Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Releasign Threadlocker w/o Wrecking Heat Treat?

I have several Italian .22LR Olympic-style "free pistols" I am repairing
for the collegiate pistol team I help coach. These are Pardini PGP-
75's, which are bolt action:

http://picturearchive.gunauction.com....jpg_thumbnail
1.jpg

To set the "headspace" (gap between the bolt face & chamber), they use a
hardened eccentric bushing at the base of the bolt handle. It rides in
the slot in the action, and rotating the bushing adjusts the headspace.
If the headspace is too large, you get unreliable ignition, and/or
reduced accuracy.

The bushing position is set at the factory, and clamped with the bolt
handle, which screws down on top of the bushing. Both the bolt handle
threads and the bushing are treated with some sort of 30 year old
Italian threadlocker (maybe even epoxy). I've experimented with a
variety of solvents, and acetone & lacquer thinner won't touch it.
Methylene chloride (paint stripper) softens it up, and allows cleaning
off the exposed threads & loose bushings.

On some pistols, the bushing slips & just needs to be repositioned. On
others, the bushing cracks & has to be replaced. Spare parts are very
scarce, and we only have a few extra bushings.

I have one pistol where the bushing is OK, but must have slipped during
installation. It works OK, but the headspace is well past the nominal
upper limit. I got the bolt handle off with a strap wrench, and
expected that the bushing had slipped, but it is firmly stuck.

I've had it soaking in paint stripper for a month now, but I suspect the
gap between the bushing & the bolt stud is too small to allow enough
solvent in to undo the bushing in less than geologic time.

The other approach for dealing with most threadlocker is heat (~ 300F?).
I can make a specialized soldering iron tip that I can slip or clamp
over the bushing to free it. The iron I currently have is temperature
controlled, but at 700F. I could also go & buy a cheap resistive iron
and use it with a variac to control the temperature down at a better
level.

Thank you for anyone who has stuck with me so far. Here's the question:

I would really like to salvage the bushing. What's the best way to get
it off without wrecking the heat treat? It's quite thin ( 0.5mm), and
I will be applying heat on the outside to get through to the inside.

The best options I've come up with a

1) Use my 700 degree iron, with a tip mounted with a small brass block
with a hole that is a slip fit over the bushing. If I cock the tip at a
slight angle to get good thermal contact, I should be able to pull the
bushing off as soon as the threadlocker lets go, and then the bushing
should fall free from the heat source.

2) By a cheap iron, and make the tip clamp securely onto the bushing.
Then use a variac/dimmer to sneak up on the temperature. I have a set
of Tempilac sticks that I can use to tell when it has reached certain
temperatures. I also have an infrared thermometer, but I don't think it
goes hot enough for this. With this approach, I am unlikely to get the
bushing much hotter than required to melt the threadlocker, but it will
be at that temperature for much longer.

3) Contact Italy and try to get more replacement bushings. That could
take months, and is not a sure thing. One reason I want to salvage this
one is the spares we obtained earlier may have been the dregs. Some of
them are not very eccentric, and many are not a very good fit on the
bolt handles.

4) I can certainly continue to leave the bolt soaking in paint stripper.
I have other projects to keep myself busy, and if I can repair all the
other pistols, the pressure will be off. It doesn't seem to affect the
metal, and if I keep it sealed up, I can try to wait it out.

5) Quench after getting it free. Given how hard they are, quenching
presumably wouldn't make it much harder. However, it could become more
brittle, and likely to crack.

6) Make new bushings. I have no idea how involved this would get. I
did a rough hardness test on a cracked one using hardness files, and it
was ~ RC60 (which may be why it cracked...). I don't have any
experience or equipment to do sophisticated heat treating. I'm assuming
that heat treating will probably distort them a bit, and/or mess up the
surface finish enough that a light grind would be in order. I can
certainly rig up a Dremel as a tool post grinder for that. The big
advantage with this is that I can make a bunch. I know of at least one
other college team that has even more dead ones than we do.

Other ideas & comments?

Thanks!

Doug White
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Default Releasign Threadlocker w/o Wrecking Heat Treat?

