Annular cutter grinding

[Clarkie]

Hello from Brisbane in Aus. I'm new at this so be kind. We are setting up to sharpen annular cutters as part of our service to customers. Can't find the golden key for the info box, or not much info about? Any info regarding setup of cutter to a datum point or center height prior to grinding would be appreciated.

[Big]

I would really like to find a tutorial for this as well. I picked up an old tool grinder that was solely designed to cut engraving cutters (V shaped tip) that are used for engraving and cutting wax models.

Can anyone help on where to find a tutorial on how to setup and grind the blanks to cut/sharpen 1/8 inch shaft, 15 degree(full), .005 thou tip cutters?

Thanks,
Greg

[VWSatOz]

I know what a Dbit grinder is, but what do you mean by an annular cutter?
Are these the hollow multi-tooth cutters used like on a Rota Broach? to drill big diameter holes in plates?

Your Dbit grinder should have an instruction manual.
It depends if the grinder has a collet-spindle that can be offset from the pivoting axis or not. A pivot axis allows you to sharpen a radius on the tip of the the tool &/or on the cutting corner if it can be offset.
The clearance angle must usually be quite high just to be able to leave the cutting edge raised sufficiently above the root-round that is left behind.
I used to make fancy form Dbits with offset radius & angle on the side, and THEN use a Nikon profile projector to measure exactly what resule I had, THEN use EzCam 2D to work out out what cutter path offset was reqd to CNC mill the result/profile I wanted.
For simple engraving cutters for plastic just try maybe even as high as 40degrees clearance angle, then gently by hand, use a fine hone stone to remove the tiny sharp-pointed tip until you get the tip diameter that you need

[Clarkie]

Yes annular cutters are the family that includes Roto Broach, Slugger and other brand names. There is 2 main regrind styles- std and stack drill grind.
Regards
Clarkie

[Switcher]

Is the attached image the same type cutter your working with?

Do you know the specs. already, If not do you have an optical comparator, that you can use to reverse engineer.

The way I would re-sharpen that is with a 11V9 grinding wheel.

Are you going to re-sharpen the cutters on a cnc?

The photo I attached looks complicated at first sight, If you only focus on 1 tooth, it really only has 2 lands on the back of each tooth, so find out what each angle is, then sharpen the small land on the back of the first tooth, then divide by the number of teeth (attached photo has 8 teeth) 360/8 = 45.0 deg., index the cutter 45.0 deg. & repeat until all the teeth are done, start back at the first tooth again for the second op., then the same thing as already done only with a sharper clearance angle than the first land that was sharpend.

Just be careful not to get into the tooth behind whatever tooth your working on, & do all the rough cuts in 1 setup, then do all the finish in 1 setup, just keep indexing to keep things balanced (wheel wear, etc...)

Again only focus on a single tooth & it won't look like much work, just keep repeating after you get that first tooth correct.



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[Clarkie]

We recently purchased a small Servian T&C grinder in good cond but no work head, also a Macson ( like a Cin No 2) with all the bits but not running. The Macson workhead has been rebuilt and is too large for the Servian. It could be mounted on a sub plate but would end up over the hand wheels.Still making up our minds wether to rebuild the Macson or find a smaller universal head for the Servian.
Also bought a Cawi drill grinder - 20mm cap. What a mechanical wizard. It has 3 chucks with 6 rods in each, that locate in a rotating head. This head appears to have a gearbox that alters the number of cam cycles per rev of the head to allow for diff flute numbers in the tool.
Fitting this in when down in staff and bus is slow makes for a long day. None of us served our time in a tool room, another apprenticeship is on the go.
Any idea on manuals for the grinders?
Hope this forum grows as info is realy needed on the subject.

Thanks
Clarkie

[smiths]

Hi Clarkie

Your situation sounds like mine, six month ago. Started sharpening annular cutters. Found that cutters coming in had been sharpened with many differant angles, even ones of the same make.
A optical comarator is only good if you have new cutters to compare, other wise you may be copying someone elses mistakes.
I do have the instuctions for Walter, Slugger and Jetbroach. I will try to attach, if does not work ,inbox me with your fax and I will send them down.
( p.s If anyone has the instructions for other brands would sure like the help)

Smiths.

[Clarkie]

Hello from Brisbane Australia. Thanks for the info you sent. I have a copy of a Hougen sharpening machine manual and some Slugger geometry in hard copy. If you email me I'll try to scan it and send it back. Not yet good at this computer thingy. We are setting up an air spindle with 5C collets.
Regards Bernie Clark
clarktech@bigpond.com

[ikaplan815]

New annulars are typically made on higher HP 5-7 axis CNC tool and cutter grinders. The material is of the M series and ground best with CBN. The geometry can be made with A1 and V1 wheels. Interpolation is the key.

[Clarkie]

Hello again from Aus
Finally we are sharpening cutters. A air spindle with 5C collets is used as a holder. This can swivel either side to setup each tooth facet. Primary clearance is provided by tilting the wheel head back. Our main problem was lack of confidence and not realising the tilted head causes the wheel to clear the tooth above that being ground.
A 38A60JV flared cup wheel gives a good finish, though a CBC wheel will be ordered soon.
The next project is the Cawi drill grinder, so far I've had no luck finding a operators manual, so it's all guessing.
Has anyone a recomendation for software to use with a 4 axis CNC machining centre to do this operation?