground ours by hand, did not know of a fixture.

Originally Posted by Limy Sami

FYI

Roller boxes with replacable inserts, self retracting too.

Roller Box Tooling Products | High Quality Rollerboxes | CNC Lathes

There are probably others.

Thanks. Anyone know of ways / products that would allow me to use replacable carbide bits with my existing box tool?

Originally Posted by camscan

I recently offered all the info. you need for screw machine tooling, this info is now on PM. Look for B & S screw m/c booklets. Enjoy your time on these machines, I surely did

Thanks cam. I have those original booklets along with all kinds of B&S manuals.