On 2/26/2017 9:26 AM, Doug White wrote:
I have several Italian .22LR Olympic-style "free pistols" I am repairing
for the collegiate pistol team I help coach. These are Pardini PGP-
75's, which are bolt action:

http://picturearchive.gunauction.com....jpg_thumbnail
1.jpg

To set the "headspace" (gap between the bolt face & chamber), they use a
hardened eccentric bushing at the base of the bolt handle. It rides in
the slot in the action, and rotating the bushing adjusts the headspace.
If the headspace is too large, you get unreliable ignition, and/or
reduced accuracy.

The bushing position is set at the factory, and clamped with the bolt
handle, which screws down on top of the bushing. Both the bolt handle
threads and the bushing are treated with some sort of 30 year old
Italian threadlocker (maybe even epoxy). I've experimented with a
variety of solvents, and acetone & lacquer thinner won't touch it.
Methylene chloride (paint stripper) softens it up, and allows cleaning
off the exposed threads & loose bushings.

On some pistols, the bushing slips & just needs to be repositioned. On
others, the bushing cracks & has to be replaced. Spare parts are very
scarce, and we only have a few extra bushings.

I have one pistol where the bushing is OK, but must have slipped during
installation. It works OK, but the headspace is well past the nominal
upper limit. I got the bolt handle off with a strap wrench, and
expected that the bushing had slipped, but it is firmly stuck.

I've had it soaking in paint stripper for a month now, but I suspect the
gap between the bushing & the bolt stud is too small to allow enough
solvent in to undo the bushing in less than geologic time.

The other approach for dealing with most threadlocker is heat (~ 300F?).
I can make a specialized soldering iron tip that I can slip or clamp
over the bushing to free it. The iron I currently have is temperature
controlled, but at 700F. I could also go & buy a cheap resistive iron
and use it with a variac to control the temperature down at a better
level.

Thank you for anyone who has stuck with me so far. Here's the question:

I would really like to salvage the bushing. What's the best way to get
it off without wrecking the heat treat? It's quite thin ( 0.5mm), and
I will be applying heat on the outside to get through to the inside.

The best options I've come up with a

1) Use my 700 degree iron, with a tip mounted with a small brass block
with a hole that is a slip fit over the bushing. If I cock the tip at a
slight angle to get good thermal contact, I should be able to pull the
bushing off as soon as the threadlocker lets go, and then the bushing
should fall free from the heat source.

2) By a cheap iron, and make the tip clamp securely onto the bushing.
Then use a variac/dimmer to sneak up on the temperature. I have a set
of Tempilac sticks that I can use to tell when it has reached certain
temperatures. I also have an infrared thermometer, but I don't think it
goes hot enough for this. With this approach, I am unlikely to get the
bushing much hotter than required to melt the threadlocker, but it will
be at that temperature for much longer.

3) Contact Italy and try to get more replacement bushings. That could
take months, and is not a sure thing. One reason I want to salvage this
one is the spares we obtained earlier may have been the dregs. Some of
them are not very eccentric, and many are not a very good fit on the
bolt handles.

4) I can certainly continue to leave the bolt soaking in paint stripper.
I have other projects to keep myself busy, and if I can repair all the
other pistols, the pressure will be off. It doesn't seem to affect the
metal, and if I keep it sealed up, I can try to wait it out.

5) Quench after getting it free. Given how hard they are, quenching
presumably wouldn't make it much harder. However, it could become more
brittle, and likely to crack.

6) Make new bushings. I have no idea how involved this would get. I
did a rough hardness test on a cracked one using hardness files, and it
was ~ RC60 (which may be why it cracked...). I don't have any
experience or equipment to do sophisticated heat treating. I'm assuming
that heat treating will probably distort them a bit, and/or mess up the
surface finish enough that a light grind would be in order. I can
certainly rig up a Dremel as a tool post grinder for that. The big
advantage with this is that I can make a bunch. I know of at least one
other college team that has even more dead ones than we do.

Other ideas & comments?

Thanks!

Doug White

I would need more info on the temperature required to affect the
heating treating of the metal. I question whether the heat required to
soften the thread blocker is enough to effect the metals heat treatment.
But, as I said,I need more info.
Mikek
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Default Releasign Threadlocker w/o Wrecking Heat Treat?

