Drilling brake Rotors

[Mr.E]

In the course of my build, I'm planning on drilling my brake rotors, and was wondering what the general opinion of this is? I've heard some for, some against. Also, to do this, I'll be making a jig to mount the rotor on (CB750), and was thinking that if anyone would like this done but doesnt have the means to, I'd offer the service for the price of shipping, since I'd already have the jig made, may as well get some use out of it right? All this depends on me NOT getting layed off in the comming weeks at work, as they are really tightening the belt there this summer I'll be playing with some patterns in the next couple weeks, so anyone having ideas please let me know! I'd like to help out as best I can around here, you guys have been a big help to me in the short time I've been lurking the boards.

 

[Mach-5(50)]

If you haven't found them already, there are several styles and patterns with templates available to download at sohc4.net. I haven't tried drilling mine, but I imagine I would look to go a similar route. (I don't have a 750 either). Maybe this helps?

Ryan

 

[NOZ69R]

I tried it on one of my previous builds & found it very difficult to drill into used rotors.

I'm presuming its because the rotors have been tempered from use, or it could of been from my cheap drill bits.

Good luck.

 

[diesel450]

Noz,

Were you using a drill press? I want the rotor drilled on my CB200 but if its a real pain I may just look for one drilled already. Also, I've read that you have to start the hole small and then gradually enlarge as you go.

 

[NOZ69R]

Noz,

Were you using a drill press? I want the rotor drilled on my CB200 but if its a real pain I may just look for one drilled already. Also, I've read that you have to start the hole small and then gradually enlarge as you go.

Diesel,

Yes I was using a drill press & started with 2mm and worked up in 2mm increments up to 8mm, it can be done but it takes some effort & a lot of drill bits.

If you are using quality drill bits and possibly some cutting fluid it would make it easier, but me being a "tight ar$e" I persevered with what I had.

Cheers

NOZ

 

[diesel450]

I hear you mate. Spend the $$ on bits to do it once? Or try to make do? A constant battle.

 

[Mr.E]

well I figured I would just set up a progam to use some carbide drills we have and let it run overnight...not like we are doing much else in the shop I figure this place has a month of steam left in it, then I'll probably be back in the market again-but until then I may as well make hay while the sun shines right? I'll check out the patterns on sohc4.net, I had no idea ppl post stuff like that, thanks mach-5. As far as drill bits go, I ALWAYS center drill before stepping up to a regular bit. And, for good drill bits, Fastenal has some good ones available brand named Norse.

 

[paultsmith]

I drilled my front rotor and was surprised how easy it was. I think I used a 1/8" bit followed by a 5/16", and then used a HSS countersink bit to clean up the edges.
I bought 1 bit in each size and they are perfectly fine now, plan on doing 3 more rotors. I used Cobalt bits.
The trick is to go fairly slow and use lots and lots of cutting oil. I was surprised how easy it was, I was cautious as I heard a bunch of people saying that it would be difficult and hard to drill through, but it was just like any regular drilling on my drill press.


It looks like bit strength goes from weakest to strongest in this order:
- regular Steel
- High-Speed Steel (HSS)
- Titanium coated HSS
- Carbide-Tipped steel
- Cobalt steel

The problem with the coated or tipped is that once the coating wears off, you are stuck with a regular bit.

 

[Mr.E]

I drilled my front rotor and was surprised how easy it was. I think I used a 1/8" bit followed by a 5/16", and then used a HSS countersink bit to clean up the edges.
I bought 1 bit in each size and they are perfectly fine now, plan on doing 3 more rotors. I used Cobalt bits.
The trick is to go fairly slow and use lots and lots of cutting oil. I was surprised how easy it was, I was cautious as I heard a bunch of people saying that it would be difficult and hard to drill through, but it was just like any regular drilling on my drill press.


It looks like bit strength goes from weakest to strongest in this order:
- regular Steel
- High-Speed Steel (HSS)
- Titanium coated HSS
- Carbide-Tipped steel
- Cobalt steel

The problem with the coated or tipped is that once the coating wears off, you are stuck with a regular bit.

Right on man! Cobalt is my fav for drilling the tough stuff. Those Norse Bits are all cobalt, I've even drilled over 15" of material (5 3" plates) at 7/16 dia. of h-13 at 45Rc between sharpening with them. The right tools make it so much more enjoyable to work. I'm interested in these carbide ones, tho, as I've only used carbide endmills before, and they work great for steel removal, but I dunno about drilling...

 

[goodfornothing]

I have to emphasize as stated above, use cobalt bits and drill SLOWLY. This means (by a hand drill) squeezing the trigger, for a couple seconds, then letting off, and doing it over and over. Cutting fluid helps. I was using titanium drill bits while holding the trigger and pushing down hard. Doing this will result in craters that will go nowhere.

I still yet to buy cobalt bits and finish drilling my rotor. This will probably be done in a couple of weeks as I work on my rearsets.

 

[souperman]

Cutting oil is not optional as far as I'm concerned. It will make your bits last 10x longer and keep the disc from getting too hot and possibly warping. A pilot hole will also make the process a lot easier and probably quicker even tho you are drilling every hole twice. I did my disc with a pattern I made in autocad. It took me about 45 minutes with a drill press and only 2 bits of each size. I also lightly chamfered mine.

 

[Fishhead]

Cutting oil and slow speeds are needed. A drill press helps out alot also. Cobalt drill bits also. A drill bit sharpener is worth getting if you drill alot of discs.

I have a mill and when I am drilling discs, the disc(s) need to be centered on my rotary table (pic 1) to get the holes an equal distance from the center and edge (to get the holes on one side the same distance from the edge on the other side-symetrical).

The discs sit out past the "table" part on my rotary table and need to be supported from underneath (pic 2).This keeps the bits from breaking if the discs should flex while being drilled. Its alot nicer to do 2 discs at a time when doing it on the table (cuts down alot of time)

CB 750 SOHC drilled discs (pic 3)

The rotary table is nice as the holes can be "degreed" and very accurate (ie- every 60 deggrees gives a "6" pattern,etc) and it makes it easier to "slot/groove" the disc (pic 4) for a unique look.

 

[Fishhead]

Forgot pic 4

 

[jmeperu]

i second fishhead.
use cobalt bits,
start with small holes and work up to the actual size hole you want,
low speed and high torque on the drill press,
lots of cutting oil so the bit doesnt over heat,
if you overheat stainless steel it will harden and make drilling 10x harder and wear out you nice new cobalt bits,
take your time (it takes forever btw)
its worth it when you are all done, looks great.

i come from a motocross background and we use drilled rotors for dry conditions and solid rotors for wet/muddy conditions to avoid buildup and ruining pads. probably doesnt matter on a street bike.

good luck

 

[Zonda]

i second fishhead.
use cobalt bits,
start with small holes and work up to the actual size hole you want,
low speed and high torque on the drill press,
lots of cutting oil so the bit doesnt over heat,
if you overheat stainless steel it will harden and make drilling 10x harder and wear out you nice new cobalt bits,
take your time (it takes forever btw)
its worth it when you are all done, looks great.

i come from a motocross background and we use drilled rotors for dry conditions and solid rotors for wet/muddy conditions to avoid buildup and ruining pads. probably doesnt matter on a street bike.

good luck

Here's what i did, have a read and you decide, but from what i've read so far, the advice is spot on

http://dotheton.com/index.php?topic=5846.105

Rod from OZ 8)