Hi all,

I recently picked up three large (7") cast iron 3/4" pipe clamps.
Second hand, but never used, and I think I know why now: the two holes
on the threaded side of the clamp don't match up very well.

It's too difficult to even get the thread started for two of them. On
the one that I can actually thread (as long as the clamp bolt is
completely extended), it is impossible to rotate the the clamp bolt
back to the open position.

Anyway, I'm thinking that the only way to salvage these is to bore out
one side of the non-threaded hole until it is parallel with the
threaded hole--about 1/4" by my estimation. The hole is 1" dia., 3"
deep, cast iron.

What's the easiest way to remove the metal? I struggled with a round
file for half hour and barely made headway (maybe 1/64"). I have a die
grinder (but not the proper bit): is that the best way? Any other
suggestions?

Thanks,
H.

Hylourgos wrote:
Any other suggestions?


Yes. Finish the quality control guy's job and see to it
they are disposed of properly.

Put a crow bar in your wallet and buy some Ponys.

UA100

would your OSS work?
Tony D.
"Unisaw A100" wrote in message
...
Hylourgos wrote:
Any other suggestions?


Yes. Finish the quality control guy's job and see to it
they are disposed of properly.

Put a crow bar in your wallet and buy some Ponys.

UA100

Suggestions? One: give up.

It sounds like you're going to spend hours trying to fix the clamps
you've got and when you're done, even if you manage to get them to
work at all, they'll probably never grip as well as brand-new, $12
Ponys.

It's not worth your trouble.


On 17 Jan 2004 02:13:42 -0800, (Hylourgos) wrote:

Hi all,

I recently picked up three large (7") cast iron 3/4" pipe clamps.
Second hand, but never used, and I think I know why now: the two holes
on the threaded side of the clamp don't match up very well.

It's too difficult to even get the thread started for two of them. On
the one that I can actually thread (as long as the clamp bolt is
completely extended), it is impossible to rotate the the clamp bolt
back to the open position.

Anyway, I'm thinking that the only way to salvage these is to bore out
one side of the non-threaded hole until it is parallel with the
threaded hole--about 1/4" by my estimation. The hole is 1" dia., 3"
deep, cast iron.

What's the easiest way to remove the metal? I struggled with a round
file for half hour and barely made headway (maybe 1/64"). I have a die
grinder (but not the proper bit): is that the best way? Any other
suggestions?

Thanks,
H.

-- jc
Published e-mail address is strictly for spam collection.
If e-mailing me, please use jc631 at optonline dot net

Hi all,

I recently picked up three large (7") cast iron 3/4" pipe clamps.
Second hand, but never used, and I think I know why now: the two holes
on the threaded side of the clamp don't match up very well.

It's too difficult to even get the thread started for two of them. On
the one that I can actually thread (as long as the clamp bolt is
completely extended), it is impossible to rotate the the clamp bolt
back to the open position.

Anyway, I'm thinking that the only way to salvage these is to bore out
one side of the non-threaded hole until it is parallel with the
threaded hole--about 1/4" by my estimation. The hole is 1" dia., 3"
deep, cast iron.

What's the easiest way to remove the metal? I struggled with a round
file for half hour and barely made headway (maybe 1/64"). I have a die
grinder (but not the proper bit): is that the best way? Any other
suggestions?

Thanks,




bend the pipe

OK...bunch of damn smartasses....

I can see that either I didn't describe the clamp or my situation well
enough. You don't have a crowbar big enough, Uni. And as for "It's not
worth your trouble", John, you'd have to know more about me to make
that call. Have you actually done something like this?

I'm only a teacher and I have kids, so I don't have much money. WW is
a hobby for me--more of an academic interest really--so I'm in no rush
and most of my equipment is second hand and what many of you would
call ****. I can't say that what I produce is that impressive, but
I've seen works of art come from nothing but handmade tools, and
pieces of crap only a mother could love come from very expensive
shops. I get at least as much pleasure from making or repairing tools
as I do making sawdust.

As for the clamp, it is a 7" deep-throat, I think it's made by Jet.
See a pic of it at:

http://www.eneva.com/hand-tools/jet-...mp-fixture.asp

So, they cost about $18 ea, and I got mine second-hand but unused for
$1 ea. These are nice, big, sturdy clamps. The $51 savings is to me a
significant thing.

If you still think my clamps are a lost cause, and they simply will
never work correctly--and you have reason for that opinion--then I
would love to hear it.

