Removing rubbery potting compound

N_Cook <diverse@tcp.co.uk> wrote in message
news:h1o157$2bo$1@news.eternal-september.org...
Sam Goldwasser <sam@minus.seas.upenn.edu> wrote in message
news:6wk5348n3g.fsf@minus.seas.upenn.edu...
Bruce Esquibel <bje@ripco.com> writes:

In sci.electronics.repair Sam Goldwasser
sam@ampersand.seas.upenn.edu
wrote:

This type is usually dark gray and soft - about the consistency of a
pencil
eraser, maybe a bit tougher. It can be removed laboriously with
knives,
picks, and elbow grease. But the question is whether there is some
easier
way to do this that would leave the underlying components undamaged.
This stuff is used in a variety of places including PCBs and laser
tube assemblies. Both of these are of interest to me. Modest heat
has no effect including immersing in boiling water - it's not
hot-melt
glue.

This probably isn't much help but we used to use a chemical called
Eccostrip 93 made by Emerson and Cuming (or cumming or cummings).

I don't know if it's sold anymore, probably on every EPA hazard
chemical
list by now but I believe the main purpose of it was to attack
something
in
the resin.

It wasn't a miracle worker, but did it's job eventually. Generally you
needed to apply it with a glass eyedropper to keep the area wet, then
periodically using a acid brush, dust off the powder, reapply.

As far as component damage, yeah, some carbon film resistors, the
bodies
would flake off but I don't remember anything else. Even ic's (chips)
that I
thought had some epoxy holding them together were no worse for wear
even
soaking in the stuff.

Yeah, for the real application I have in mind, this is probably going to
take about 1,423 years (give or take a century). :)

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.

Thanks.

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header
above
is
ignored unless my full name AND either lasers or electronics is included
in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.


-bruce
bje@ripco.com

Can you make a pilot hole with a thin steel rod, chisel ground at the end.
Then pass through it one of those carbide covered wire saw , garotte type
things, or even a coping saw blade, kept under tension. Would some scratch
damage matter? If so then perhaps spaced , glued-on, guard rings along the
blade


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
Click to expand...
or after a pilot hole then a current carrying length of straightened heater
element wire perhaps would work to cut around
 
In sci.electronics.repair Sam Goldwasser <sam@ampersand.seas.upenn.edu> wrote:

This type is usually dark gray and soft - about the consistency of a pencil
eraser, maybe a bit tougher. It can be removed laboriously with knives,
picks, and elbow grease. But the question is whether there is some easier
way to do this that would leave the underlying components undamaged.
This stuff is used in a variety of places including PCBs and laser
tube assemblies. Both of these are of interest to me. Modest heat
has no effect including immersing in boiling water - it's not hot-melt glue.
Click to expand...

This probably isn't much help but we used to use a chemical called
Eccostrip 93 made by Emerson and Cuming (or cumming or cummings).

I don't know if it's sold anymore, probably on every EPA hazard chemical
list by now but I believe the main purpose of it was to attack something in
the resin.

It wasn't a miracle worker, but did it's job eventually. Generally you
needed to apply it with a glass eyedropper to keep the area wet, then
periodically using a acid brush, dust off the powder, reapply.

As far as component damage, yeah, some carbon film resistors, the bodies
would flake off but I don't remember anything else. Even ic's (chips) that I
thought had some epoxy holding them together were no worse for wear even
soaking in the stuff.

-bruce
bje@ripco.com
 
On Mon, 22 Jun 2009 08:33:23 -0400, Sam Goldwasser
<sam@minus.seas.upenn.edu> wrote:

Bruce Esquibel <bje@ripco.com> writes:

In sci.electronics.repair Sam Goldwasser <sam@ampersand.seas.upenn.edu> wrote:

This type is usually dark gray and soft - about the consistency of a pencil
eraser, maybe a bit tougher. It can be removed laboriously with knives,
picks, and elbow grease. But the question is whether there is some easier
way to do this that would leave the underlying components undamaged.
This stuff is used in a variety of places including PCBs and laser
tube assemblies. Both of these are of interest to me. Modest heat
has no effect including immersing in boiling water - it's not hot-melt glue.

