Eric

Caroline wrote:
>
> "Eric" <say.no@spam.now> wrote
> > Caroline wrote:
> > >
> > > The head on the lower mounting bolt of my 91 Civic's rear left shock
> > > absorber sheared off.
> >
> > To clarify, do you mean the bolt that goes through bushing #20 in this
> > diagram http://tinyurl.com/3n3up ?
>
> Yes. The bolt itself appears in the "rear shock absorber" drawing at
> http://tinyurl.com/59d5k (item #20).
>
> > > Same for the bolt joining the control arm to the trailing arm.
> >
> > That sounds like bolt #25 at the trailing arm in the above diagram,
> > correct?
>
> Correct.
>
> I anticipate the same problem with *both* #25 bolts in this drawing. So
> far, only the outboard bolt's head is sheared off.
>
> If I want to replace the spring-over-shock absorber assembly, at least
> one of those #25 bolts must come free, and in a way that doesn't damage
> the lower arm (= trailing arm) or its bushing or the other #25 bolt's
> female fitting.
>
> I'm not in any trouble per se (yet). The car is still drivable. This, as
> is usually the case lately with my car work, is more about the journey
> (and maybe overkill pre-emptive maintenance) than the destination.

I may be mistaken, but it sounds to me like you may have been bitten by the
same problem that attacks the front suspension lower mounting bolt. That
is, it seems that Honda did not use any antiseize compound on these bolts
and they tend to rust up in the bushing. You may have success by twisting
off the captive nut on the back side of the strut yoke as others have
suggested. However, if the bolt is truly seized up in the bushing, then it
may require you to get a new bushing pressed into the control arm. It seems
unlikely that the small captive nut could provide enough clamping force on
the bolt to allow the head to be twisted off. It seems more likely that the
bolt shank is frozen up in the bushing. However, you may get lucky pounding
it out.

The trailing arm bolt is likely to more of a hassle. Here again, it may be
the case that the bolt is rusted into the metal sleeve of the bushing. You
could try drilling the end of the bolt where the head broke off so that you
can then insert a spiral screw extractor into it (always use a center punch
when drilling a bolt to get your drill started correctly). You'll likely
need a right angle drill due to the close quarters. If you can get a screw
extractor into it, then you might have luck by applying some gentle heat to
the captive nut on the far side. The other posters are correct in that a
mapp gas torch will be better than a propane torch as they burn hotter.
Heat the nut up until it just begins to turn red and then try loosening the
bolt (be careful of any fuel lines or brake lines in the neighborhood).
However, if the bolt shank is truly rusted up in the bushing, then this
process may not get you anywhere. If that's the case, then you may be able
to get a rotary cut off tool between the bushing and the trailing arm to cut
the bolt at both ends of the bushing. If you follow this procedure, you'll
need to get a new bushing pressed into the control arm so don't worry about
cutting it and keep your cut off tool away from the trailing arm. Note that
you'll still need to drill out the remaining bolt in the trailing arm or
find some way of removing the captive nut and replacing it with something
else. Good luck.

Another possibility is that you may have success by whacking the bolts with
an air hammer once you get the captive nuts removed. Unfortunately, this
might mushroom the end of the bolt and make drilling it much more difficult
if you wish to try that avenue later.

By the way, be sure to put some antiseize compound on any of the bolts that
you reinstall back into the suspension. I happen to be biased towards the
copper based antiseize but the other type (zinc based I think) should work
as well. Note that with the bushings, the antiseize should go on the bolt
shank as well as on the threads.

