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Focal7175
Tinkerer
Username: Focal7175
Post Number: 9
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2007 - 05:58 pm: | 
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I have a Fujica ST-801 that I'm trying to remove the top cover from. It seems a previous owner has epoxied the screws into the body (!). There is absoultely zero clearance (true, I'm afraid) between the screw head and the camera body, so Naphtha, WD40, and PB Blaster have all failed to loosen anything because they simply cannot soak into the threads.
The screw head is starting to strip, so I'm reluctant to try anything that won't work.
Doesa anybody have any suggestions?
Thanks |
Focal7175
Tinkerer
Username: Focal7175
Post Number: 10
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2007 - 05:59 pm: |
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Oh, I've also tried Liquid Wrench. No effect, presumably because it cannot reach the threads |
Glenn
Tinkerer
Username: Glenn
Post Number: 248
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 27, 2007 - 06:43 pm: |
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You need to apply a bit of heat. Get an electric soldering iron and file the tip down, so that it is a good fit on the screwhead. Apply the tip to the screw for long enough to warm up the threadlock, then use a good fitting screwdriver to break the screw free. |
Focal7175
Tinkerer
Username: Focal7175
Post Number: 11
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 28, 2007 - 08:50 am: |
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Glenn, I tried that this morning but it did not work. Based on the earlier screw that I did manage to remove, this is not a threadlock-type glue - it's a paste-based epoxy.
Any other suggestions? |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 466
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 28, 2007 - 10:47 am: |
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If it's really epoxy, I can't think of any solvent that will soften it.... the only chance I can think of is more heat - enough to destroy the polymer. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 228
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 28, 2007 - 12:55 pm: |
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I had to solve a similar problem not so long ago, heat and acetone (applied with cotton swabs) did the trick, no quick job, though. W. |
Pablomartinez
Tinkerer
Username: Pablomartinez
Post Number: 85
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 30, 2007 - 10:26 am: |
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As Werner says, acetone and heat should do it.
However, acetone is EXTREMLY flamable. Be careful with your source of heat. No sparks, no flames, no heatguns... |
Glenn
Tinkerer
Username: Glenn
Post Number: 249
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 30, 2007 - 02:12 pm: |
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I think you will find that the solvent - acetone in this case - plays no part in the actual breakdown of the epoxy. The solvent is actually 'removing' any sticky/gummy breakdown products, that the heating process produces. Obviously if you apply the acetone to the heated screw, it will evaporate before it has a chance to penetrate the screw hole.
I tend to use methylene chloride, as the solvent of choice on epoxy adhesives. However it will not work on all heated epoxies and I hesitate to recommend its use, because of the health and safety issues associated with this solvent. Having used many solvents throughout my working life, I thus still tend to use and be able to obtain chemicals that are not ideal for the home workshop - unless it is fitted with proper and adequate extraction. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 229
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 30, 2007 - 04:12 pm: |
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Pablo is right, acetone first, heat in the second place. |
Mikel
Tinkerer
Username: Mikel
Post Number: 67
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 30, 2007 - 06:24 pm: |
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And if all else fails, sometimes you just need to drill the damn thing out. |
Pablomartinez
Tinkerer
Username: Pablomartinez
Post Number: 86
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 01, 2008 - 08:52 am: |
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There is another option that might work but requires LOTS of work and patience:
If everything else fails and you ABSOLUTELY do not want to drill your screw, you can "build" an impact scredriver.
To do this, take an old screwdriver that PERFECTLY fits the groove of your screw. If you do not find one, file down the tip of the screwdriver till you have a perfect fit.
Now, you have to cut out the last 2 or 3 inches of your screwdriver to fit it on your power screwdriver or battery drill. Set the power screwdriver to a rather loose clutch position(in my metabo power screwdriver it's position 5 out of 20) and try to unscrew the reluctant screw.
Be patient, its not a big blow that you need, but continuous smooth hammering during many, many minutes!!
Needless to say that if you can file down an old scredriver hexagonal tip you will spare one screwdriver. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 474
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 01, 2008 - 10:58 am: |
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I agree with Glenn on solvents (though, again, nothing dissolves cured epoxy); acetone has not seemed to be the most effective one in my experience, except for cleaning up uncured epoxy resin which it's very good at. One problem with Acetone is that it evaporates so fast it's often gone before it can do its work. Methylene chloride, available commercially as "weld-on 3", is a very effective solvent for amorphous polymers, as is MEK (methyl ethyl ketone). Neither of these should be used without lots of ventilation, and the odor of MEK is particularly unpleasant. If you have a workshop that's separate from your house, these are handy to have around. |
Focal7175
Tinkerer
Username: Focal7175
Post Number: 12
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 12, 2008 - 06:14 pm: |
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I'm glad to say that I tried the soldering iron approach once again with a 30w iron and, after applyint heat for about 90 seconds, I was able to unscrew the screw. |