This probably isn't much help but we used to use a chemical called
Eccostrip 93 made by Emerson and Cuming (or cumming or cummings).

I don't know if it's sold anymore, probably on every EPA hazard chemical
list by now but I believe the main purpose of it was to attack something in
the resin.

It wasn't a miracle worker, but did it's job eventually. Generally you
needed to apply it with a glass eyedropper to keep the area wet, then
periodically using a acid brush, dust off the powder, reapply.

As far as component damage, yeah, some carbon film resistors, the bodies
would flake off but I don't remember anything else. Even ic's (chips) that I
thought had some epoxy holding them together were no worse for wear even
soaking in the stuff.

Yeah, for the real application I have in mind, this is probably going to
take about 1,423 years (give or take a century). :)

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.
Click to expand...
Maybe one of the oscillating-face tools, like the Fein MultiMaster?
http://www.fein.de/fein-multimaster/us/en/main/

There are flexible blades that might do the trick. Won't work (very
well) to de-pot an SMT-stuffed PCB but might get you a long way towards
getting the stuff off of the tube.
<http://www.fein.de/fein-multimaster/us/en/products/accessories_scraping.php>

--
Rich Webb Norfolk, VA
 
On 6/22/2009 7:16 AM Rich Webb spake thus:

Maybe one of the oscillating-face tools, like the Fein MultiMaster?
http://www.fein.de/fein-multimaster/us/en/main/
Click to expand...
Don't think so; those tools work on a principle that's the complete
opposite of what is needed here. That is, they'll cut something hard but
not damage something soft next to it, like the saws used for cutting off
plaster casts that don't harm skin. They'll just jiggle the rubbery
stuff without cutting it.

How about careful use of a cutoff wheel in a Dremel or equivalent tool,
to make slices in the rubbery stuff?

[note post trimming]


--
Found--the gene that causes belief in genetic determinism
 
On Mon, 22 Jun 2009 10:42:46 -0700, David Nebenzahl
<nobody@but.us.chickens> wrote:

On 6/22/2009 7:16 AM Rich Webb spake thus:

Maybe one of the oscillating-face tools, like the Fein MultiMaster?
http://www.fein.de/fein-multimaster/us/en/main/

Don't think so; those tools work on a principle that's the complete
opposite of what is needed here. That is, they'll cut something hard but
not damage something soft next to it, like the saws used for cutting off
plaster casts that don't harm skin. They'll just jiggle the rubbery
stuff without cutting it.
Click to expand...
Roger that. However, from watching the infomercial it looks like the
flexible, spatulate heads are used to separate stuff like caulk beads
from porcelain bathtubs. The working face isn't toothed and might just
do the trick in this app.

I don't speak from personal experience, just what I've seen on the tube.
But, since "He who dies with the most tools, wins!" I'll probably have
to break down someday and get one.

--
Rich Webb Norfolk, VA
 
"William Sommerwerck" <grizzledgeezer@comcast.net> writes:

Whatever this stuf is, common sense suggests it was designed not to be
easily removed, especially by chemical means. Otherwise, there would be
little point to it.
Click to expand...

I think that's only true in some cases. Since this CAN be removed
using just brute force, it's a lot easier to reverse engineer
PCBs and such with it than, say, hard Epoxy.

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
"N_Cook" <diverse@tcp.co.uk> writes:

Sam Goldwasser <sam@minus.seas.upenn.edu> wrote in message
news:6wk5348n3g.fsf@minus.seas.upenn.edu...
Bruce Esquibel <bje@ripco.com> writes:

In sci.electronics.repair Sam Goldwasser <sam@ampersand.seas.upenn.edu
wrote:

This type is usually dark gray and soft - about the consistency of a
pencil
eraser, maybe a bit tougher. It can be removed laboriously with
knives,
picks, and elbow grease. But the question is whether there is some
easier
way to do this that would leave the underlying components undamaged.
This stuff is used in a variety of places including PCBs and laser
tube assemblies. Both of these are of interest to me. Modest heat
has no effect including immersing in boiling water - it's not hot-melt
glue.

This probably isn't much help but we used to use a chemical called
Eccostrip 93 made by Emerson and Cuming (or cumming or cummings).

