DIY Cross drilled rotors

A few years ago, I purchased a drill press from harbor freight with the idea that I was going to build an AR15 lower by drilling out a piece of plastic.

That project failed due various reasons, and I haven't really used the drill until I decided that I was going to drill my solid rotor. Internet wisdom seems to indicate that drilling rotors are not necessary in this day and age due to the advances in brake pad technology. I've wondered why everyone sports drilled rotors on new vehicles, especially the high end sports cars.  I put a set of ebay drilled and slotted rotors on 2 of my cars and the braking improvement was so drastically better that I felt like I needed to do this for my old cb750c.

My original intention was to send the rotor out during the winter and pay someone $50 to do it. But I found a couple of drill patterns and thought I would give it a try.  Worst case scenario, I could just buy another rotor on ebay.  I may eventually upgrade the old 35mm front suspension to 41mm Nighthawk 750 suspension and brakes but that's going to wait for another year down the road.  I'm planning on swapping out the steering bearings this winter and replacing the headlight bracket over the winter so I may even keep the original front suspension. We will see if I lose interest in 2020.

The whole cross drilling project took me roughly 3 days of trying various approaches and researching.

Here's a couple of things I learned along the way. Clearly someone with machining or drilling experience would have done it easier and quicker but my dad never let me near the cars he worked on and I've spent almost ALL of my life behind a computer screen.

• Proper equipment is the only way to do it right. I can't imagine doing it with a hand held drill
• PPE - personal protective equipment: eye protection and hearing protection are required
• The harbor freight automatic carbide tipped punches don't go really deep and  doesn't last long enough to punch the whole rotor. figure you'll need 2 per rotor.
• The rotor is really hard, maybe from work hardening from years of braking or when I was drilling it. There were clearly some portions that were harder to drill than others.
• Sharpening bits is an absolute must. I was sharpening or swapping bits every 3 holes
• Pilot holes help to keep the larger bit from wandering. I had 3 or 4 holes that got off center in the beginning when I read that 1/4" holes didn't need a pilot. 
• Don't let the bit heat up because it goes dull faster
• Masonry drill bits stay sharp much longer and drill much better but sharpening them makes the bit smaller (ok to sharpen once maybe twice, but replace after that)
• Use oil at least twice for each hole
• Clean out the hole at least once while drilling, a shop vac keeps the work space tidy
• Stop drilling once the oil starts smoking. Work up a cadence drill 20 sec, wait 1 min etc.
• Press hard enough to get chips but not so hard as to get twisted strings of metal
• I didn't have good luck using harbor freight titanium coated bits even after sharpening them
• The process was frustrating and loud but ultimately rewarding.
• The braking ability has improved and I expect it to get better once the old pads bed in.

New HH pads would be nice, but I'll reassess in 2020 when the front suspension direction becomes clearer.