I'm looking at this from a materials and engineering standpoint. I see
no reason why boring out the hole won't make the clamps work as well
as they should (that hole in the clamp is supposed to be loose anyway,
FWW). Even if I have to spend an hour with a file on each one, it
would be worth it to me. I'm just hoping to find something easier.

H

"Hylourgos" wrote in message

I'm only a teacher and I have kids, so I don't have much money.


What does being a teacher have to do with not having money? Around here
(Connecticut) most make a better wage than tradesmen or mid level managers
and the guy on the assembly line..

Sorry guys, but I hate to see people making a respectable wage and whining.
If the money is not enough, get a job in an industry or profession that pays
more.
Ed

http://pages.cthome.net/edhome

(Hylourgos) wrote in message . com...
Anyway, I'm thinking that the only way to salvage these is to bore out
one side of the non-threaded hole until it is parallel with the
threaded hole--about 1/4" by my estimation. The hole is 1" dia., 3"
deep, cast iron.

Taking off 1/4" of metal to get the holes parallel seems like a lot.
The hole is suppose to be loose, but enlarging a 4/4" hole to 5/4" in
one direction seems excessive.

You might want to attack the problem where the screw attaches to the
jaw. Remove the screw from the moving jaw, and then try to thread
everything together. This should let you see exactly how far off the
alignment is. You might be able to fix the attachment point with a
lot less metal removal than filing out the other hole.

--Stan Graves

"Hylourgos" wrote in message
om...
OK...bunch of damn smartasses....

I can see that either I didn't describe the clamp or my situation well
enough. You don't have a crowbar big enough, Uni. And as for "It's not
worth your trouble", John, you'd have to know more about me to make
that call. Have you actually done something like this?

I'm only a teacher and I have kids, so I don't have much money. WW is
a hobby for me--more of an academic interest really--so I'm in no rush
and most of my equipment is second hand and what many of you would
call ****. I can't say that what I produce is that impressive, but
I've seen works of art come from nothing but handmade tools, and
pieces of crap only a mother could love come from very expensive
shops. I get at least as much pleasure from making or repairing tools
as I do making sawdust.

As for the clamp, it is a 7" deep-throat, I think it's made by Jet.
See a pic of it at:

http://www.eneva.com/hand-tools/jet-...mp-fixture.asp

So, they cost about $18 ea, and I got mine second-hand but unused for
$1 ea. These are nice, big, sturdy clamps. The $51 savings is to me a
significant thing.

If you still think my clamps are a lost cause, and they simply will
never work correctly--and you have reason for that opinion--then I
would love to hear it.

I'm looking at this from a materials and engineering standpoint. I see
no reason why boring out the hole won't make the clamps work as well
as they should (that hole in the clamp is supposed to be loose anyway,
FWW). Even if I have to spend an hour with a file on each one, it
would be worth it to me. I'm just hoping to find something easier.

H

I missed your original post but if I get the gist of the problem I'd be
curious to know if you turned the handle such as to maximize the distance
between the two pieces? I've got pipe clamps that would simply not go
together without doing that...

John

Why not just put a 3/4" to 1/2" reducer in and use 1/2" pipe? I forget the
exact name of them, but I've seen them in different size configurations.

--
"Cartoons don't have any deep meaning.
They're just stupid drawings that give you a cheap laugh."
Homer Simpson
Jerry© The Phoneman®
"John Grossbohlin" wrote in message
...

"Hylourgos" wrote in message
om...
OK...bunch of damn smartasses....

I can see that either I didn't describe the clamp or my situation well
enough. You don't have a crowbar big enough, Uni. And as for "It's not
worth your trouble", John, you'd have to know more about me to make
that call. Have you actually done something like this?

I'm only a teacher and I have kids, so I don't have much money. WW is
a hobby for me--more of an academic interest really--so I'm in no rush
and most of my equipment is second hand and what many of you would
call ****. I can't say that what I produce is that impressive, but
I've seen works of art come from nothing but handmade tools, and
pieces of crap only a mother could love come from very expensive
shops. I get at least as much pleasure from making or repairing tools
as I do making sawdust.

As for the clamp, it is a 7" deep-throat, I think it's made by Jet.
See a pic of it at:

http://www.eneva.com/hand-tools/jet-...mp-fixture.asp

So, they cost about $18 ea, and I got mine second-hand but unused for
$1 ea. These are nice, big, sturdy clamps. The $51 savings is to me a
significant thing.