I don't know if it's sold anymore, probably on every EPA hazard chemical
list by now but I believe the main purpose of it was to attack something
in
the resin.

It wasn't a miracle worker, but did it's job eventually. Generally you
needed to apply it with a glass eyedropper to keep the area wet, then
periodically using a acid brush, dust off the powder, reapply.

As far as component damage, yeah, some carbon film resistors, the bodies
would flake off but I don't remember anything else. Even ic's (chips)
that I
thought had some epoxy holding them together were no worse for wear even
soaking in the stuff.

Yeah, for the real application I have in mind, this is probably going to
take about 1,423 years (give or take a century). :)

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.

Thanks.

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/

-bruce
bje@ripco.com

Can you make a pilot hole with a thin steel rod, chisel ground at the end.
Then pass through it one of those carbide covered wire saw , garotte type
things, or even a coping saw blade, kept under tension. Would some scratch
damage matter? If so then perhaps spaced , glued-on, guard rings along the
blade
Click to expand...
That's sort of what I've been doing, and have been contemplating making
a tool that is more matched to the job than the strips of aluminum and
other random items I've been using.

I'm coming to believe that any chemical approach will take to long, not
to mention the mess and health issues.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
Click to expand...
 
Rich Webb <bbew.ar@mapson.nozirev.ten> writes:

On Mon, 22 Jun 2009 08:33:23 -0400, Sam Goldwasser
sam@minus.seas.upenn.edu> wrote:

Bruce Esquibel <bje@ripco.com> writes:

In sci.electronics.repair Sam Goldwasser <sam@ampersand.seas.upenn.edu> wrote:

This type is usually dark gray and soft - about the consistency of a pencil
eraser, maybe a bit tougher. It can be removed laboriously with knives,
picks, and elbow grease. But the question is whether there is some easier
way to do this that would leave the underlying components undamaged.
This stuff is used in a variety of places including PCBs and laser
tube assemblies. Both of these are of interest to me. Modest heat
has no effect including immersing in boiling water - it's not hot-melt glue.

This probably isn't much help but we used to use a chemical called
Eccostrip 93 made by Emerson and Cuming (or cumming or cummings).

I don't know if it's sold anymore, probably on every EPA hazard chemical
list by now but I believe the main purpose of it was to attack something in
the resin.

It wasn't a miracle worker, but did it's job eventually. Generally you
needed to apply it with a glass eyedropper to keep the area wet, then
periodically using a acid brush, dust off the powder, reapply.

As far as component damage, yeah, some carbon film resistors, the bodies
would flake off but I don't remember anything else. Even ic's (chips) that I
thought had some epoxy holding them together were no worse for wear even
soaking in the stuff.

Yeah, for the real application I have in mind, this is probably going to
take about 1,423 years (give or take a century). :)

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.

Maybe one of the oscillating-face tools, like the Fein MultiMaster?
http://www.fein.de/fein-multimaster/us/en/main/

There are flexible blades that might do the trick. Won't work (very
well) to de-pot an SMT-stuffed PCB but might get you a long way towards
getting the stuff off of the tube.
http://www.fein.de/fein-multimaster/us/en/products/accessories_scraping.php
Click to expand...
Could be. The only real problem is getting the tube out. Once it's out,
getting the stuff off of it and the cylinder it was in is no problem,
the adhesion is not very strong, just enough that you can't push the
tube out without likely smashing it.


Thanks!

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
Sam Goldwasser <sam@minus.seas.upenn.edu> wrote in
news:6weitbx1oj.fsf@minus.seas.upenn.edu:

The only real problem is getting the tube out. Once it's out,
getting the stuff off of it and the cylinder it was in is no problem,
the adhesion is not very strong, just enough that you can't push the
tube out without likely smashing it.
Click to expand...
So do it the way a capacitor is removed from the PFN for the SSY-1. Use a
fast cutting disk, or slow hacksaw, to cut the outer cylinder parallel to
axis, peel it back enough to remove the innards, then peel the gunk off the
internal cylinder (cap, or laser in this case).
 
