Topic: Drilling Rotors

[Terry in Australia]

Dammit, now I want a blanchard grinder, I think I've got tool envy! I just spent a few hours drilling a couple of discs for my K1, (the front wheel on the bike at the moment is actually a Suzuki item) what a nightmare that is!

One disc was great, the cobalt drill bit chewed thru it like a hot knife in butter, but the second disc must have been a different stainless mix, it took twice as long as the first one, bummer! Cheers, Terry.

[Zane]

Here's a cheaper one (ebay item # 180099933435).  Not really a Blanchard though - but only a couple hundred bucks compared to $35,000.00 (US) for the one above .....

You could buy it for 250, say, and then pay the other 34,000 to ship it to Melbourne.   

[Terry in Australia]

Here's a cheaper one (ebay item # 180099933435).  Not really a Blanchard though - but only a couple hundred bucks compared to $35,000.00 (US) for the one above .....
You could buy it for 250, say, and then pay the other 34,000 to ship it to Melbourne.   

Looks good mate, got a link? 

[bryanj]

Clean up the caliper and master, fit new pads and just use it, Done that to far worse in my too many years and its always been OK

[Zane]

Looks good mate, got a link? 

Search the item # on ebay if you want to see the listing.  Unfortunately (or fortunately, as the case may be) the guy only ships to the Americas.

Actually, I posted the picture because I thought the idea of modifying a milling machine to work as a grinder (after a fashion) seemed interesting (and evidently reasonably economical). 

It would take someone with a more experience than me though, to say if such a modification was a useful idea.

In my case, with my 400F rotor, I found that after I drilled it, over time it seemed to smooth out the surface of the rotor.

I've also heard (I think - my memory isn't what it used to be) of replacing the pads with something abrasive to stainless steel, running the brake with those for some time (very carefully, I would imagine) and that this will smooth out the rotor.  I'll find out from my friend who told me that, what the stuff you use in place of the pads is, actually.

[Terry in Australia]

Sorry mate, you're quite right, the info was there right in front of me all the time, I really shouldn't drink so much, ha ha! Good idea too, I've already got the rotary table for my mill/drill (fantastic for drilling rotors) so all I need is to find a grinding attachment. Cheers, Terry.

[speedracer741]

tsflstb, when you gonna get that thing mounted? Your rotor only took a few thousandths per side to clean up.

Didn't realize you were the same guy that did the ebay auctions.  You do good work.  Glad it stayed in the "family".

I'll get the rotor mounted soon...got sidetracked when my transmission siezed up a while back and never got around to it.  Working on getting my other bike running now so I can still ride while I tinker with the 400.

Thanks! Yeah I would say a siezed transmission would put a damper on things. Hope the incidnet wasn't too eventfull while you were riding

[ProTeal55]

yO,

I am gonna take a wack at cross drilling the rotor on my CB450 project, and wanted to know what others have used as far as drill bits ? I know these rotors are hard as hell, and I ALSO know I am gonna need better drill bits then what I currently have...

So...

What kinda drill bits should I buy that will handle drilling thru a rotor ?
As usual, all help is great appreciated 

[tmht]

Using a drill press or a mill? I did mine on a mill and used the crappiest drill bits I could buy at Harbor Freight. I think they were something like 8 for $2. I ended up using 3. I don't know if you can get the same result on a drill press as ours is only single speed and doesn't have the torque to drill rotors.

[lrutt]

I did it once before, 3/8's. I bought the best bit I could find and used a lot of oil during drilling. Did 3 rotors though with the same bit. that was a long time ago though, before they had the Ti coated bits. I think it was just a very good carbide bit. Secret it lots of oil and don't rush it. Don't get things hot.

[ProTeal55]

I will be drilling the rotor with a drill press my buddy has at the post office.
So I guess I should just go get some decent bits and use lots of oil eh ?
Sounds simple enough...

[Steve F]

Joe, you're gonna need COBALT bits, and the shorter the better.  What diameter holes are you putting in?  Just remember to keep the speed as slow as you can and the feed heavy to avoid work hardening the material.  The rotors really aren't that hard, and I drilled three whole rotors with just one bit.
You got my phone number still? call me if you have any questions.

