Author Topic: Making 4 PSX-1s out of a PSX-4  (Read 257 times)

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Maletrain

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Making 4 PSX-1s out of a PSX-4
« on: March 13, 2021, 09:46:58 PM »
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I have a PSX-4 panel of 4 circuit breakers that I want to separate into 4 PSX-1 panels. 

The circuit board is scribed to facilitate breaking apart the 4 breaker circuits.  But, I am reluctant to put the stress on the soldered circuits to make the 3 breaks needed. 

I am thinking that it would be better to use my Micro Mark tilt-arbor mini saw table to saw the panel sections apart.  I am wondering which saw blade is appropriate to cut (what I think is) hard epoxy/fiberglass circuit board stock.  I have several saw blades available, including a 40-tooth carbide blade that looks quite thick for this task (0.070" kerf), plus very thin steel blades with 168 teeth (0.032" kerf) and 230 teeth (0.020" kerf), and cutoff disks in both silicon carbide and aluminum oxide.

Looking for advice on what would work best, mainly for the circuit board integrity, but also with some thought about wear on the saw blades.


MK

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Re: Making 4 PSX-1s out of a PSX-4
« Reply #1 on: March 13, 2021, 11:13:33 PM »
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The circuit board will chew right through the steel blade.  Years ago I ruined a very thin steel blade trying to a small board and it was a tiny cut.

I would go with the carbide blade.  If the kerf is too thick, my second choice would the cut off disks.

peteski

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Re: Making 4 PSX-1s out of a PSX-4
« Reply #2 on: March 14, 2021, 01:39:17 AM »
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Yes, fiberglas/epoxy PC boards are really rough on machining tools. That's why they are drilled and routed with tungsten carbide bits.
While just making few cuts will probably not ruin the steel blade, how about just cutting with a Dremel using a cutoff disk?  You probbably just need to score the grooves deeper, then snap the board with very light pressure.

Make sure not to inhale the glass/epoxy dust!
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Maletrain

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Re: Making 4 PSX-1s out of a PSX-4
« Reply #3 on: March 14, 2021, 11:17:26 AM »
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OK, I'm thinking about using the cutoff disks on the saw, rather than trying to free-hand it with a Dremel.  Any preference between silicon carbide and aluminum oxide for cutting this material?

And good point about the dust.  I can't use the blade guard for these cuts, because of the components already soldered to the board, so the vacuum attachment isn't going to do much.  Think I will be making these cuts outside while the sun shines.

Steveruger45

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Re: Making 4 PSX-1s out of a PSX-4
« Reply #4 on: March 14, 2021, 02:27:59 PM »
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The last time I cut some pcb boards I used a dremel with aluminum oxide cut off wheel making several light freehand passes and snapping when about half way through with gentle pressure.
Yes, the dust is not good for you so I wore an N95 mask (before the pandemic made this part of everyday vocabulary) and set up my shop vac by sticking the nozzle onto the workbench with duct tape and zip ties and having the motor end away from me near the open garage door.
It worked fine and I’m still alive.
Good luck.
Steve
Atascocita, Texas

peteski

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Re: Making 4 PSX-1s out of a PSX-4
« Reply #5 on: March 14, 2021, 02:47:31 PM »
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OK, I'm thinking about using the cutoff disks on the saw, rather than trying to free-hand it with a Dremel.  Any preference between silicon carbide and aluminum oxide for cutting this material?


Either will work. No worries about the disks - they are sacrificial anyway. Silicon Carbide would probably last longer, but the small amount of cuts you're making will likely barely put a dent in the disks.
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Maletrain

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Re: Making 4 PSX-1s out of a PSX-4
« Reply #6 on: March 14, 2021, 02:48:54 PM »
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I tried another approach, and it worked.  The dust thing was getting worrisome, which means troublesome.

What I did was use a box cutter with snap-off blade ends to deepen the score marks that were already on the PSX board, until I had weakened it enough to snap off with the pressure I was (mentally) comfortable applying to it.  Those as-delivered score marks were already quite deep, but the board was still surprisingly stiff.  So, it took a lot of passes with a new knife point on each score mark, but it worked faster and safer than trying to setup a saw to handle the dust problem.

So, now on to sanding the edges by hand outside in a stiff breeze.

Thanks to all for the thoughtful inputs.
« Last Edit: March 14, 2021, 02:50:48 PM by Maletrain »