"Sam Goldwasser" <sam@ampersand.seas.upenn.edu> wrote in message
news:6wws755z1c.fsf@ampersand.seas.upenn.edu...
This type is usually dark gray and soft - about the consistency of a
pencil
eraser, maybe a bit tougher. It can be removed laboriously with knives,
picks, and elbow grease. But the question is whether there is some easier
way to do this that would leave the underlying components undamaged.
This stuff is used in a variety of places including PCBs and laser
tube assemblies. Both of these are of interest to me. Modest heat
has no effect including immersing in boiling water - it's not hot-melt
glue.

Thanks!
Click to expand...
If it is silicone based, you might try Varsol. It causes one part silicone
to swell and get even more rubbery, so maybe it will behave similiarly
on that stuff. It tends to be easier to remove in this state.

Mike
 
That might work for the PCBs, though what will it do to the components?

However, what I really need to remove it from are special HeNe laser tube
assemblies. Not the common laser heads, but ones where the tube is totally
surrounded by the stuff as well as in front and back. So, the tube will
still be stuck inside surrounded by brittle hard stuff. :)

Thanks for thinking about it!
Click to expand...
That sounds like a real pain. If you can use a long drill to drill a
tunnel parallel to the tube, you might be able to saw around the tube
with some piano wire.
 
Sam Goldwasser wrote:
"William Sommerwerck" <grizzledgeezer@comcast.net> writes:

Whatever this stuf is, common sense suggests it was designed not to be
easily removed, especially by chemical means. Otherwise, there would be
little point to it.


I think that's only true in some cases. Since this CAN be removed
using just brute force, it's a lot easier to reverse engineer
PCBs and such with it than, say, hard Epoxy.
Click to expand...

Even hard epoxy is no real matter when it comes to reverse engineering
if you are willing to destroy the thing you are analyzing. I've found
that it's quite brittle stuff, and applying pressure in the right places
with a bench vise will usually cause it to crumble. Some components will
get broken in the process but they can usually still be identified.
 
Sam Goldwasser <sam@minus.seas.upenn.edu> wrote in message
news:6weitbx1oj.fsf@minus.seas.upenn.edu...
Rich Webb <bbew.ar@mapson.nozirev.ten> writes:

On Mon, 22 Jun 2009 08:33:23 -0400, Sam Goldwasser
sam@minus.seas.upenn.edu> wrote:

Bruce Esquibel <bje@ripco.com> writes:

In sci.electronics.repair Sam Goldwasser
sam@ampersand.seas.upenn.edu
Could be. The only real problem is getting the tube out. Once it's out,
getting the stuff off of it and the cylinder it was in is no problem,
the adhesion is not very strong, just enough that you can't push the
tube out without likely smashing it.


Thanks!

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above
is
ignored unless my full name AND either lasers or electronics is included
in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
Click to expand...

In that case would mounting a vacuum chamber around the outside give enough
force for air pressure to shift it. Or compressed air around it with
appropriate seal? With some nearby soft physical restraint of course for if
it does move.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser
<sam@minus.seas.upenn.edu> wrote in Message id:
<6wk5348n3g.fsf@minus.seas.upenn.edu>:

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.
Click to expand...
How about using a thin blade from a coping saw? Once you manage to slip it
all the way through the length of the cylinder it should work fairly well.
I don't think it'd damage the glass either.
 
Lostgallifreyan <no-one@nowhere.net> writes:

Sam Goldwasser <sam@minus.seas.upenn.edu> wrote in
news:6weitbx1oj.fsf@minus.seas.upenn.edu:

The only real problem is getting the tube out. Once it's out,
getting the stuff off of it and the cylinder it was in is no problem,
the adhesion is not very strong, just enough that you can't push the
tube out without likely smashing it.

So do it the way a capacitor is removed from the PFN for the SSY-1. Use a
fast cutting disk, or slow hacksaw, to cut the outer cylinder parallel to
axis, peel it back enough to remove the innards, then peel the gunk off the
internal cylinder (cap, or laser in this case).
Click to expand...
That's what someone else did, but the important part is really the cylinder.
I'd like to get the tube out intact as well, but the solution of last
resort is to simply smash the tubes. Yes, I know, that's going to upset
the gods of dead lasers, but we'll see how the alternatives work out! :)

Thanks!

