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bent scalpel thing for conformal coating removal?

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jpanhalt:

--- Quote from: coppercone2 on December 07, 2021, 09:01:23 pm ---So if I cut stainless shim, how do i sharpen something so flat? I have a feeling I will end up getting a mangled edge. I thought to tie it to my finger and try to 'pet' a wet stone with it to get a blade (like a fingernail extension).

--- End quote ---

Why bother sharpening a "stainless shim" when virtually all modern razor blades have really sharp stainless shim built into the blade cartridge?  Even more important, why does it need to be stainless or even sharp?  Why not use a dental pick/scraper as suggested long ago?  Please answer.  Or is your purpose simply to prolong this thread into a discussion of Mohs surgery, and its alternatives.  Glad to oblige if that is what you want.

thm_w:

--- Quote from: coppercone2 on December 06, 2021, 11:43:22 pm ---but I want the blade curved in both driections. Those kits are only shaped correctly in 1 dimension.

Maybe I will try to heat a exacto blade and bend it into a shape, if that works then the 'weird' attachment kit might work.

--- End quote ---

They show them being bent in the photos.
May or may not have to apply heat to get it to keep a new shape.

coppercone2:
just don't post in the thread if you dont like it

their annoying oval shaped resistors (~3W) that have 'softened skin' (maybe from the potting compound reacting with them) and are wedged between tons of potted capacitors, inductors, heatsinked transistors, etc. I have a dental pick kit but none of that worked well for the situation. if I braze a thin sharpened shim to one of the picks it might work. THF and Xylene both dissolve the text and its too cramped for any heated tools (pace) to fit in there to de polymerize the goo.

I think I need something along the lines of a extruded sharp question mark added to a standard flat pick so I can cut through it like a ice cream scoop. If I sharpen a shim, I will braze it to the end of a pick to make a tool that looks like a extruded question mark so I can insert it from the top and then rotate it to force the shim to cut the compound under the resistor.

I want to be able to target single parts on a heavy copper heavy soldered heavy populated conformal coated PCB without having to mess the entire thing up.

Think of like a modern computer power supply thats made cheap, working on them SUCKS. You need to do a shit load of desoldering to be able to use standard tools on weird shit like power resistors tucked under weird shaped heat sinks

something like this maybe, with the blade being cut to be slightly smaller then the resistor body. The action would be similar to a 'pry bar'. The closest thing I have seen to what I want is those heat gun tips that allow you to work with heat shrink with a little curved shield so you block the hot air from getting behind the wire


So you would place the tool at a shallow angle and then rotate it past orthogonal and it should complete the entire cut. Just prying at it with a needle after de soldering (the hook dentist tool) breaks the resistors.


Why stainless shim? Because I have like 2 big ass rolls of stainless steel sheet that I should be able to form into the correct shape, but it would need to be sharpened. If it works I can make a few different sized tools for different barrel components (i imagine a axial potted electrolytic to be a nightmare to deal with).

I feel if the tool is properly sized you can work at nearly 90 degrees, so long you see the component from the top it should be easy to remove, no matter the PCB density.



I am actually wondering if maybe a right angle slicer (right angle bent razor blade segment) might be good enough to just insert from the side too, without the fancy curve.

All the suggestions in this thread are appropriate for a ideal PCB, but not suitable for the 'marinara trench' formed by heat sink + transformer + soldered on daughter boards. This is really common in switching power supplies.

There is a medical tool that is kind of like a chisel meant for piercing the skin above the fingernail to drain fingernail infections (swolen fingertip cure) that would work if it was longer (it is plastic and you can heat bend it into shape),  but I have only seen it in a medical office, and the blade is too short (only 2mm or so, I would need like 5mm), but IIRC its made flat so it 'slides' on top of the fingernail to offer a very clean and repeatable cut in order to pop open infected tissue in such a way to allow for drainage with minimal injury.

I also don't like working with razor blades, and I don't like tools that require tension to bend into the correct shape while in use, that feels like struggling to me. (desperado shit).. save the nail clippers for defusing the nuclear bomb lol

gnavigator1007:
I'm wondering if an attachment for one of those cheap electric grinding pens might work for you. Probably depends on how much space you have to come at it from the side while the tool is upright

coppercone2:
I kinda want one but it seems like wank since I have a dremel pen. I am not sure if it would help, i really need to make  sure the coating is broke under neath the parts so the belly is not ripped off. I had bad experiences with those mini screw drivers.

The thermal tool can do the same job as the dremel of getting through the side goop.

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