[chrisf]

SteveF hit the nail on the head. Put the drill on the slowest setting and use good cutting oil. I too like cobalt bits. Just don't drop the

--Chris

[Jim F]

Steve hit when he said you need COBALT

rotors are a very tuff stainless steel

If you can find a Titanium nitride coated cobalt drill that is the best

and keep it as short in length as possible

good luck

Jim

[Jinxracing]

Even with short bits, cutting oil, slow speeds, etc, you're probably gonna dull/chip cobalt or solid carbide. Do you have a Drill Doctor bit sharpener? No bit's gonna do you any good once it starts to get dull, and they start to get dull pretty darn quickly.

If I didn't have a Drill Doctor handy, I'd buy a dozen HSS bits (or cobalt if you're feeling wealthy) in the size required and go to town. You can use a center drill to start the holes which will take some of the strain off of your regular bits and it will also give you a little edge chamfer, then just finish them off with your regular bits.

[LoopsAndLogic]

Where would I find instructions on drilling rotors?

All that comes up on google is for cars.

I would be drilling rotors for a CB400F.

 Is 500rpm slow enough for drilling or is something like 350rpm better. My drill press for 12 years just went.

I would like to base my next drill press on the proper rpm for working on my bikes. Like Speed holes, rotors and tapping for aftermarket parts.

Thank you

LL

[tmht]

Where would I find instructions on drilling rotors?

All that comes up on google is for cars.

I would be drilling rotors for a CB400F.

 Is 500rpm slow enough for drilling or is something like 350rpm better. My drill press for 12 years just went.

I would like to base my next drill press on the proper rpm for working on my bikes. Like Speed holes, rotors and tapping for aftermarket parts.

Thank you

LL

Jeff Chennevert (sp?) from the 400 yahoo list developed a template for the 400. It's a pretty simple procedure with a template, overlay the template, mark the holes and drill. I had the mill turned down pretty low, If I had to guess I would say ~300 rpm maybe a bit less. I am sure someone around here may have the .pdf file with the template,

[Jinxracing]

Where would I find instructions on drilling rotors?

There have been quite a few posts on here about drilling rotors, I imagine you'll find as many different techniques as there are people doing it. I even remember one thread that had a template for laying out the holes (I'm assuming you don't have a rotary table).

Is 500rpm slow enough for drilling or is something like 350rpm better. My drill press for 12 years just went.

That's really dependent on what size and type of bits you'll be using, what material you're drilling, etc. Feed and speed charts will give you hard numbers, but those rates are usually geared towards production machining...slower is usually better. Most presses seem to give you a fair range of speeds if you don't mind changing belts around, but the spindle runout and chuck availability on most presses bug me. I'm using a small benchtop mill for milling and drilling with infinitely variable speeds and a decent keyless chuck. I won't be making parts for NASA with it, but it works worlds better than a regular drill press.

If you want your rotor to look like it came from the factory with perfectly spaced, burrless sharp-edged holes, I don't think you'll get there with a regular old drill press. But with a good drill press, sharp bits, a little luck and LOTS of patience you should be able to get pretty close. Like everything else, it all comes down to how much you want to spend.

[ProTeal55]

Well I am def. gonna give it the old college try and drill the rotor on my CB450.
I might wait to do it till after next weeks Rockers Reunion Bike show/run I wanna debut my bike it. I dont wanna crack this rotor or screw it up a week before the show (my luck I would/will)...

[LoopsAndLogic]

Well, after looking into mills. I don't think spending $500 for the one a HF is a good idea. Unless someone has tried that model??

Where would I even look for a good mill?  Hardware shops don't carry them.

I just found a site that does have a template for my 400F. Took me awhile to find it, but it was well worth it.

One last question on drilling. Would I need to taper the out side edges with a slightly larger bit or do you want them to be perfectly sharp??

Thanks again for the help

LL

[Jinxracing]

Well, after looking into mills. I don't think spending $500 for the one a HF is a good idea. Unless someone has tried that model??