If you still think my clamps are a lost cause, and they simply will
never work correctly--and you have reason for that opinion--then I
would love to hear it.

I'm looking at this from a materials and engineering standpoint. I see
no reason why boring out the hole won't make the clamps work as well
as they should (that hole in the clamp is supposed to be loose anyway,
FWW). Even if I have to spend an hour with a file on each one, it
would be worth it to me. I'm just hoping to find something easier.

H

I missed your original post but if I get the gist of the problem I'd be
curious to know if you turned the handle such as to maximize the distance
between the two pieces? I've got pipe clamps that would simply not go
together without doing that...

John

Dear Ed,

Several points of your post below make reason stare.

I'm not sure why you assume when I say teacher that I mean secondary
(or primary for that matter).

I am well aware of what Conn. (secondary) teachers make, but find it
odd that anyone would use that as the standard. If you think that
(secondary) teachers across this nation make a decent living or are
anywhere close to the Conn. standard, then you haven't done much
reading for the past 50 years or so.

As for your analogy with tradesmen/mid-levels/assembly workers, your
assumption seems to be that they too should be above tinkering with
tools. Sorry, but I don't understand that kind of snobbery. I know
plenty of JDs, MDs and MBAs who are happy to the enjoy the process of
fixing tools rather than buying new ones.

Of course, the wealthier you are the less likely you might be to spend
time in such pursuits, unless you enjoyed those pursuits in
themselves. Was that your (rather obvious) point?

You apparently assume I was whining. Far from it: I willingly accept
the economic limitations of a profession I have chosen because I love
it. Thus my willingness also to work within its economic limitations.
Thus my query for suggestions about how to do so more efficiently. My
explanation, which you took for whine, was in answer to several
respondents who suggested (without reason I might add) that I scrap my
repair plans and just buy new clamps.

Perhaps I am mistaken in reading your post as snobby and ignorant. I
have seldom met a man for whom "the money is ... enough", regardless
the net worth.

H


"Edwin Pawlowski" wrote in message .com...
"Hylourgos" wrote in message

I'm only a teacher and I have kids, so I don't have much money.


What does being a teacher have to do with not having money? Around here
(Connecticut) most make a better wage than tradesmen or mid level managers
and the guy on the assembly line..

Sorry guys, but I hate to see people making a respectable wage and whining.
If the money is not enough, get a job in an industry or profession that pays
more.
Ed

http://pages.cthome.net/edhome

"Hylourgos" wrote in message

I am well aware of what Conn. (secondary) teachers make, but find it
odd that anyone would use that as the standard. If you think that
(secondary) teachers across this nation make a decent living or are
anywhere close to the Conn. standard, then you haven't done much
reading for the past 50 years or so.

You brought up the fact that you are a only a teacher. It is your chosen
profession so please don't use it as a crutch. There are a lot of people
happy with their chosen profession that do not make a lot of money. They
don't bring it up as a whine that they must save money on clamps. Everyone
has priorities for their spending and thier allocationof free time.


As for your analogy with tradesmen/mid-levels/assembly workers, your
assumption seems to be that they too should be above tinkering with
tools. Sorry, but I don't understand that kind of snobbery. I know
plenty of JDs, MDs and MBAs who are happy to the enjoy the process of
fixing tools rather than buying new ones.

I said nothing of the kind. What I did say was that many teachers work less
days a year and make more money than those in other occupations. But I
don't hear those guys poor mouthing.


Of course, the wealthier you are the less likely you might be to spend
time in such pursuits, unless you enjoyed those pursuits in
themselves. Was that your (rather obvious) point?

No, for an educated person, you seem to have no perception of what I said.



You apparently assume I was whining.

YES. Now we are getting someplace.

My
explanation, which you took for whine, was in answer to several
respondents who suggested (without reason I might add) that I scrap my
repair plans and just buy new clamps.

Well, sometimes that is the best way regardless of how much time you are
willing to expend on a project. Maybe these guys are offering good advice
based on their experiences.


Perhaps I am mistaken in reading your post as snobby and ignorant. I
have seldom met a man for whom "the money is ... enough", regardless
the net worth.

I'm not sure where you get snobbery. If you think I'm ignorant that is your
opinion. Nothing wrong with fixing tools for the satisfaction of the job
well done, saving a few bucks, but just don't complain that you are doing it
because you are a teacher and don't have a lot of money.

Your words: I'm only a teacher and I have kids, so I don't have much
money.