Eric

Eric

Caroline wrote:
>
> "Eric" <say.no@spam.now> wrote
> > Caroline wrote:
> > >
> > > The head on the lower mounting bolt of my 91 Civic's rear left shock
> > > absorber sheared off.
> >
> > To clarify, do you mean the bolt that goes through bushing #20 in this
> > diagram http://tinyurl.com/3n3up ?
>
> Yes. The bolt itself appears in the "rear shock absorber" drawing at
> http://tinyurl.com/59d5k (item #20).
>
> > > Same for the bolt joining the control arm to the trailing arm.
> >
> > That sounds like bolt #25 at the trailing arm in the above diagram,
> > correct?
>
> Correct.
>
> I anticipate the same problem with *both* #25 bolts in this drawing. So
> far, only the outboard bolt's head is sheared off.
>
> If I want to replace the spring-over-shock absorber assembly, at least
> one of those #25 bolts must come free, and in a way that doesn't damage
> the lower arm (= trailing arm) or its bushing or the other #25 bolt's
> female fitting.
>
> I'm not in any trouble per se (yet). The car is still drivable. This, as
> is usually the case lately with my car work, is more about the journey
> (and maybe overkill pre-emptive maintenance) than the destination.

I may be mistaken, but it sounds to me like you may have been bitten by the
same problem that attacks the front suspension lower mounting bolt. That
is, it seems that Honda did not use any antiseize compound on these bolts
and they tend to rust up in the bushing. You may have success by twisting
off the captive nut on the back side of the strut yoke as others have
suggested. However, if the bolt is truly seized up in the bushing, then it
may require you to get a new bushing pressed into the control arm. It seems
unlikely that the small captive nut could provide enough clamping force on
the bolt to allow the head to be twisted off. It seems more likely that the
bolt shank is frozen up in the bushing. However, you may get lucky pounding
it out.

The trailing arm bolt is likely to more of a hassle. Here again, it may be
the case that the bolt is rusted into the metal sleeve of the bushing. You
could try drilling the end of the bolt where the head broke off so that you
can then insert a spiral screw extractor into it (always use a center punch
when drilling a bolt to get your drill started correctly). You'll likely
need a right angle drill due to the close quarters. If you can get a screw
extractor into it, then you might have luck by applying some gentle heat to
the captive nut on the far side. The other posters are correct in that a
mapp gas torch will be better than a propane torch as they burn hotter.
Heat the nut up until it just begins to turn red and then try loosening the
bolt (be careful of any fuel lines or brake lines in the neighborhood).
However, if the bolt shank is truly rusted up in the bushing, then this
process may not get you anywhere. If that's the case, then you may be able
to get a rotary cut off tool between the bushing and the trailing arm to cut
the bolt at both ends of the bushing. If you follow this procedure, you'll
need to get a new bushing pressed into the control arm so don't worry about
cutting it and keep your cut off tool away from the trailing arm. Note that
you'll still need to drill out the remaining bolt in the trailing arm or
find some way of removing the captive nut and replacing it with something
else. Good luck.

Another possibility is that you may have success by whacking the bolts with
an air hammer once you get the captive nuts removed. Unfortunately, this
might mushroom the end of the bolt and make drilling it much more difficult
if you wish to try that avenue later.

By the way, be sure to put some antiseize compound on any of the bolts that
you reinstall back into the suspension. I happen to be biased towards the
copper based antiseize but the other type (zinc based I think) should work
as well. Note that with the bushings, the antiseize should go on the bolt
shank as well as on the threads.