On Sun, 26 Feb 2017 15:26:07 GMT
Doug White wrote:

snip
4) I can certainly continue to leave the bolt soaking in paint stripper.


If you have the whole thing off couldn't you just place it in your oven
at say 400 deg?

When trying to transfer heat like that I've used solder before.
Depending on the solder you know you would be at 600 to 700 deg.
Usually those kinda of temps are used for tempering more so than
hardening from my understanding, which isn't much on that subject

I couldn't get your link to work but I found this with a general search:

http://www.pilkguns.com/tenp/spppgp75.htm

Might help some others visualize your dilemma. I'm guessing it is item
26 on the exploded view page.

Oh and its an interesting gun. Wouldn't mind shooting it a few times ;-)

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

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Default Releasign Threadlocker w/o Wrecking Heat Treat?

"Leon Fisk" wrote in message
news
On Sun, 26 Feb 2017 15:26:07 GMT
Doug White wrote:

When trying to transfer heat like that I've used solder before......
--
Leon Fisk


I've placed a short piece of fine electronic solder on a part held in
the vise and heated it from below with a torch until the solder melted
and shrank into a ball.


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Default Releasign Threadlocker w/o Wrecking Heat Treat?

Leon Fisk wrote in
news
On Sun, 26 Feb 2017 15:26:07 GMT
Doug White wrote:

snip
4) I can certainly continue to leave the bolt soaking in paint
stripper.


If you have the whole thing off couldn't you just place it in your
oven at say 400 deg?

When trying to transfer heat like that I've used solder before.
Depending on the solder you know you would be at 600 to 700 deg.
Usually those kinda of temps are used for tempering more so than
hardening from my understanding, which isn't much on that subject

I couldn't get your link to work but I found this with a general
search:

http://www.pilkguns.com/tenp/spppgp75.htm


The link apparently got busted by word wrap. If you splice it together
it works fine.

Might help some others visualize your dilemma. I'm guessing it is item
26 on the exploded view page.


That's the critter.

Oh and its an interesting gun. Wouldn't mind shooting it a few times
;-)


Shooting "free pistol" is a whole different game from any other sort of
pistol shooting. The "free" is because it is relatively free of
restrictions. Typical trigger pulls run about an ounce. The grip is
set up so that it hangs onto you as much as vice versa. The bore is
very low, so the recoil is very staight back into your hand, with very
little muzzle flip. Matches are 60 shots at 50 meters over 2 hours.
The target is the same one they used when the modern Olympics got going
in the late 1800's. No one has ever fired a perfect score.

Unfortunately, they are threatening to remove it from the Olympics,
which would be a real shame. Spectating is like watching paint dry
unless you are really into subtleties, so it isn't telegenic enough for
the modern short attention span of TV audiences.

Doug White



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Default Releasign Threadlocker w/o Wrecking Heat Treat?

Doug White wrote:
Leon Fisk wrote in
news
On Sun, 26 Feb 2017 15:26:07 GMT
Doug White wrote:

snip
4) I can certainly continue to leave the bolt soaking in paint
stripper.

If you have the whole thing off couldn't you just place it in your
oven at say 400 deg?

When trying to transfer heat like that I've used solder before.
Depending on the solder you know you would be at 600 to 700 deg.
Usually those kinda of temps are used for tempering more so than
hardening from my understanding, which isn't much on that subject

I couldn't get your link to work but I found this with a general
search:

http://www.pilkguns.com/tenp/spppgp75.htm


The link apparently got busted by word wrap. If you splice it together
it works fine.

Might help some others visualize your dilemma. I'm guessing it is item
26 on the exploded view page.


That's the critter.

Oh and its an interesting gun. Wouldn't mind shooting it a few times
;-)


Shooting "free pistol" is a whole different game from any other sort of
pistol shooting. The "free" is because it is relatively free of
restrictions. Typical trigger pulls run about an ounce. The grip is
set up so that it hangs onto you as much as vice versa. The bore is
very low, so the recoil is very staight back into your hand, with very
little muzzle flip. Matches are 60 shots at 50 meters over 2 hours.
The target is the same one they used when the modern Olympics got going
in the late 1800's. No one has ever fired a perfect score.

