Drilling out SS rivits and what does HSO mean on a drill bit?

[Cliff_Johns]

I'm trying to drill out some stainless steel rivits. I'm going through
my pile of old drill bits acquired from various places and found some
that are marked HSO instead of HSS. The markings are quite clear.

So 2 questions:
First, what does HSO mean on a drill bit?
Second, To drill out the rivits, I figure use slow speed and a little
wd-40 -- this has to be hand drilled. Any other advice?

Cliff

[Scooby074]

Is HSO the brand?

And if the rivets are anything besides pop rivets, I'd probably use a cobalt bit anyways.

[bcp]

HLH and HSO example:

HLH HSO 7/16" Drill Bit 5 5/8" Reduced 3/8" Straight Shank | eBay

I don't know what either means.

Bruce

[CNC Dan]

HLH and HSO example:

HLH HSO 7/16" Drill Bit 5 5/8" Reduced 3/8" Straight Shank | eBay

I don't know what either means.

Bruce

I don't have a link, but there is a website (acronymfinder.com?) that has a lot of odd thing listed.

[Cliff_Johns]

They are pop rivits.

Is HSO the brand?

And if the rivets are anything besides pop rivets, I'd probably use a cobalt bit anyways.

[BIG DOOLEY]

Is there a size on the bit?
could the O be a letter "O" which is 0.316"
HSO = High Speed letter O
i have seen many bits marked HS and then the size
or
maybe it is for Oxide
black oxide bit ?
have never read or heard of an HSO category drill bit.
tom

[BIG DOOLEY]

About removing the rivets.
if you are not worried about a painted surface or emery wheel marks. i remove alot of s.s. rivets at work by using an angle grinder with a 60 or 80 grit flap disc.
grind the rivet front or back flush to the sheet metal and use a drift punch or a center punch to remove the other half.
drilling many times will spin the rivet if you use too much pressure and will usually mark up the mounting surface too.
tom

[Cliff_Johns]

Specifically, it says HSO then on the next line it says 3/16

Is there a size on the bit?
could the O be a letter "O" which is 0.316"
HSO = High Speed letter O
i have seen many bits marked HS and then the size
or
maybe it is for Oxide
black oxide bit ?
have never read or heard of an HSO category drill bit.
tom

[Cliff_Johns]

It's on a painted surface that I don't want to dammage, otherwise, I suppose that would work pretty fast.
Cliff

About removing the rivets.
if you are not worried about a painted surface or emery wheel marks. i remove alot of s.s. rivets at work by using an angle grinder with a 60 or 80 grit flap disc.
snip . . .
tom

[texasjohn]

how about using a dremel type grinder...or a stone in a drill...just brainstorming...I almost always grind out a rivet than drill it out...