Potentiometer thermo plastic "grommet" repair

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Potentiometer thermo plastic "grommet" repair

Ok, so you're me.  You google scratchy Apple IIC potentiometer and you end up at this page:  http://www.apple2faq.com/apple2faq/apple-iic-volume-knobpotentiometer-repair/  ou desolder your audio pot from the motherboard.  Of course, tThe potentiometer in the picture is nothing like yours, and the instructions don't make any sense.  You proceed happily cut away at the plastic grommet holding the inner wheel anyway.  The inner wheel slips out.  You DeOxit F5 your wheel to death and scrub it with a toothbrush.  You're confident that your metal bits and pieces are as good as brand new and now you're ready to reassemble everything and test out your audio port by using a copy of Music Construction Set to listen to an 8-bit rendition of Flight of the Bumblebee.

You put the wheel back on and realize you're screwed because the grommet was thermo plastic welded using magical 1980's technology that is no longer available and you've just cut the plastic to smithereens.  You're doomed!  Your pot wheel can never be put back together.  Or can it?

It turns out that we all have access to crude thermoplastic welding methods.  For just $39.99 plus shipping.  Enter "Super 3D Pen" 3D printer pen.  This one from MYNT3D.  Used white PETG 1.75mm filament I had laying around.  Problem solved!  Wheel is back on now, and flat and flush again, and turns nicely.  Found a nice wrench from some furniture that was just the right size to hold the parts flatly in place with one hand, while I "welded" with the other.  Then you can use an xacto knife to trim away excess as needed.

 

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Thanks for that. That's a brilliant idea!

Really appreciate hints and tips like this. I cn already think of many different uses!

 

Cheers!

 

Chesh

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Yes, while you mention it.  I

Yes, while you mention it.  I was just reassembling this Apple IIC and realized I had more thermo welding to do....

 

 

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interesting

Very interesting! I had seen those extruder pens a while ago but never had confirmation they were useful. Something new to try.

It might be useable to re-fix heat staked panels like the shield in the IIgs.

One thought, however. Can you elaborate how the practicalities of using the extruder compare with simply melting and mixing using a soldering gun? I gather that the workpieces need to be engraved to give the filament something to key into?

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Experimental at this time

Experimental at this time with long-term results unknown.  This is the first time I've used the PETG through the 3D pen.  Could end up with the plastic coming loose and the volume knob popping off later or something like that.  The 3D pen doesn't have digital controls so I'm shooting in the dark as to what the temperature is on the 3D printer pen.  I do have to press the 3D pen's hot tip into the original plastic to get that melted a little bit and get it to meld with the PETG coming out of the 3D pen.  I'd say if you have the patience and a little extra apple original plastic laying around, using an old soldering iron is probably going to last longer.  This pen is a bit annoying to use, if I could get a better pen or fix this one, I'd crank the temp up a bit and somehow improve the extruder because it's hard to control the rate of plastic coming out.

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