Unfortunately, they are threatening to remove it from the Olympics,
which would be a real shame. Spectating is like watching paint dry
unless you are really into subtleties, so it isn't telegenic enough for
the modern short attention span of TV audiences.

Doug White


Well then you need to go talk to some of the female beach volleyball
crowd and see if they want to be on the teams. In the same "uniforms"
they normally wear. I'd bet the sport would gain viewers....

--
Steve W.
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Default Releasign Threadlocker w/o Wrecking Heat Treat?

On Sun, 26 Feb 2017 15:26:07 GMT, Doug White
wrote:

I have several Italian .22LR Olympic-style "free pistols" I am repairing
for the collegiate pistol team I help coach. These are Pardini PGP-
75's, which are bolt action:

http://picturearchive.gunauction.com....jpg_thumbnail
1.jpg

To set the "headspace" (gap between the bolt face & chamber), they use a
hardened eccentric bushing at the base of the bolt handle. It rides in
the slot in the action, and rotating the bushing adjusts the headspace.
If the headspace is too large, you get unreliable ignition, and/or
reduced accuracy.

The bushing position is set at the factory, and clamped with the bolt
handle, which screws down on top of the bushing. Both the bolt handle
threads and the bushing are treated with some sort of 30 year old
Italian threadlocker (maybe even epoxy). I've experimented with a
variety of solvents, and acetone & lacquer thinner won't touch it.
Methylene chloride (paint stripper) softens it up, and allows cleaning
off the exposed threads & loose bushings.

On some pistols, the bushing slips & just needs to be repositioned. On
others, the bushing cracks & has to be replaced. Spare parts are very
scarce, and we only have a few extra bushings.

I have one pistol where the bushing is OK, but must have slipped during
installation. It works OK, but the headspace is well past the nominal
upper limit. I got the bolt handle off with a strap wrench, and
expected that the bushing had slipped, but it is firmly stuck.

I've had it soaking in paint stripper for a month now, but I suspect the
gap between the bushing & the bolt stud is too small to allow enough
solvent in to undo the bushing in less than geologic time.

The other approach for dealing with most threadlocker is heat (~ 300F?).
I can make a specialized soldering iron tip that I can slip or clamp
over the bushing to free it. The iron I currently have is temperature
controlled, but at 700F. I could also go & buy a cheap resistive iron
and use it with a variac to control the temperature down at a better
level.

Thank you for anyone who has stuck with me so far. Here's the question:

I would really like to salvage the bushing. What's the best way to get
it off without wrecking the heat treat? It's quite thin ( 0.5mm), and
I will be applying heat on the outside to get through to the inside.

The best options I've come up with a

1) Use my 700 degree iron, with a tip mounted with a small brass block
with a hole that is a slip fit over the bushing. If I cock the tip at a
slight angle to get good thermal contact, I should be able to pull the
bushing off as soon as the threadlocker lets go, and then the bushing
should fall free from the heat source.

2) By a cheap iron, and make the tip clamp securely onto the bushing.
Then use a variac/dimmer to sneak up on the temperature. I have a set
of Tempilac sticks that I can use to tell when it has reached certain
temperatures. I also have an infrared thermometer, but I don't think it
goes hot enough for this. With this approach, I am unlikely to get the
bushing much hotter than required to melt the threadlocker, but it will
be at that temperature for much longer.

3) Contact Italy and try to get more replacement bushings. That could
take months, and is not a sure thing. One reason I want to salvage this
one is the spares we obtained earlier may have been the dregs. Some of
them are not very eccentric, and many are not a very good fit on the
bolt handles.

4) I can certainly continue to leave the bolt soaking in paint stripper.
I have other projects to keep myself busy, and if I can repair all the
other pistols, the pressure will be off. It doesn't seem to affect the
metal, and if I keep it sealed up, I can try to wait it out.

5) Quench after getting it free. Given how hard they are, quenching
presumably wouldn't make it much harder. However, it could become more
brittle, and likely to crack.