I had kids too. One reason I did not do woodworking when the kids were
small was that I could not afford it. Nothing wrong with not having a lot
of money, but don't use the teacher excuse. "Tis you that comes across as a
snob that way. There are probably people that read this group that make a
very good income but don't have a lot of money because they are paying
medical expenses, supporting sick parents, or a million other things.
Ed

On 17 Jan 2004 02:13:42 -0800, (Hylourgos) wrote:

Any other
suggestions?

Yeah go over to rec.crafts.metalworking and ask those guys.

"John Grossbohlin" wrote in message ...
snip
I missed your original post but if I get the gist of the problem I'd be
curious to know if you turned the handle such as to maximize the distance
between the two pieces? I've got pipe clamps that would simply not go
together without doing that...

John

Yes, I did have them fully extended and they (2/3) still wouldn't
thread. I've noticed that the one that did thread, once I got it
installed, would not then screw open or shut easily (the clamp action,
that is), so it suffers from the same problem, just less so. Removing
some material from it should help it too.

H.

That's a great idea I hadn't thought of, Jerry. A problem may lie in
the fact that the clamp is threaded 3/4" and the space between the
threaded portion and its mating piece might be too short to put a
reducer there (I'm not sure where else it would go.

But I'll try fiddling with it somehow.

Thanks,
H

"Jerry Gilreath" wrote in message news:3cIOb.81197$Rc4.292767@attbi_s54...
Why not just put a 3/4" to 1/2" reducer in and use 1/2" pipe? I forget the
exact name of them, but I've seen them in different size configurations.
snip

(Stan Graves) wrote in message . com...
(Hylourgos) wrote in message . com...
Anyway, I'm thinking that the only way to salvage these is to bore out
one side of the non-threaded hole until it is parallel with the
threaded hole--about 1/4" by my estimation. The hole is 1" dia., 3"
deep, cast iron.

Taking off 1/4" of metal to get the holes parallel seems like a lot.
The hole is suppose to be loose, but enlarging a 4/4" hole to 5/4" in
one direction seems excessive.

You might want to attack the problem where the screw attaches to the
jaw. Remove the screw from the moving jaw, and then try to thread
everything together. This should let you see exactly how far off the
alignment is. You might be able to fix the attachment point with a
lot less metal removal than filing out the other hole.

--Stan Graves

Also a good suggestion. I'll give it a shot. Thanks, H.

I did, thanks rjs, they had some good suggestions.

H.

rjs wrote in message . ..
On 17 Jan 2004 02:13:42 -0800, (Hylourgos) wrote:

Any other
suggestions?

Yeah go over to rec.crafts.metalworking and ask those guys.

Well, what I'm thinking of and have seen, is nothing more than threads.
Dammit, I can't think what they're called but I've used them on manifold
bolts and the like. They just screw into the tapped out hole and make the
size to fit the bolt your using. Oh wait!!!! Helicoil!!! That's it!!! Don't
take up no room at all! They say the memory is the firstthing to go! You
might have to go to a machine shop or good parts house (not autozone or
pepeboys) to find them.

--
"Cartoons don't have any deep meaning.
They're just stupid drawings that give you a cheap laugh."
Homer Simpson
Jerry© The Phoneman®
"Hylourgos" wrote in message
om...
That's a great idea I hadn't thought of, Jerry. A problem may lie in
the fact that the clamp is threaded 3/4" and the space between the
threaded portion and its mating piece might be too short to put a
reducer there (I'm not sure where else it would go.

But I'll try fiddling with it somehow.

Thanks,
H

"Jerry Gilreath" wrote in message
news:3cIOb.81197$Rc4.292767@attbi_s54...
Why not just put a 3/4" to 1/2" reducer in and use 1/2" pipe? I forget
the
exact name of them, but I've seen them in different size configurations.
snip

"Edwin Pawlowski" wrote in message .com...

Ed, you have misunderstood the argument, you veer here and there worse
than a dial-a-dado with a loose nut, and you either forget or
puposefully take out of context much of what I wrote.

snip
You brought up the fact that you are a only a teacher.

No, not out of context I didn't, and the fact that you leave that
context out leaves you arguing with someone else, not me.

