drill bit selection

[Rapid Robert]

which of these drill bit types would be the best/hardest? titanium or black oxide. drilling block oil passages where if a bit breaks the block is junk should I use a cheapie if it would be less likely to catch & break or the best/hardest I can get? thank you for your time. RR

 

[YY1]

Neither.

Cobalt.

 

[Rapid Robert]

Alright cobalt it will be

 

[YY1]

Didn't see the rest of your post.

Not qualified to comment on that part.

However, I have only bought one drill bit since I switched to cobalt about 3 years ago.

One.

1/8"

Because those just break from a bad drill angle.

Kind of hard to find cobalt, and they're about 2.5 times the price of "regular" bits.

...but as far as keeping an edge, they far outweigh getting new ones every few months.

I attempted to re-sharpen bits a few times...and learned that is not "for me".

 

[Desoto291hemi]

Block would not be junk
It might be difficult to remove but it can be done

Tommy

 

[Inertia]

I hope it's an easy block to replace.

 

[BSB67]

which of these drill bit types would be the best/hardest? titanium or black oxide. drilling block oil passages where if a bit breaks the block is junk should I use a cheapie if it would be less likely to catch & break or the best/hardest I can get? thank you for your time. RR

Curious as to what your application is, and why you are wanting to drill oil passages.

 

[LO23M8B]

I've always had luck with the HSS. If you can still find real HHS. My sets are about 50 years old. I've never compared them against cobalt. I don't sharpen anything smaller them 1/8 and I buy the 1/8 buy the pkg. 10 at a time for my pilot holes.

 

[Dana67Dart]

I drill and tap Stainless. I broke 2 taps (run of the mill hardware store) but now only buy HSS, they are good for 4 or 5 tapped holes.

If you can have a machinest do it that would be your best bet. (Plus younger insurance of sorts) They know about speeds and feeds and lubrications that the average joe ( like me) just guesses at.

 

[ch1ll]

If your drilling out oil lines, cobalt is going to be your toughest, but it going to take a long drill, like 9 inches, right? That's going to be expensive in cobalt. A 9/32 or 5/16 drill that long is going to twist and chatter cause it's just cutting on the outside edges. To stop all that, flatten the cutting lip on a grinder and radius the edges. That will keep it from grabbing and chattering and the radius edges will give it more cutting surface area. I can post a picture of one sharpened like this if you want. Also start with a shorter drill bit and drill in 2 inches or more before going to the long drill. Use a drill press if you got one and blow out the chips every inch or so when you feel the chips binding up with compressed air. Also your going to have to reshaped the drill often.

I'm a life long tool and die maker.

 

[Rapid Robert]

circle track app. restricting oil to the cam bearings & herb mcandles & sanborns oil mods. Yes a picture would be very much appreciated & very helpfull. RR

 

[ch1ll]

These are crappy pictures and a gfs drill I found in my dad's basement. I used a big drill so you could see it better and the grinding wheel has been abused, big corner radius. I don't have a dresser here and I just haven't gotten to it.

I use the side of the wheel to flatten the cutting lip.

it doesn't take much.

Then radius the corners and relieve them so the back of the drill doesn't rub. They don't have to be perfect, the more you sharpen the radius, the better you will get at it and your going to be redressing those radiuses alot.

 

[ch1ll]

Check size. Make sure your drills are drilling size. Low rpm and slow feed. Make sure your drill is drilling straight.

 

[ch1ll]

There's afew videos on YouTube at slant daily garage dealing with oil mods and tubing the oil valleys. There's is also a video at unity Motorsports garage with the mission impossible oil mods. We'll worth the watch.

 

[ch1ll]

I'll be doing these mods in the future, but I will try using reamer instead of drills cause they cut straighter and maintain size better especially when cutting through cross holes.

 

[RustyRatRod]

Neither.

Cobalt.

That ^^^^^

 

[green72]

Cobalt is great. Drilling the block will be easier than you think, the cast iron drills nicely.

 

[Bobzilla]

which of these drill bit types would be the best/hardest? titanium or black oxide. drilling block oil passages where if a bit breaks the block is junk should I use a cheapie if it would be less likely to catch & break or the best/hardest I can get? thank you for your time. RR

You can use either one of those or the cobalt recomended. Use a sharp new bit with cutting oil and don't go too fast. The cast iron will drill much easier than you are expecting.

If you do break one of those three types of bits, which are really just coatings on the bits, you will have one more chance to drill out the broken bit using a solid carbide bit. Solid carbide is excellent for drilling through broken drill bits and taps.

 

[toolmanmike]

which of these drill bit types would be the best/hardest? titanium or black oxide. drilling block oil passages where if a bit breaks the block is junk should I use a cheapie if it would be less likely to catch & break or the best/hardest I can get? thank you for your time. RR

Cast iron drills easily with High speed steel bits (HHS) Cobalt will hold an edge and last longer. Your choice but you may be limited because of the length you need. Drill slow with medium pressure and keep pulling the bit out of the hole to clear the chips. You are just enlarging a previously drilled hole I am guessing.

 

[mopowers]

Cast iron drills easily with High speed steel bits (HHS) Cobalt will hold an edge and last longer. Your choice but you may be limited because of the length you need. Drill slow with medium pressure and keep pulling the bit out of the hole to clear the chips. Cutting oil is recommended. You are just enlarging a previously drilled hole I am guessing.

Is this true? I've always been told cutting oil should not to be used for cast iron, though I've always wondered why.

 

[toolmanmike]

Is this true? I've always been told cutting oil should not to be used for cast iron, though I've always wondered why.

Let me edit my post. Drilling cast dry is ok. We always used an oil based coolant when drilling cast at Viking Pump. But that coolant was in every machine.

 

[Rapid Robert]

dynamite tech! & very much appreciated. I will put it to use. thank you. RR

 

[go-fish]

I think Slant Daily Garage mentions it but is there a published list of drill bit sizes and lengths needed? Also taps, fittings and tube diameter for crossovers; he mentions some things about re-tapping in his updated video on block drilling.