6) Make new bushings. I have no idea how involved this would get. I
did a rough hardness test on a cracked one using hardness files, and it
was ~ RC60 (which may be why it cracked...). I don't have any
experience or equipment to do sophisticated heat treating. I'm assuming
that heat treating will probably distort them a bit, and/or mess up the
surface finish enough that a light grind would be in order. I can
certainly rig up a Dremel as a tool post grinder for that. The big
advantage with this is that I can make a bunch. I know of at least one
other college team that has even more dead ones than we do.

Other ideas & comments?

Thanks!

Doug White


Generally speaking, any substance used as a thread locker would
probably soften by the time it reaches, say 200 degrees F. And again,
generally speaking, a thread locker probably wouldn't be very soluble
in various solvents.

I think my first attempt would be by heating the bolt in boiling
water, keep it boiling until you are sure that the bolt actually
reaches ~212 degrees.

Another point RC 60 is pretty hard stuff. For a .22 pistol I would
suggest that if it is that hard it is probably for something other
than strength.

I once converted a bunch of S. American , small ring, Mausers to
sporting rifles and as I had to forge the bolt handles I tested both
the bolts and the receivers first and found that were in the range of
un-heatreated steel, relatively soft. I can't believe that a .22 would
have to be harder ;-)

I had a look at the break down drawing of the PDP-75 and if you are
talking abut the ring, at the rear of the bolt, that the bolt handle
seems to fit through, index 25, the drawing seems show a straight
forward sleeve (but it is a pretty vague drawing :-)
--
Cheers,

John B.

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Default Releasign Threadlocker w/o Wrecking Heat Treat?

John B. wrote in
:

On Sun, 26 Feb 2017 15:26:07 GMT, Doug White
wrote:

I have several Italian .22LR Olympic-style "free pistols" I am
repairing for the collegiate pistol team I help coach. These are
Pardini PGP- 75's, which are bolt action:


http://picturearchive.gunauction.com...2.jpg_thumbnai
l 1.jpg

To set the "headspace" (gap between the bolt face & chamber), they use
a hardened eccentric bushing at the base of the bolt handle. It rides
in the slot in the action, and rotating the bushing adjusts the
headspace. If the headspace is too large, you get unreliable
ignition, and/or reduced accuracy.

The bushing position is set at the factory, and clamped with the bolt
handle, which screws down on top of the bushing. Both the bolt handle
threads and the bushing are treated with some sort of 30 year old
Italian threadlocker (maybe even epoxy). I've experimented with a
variety of solvents, and acetone & lacquer thinner won't touch it.
Methylene chloride (paint stripper) softens it up, and allows cleaning
off the exposed threads & loose bushings.

On some pistols, the bushing slips & just needs to be repositioned.
On others, the bushing cracks & has to be replaced. Spare parts are
very scarce, and we only have a few extra bushings.

I have one pistol where the bushing is OK, but must have slipped
during installation. It works OK, but the headspace is well past the
nominal upper limit. I got the bolt handle off with a strap wrench,
and expected that the bushing had slipped, but it is firmly stuck.

I've had it soaking in paint stripper for a month now, but I suspect
the gap between the bushing & the bolt stud is too small to allow
enough solvent in to undo the bushing in less than geologic time.

The other approach for dealing with most threadlocker is heat (~
300F?). I can make a specialized soldering iron tip that I can slip
or clamp over the bushing to free it. The iron I currently have is
temperature controlled, but at 700F. I could also go & buy a cheap
resistive iron and use it with a variac to control the temperature
down at a better level.

Thank you for anyone who has stuck with me so far. Here's the
question:

I would really like to salvage the bushing. What's the best way to
get it off without wrecking the heat treat? It's quite thin (
0.5mm), and I will be applying heat on the outside to get through to
the inside.

The best options I've come up with a

1) Use my 700 degree iron, with a tip mounted with a small brass block
with a hole that is a slip fit over the bushing. If I cock the tip at
a slight angle to get good thermal contact, I should be able to pull
the bushing off as soon as the threadlocker lets go, and then the
bushing should fall free from the heat source.

2) By a cheap iron, and make the tip clamp securely onto the bushing.
Then use a variac/dimmer to sneak up on the temperature. I have a set
of Tempilac sticks that I can use to tell when it has reached certain
temperatures. I also have an infrared thermometer, but I don't think
it goes hot enough for this. With this approach, I am unlikely to get
the bushing much hotter than required to melt the threadlocker, but it
will be at that temperature for much longer.