My original post was a purely technical question, no personal info
included. Parenthetically I note that you have yet to contribute one
word towards it--makes you look like you're itching for a fight with
someone. In response to my orignial query, Uni and John give their
opinions, without reason, that I should abort my repair attempts and
spend more money on new items. Not bad advice per se, but not really
helpful either. Note the many helpful responses that followed later in
this thread, and in the rec.crafts.metalworking thread of the same
question. Anyway, I responded to Uni and John hoping to elicit some
response from them demonstrating that they have actual experience with
machining clamps holes, or that they have some other compelling reason
that I should abort the attempt. Either there is a way to repair them
or there isn't. Whether it is worth my time is not something they are
in a position to judge--that was the point in telling them that my
income is such that it *is* worth it, to me, to try to repair them. I
have assumed that the teaching profession is a commonplace for a not
decent income. Whether that is strictly true or not was not relevant
to the logic of my argument, it is a rhetorical commonplace (DAGS,
however and note the millions of provocative titles that
return).Pointing out the exception to the rule does not affect the
logic. Whether I'm a teacher or a journeyman or manager or
assembly-line worker or other tradesman, or even white collar with a
decent salary but yet am strechted thin enough to want to repair
rather than buy new ones, that is solely up to me--a personal question
of value.

For some reason you focus on "teacher" as if that were an important
part of the argument. I've no idea what you have against teachers
(apparently it's their decent pay in Conn., which, I assure you, has
nothing to do with me), but that has nothing to do with the logic of
my argument.

It is your chosen
profession so please don't use it as a crutch.

It is you, sir, who are trying to put a crutch on a healthy man. Get
thee hence, Procrustes.

There are a lot of people happy with their chosen profession that do
not make a lot of money. They don't bring it up as a whine that they
must save money on clamps.

The crux may lie in your definition of whine.

Let's assume you're happy with your profession. It doesn't matter how
much you make, as long as it is limited (represent that limit with an
"X"). Now let's assume you want a tool (any tool: to limit it to
clamps would be to go from generalization to the specific within the
same example, pretty bad logic, although you seem comfortable with it
above) whose price is above your limit (we'll call the tool's value
"Y"). So, you get a chance to buy a used and broken Y well within your
budget and certainly worthwhile if you can fix it.

Is this scenario so foreign to you? Man, I think most everyone on this
board has been in this scene.

OK, now someone tells you: "don't waste your time repairing a broken
Y, get a new Y. " You explain to him that your constraints (X)
prevent that; it would be more helpful if he could explain *why*
repairing Y is a waste of time. Nine times out of ten your friend is
simply not constrained by X, so it seems to him that anything short of
buying a new Y is not worth the time or effort. But not for you of
course.

Again I ask, is this such a strange scenario to you? More to the
point: when you explain to your friend your own constraints, is that
by your definition a "whine". If so,then mea culpa.

The way you immediately seized upon Conn. (secondary) teachers leads
me to believe that this is something personal for you. It has nothing
to do with me, and even less to do with the logic of my argument. I
could've said "I don't feel like I'm in a position to buy them new",
but that would NOT have changed the logic of my argument. I could've
elaborated, pointed out that I lost a lot in Hurricane Floyd, that my
baby girl was sick for years, that my wife is pregnant now. But that's
wasn't really germane to the argument. Was the fact that I was a
teacher? No. However, I trusted that a reference to being a teacher
with kids would resonate with my audience. I didn't count on you
ignoring my technical questions to grab your hobby-horse (teachers)
and swing it around, then take an exception (Conn. secondary teachers)
to try to disprove the rule.

Everyone
has priorities for their spending and thier allocationof free time.

Gee, that's my point, Ed.

snip
I said nothing of the kind. What I did say was that many teachers work less
days a year and make more money than those in other occupations.
But I
don't hear those guys poor mouthing.

No, you didn't say that. What you said was, "Around here (Connecticut)
most [teachers] make a better wage than tradesmen or mid level
managers and the guy on the assembly line.."

And do you really want to argue that tradesmen, managers, or
assembly-line workers don't "poor mouth"? I think I'll let that one
stand on it's own wobbly leg.

My
explanation, which you took for whine, was in answer to several
respondents who suggested (without reason I might add) that I scrap my
repair plans and just buy new clamps.

Well, sometimes that is the best way regardless of how much time you are
willing to expend on a project. Maybe these guys are offering good advice
based on their experiences.

And I'm willing to accept that possibility. But certainly not without
some better reason offered than "it's not worth your time", or "just
buy new clamps". I was asking them to offer those reasons when you
jumped in about teachers. And if you'll bother to read the subsequent
answers both here and in rec.crafts.metalworking, you'll see quite a
few opinions that offer good ideas about helping me repair those
clamps.