Eric

Caroline

"Eric" <say.no@spam.now> wrote
> Caroline wrote:
> >
> > "Eric" <say.no@spam.now> wrote
> > > Caroline wrote:
> > > >
> > > > The head on the lower mounting bolt of my 91 Civic's rear left shock
> > > > absorber sheared off.
> > >
> > > To clarify, do you mean the bolt that goes through bushing #20 in this
> > > diagram http://tinyurl.com/3n3up ?
> >
> > Yes. The bolt itself appears in the "rear shock absorber" drawing at
> > http://tinyurl.com/59d5k (item #20).
> >
> > > > Same for the bolt joining the control arm to the trailing arm.
> > >
> > > That sounds like bolt #25 at the trailing arm in the above diagram,
> > > correct?
> >
> > Correct.
> >
> > I anticipate the same problem with *both* #25 bolts in this drawing. So
> > far, only the outboard bolt's head is sheared off.
> >
> > If I want to replace the spring-over-shock absorber assembly, at least
> > one of those #25 bolts must come free, and in a way that doesn't damage
> > the lower arm (= trailing arm) or its bushing or the other #25 bolt's
> > female fitting.
> >
> > I'm not in any trouble per se (yet). The car is still drivable. This, as
> > is usually the case lately with my car work, is more about the journey
> > (and maybe overkill pre-emptive maintenance) than the destination.
>
> I may be mistaken, but it sounds to me like you may have been bitten by the
> same problem that attacks the front suspension lower mounting bolt. That
> is, it seems that Honda did not use any antiseize compound on these bolts
> and they tend to rust up in the bushing. You may have success by twisting
> off the captive nut on the back side of the strut yoke as others have
> suggested. However, if the bolt is truly seized up in the bushing, then it
> may require you to get a new bushing pressed into the control arm. It seems
> unlikely that the small captive nut could provide enough clamping force on
> the bolt to allow the head to be twisted off. It seems more likely that the
> bolt shank is frozen up in the bushing.

Based on my efforts today, you are correct.

Today I was stuck workingmostly on the rear outboard lower control arm bolt. I
ground it down with a hand drill grinding block. I then successfully drilled the
distance of its nut (or threaded female end; there's really no nut there that I
can see), starting with a cobalt 1/6" bit, then 1/8" bit, then another size up,
per the screw extractor table. I used Sears' cutting oil.

I tried some screw extractors with the cutting oil for a few hours but did not
want to break any and so finally gave up on it to ponder this overnight.

I then gave the inboard #25 bolt a try. I'd sprayed it a couple times with PB
Blaster since this morning. Hurrah! It came out pretty easily for a 13-year-old,
never been changed before, seen northern U.S. winters bolt.

I thought, "Great. I should be able to get the middle control arm bolt off and
at least change out the strut assembly today."

Wrong. What you described above is dead-on correct. I snapped off the
(middle)welded nut with a 1/2-inch drive 19 mm socket and a five-foot breaker
bar. It wasn't as dramatic as the crankshaft bolt but it came close. I then
tried pounding the bolt through the bushing, which didn't work. I then tried
double-nutting the forward, threaded end. I quickly found the whole bushing was
trying to turn as I turned the bolt!

As you suggested, the bushing is frozen to the splines of the bolt big time. I'd
likely end up destroying the bushing if I force the bolt out.

> However, you may get lucky pounding
> it out.

Yes. Luck. It was at a mininum today.

> The trailing arm bolt is likely to more of a hassle. Here again, it may be
> the case that the bolt is rusted into the metal sleeve of the bushing. You
> could try drilling the end of the bolt where the head broke off so that you
> can then insert a spiral screw extractor into it (always use a center punch
> when drilling a bolt to get your drill started correctly). You'll likely
> need a right angle drill due to the close quarters. If you can get a screw
> extractor into it, then you might have luck by applying some gentle heat to
> the captive nut on the far side. The other posters are correct in that a
> mapp gas torch will be better than a propane torch as they burn hotter.
> Heat the nut up until it just begins to turn red and then try loosening the
> bolt (be careful of any fuel lines or brake lines in the neighborhood).
> However, if the bolt shank is truly rusted up in the bushing, then this
> process may not get you anywhere. If that's the case, then you may be able
> to get a rotary cut off tool between the bushing and the trailing arm to cut
> the bolt at both ends of the bushing. If you follow this procedure, you'll
> need to get a new bushing pressed into the control arm so don't worry about
> cutting it and keep your cut off tool away from the trailing arm. Note that
> you'll still need to drill out the remaining bolt in the trailing arm or
> find some way of removing the captive nut and replacing it with something
> else. Good luck.

Yes, this is where I'm at.

Given what I'm seeing with the middle bolt, I think the screw extractors will
just keep breaking.

I think I'm going to put everything back together tomorrow, antiseizing the
inboard bolt like mad, of course, and give this a week to ponder.