3) Contact Italy and try to get more replacement bushings. That could
take months, and is not a sure thing. One reason I want to salvage
this one is the spares we obtained earlier may have been the dregs.
Some of them are not very eccentric, and many are not a very good fit
on the bolt handles.

4) I can certainly continue to leave the bolt soaking in paint
stripper. I have other projects to keep myself busy, and if I can
repair all the other pistols, the pressure will be off. It doesn't
seem to affect the metal, and if I keep it sealed up, I can try to
wait it out.

5) Quench after getting it free. Given how hard they are, quenching
presumably wouldn't make it much harder. However, it could become
more brittle, and likely to crack.

6) Make new bushings. I have no idea how involved this would get. I
did a rough hardness test on a cracked one using hardness files, and
it was ~ RC60 (which may be why it cracked...). I don't have any
experience or equipment to do sophisticated heat treating. I'm
assuming that heat treating will probably distort them a bit, and/or
mess up the surface finish enough that a light grind would be in
order. I can certainly rig up a Dremel as a tool post grinder for
that. The big advantage with this is that I can make a bunch. I know
of at least one other college team that has even more dead ones than
we do.

Other ideas & comments?

Thanks!

Doug White


Generally speaking, any substance used as a thread locker would
probably soften by the time it reaches, say 200 degrees F. And again,
generally speaking, a thread locker probably wouldn't be very soluble
in various solvents.

I think my first attempt would be by heating the bolt in boiling
water, keep it boiling until you are sure that the bolt actually
reaches ~212 degrees.

Another point RC 60 is pretty hard stuff. For a .22 pistol I would
suggest that if it is that hard it is probably for something other
than strength.

I once converted a bunch of S. American , small ring, Mausers to
sporting rifles and as I had to forge the bolt handles I tested both
the bolts and the receivers first and found that were in the range of
un-heatreated steel, relatively soft. I can't believe that a .22 would
have to be harder ;-)

I had a look at the break down drawing of the PDP-75 and if you are
talking abut the ring, at the rear of the bolt, that the bolt handle
seems to fit through, index 25, the drawing seems show a straight
forward sleeve (but it is a pretty vague drawing :-)


Thanks for the feedback.

The bushing/sleeve is hardened because it is what slides in the slot in
the action. It's to prevent wear, not for strength. In the exploded
diagram, the sleeve is part #26. #25 is the bolt handle, and #27 is the
knob that screws onto a stud that stick out of the bolt handle. The
eccentric sleeve fits on an unthreaded section at the base of the stud.

The sleeve is about 7.5mm in diameter, and the inner hole is about 6mm,
but offset about half a mm from center to produce the required
eccentricity.

I could certainly try boiling water, but none of the modern
threadlockers I've encountered soften up much at that temperature. The
vast majority of Locktite products are rated for use up to at least
300F. I would expect them not to soften until they get even hotter than
that.

Doug White
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Default Releasign Threadlocker w/o Wrecking Heat Treat?

On Mon, 27 Feb 2017 03:28:28 GMT, Doug White
wrote:

John B. wrote in
:

On Sun, 26 Feb 2017 15:26:07 GMT, Doug White
wrote:

I have several Italian .22LR Olympic-style "free pistols" I am
repairing for the collegiate pistol team I help coach. These are
Pardini PGP- 75's, which are bolt action:


http://picturearchive.gunauction.com...2.jpg_thumbnai
l 1.jpg

To set the "headspace" (gap between the bolt face & chamber), they use
a hardened eccentric bushing at the base of the bolt handle. It rides
in the slot in the action, and rotating the bushing adjusts the
headspace. If the headspace is too large, you get unreliable
ignition, and/or reduced accuracy.

The bushing position is set at the factory, and clamped with the bolt
handle, which screws down on top of the bushing. Both the bolt handle
threads and the bushing are treated with some sort of 30 year old
Italian threadlocker (maybe even epoxy). I've experimented with a
variety of solvents, and acetone & lacquer thinner won't touch it.
Methylene chloride (paint stripper) softens it up, and allows cleaning
off the exposed threads & loose bushings.