Perhaps I am mistaken in reading your post as snobby and ignorant. I
have seldom met a man for whom "the money is ... enough", regardless
the net worth.

I'm not sure where you get snobbery.

I take it as snobbery when someone tells me "it's not worth your time"
when they have no earthly idea what value I put on my time--or clamps
(not you directly but you quickly jumped to their rescue). I take it
as snobbery when someone assumes that teacher means secondary or that
all teachers must make what Conn. teachers make. I took it as snobbery
when you presumed to know that I make a respectable wage and was a
whiner--all couched in a cowardly generalization (from your first
post, and quite clearly with reference to me, "Sorry guys, but I hate
to see people making a respectable wage and whining").

If you think I'm ignorant that is your
opinion. Nothing wrong with fixing tools for the satisfaction of the job
well done, saving a few bucks, but just don't complain that you are doing it
because you are a teacher and don't have a lot of money.

Why not? Do you see those as exclusive arguments?

snip

Nothing wrong with not having a lot
of money, but don't use the teacher excuse. "Tis you that comes across as a
snob that way.

You lost me here. If I were in fact whining and making excuses about
being a teacher, then what you're describing is the opposite of
snobbery, something more like victim-mongering, no?

There are probably people that read this group that make a
very good income but don't have a lot of money because they are paying
medical expenses, supporting sick parents, or a million other things.

That, again, would be my point.

H.

Got access to a oxyacetylene torch? Had the same trouble- with some cheapie
clamps- cut a clearance slot in the offending section of the clamp, heated
to cherry red, then applying corrective force. Brazed the slot that I'd cut
to make the part a little easier to work with. Looks a bit ugly but 100%
functional. Pat

Let me understand this: you cut a "clearance slot" down the length of
the hole with a (cutter?) torch? Or just heated it up (with a regular
welding tip) then cut it with another tool ("corrective force")? Then
cleaned up that slot by putting brazing metal in it?

Another scenario I'd imagined was you heating up the *clampscrew* on
one side and bending it until it was directionally functional.

Help me out here, I'm having a hard time imagining what you describe.

Thanks,
H


"patrick mitchel" wrote in message ...
Got access to a oxyacetylene torch? Had the same trouble- with some cheapie
clamps- cut a clearance slot in the offending section of the clamp, heated
to cherry red, then applying corrective force. Brazed the slot that I'd cut
to make the part a little easier to work with. Looks a bit ugly but 100%
functional. Pat

Hylourgos wrote in message
m...
Let me understand this: you cut a "clearance slot" down the length of
the hole with a (cutter?) torch? Or just heated it up (with a regular
welding tip) then cut it with another tool ("corrective force")? Then
cleaned up that slot by putting brazing metal in it?

Another scenario I'd imagined was you heating up the *clampscrew* on
one side and bending it until it was directionally functional.

Help me out here, I'm having a hard time imagining what you describe.

Thanks,
H
Ok, On mine, there was a misalignment between the threaded portion(fixed to
the pipe) and the slip on section that applies the pressure to the object
being squeezed. I put a slice (not a through cut) in the web section between
the threaded boss for the pipe and the threaded section of the clamping
screw. That allowed me to align the hole in the clamping section and the
hole in the fixed threaded section after a bit of heating to the web of the
fixed section. It wasn't much of an angle change to the cheap clamps I was
massaging. I might have been able to do the same modification without the
cut. The cut made the whole thing a bit easier . The slot I cut was then
filled with brazing.

Bridgeport with boring head.

"Hylourgos" wrote in message
om...
Hi all,

I recently picked up three large (7") cast iron 3/4" pipe clamps.
Second hand, but never used, and I think I know why now: the two holes
on the threaded side of the clamp don't match up very well.

It's too difficult to even get the thread started for two of them. On
the one that I can actually thread (as long as the clamp bolt is
completely extended), it is impossible to rotate the the clamp bolt
back to the open position.

Anyway, I'm thinking that the only way to salvage these is to bore out
one side of the non-threaded hole until it is parallel with the
threaded hole--about 1/4" by my estimation. The hole is 1" dia., 3"
deep, cast iron.

What's the easiest way to remove the metal? I struggled with a round
file for half hour and barely made headway (maybe 1/64"). I have a die
grinder (but not the proper bit): is that the best way? Any other
suggestions?

Thanks,
H.