This is the one I've got: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47158
It's not what I would call a "good mill" out of the box. It works great for precision drilling (once you ditch the chuck that comes with it), and I can make nice parts with it but it took some setup work to make it nice...lapping the ways, tramming, etc. $300 is as cheap as they come, and it's very limited in the size of work you can do with it. Having said all that, I really like it and use it very regularly for all sorts of machining operations. If I had it to do all over again though, I would save my pennies and buy one of these: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93885 I've heard good things about them; they're still small enough to fit in a garage shop and are supposedly much nicer in construction than the usual Harbor Freight fare.

Where would I even look for a good mill?  Hardware shops don't carry them.

Hardware stores are definitely not the place to go. Even inexpensive "real" mills will run well into the thousands of dollars. Unless you've got lots of money lying around and/or want to start a commercial machine shop, Harbor Freight is a decent place to start. Watch out though, once you get into machining, the price of the initial machine is only about 10% of the money you'll end up spending; accessories and attachments are addictive and expensive. Kinda like motorcycles I guess. 

One last question on drilling. Would I need to taper the out side edges with a slightly larger bit or do you want them to be perfectly sharp??

I'll be chamfering the edges of my rotor holes with something like this: http://www.use-enco.com/CGI/INSRIT?PMAKA=369-0641&PMPXNO=942834&PARTPG=INLMK32
I don't know that it's absolutely necessary to do so, but I'm doing it anyway.

[rbmgf7]

i just drilled my KZ rotor and all i used was a HSS bit and drill press. i just used a template to plot points and clearly marked them.

like everyone is saying, set the speed on the lowest rpm (in the neighborhood of 250-300 rpms) and just ease the press. don't try to powerf*ck it and get in a hurry. the rotor has gone under numerous heat treatment processes from braking and cooling so it's very hard.

it took me about an hour to do 50 holes. if you do need to resharpen the bit, make sure you sharpen it at 118 degrees (drill dr. will do it automatically. it takes experience to freestyle it on a grinder  )

mill with a rotary table would be the ultimate way but unless you have access to a machine shop, any decent drill press will do the job.

Be sure to get rid of the burrs! don't want someone chewing up their pads because of burrs. I just countersunk the holes with a larger bit.

someone stated earlier that the rotors were made of stainless. not really. just a mild carbon steel. we just take better care of our bikes and can't watch them rust like the rotors on our daily drivers 

[Chicago550]

Hey ProTeal, how difficult is it to set up dual discs? BTW, I don't think I ever got back to you about Triple O. He does great work  but was really pricey, those Italian bike owners must like to spend $$$. I worked with a guy who recommended Motoworks. I am really trying to do as much work myself as possible (this is hard since I live in the city and don't have a garage to work in).

[eurban]

someone stated earlier that the rotors were made of stainless. not really. just a mild carbon steel. we just take better care of our bikes and can't watch them rust like the rotors on our daily drivers 

No, all the stock rotors I have seen for the sohcs are stainless steel.  No rust but they may not perform as well as mild steel ones.  Some of the aftermarket rotors may be mild steel.

[cb(r)]

teal,

I am not sure what the mat'l of your rotors are but I completely agree with stevef:  short cobalt drill, the feed...
I would like to add a few things things though.  definintely use a combination center drill/ countersink.  you can buy this for a few bucks  and it helps so the actual drill does not walk.  also I use a coolant called "cool tool II"  I mainly use it for drilling and tapping 304 stainless and other tough alloy  even cast mat'l and it works great!  might be a little costly?  I buy it in minimum of quart containers but I think they sell small versions.  if interested in drills coolants and center drill.  then look at
www.mscdirect.com  they have store in tinley park  wood dale and rockford.  I believe you are in the chicago area?
they also have next day ship.  hope this help!

one last thing to reduce burrs (stainless)  and chipping (cast)  clamp your rotor directly to a backing plate made of aluminum.  where the opposite face of the rotor that you are drilling  is in direct contact with the aluminun plate.  I used thicker more ridgid and flat aluminum.  aluminum also adds a heat sink.  this in not necessary but very helpful