On some pistols, the bushing slips & just needs to be repositioned.
On others, the bushing cracks & has to be replaced. Spare parts are
very scarce, and we only have a few extra bushings.

I have one pistol where the bushing is OK, but must have slipped
during installation. It works OK, but the headspace is well past the
nominal upper limit. I got the bolt handle off with a strap wrench,
and expected that the bushing had slipped, but it is firmly stuck.

I've had it soaking in paint stripper for a month now, but I suspect
the gap between the bushing & the bolt stud is too small to allow
enough solvent in to undo the bushing in less than geologic time.

The other approach for dealing with most threadlocker is heat (~
300F?). I can make a specialized soldering iron tip that I can slip
or clamp over the bushing to free it. The iron I currently have is
temperature controlled, but at 700F. I could also go & buy a cheap
resistive iron and use it with a variac to control the temperature
down at a better level.

Thank you for anyone who has stuck with me so far. Here's the
question:

I would really like to salvage the bushing. What's the best way to
get it off without wrecking the heat treat? It's quite thin (
0.5mm), and I will be applying heat on the outside to get through to
the inside.

The best options I've come up with a

1) Use my 700 degree iron, with a tip mounted with a small brass block
with a hole that is a slip fit over the bushing. If I cock the tip at
a slight angle to get good thermal contact, I should be able to pull
the bushing off as soon as the threadlocker lets go, and then the
bushing should fall free from the heat source.

2) By a cheap iron, and make the tip clamp securely onto the bushing.
Then use a variac/dimmer to sneak up on the temperature. I have a set
of Tempilac sticks that I can use to tell when it has reached certain
temperatures. I also have an infrared thermometer, but I don't think
it goes hot enough for this. With this approach, I am unlikely to get
the bushing much hotter than required to melt the threadlocker, but it
will be at that temperature for much longer.

3) Contact Italy and try to get more replacement bushings. That could
take months, and is not a sure thing. One reason I want to salvage
this one is the spares we obtained earlier may have been the dregs.
Some of them are not very eccentric, and many are not a very good fit
on the bolt handles.

4) I can certainly continue to leave the bolt soaking in paint
stripper. I have other projects to keep myself busy, and if I can
repair all the other pistols, the pressure will be off. It doesn't
seem to affect the metal, and if I keep it sealed up, I can try to
wait it out.

5) Quench after getting it free. Given how hard they are, quenching
presumably wouldn't make it much harder. However, it could become
more brittle, and likely to crack.

6) Make new bushings. I have no idea how involved this would get. I
did a rough hardness test on a cracked one using hardness files, and
it was ~ RC60 (which may be why it cracked...). I don't have any
experience or equipment to do sophisticated heat treating. I'm
assuming that heat treating will probably distort them a bit, and/or
mess up the surface finish enough that a light grind would be in
order. I can certainly rig up a Dremel as a tool post grinder for
that. The big advantage with this is that I can make a bunch. I know
of at least one other college team that has even more dead ones than
we do.

Other ideas & comments?

Thanks!

Doug White


Generally speaking, any substance used as a thread locker would
probably soften by the time it reaches, say 200 degrees F. And again,
generally speaking, a thread locker probably wouldn't be very soluble
in various solvents.

I think my first attempt would be by heating the bolt in boiling
water, keep it boiling until you are sure that the bolt actually
reaches ~212 degrees.

Another point RC 60 is pretty hard stuff. For a .22 pistol I would
suggest that if it is that hard it is probably for something other
than strength.

I once converted a bunch of S. American , small ring, Mausers to
sporting rifles and as I had to forge the bolt handles I tested both
the bolts and the receivers first and found that were in the range of
un-heatreated steel, relatively soft. I can't believe that a .22 would
have to be harder ;-)

I had a look at the break down drawing of the PDP-75 and if you are
talking abut the ring, at the rear of the bolt, that the bolt handle
seems to fit through, index 25, the drawing seems show a straight
forward sleeve (but it is a pretty vague drawing :-)


Thanks for the feedback.