It seems to me I am going to have to cut the bushings of the outboard bolt, then
extract, piece-by-piece, the remaining bolt, along the lines of what you
suggest. Probably have to tap the female threaded fitting on it. Tapping looks
very do-able right now, due to my fine drilling job. I think.

> Another possibility is that you may have success by whacking the bolts with
> an air hammer once you get the captive nuts removed. Unfortunately, this
> might mushroom the end of the bolt and make drilling it much more difficult
> if you wish to try that avenue later.
>
> By the way, be sure to put some antiseize compound on any of the bolts that
> you reinstall back into the suspension.

Do I read like the guys who put this car together?!

;-)

> I happen to be biased towards the
> copper based antiseize but the other type (zinc based I think) should work
> as well. Note that with the bushings, the antiseize should go on the bolt
> shank as well as on the threads.

Yes, indeedy. (I draw from my ship experience here.) :-)

Seriously, thank you for your help. It seems to me the key to this endeavor is
realizing it's the bushing, not the nut, freezing to the bolt. For it's whole
length.

Caroline

"Eric" <say.no@spam.now> wrote
> Caroline wrote:
> >
> > "Eric" <say.no@spam.now> wrote
> > > Caroline wrote:
> > > >
> > > > The head on the lower mounting bolt of my 91 Civic's rear left shock
> > > > absorber sheared off.
> > >
> > > To clarify, do you mean the bolt that goes through bushing #20 in this
> > > diagram http://tinyurl.com/3n3up ?
> >
> > Yes. The bolt itself appears in the "rear shock absorber" drawing at
> > http://tinyurl.com/59d5k (item #20).
> >
> > > > Same for the bolt joining the control arm to the trailing arm.
> > >
> > > That sounds like bolt #25 at the trailing arm in the above diagram,
> > > correct?
> >
> > Correct.
> >
> > I anticipate the same problem with *both* #25 bolts in this drawing. So
> > far, only the outboard bolt's head is sheared off.
> >
> > If I want to replace the spring-over-shock absorber assembly, at least
> > one of those #25 bolts must come free, and in a way that doesn't damage
> > the lower arm (= trailing arm) or its bushing or the other #25 bolt's
> > female fitting.
> >
> > I'm not in any trouble per se (yet). The car is still drivable. This, as
> > is usually the case lately with my car work, is more about the journey
> > (and maybe overkill pre-emptive maintenance) than the destination.
>
> I may be mistaken, but it sounds to me like you may have been bitten by the
> same problem that attacks the front suspension lower mounting bolt. That
> is, it seems that Honda did not use any antiseize compound on these bolts
> and they tend to rust up in the bushing. You may have success by twisting
> off the captive nut on the back side of the strut yoke as others have
> suggested. However, if the bolt is truly seized up in the bushing, then it
> may require you to get a new bushing pressed into the control arm. It seems
> unlikely that the small captive nut could provide enough clamping force on
> the bolt to allow the head to be twisted off. It seems more likely that the
> bolt shank is frozen up in the bushing.

Based on my efforts today, you are correct.

Today I was stuck workingmostly on the rear outboard lower control arm bolt. I
ground it down with a hand drill grinding block. I then successfully drilled the
distance of its nut (or threaded female end; there's really no nut there that I
can see), starting with a cobalt 1/6" bit, then 1/8" bit, then another size up,
per the screw extractor table. I used Sears' cutting oil.

I tried some screw extractors with the cutting oil for a few hours but did not
want to break any and so finally gave up on it to ponder this overnight.

I then gave the inboard #25 bolt a try. I'd sprayed it a couple times with PB
Blaster since this morning. Hurrah! It came out pretty easily for a 13-year-old,
never been changed before, seen northern U.S. winters bolt.

I thought, "Great. I should be able to get the middle control arm bolt off and
at least change out the strut assembly today."

Wrong. What you described above is dead-on correct. I snapped off the
(middle)welded nut with a 1/2-inch drive 19 mm socket and a five-foot breaker
bar. It wasn't as dramatic as the crankshaft bolt but it came close. I then
tried pounding the bolt through the bushing, which didn't work. I then tried
double-nutting the forward, threaded end. I quickly found the whole bushing was
trying to turn as I turned the bolt!

