WTB: 4” Dia. T&C Grinder Index Plates

My HDT610 T&C grinder came with a 30 division index plate, which is fine for 2,3 &5 flute tools, but not 4. The OD of the plate is about 4” (100mm). It has 2 mounting holes, but I’m not picky if I can adapt it. Anything divisible by 4 would work.

I suppose I could just drill another pair of mounting holes, so the plate could be rotated 90deg., so that’s the PITA plan B.

Check fleabay. There are KO Lee index plates that might be modified to fit.

I have a bunch at the other shop will check next time I am there
Bob

Illinoyance said:

Check fleabay. There are KO Lee index plates that might be modified to fit.

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I already checked. The KO Lee plates are very similar but 3.25” dia. Instead of 4”.

You don't need a hole and pin index on a TC grinder. Notches on the OD of a disk and a snap finger works just as well/better.
24 is a good choice for 4 with 6 clicks.
The TC grinder can make its own 24 index by placing a 24 gear in front and fingering off that gear to notch the OD of a disk.
Possible you can 24 notch the OD of your 30 if it is a pin hole index.

OD notched indexes are much faster than a pin hole one.

Yes, you might make a 12 index.

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The one on left is 4" rest are 4 1/8 if they are any use to you free for shipping
Bob

bob said:

The one on left is 4" rest are 4 1/8 if they are any use to you free for shipping
Bob

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Thanks Bob, but as Buck said, I need the kind with the notches on the outside. I will make one if one doesn’t turn up. The one I have has 30 notches on the outside.

Making a new one is an interesting problem. The notches on the one I have are not straight cut, they spiral in. I am sure there are lots of ways to do that, but the way that occurs to me is to put the plate on a rotary table with the plane of the table parallel to the mill spindle axis, cut the notch edge on, and rotate the table to do the next notch. Each notch is about .060 deep.

I might as well make a couple index plates once I get setup. I checked my cutting tools to see how many flutes they have. My end mills are all 2,3,4 or 6 flutes. My reamers are 4,6,8,10 & 12 flutes. Dovetail cutters, t-slot cutters and key seat cutters have 10,12,14 & 16 flutes. Trepanning tools are the odd ones, several have 5 flutes. Saw blades too many teeth to count. Didn’t check the horizontal milling cutters, but those don’t get used much. So the 30 tooth index plate covers everything except 4,8,12,14 & 16.

So, it looks like if I made a 12,14 & 16 I would be good to go.

Is having notches at spiral needed? Making straight notches is so much easier.
I have made indexes with straight notches so a snap or spring finger would intersect. A two point finger can sometimes be handy. One point higher and one lower. perhaps one straight and one bent a tad. The function is to have one point the tooth rest, and the other to stabilize the tooth rest by bearing on another surface like the face of an index, or from a feature of the thing being sharpened.

Making index of mild steel you might use brass fingers so the index wont be harmed.

The rule of 87 can be used to drop cutter tooth below center to correct clearance angle needed.
3" cutter needing 8* clearance angle
3 x 8 x 87 = 2.088.. move the decimal and get .208 the needed drop.

I just did x 9 as that is plenty close enough anf you can think that in you head.

Good to go on the net and free download Cincinnati #2 TC grinder operator manual..it is handy with any TC grinder.

Some times indexing a cutter does not work, but to finger the tooth face and correct the heal off the face, and then grind the sharpening off the corrected heal does work.
Another, and best way is to OD grind the cutter a light tickle, and then grind the heal/clearance to just take away the OD land.

rimcanyon said:

I already checked. The KO Lee plates are very similar but 3.25” dia. Instead of 4”.

Click to expand...

I thot you had an Ellis DH // Indexer in your "treasure trove"?

A 24 slot index plate is standard.

If you have the Dividing plates (I have them all) it can then make more Index plates - which are faster to use and harder to FUBAR than the DH monkey-motion, thereafter.

Not in the same league as sync-geared K&T, B&S, etc. DH.

But then again, you can lift an Ellis with one hand, and the ability to EITHER crank-and-fiddle-fart-sector Divide or directly "spin" Index is downright lovely.

michiganbuck said:

Is having notches at spiral needed? Making straight notches is so much easier.

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Probably not needed, but making them would be a useful technique to learn how to generate clearance. I.e. if the index plates were being made on the T&C grinder directly, as you suggested above, you could plunge grind the notch, and if the holder could be rotated away from the grinding wheel to generate the clearance (on a center slightly offset from the index plate’s center), it would be a simple operation. I don’t have a holder like that, but I can see how it would work, so I might make one. Still thinking about it.

michiganbuck said:

I have made indexes with straight notches so a snap or spring finger would intersect. A two point finger can sometimes be handy. One point higher and one lower. perhaps one straight and one bent a tad. The function is to have one point the tooth rest, and the other to stabilize the tooth rest by bearing on another surface like the face of an index, or from a feature of the thing being sharpened.

Making index of mild steel you might use brass fingers so the index wont be harmed.

Click to expand...

Great ideas. I like the two finger rest idea and I get why a straight notch would help lock it in. Maybe the second finger should have some spring to it, and would bear on the index plate or holder to keep it locked in. I would love to see some setup photos... I’ll look for a Cincinatti T&C grinder manual.

likely I would have to see one to know how they are and how they work.
For the ones I made I would dress two sides of a straight wheel to perhaps 1/8" then incremental cross with a down feed on both sides off the part, I would quarte turn the part every once and a while so wheel wear would not show in the part. At desired depth I would quarter a few times to be sure to get a spark from all notches.

For a primary/secondary I would use the 87 rule and raise or lower my tooth rest finger.

Is your TC grinder the air spindle type?

I would do the OD with the air spindle and the run ends out of a work head, Tat seemed faster and keot the air spindle covered when needed.

The work head that came with the grinder is not an air spindle. I have a Harig air spindle for doing flutes.

I have been reading the Cincinnati T&C manual, it is a good source of information. If I am interpreting it correctly, the Cincinnati work heads have a built in eccentric to allow for relief grinding, so no finger adjustment is needed. I.e. the work head spindle must be bored off-center, so by rotating the outside of the spindle you can adjust the relief angle of the grind. That is just a guess, please let me know if the relief setting works differently than I imagine.

My work head does not have that feature, so raising/lowering the tooth rest finger (or raising/lowering the grinding head, if the rest is attached to it instead of the work holder) is what I need to do to generate relief.

Re[ If I am interpreting it correctly, the Cincinnati work heads have a built in eccentric to allow for relief grinding]

No, the Cinci work head is just a tapered ID and to center rotation only, with having the ability to tilt for angle. The primary and secondary are faceted or flat grind. One can grind the primary and the butterfly with increments rolling into the clearance to make a mock(phony) radial relief.

I used to do that with fingering to my index fo the primary, then come off the index to butterfly just to the next index notch so it gave the looks of radial relief for a specific distance