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
JW <none@dev.null> writes:

On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser
sam@minus.seas.upenn.edu> wrote in Message id:
6wk5348n3g.fsf@minus.seas.upenn.edu>:

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.

How about using a thin blade from a coping saw? Once you manage to slip it
all the way through the length of the cylinder it should work fairly well.
I don't think it'd damage the glass either.
Click to expand...
Yeah, that's been my thinking as well. I don't like chemicals and anything
that would get through several inches of the close-fitting cylinder would
almost certainly be rather ansty.

Whether a coping saw blade is optimal I don't know, but something that
can be forced through and then fastened at both ends with enough "teeth"
to be able to eat away at the rubber.

Thanks!

--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
"James Sweet" <jamessweet1@trashmail.net> wrote in message
news:h1pisl$4aj$2@news.eternal-september.org...
Sam Goldwasser wrote:
"William Sommerwerck" <grizzledgeezer@comcast.net> writes:

Whatever this stuf is, common sense suggests it was designed
not to be easily removed, especially by chemical means.
Otherwise, there would be little point to it.

I think that's only true in some cases. Since this CAN be removed
using just brute force, it's a lot easier to reverse engineer
PCBs and such with it than, say, hard Epoxy.

Even hard epoxy is no real matter when it comes to reverse engineering
if you are willing to destroy the thing you are analyzing. I've found
that it's quite brittle stuff, and applying pressure in the right places
with a bench vise will usually cause it to crumble. Some components will
get broken in the process but they can usually still be identified.
Click to expand...
Please note the adverb in my original post.
 
JW <none@dev.null> wrote in message
news:4e7145psh26ir5dcrgqem5i1m5612m639d@4ax.com...
On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser
sam@minus.seas.upenn.edu> wrote in Message id:
6wk5348n3g.fsf@minus.seas.upenn.edu>:

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.

How about using a thin blade from a coping saw? Once you manage to slip it
all the way through the length of the cylinder it should work fairly well.
I don't think it'd damage the glass either.
Click to expand...
My coping saw blades are only 6 inches long, I doubt they come any longer as
only intended for small light work.

After drilling a pilot hole I would try one of these sort of wire saws
http://www.ecamo.co.uk/product/webtex-commando-survival-wire-saw/265.html
fed through and then bodge fixed in a 12 inch hacksaw frame for rigidity.

Or straightened out bit of heater element wire


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
Sam Goldwasser wrote:
JW <none@dev.null> writes:

On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser
sam@minus.seas.upenn.edu> wrote in Message id:
6wk5348n3g.fsf@minus.seas.upenn.edu>:

The PCB was just an example. But where this is needed is to remove
the stuff surrounding a glass laser tube - about 6 inches in length
and a space of 2 or 3 mm between the tube and the cylinder it's in.
Both the cylinder and tube need to come out undamaged.
How about using a thin blade from a coping saw? Once you manage to slip it
all the way through the length of the cylinder it should work fairly well.
I don't think it'd damage the glass either.

Yeah, that's been my thinking as well. I don't like chemicals and anything
that would get through several inches of the close-fitting cylinder would
almost certainly be rather ansty.

Whether a coping saw blade is optimal I don't know, but something that
can be forced through and then fastened at both ends with enough "teeth"
to be able to eat away at the rubber.
Click to expand...
Might I suggest a flexible wire saw such as this one:

http://www.vtarmynavy.com/commando-wire-saw.htm

or this

http://au.farnell.com/abrafile/250130/flexisaw-15-pack-of-2-blades-handles/dp/108078

Perhaps you could stretch the saw between two fixed vices having first
threaded the tube over it, then work it back and forth while rotating it
to cut throught the rubber compound.

Ron(UK)
 
Sam Goldwasser <sam@ampersand.seas.upenn.edu> wrote:
Whether a coping saw blade is optimal I don't know, but something that
can be forced through and then fastened at both ends with enough "teeth"
to be able to eat away at the rubber.

Thanks!
Click to expand...
I've lost track of how long the laser tube is. If you can thread
dental floss along the length of the tube you can saw the tube
out with the floss.
 
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