As you suggested, the bushing is frozen to the splines of the bolt big time. I'd
likely end up destroying the bushing if I force the bolt out.

> However, you may get lucky pounding
> it out.

Yes. Luck. It was at a mininum today.

> The trailing arm bolt is likely to more of a hassle. Here again, it may be
> the case that the bolt is rusted into the metal sleeve of the bushing. You
> could try drilling the end of the bolt where the head broke off so that you
> can then insert a spiral screw extractor into it (always use a center punch
> when drilling a bolt to get your drill started correctly). You'll likely
> need a right angle drill due to the close quarters. If you can get a screw
> extractor into it, then you might have luck by applying some gentle heat to
> the captive nut on the far side. The other posters are correct in that a
> mapp gas torch will be better than a propane torch as they burn hotter.
> Heat the nut up until it just begins to turn red and then try loosening the
> bolt (be careful of any fuel lines or brake lines in the neighborhood).
> However, if the bolt shank is truly rusted up in the bushing, then this
> process may not get you anywhere. If that's the case, then you may be able
> to get a rotary cut off tool between the bushing and the trailing arm to cut
> the bolt at both ends of the bushing. If you follow this procedure, you'll
> need to get a new bushing pressed into the control arm so don't worry about
> cutting it and keep your cut off tool away from the trailing arm. Note that
> you'll still need to drill out the remaining bolt in the trailing arm or
> find some way of removing the captive nut and replacing it with something
> else. Good luck.

Yes, this is where I'm at.

Given what I'm seeing with the middle bolt, I think the screw extractors will
just keep breaking.

I think I'm going to put everything back together tomorrow, antiseizing the
inboard bolt like mad, of course, and give this a week to ponder.

It seems to me I am going to have to cut the bushings of the outboard bolt, then
extract, piece-by-piece, the remaining bolt, along the lines of what you
suggest. Probably have to tap the female threaded fitting on it. Tapping looks
very do-able right now, due to my fine drilling job. I think.

> Another possibility is that you may have success by whacking the bolts with
> an air hammer once you get the captive nuts removed. Unfortunately, this
> might mushroom the end of the bolt and make drilling it much more difficult
> if you wish to try that avenue later.
>
> By the way, be sure to put some antiseize compound on any of the bolts that
> you reinstall back into the suspension.

Do I read like the guys who put this car together?!

;-)

> I happen to be biased towards the
> copper based antiseize but the other type (zinc based I think) should work
> as well. Note that with the bushings, the antiseize should go on the bolt
> shank as well as on the threads.

Yes, indeedy. (I draw from my ship experience here.) :-)

Seriously, thank you for your help. It seems to me the key to this endeavor is
realizing it's the bushing, not the nut, freezing to the bolt. For it's whole
length.

Caroline

Update:
Unfastening the bolt connecting the rear lower control arm and trailing arm was
as ugly as others in the archives reported. I never actually got it free from
the bushing or its nut.

I never tried a torch, but that would be my next suggestion.

I eventually drilled and cut (by hand) the outside-most control arm
bushing/bolt. Then I ground down the female bolt receptacle (it's not actually a
nut, unfortunately, or I would have snapped it off, the way I did with the strut
fork bolt) welded to the trailing arm. I used a cheap-o electric hand drill and
grinding stone attachment. Grinding it down was no fun but at least I could see
some kind of steady progress. Cobalt drill bits are essential but still very,
very slow, even with the best cutting oil.

I installed the "new" (= 8k miles used) control arm last night, attaching it
with a separate nut at the trailing arm, as I think Eric and/or others
suggested. The new strut and control arm did not fix the tilt, but I wasn't
expecting it too.

The ride seems a bit smoother, but I may have talked myself into this.

I took apart the old strut in my suspension course today, borrowing the school's
spring compressor. The shock absorber seemed in excellent shape at 157k miles
old. The spring is a tougher call.

