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How to get through heat hardened stainless bolts?

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kooldino

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A lot of what I do is work on turbocharged cars. We tend to use stainless bolts (this may not be the best idea), which will often shear flush with the flange when you try to remove them.

I recently picked up a couple sets of carbide drill bits to make drilling these out easier. Unfortunately, these still weren't very effective. It took about 2 hours to get 1/8" into the bolt.

I have a feeling that drilling them out isn't the answer. I ended up getting some mini grinder bits for the dremel and using them to grind through it along with drilling. That worked, but it still took all day.

Bottom line, I don't ever want to go through this again. I need a better solution of getting through sheared bolts.

Garage Journal - what say you?
 
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ptschram

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What is the material they are going into and passing through? Cast iron?

Most of the turbocharged vehicles I've been around used studs and copper nuts to retain things, similar to how some exhaust manifolds are retained.

If these are going into cast iron or steel, the stainless is no doubt galling or otherwise seizing and the heat/cool cycles aren't helping you any.

As for getting them out, use a left-hand bit, lots of oil and heat the surrounding metal-if it won't damage anything with the heat.
 
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ourkid2000

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Whenever I have to drill out stainless hardware on aircraft, I have to admit.....it's much more difficult.

However, I use plenty of Rapid-tap and good quality cobalt drill bits (Dormer) and they will get through them eventually. I would guess that it definitely takes me twice as long to drill out a stainless screw enough to get an EZ-out in them than it does to drill out a regular hardened steel screw (AN/MS grade). I use a fairly low speed on my hand held air drill and take my time.
 
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yasha32

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Nov 19, 2011
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this doesnt answer the question, but is it possible to heat them prior to removal? might make it easier
 
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Outlawmws

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Stainless work hardens very easily, on top of the factory heat treatment. I'd start with smaller bits, and make sure you are using the right speeds and feeds...
 
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tyndall

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Check with a place that sell machinery. Tell them what you are doing and get the correct cutting oil. Most regular cutting oils can make stainless even harder to drill.
 
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kooldino

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ptschram said:
What is the material they are going into and passing through? Cast iron?
Click to expand...

Generally cast iron and cast stainless.

Most of the turbocharged vehicles I've been around used studs and copper nuts to retain things, similar to how some exhaust manifolds are retained.
Click to expand...

I'm trying to avoid using studs for this application, since they prevent me from removing the manifold without removing the turbo with it. It's about 5x as much work to do the turbo and the mani rather than just the mani alone.

If these are going into cast iron or steel, the stainless is no doubt galling or otherwise seizing and the heat/cool cycles aren't helping you any.
Click to expand...

This much is true.

As for getting them out, use a left-hand bit, lots of oil and heat the surrounding metal-if it won't damage anything with the heat.
Click to expand...

I drilled one out saturday with a good set of cobalt bits and some grinding bits. It took me around 9 hours. I never want to live through that again. There has to be a better way.
 
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Milton Shaw

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Feb 11, 2011
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Buy a set of drill bits from Bad Dog.. I have not found anything they would not drill. The harder the material the better it drills. Also have a life time warranty. Will drill into the hard part of files, glass, stainless everything I have tried. These work at a very fast speed, not like typical bits that you use slow, 1/4 inch takes like 4,000 rpm to work.
 
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skruft

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Do you use some sort of anti-seize compound when you install them? The dissimilar metals without that would seem to be looking for trouble.
 
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