Driling My Discs

[xschop]

cobalt

i used cobalt bits. and a press...

[mason79]

it appears to me the split point would not center into the centerpunch reference and walk, is this not true?

[DiverRay]

A LIGHT pressure as you start will keep the bit on center. I used one bit for my rotors, and I did bolt together the two front rotors so they would be a mirror of each other.
I also used a large plastic "planter dish" as a catch for the oil. it keeps the mess WAY down. I put some small bits of 1X4 wood under the rotors, and then kept the oil flowing as I drilled. It took about 1 hour per rotor.
Ray

[mason79]

Originally posted by DiverRay
I did bolt together the two front rotors so they would be a mirror of each other.
I also used a large plastic "planter dish" as a catch for the oil. it keeps the mess WAY down. I put some small bits of 1X4 wood under the rotors, and then kept the oil flowing as I drilled. It took about 1 hour per rotor.
Ray

diverray,
did you drill the two rotors bolted together? is that the reason to bolt?

and was the dish between the stand and the woods?

[DiverRay]

Yes, that was the reason for bolting them together. I was able to drill through two disks in just a little more time than one would take. It is harder getting the bit aligned and started than drilling.
I bought a large diameter, 4" deep plastic "pan", put the wood in, and put the rotors on the wood. I turned the complete assembly, not just the rotor, as I started a new hole. I did keep the cutting fluid flowing, with a "squirt" bottle to hold it. I mostly let it dribble down the bit as it turned.
Ray

[TopCatGr58]

Originally posted by mason79
it appears to me the split point would not center into the centerpunch reference and walk, is this not true?

Mason,
The tip of the bit is complete, it's just split down the edge of the cutting surface. Here's a photo:

T.C.

[mason79]

Originally posted by DiverRay
Yes, that was the reason for bolting them together. I was able to drill through two disks in just a little more time than one would take. It is harder getting the bit aligned and started than drilling.
I bought a large diameter, 4" deep plastic "pan", put the wood in, and put the rotors on the wood. I turned the complete assembly, not just the rotor, as I started a new hole. I did keep the cutting fluid flowing, with a "squirt" bottle to hold it. I mostly let it dribble down the bit as it turned.
Ray

what happen to your clamping the unit down? none?

[Dennyz]

My pattern

[mason79]

Re: My pattern

Originally posted by Dennyz

no offense to anyone else but i like your pattern the best, slick

can you send me a pattern?

[pggg]

Again, DON'T do what I did, the holes are supposed to stop these streaks on your discs - only if the pattern of holes cover all the swept surface so drill em' different on each line

[Ken Talbot]

Originally posted by mason79
it appears to me the split point would not center into the centerpunch reference and walk, is this not true?

Actually, a split point centers much better into a centrepunch mark. For illustration, here's a shot of a freshly ground 135 degree standard point. Notice the fairly wide, flat section in the middle of the bit. As you start drilling, this section does not cut at all. You actually force the bit into the metal a small ways so the flutes can start digging. This is also part of the reason why a standard grind bit wanders so much.



Next, here's a shot of the same 135 degree bit, but this time with the point split. Notice the gap right in the middle where the wide, flat saddle has been ground away. Now, there are two fine, sharp points ready to start removing metal as soon as the bit contacts the workpiece. Those two points are close enough they both sit nicely down into a centrepunch mark.

[TopCatGr58]

Hey Ken,

I stand corrected, cause your photo clearly shows the split on the actual tip, not halfway down the side of the cutting surface like the one I showed!? I guess what I found was actually Split "Tip", but not Split POINT?? I've got some bits where theres a small groove cut into the cutting edge about halfway down from the tip!

Learn something new every day on Channel 11!
T.C.

[Dennyz]

The holes on my rotors overlap to prevent streaking.

[Dennyz]

can you send me a pattern?

I don't have a drawing of the pattern to send. The pattern is pretty easy to set up, however.

If you notice, the top hole lines up with the previous set's bottom hole. This makes it easy to create a template that locates on the rotor's center hole and only has locations of one set of holes.

I center punched a set of holes, rotate the template (indexing with the last (bottom) hole and punch another set.

To make sure the right side and left side would match. I started from a rotor mounting bolt hole.

[DiverRay]

Mason,
I (gasp) held the disk down by hand!! And no, it wasn't that hard, There is a LOT of mass, so it didn;t try to spin very much.
Ray