I reckon I spent around $35 just on cutting tools for this job. About half the
tools are broken or now severely worn. I'm worn, too! :-)

I am contemplating doing the other side but not for another week or so.
Meanwhile, the other side's bolts get sprayed with PB Blaster regularly. Not
that I have much hope this will help.

Moral of the story: The classic, "If it ain't broke, don't fix it"?

I dunno. I learned a lot: -)

Caroline

Update:
Unfastening the bolt connecting the rear lower control arm and trailing arm was
as ugly as others in the archives reported. I never actually got it free from
the bushing or its nut.

I never tried a torch, but that would be my next suggestion.

I eventually drilled and cut (by hand) the outside-most control arm
bushing/bolt. Then I ground down the female bolt receptacle (it's not actually a
nut, unfortunately, or I would have snapped it off, the way I did with the strut
fork bolt) welded to the trailing arm. I used a cheap-o electric hand drill and
grinding stone attachment. Grinding it down was no fun but at least I could see
some kind of steady progress. Cobalt drill bits are essential but still very,
very slow, even with the best cutting oil.

I installed the "new" (= 8k miles used) control arm last night, attaching it
with a separate nut at the trailing arm, as I think Eric and/or others
suggested. The new strut and control arm did not fix the tilt, but I wasn't
expecting it too.

The ride seems a bit smoother, but I may have talked myself into this.

I took apart the old strut in my suspension course today, borrowing the school's
spring compressor. The shock absorber seemed in excellent shape at 157k miles
old. The spring is a tougher call.

I reckon I spent around $35 just on cutting tools for this job. About half the
tools are broken or now severely worn. I'm worn, too! :-)

I am contemplating doing the other side but not for another week or so.
Meanwhile, the other side's bolts get sprayed with PB Blaster regularly. Not
that I have much hope this will help.

Moral of the story: The classic, "If it ain't broke, don't fix it"?

I dunno. I learned a lot: -)

John Ings

On Thu, 23 Sep 2004 22:28:53 GMT, "Caroline"
<caroline10027remove@earthlink.net> wrote:

> I used a cheap-o electric hand drill and
>grinding stone attachment. Grinding it down was no fun

I bet! Is there any chance you can get ahold of an air tool?
A die grinder with a 3" abrasive cutoff wheel is the weapon of choice.
Electric drills just don't turn fast enough.

John Ings

On Thu, 23 Sep 2004 22:28:53 GMT, "Caroline"
<caroline10027remove@earthlink.net> wrote:

> I used a cheap-o electric hand drill and
>grinding stone attachment. Grinding it down was no fun

I bet! Is there any chance you can get ahold of an air tool?
A die grinder with a 3" abrasive cutoff wheel is the weapon of choice.
Electric drills just don't turn fast enough.

Caroline

"John Ings" <nodamned@spam.org> wrote
> On Thu, 23 Sep 2004 22:28:53 GMT, "Caroline"
> <caroline10027remove@earthlink.net> wrote:
>
> > I used a cheap-o electric hand drill and
> >grinding stone attachment. Grinding it down was no fun
>
> I bet! Is there any chance you can get ahold of an air tool?
> A die grinder with a 3" abrasive cutoff wheel is the weapon of choice.
> Electric drills just don't turn fast enough.

Hi John, thanks for the suggestion. I'm a little overbudget on "tool toys" right
now, but I'll make some inquiries of classmates in my auto course and ponder it
for a few weeks before I go seriously after the other rear shock assembly, if I
go after it. I also want to keep an eye on my "re-design" of the one rear
trailing arm/control arm linkage for awhile.

At least I am now the proud owner of a 115 psi, 8 gallon reservoir, "uses oil"
air compressor (which may or may not do the trick for this tool you suggest).

Caroline

"John Ings" <nodamned@spam.org> wrote
> On Thu, 23 Sep 2004 22:28:53 GMT, "Caroline"
> <caroline10027remove@earthlink.net> wrote:
>
> > I used a cheap-o electric hand drill and
> >grinding stone attachment. Grinding it down was no fun
>
> I bet! Is there any chance you can get ahold of an air tool?
> A die grinder with a 3" abrasive cutoff wheel is the weapon of choice.
> Electric drills just don't turn fast enough.