The bushing/sleeve is hardened because it is what slides in the slot in
the action. It's to prevent wear, not for strength. In the exploded
diagram, the sleeve is part #26. #25 is the bolt handle, and #27 is the
knob that screws onto a stud that stick out of the bolt handle. The
eccentric sleeve fits on an unthreaded section at the base of the stud.

The sleeve is about 7.5mm in diameter, and the inner hole is about 6mm,
but offset about half a mm from center to produce the required
eccentricity.

I could certainly try boiling water, but none of the modern
threadlockers I've encountered soften up much at that temperature. The
vast majority of Locktite products are rated for use up to at least
300F. I would expect them not to soften until they get even hotter than
that.

Doug White


The original Loctite Blue had a heat range of somewhere in the 200
degree (F) range and your pistols were made in the late 1970's I
believe :-) And it is so cheap to try boiling water :-)

Does the exocentric sleeve have any manner of hold it, or turning it,
when adjusting the head space? I would think it would require
something.

I rebarrelled a number of NRA target pistols at one time or another
and the major problem I had was actually too tight headspace and
chamber dimensions. Although admittedly NRA target shooting is a bit
different than Free Pistol :-)

If it is just an ex centric sleeve I would think that any competent
machinist could churn out a bunch in a morning. If you made them out
of something like "drill rod" they could easily be hardened and
tempered to RC 60
--
Cheers,

John B.

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Default Releasign Threadlocker w/o Wrecking Heat Treat?

On Mon, 27 Feb 2017 09:11:15 +0700, John B.
wrote:

[200 lines of junk deleted]

Generally speaking, any substance used as a thread locker would
probably soften by the time it reaches, say 200 degrees F. And again,
generally speaking, a thread locker probably wouldn't be very soluble
in various solvents.


Since ordinary blue Locktite is used to set engine studs in air-cooled
engines, probably not. Probably closer to 400 deg.

I think my first attempt would be by heating the bolt in boiling
water, keep it boiling until you are sure that the bolt actually
reaches ~212 degrees.


Predict a waste of time. First thing I'd do is give the ring a visual
using the most powerful magnification I had. I'd be looking for
corrosion as much as thread locker, given the age. I'd try a really
good penetrator such as Kroil or Knock'em (Kroil knockoff).


Another point RC 60 is pretty hard stuff. For a .22 pistol I would
suggest that if it is that hard it is probably for something other
than strength.


If the penetrant doesn't work then I'd plan on heating until
looseness, followed by heat treatment after removal and cleanup.
Templaq and a heat gun will work fine for the heat treating.

John

John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address



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Default Releasign Threadlocker w/o Wrecking Heat Treat?

On Mon, 27 Feb 2017 14:44:33 -0500, Neon John wrote:

On Mon, 27 Feb 2017 09:11:15 +0700, John B.
wrote:

[200 lines of junk deleted]

Generally speaking, any substance used as a thread locker would
probably soften by the time it reaches, say 200 degrees F. And again,
generally speaking, a thread locker probably wouldn't be very soluble
in various solvents.


Since ordinary blue Locktite is used to set engine studs in air-cooled
engines, probably not. Probably closer to 400 deg.


I believe that Loctite states that the temperature limits of Loctite
"blue" is -65F to 300F. But a bit more reading shows that this is the
"improved" version so it is possible that a pistol assembled 38 years
ago might have been assembled with something with lower temperature
limits.

--
Cheers,

John B.

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Default Releasign Threadlocker w/o Wrecking Heat Treat?

On Tue, 28 Feb 2017 07:47:35 +0700, John B.
wrote:

I believe that Loctite states that the temperature limits of Loctite
"blue" is -65F to 300F. But a bit more reading shows that this is the
"improved" version so it is possible that a pistol assembled 38 years
ago might have been assembled with something with lower temperature
limits.


In another life back in that time frame, I had a business building
racing motorcycle engines. Loctite was/is the standard thread locker
for cylinder studs.

The base of a mud-encrusted motocross engine could easily reach 400
deg.

Some engines used stretch, single use studs. When it came time for a
rebuild, I bolted the cases together and put them in an oven at 450
deg. I could shake the shrink-fit ball bearings out but it took vice
grips to remove the studs. The Loctite was softened but certainly not
broken down.

John

John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address

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