Small carbide drills?

CLIP

CLIP

Would coated tooling possibly work rather than going to the potentially brittle carbide? It's between HSS and carbide in overall toughness, eh?

Not sure. The 1/16" drill bits looked like they had been used on granite after a few seconds.

jsw

In your mill, with the work clamped rigidly, you should be OK with carbide. But carbide drill bits depend on a pretty smooth entry. If you're starting in the center of a buggered Phillips head screw, it might bang around until it gets started. That could chip the cutting edge of the bit or break it.

But if your HSS bits are getting chewed up in a work-hardened screw, it sounds like you have a less-than-rigid setup (or crappy bits, or you're spindle speed is too high). HSS bits shouldn't give up on a screw like that unless they're bouncing around or overheating.

We could get into cutting-edge types, brands and grades, but something more fundamental may be wrong. Unless you're using Chinese or other cheap bits, I'd make sure, first, that you have a smooth entry for the bit and rigid clamping of the work.

BTW, getting the screw up to 700 deg F. or so should remove most of the work-hardening, but you'd be getting close to the melting temp. of the aluminum. I like using red-hot nails for jobs like that, just to take the hardness out of my starting spot. Either that, or chuck a nail into your drill or mill and heat the spot with friction, like they do for drilling through case-hardening.

-- Ed Huntress

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Crappy bits possibly, I saved the good one to drill straight down the screw shank. The spindle speed is 600 RPM, A 1/16" bit clears the ridges, which aren't damaged yet because I used ViseGrips on the outside after trying 'reasonable' force, and the bottom was smoothed and rounded with a diamond ball burr.

See the photo. The expensive plastic sensor prevents the usual heat tricks. I only want to clean the platinum wires with CRC MAF Cleaner at this point. Are straight-flute drills less likely to break?

jsw

Crappy bits possibly, I saved the good one to drill straight down the screw shank. The spindle speed is 600 RPM, A 1/16" bit clears the ridges, which aren't damaged yet because I used ViseGrips on the outside after trying 'reasonable' force, and the bottom was smoothed and rounded with a diamond ball burr.

If you're referring to the spade bits, they might be better for starting a hole, and the edges can be stronger, but they won't get you very deep.

-- Ed Huntress

I don't think they need to. The outside of the screw head is soft enough to file. I don't want to disable this expensive part before I know that I can repair it

jsw

Those look like 'tamper proof' torx, but if the one you're working on has Phillips heads they shouldn't be especially hard, but the initial geometry would make it hard to start a small bit. My suggestion would be to use a rigid setup, and a 1/4" drill or a center drill to start the hole. This will guide whatever smaller bit you want to use. If at all possible, just drill deep enough to remove the head. (i.e., if it's a

1/4" bolt, use a 5/16" or so and just drill till the head pops off.) Do this to each bolt and you should be able to wiggle the sensor off. You can then apply a bit of heat to get the rest out. If you can lay your hands on a Left Hand twist drill bit, the bolt will probably come out while you are drilling.

Pete

Gotta U-Pullit around? Sometimes it's cheaper to give up on the original part and go get another. Or at least learn how on somebody else's junk! Locally, most of the engine management sensor stuff is $10 or less off the wreck.

Stan

Harbor Freight sells compatible driver bits btw...

Why f*ck around?

Gunner

"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"

Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno

remember that the codes do not always tell you what is wrong - ask what single failure could set both codes? MAF can do it, but probably so can a stuck injector or a leaking manifold - generaly there is diagnosis info in the dealer manual that can help you localize the failure rather than shotgunning.

Is the 02 sensor active? you can read with a decent reader and watch %O2, or you can put a meter on it - if it's active, it's probably OK - same for MAF

On Tue, 16 Jun 2009 14:18:22 -0700, the infamous Gunner Asch scrawled the following:

I've used my 91310 set several times. The only thing I don't like is that the box doesn't prevent half the bits from falling out while in transit. Store the box FLAT, eh?

-- Do what you feel in your heart to be right - for you'll be criticized anyway. You'll be damned if you do, and damned if you don't. -- Eleanor Roosevelt

All fixed now. The 1/16" carbide bits were only notched at the end and won't drill deep, the 1/8" ones have lengthwise flutes. Once the carbide had started a hole the 1/16" HSS bit I had been repeatedly trying, dulling and regrinding drilled straight through the screws easily. It certainly seems that the head stamping operation seriously hardened the steel at the center of the Phillips recess.

CRC MAF sensor cleaner fixed the rough running and Check Engine problem, saving me about $90.

jsw

What kind of screws were they? Could they have been case hardened?

Pete Stanaitis

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Jim Wilk>

Plated 4mm Phillips round head. ViseGrips bit into the outside of the head and after drilling through them, the shells of threads didn't seem hard or brittle when I twisted them out with needlenose pliers.

I use Grade 5 or 8 bolts to make small parts and so far HSS has cut them well, with decent edge life and a nice smooth finish.

jsw