Hi John, thanks for the suggestion. I'm a little overbudget on "tool toys" right
now, but I'll make some inquiries of classmates in my auto course and ponder it
for a few weeks before I go seriously after the other rear shock assembly, if I
go after it. I also want to keep an eye on my "re-design" of the one rear
trailing arm/control arm linkage for awhile.

At least I am now the proud owner of a 115 psi, 8 gallon reservoir, "uses oil"
air compressor (which may or may not do the trick for this tool you suggest).

John Ings

On Fri, 24 Sep 2004 05:25:35 GMT, "Caroline"
<caroline10027remove@earthlink.net> wrote:

>At least I am now the proud owner of a 115 psi, 8 gallon reservoir, "uses oil"
>air compressor (which may or may not do the trick for this tool you suggest).

Then get a die grinder with a cutoff wheel. They're relatively cheap
as air tools go. Get one without a guard or with a removable guard.
They are more dangerous to use, but often you just can't get the ones
with a guard into confined spaces.

Small compressors sometimes don't pack enough oomph for big air tools
like 3/4" impact wrenches, but they are plenty good enough for things
like a die grinder, air chisels, air ratchets etc. I worked on cars
for a long time before I discovered air tools, and when I did wished I
had found out about them earlier.

John Ings

On Fri, 24 Sep 2004 05:25:35 GMT, "Caroline"
<caroline10027remove@earthlink.net> wrote:

>At least I am now the proud owner of a 115 psi, 8 gallon reservoir, "uses oil"
>air compressor (which may or may not do the trick for this tool you suggest).

Then get a die grinder with a cutoff wheel. They're relatively cheap
as air tools go. Get one without a guard or with a removable guard.
They are more dangerous to use, but often you just can't get the ones
with a guard into confined spaces.

Small compressors sometimes don't pack enough oomph for big air tools
like 3/4" impact wrenches, but they are plenty good enough for things
like a die grinder, air chisels, air ratchets etc. I worked on cars
for a long time before I discovered air tools, and when I did wished I
had found out about them earlier.

Eric

Caroline wrote:

[snip]

> Cobalt drill bits are essential but still very, very slow, even with
> the best cutting oil.

This is by design. Cobalt bits are made for drilling into hardened metals.
As such, the angle of the cutting edges is shallower than it is on high
speed steel bits. This enables the drill bit to take off smaller chips of
metal which has advantages when drilling into hardened metal.

A disadvantage with cobalt bits is that they're typically rather brittle and
easy to break. I've broken large bits simply by accidentally dropping them
onto concrete. I've also broken smaller ones by applying too much side
pressure while drilling.

Eric

Eric

Caroline wrote:

[snip]

> Cobalt drill bits are essential but still very, very slow, even with
> the best cutting oil.

This is by design. Cobalt bits are made for drilling into hardened metals.
As such, the angle of the cutting edges is shallower than it is on high
speed steel bits. This enables the drill bit to take off smaller chips of
metal which has advantages when drilling into hardened metal.

A disadvantage with cobalt bits is that they're typically rather brittle and
easy to break. I've broken large bits simply by accidentally dropping them
onto concrete. I've also broken smaller ones by applying too much side
pressure while drilling.

Eric

Eric

Caroline wrote:

[snip]

> Cobalt drill bits are essential but still very, very slow, even with
> the best cutting oil.

This is by design. Cobalt bits are made for drilling into hardened metals.
As such, the angle of the cutting edges is shallower than it is on high
speed steel bits. This enables the drill bit to take off smaller chips of
metal which has advantages when drilling into hardened metal.

A disadvantage with cobalt bits is that they're typically rather brittle and
easy to break. I've broken large bits simply by accidentally dropping them
onto concrete. I've also broken smaller ones by applying too much side
pressure while drilling.

Eric