Cutting populated PCB's into new shapes

[nctnico]

Remove hazardous stuff (like batteries, electrolytics) and really tough stuff (eg. heavy duty screw terminals etc) and throw in a router with a serrated edge tungsten carbide endmill, preferably 1/4" or thereabouts, 1/8" is a lot cheaper but you'll need to be conservative about feedrates. Then press go and observe as the carbide shreds through all the stuff on the board.

I agree. I have actually used that method in the past to cut interesting bits from old motherboards like the ISA slots and the oscillator circuit.

[Auzeras]

I plan to refine the designs a lot more once I know what I can deal with and the time frame, no point in churning out heaps if I can't possibly make them! Also no point in working on something impossibly small and detailed if it's possibly to cut but incredibly difficult/time consuming.

Photos are pretty average phone snaps from my Nexus for including in the workbook. Table is 500x1000x450  and made from 4lm of 50mm Kwila ($207 worth.. poor student tears!) The design is meant to resemble a DIP package somewhat. The legs are made from 22.5mm mild steel tube machined down to ~22mm to fit in the holes (they don't make 22.5mm forstner bits, and the .5mm shoulder gives a nice finish to the hole)

The table is 3x planks of 200x50 Kwila wide, glued and biscuit jointed with Tightbond II, I plan to finish it with teak oil and buff to a shine. I have danish oil but I feel that the glossier teak finish will go better with the inlaid epoxy.

Photos in order:

Gluing & Clamping table top

Machined steel (mild steel is ugly to machine)

Testing fit in legs

How it will look once table holes drilled

Table being drilled

Realising a few holes are a mm or so out and the compound error has screwed you (not shown, manic crying at prospect of ruining $200 in timber)

Working out a solution to aformentioned errors

Timber cut to size (this pic should be first but order got messed)

[nctnico]

Can't you use unpopulated PCBs as an alternative? You can have these made by Itead, Seeedstudio, etc.

[tggzzz]

As far as tools go I've got a pretty well kitted out workshop and fabrication workshop at my disposal. I talked to the lady who runs the fab lab and she's refusing to allow me to use their CNC routers to cut PCB, the PCB they cut is epoxy and cloth instead of fibre based like most commercial stuff. Also she's adverse to me even trying to cut through a populated board 

I wonder why!

More seriously, it might be worth you knowing why. Equipment safety/damage is one thing, but people's safety/injury is another.

Possible angle grinder with a thin cutting disk on it - danger of fine dust management. At least the jet cutter and bandswaw have pretty decent vacuums/disposal systems to minimise harmful particulate matter.

Don't forget it isn't necessarily solely dust that will damage people. Fumes can be pretty nasty too, and they wouldn't be caught by a dust filter, of course.

I'm sure you don't want your project to endanger other people in the vicinity.

[Auzeras]

[quote author=tggzzz link=topic=37109.msg522602#msg522602 date=1412152651

I wonder why!

More seriously, it might be worth you knowing why. Equipment safety/damage is one thing, but people's safety/injury is another.

Don't forget it isn't necessarily solely dust that will damage people. Fumes can be pretty nasty too, and they wouldn't be caught by a dust filter, of course.

I'm sure you don't want your project to endanger other people in the vicinity.
[/quote]

I know why was just letting other people know that any CNC routing was out of business, even with a good carbide bit. They don't want to deal with the dust & mess as well as they fab lab crew are a tad less into trying things out, preferring instead the more engineered proven approaches.

Fumes are a good point, although I should think they'll be at a minimum and any caused by friction will swiftly drawn out by the dust extractors, there's pretty solid airflow. Dust is the main concern.

If I suspect it could be a little dicey the n I'll just grab a grinder and go outside (assuming I go the grinding route) if not I can arrange to come into the shop early and seal off the area to work so no one else has to deal with my dust & fumes.

Even without the extractors I  think that the fumes produced would be pretty mild in terms of ppm. I'm more worried about the dust


All valid points though, and taken into consideration.

[Kjelt]

Another reason is that an industry cnc mill can reach speeds of 50000 rpm (even double that) and if a small smd component shoots loose with those speeds it is a small projectile, that is why industry routers are almost all completely encased.

[Alex Eisenhut]

Here we go...

[Auzeras]

Well that's cool! Mind if I use that photo for my workbook? Although I searched I never managed to find any examples of PCB's being set or encased in anything other than their intended machinery

[Richard Crowley]

Well that's cool! Mind if I use that photo for my workbook? Although I searched I never managed to find any examples of PCB's being set or encased in anything other than their intended machinery

https://www.google.com/search?q=circuit+board+art&source=lnms&tbm=isch

[ozwolf]

I've attached a picture of a desktop computer motherboard that I'm using to mount three analogue meters as a clock.  This will be a piece of "tech art" for my office.

The board had a lot of surface mount components removed (hot air gun) as I wanted the trace artwork to show.  I hot glued the pcb to an aluminium frame which will be used to mount to the office wall.  This picture is early stages of developing the Arduino board/software and RTC workings.  I'm now working on my on PCB to drive the meters.

I used a hole saw to cut three 50mm holes, messy but manageable.  I understand people issuing you cautions about dust, but I believe normal personal protection and normal safe working practices will suffice for hobby type projects (one off quantities).  I'd take a different approach if this was production and much larger quantities.

[Auzeras]

Very Cool ozwolf! I agree with your sentiments on the low impact of a small batch but since this is a university workshop the trick will be keeping within the OSH regulations for the department. That being said the workshop staff aren't worried about dust, it's only the people in the fabrication building (and the ones with the CNC router) who don't want me within a 10 mile radius with my FR4 boards I will be routing out the recesses for the PCBs with the CNC though.

Will get back with updates when the time comes, thanks for your cautions, suggestions and comments so far!

[Seekonk]

I cut up old circuit boards all the time.  I have great access to parts except when I go to my camp in the summer.  My entire colar/fridge UNO controller is from parts cut out old UPS and other boards.  Need a FET or regulator, cut out a square inch and hot melt glue it to a board.  I just use an angle grinder and a thin cutoff wheel then a hand file to clean the edged.

WARNING!!!!!!!!STAY AWAY FROM PRE 90'S COMPUTER BOARDS.  SOME COMPUTER CHIP HOUSINGS WERE MADE OF BERILIUM ( however you spell it) GRIND ONE OF THEM AND THE DUST IS POISONOUS.

[Auzeras]

UPDATE TIME! With pictures!

I was advised the best way to do this would be to to cast the resin, cut it out and stick it in. WRONG! If anyone does this in the future don't waste $50 in kleer kast like me and destroy the only large PCB you have lying around the day before you need to finish the piece  I recommend cutting out the PCB on a bandsaw with a blade designed for cutting metals then casting over the top  & sanding a finish instead of casting face down on glass & cutting into shape later.

Basically I f'ed up the cuts and it's nearly impossible to get them to fit well. I got one simple shape in after about an hour of sanding.

So yeah the CNC routing came up beautiful but unfortunately the PCB inlay looks a bit shite. I'll do my best and hope to re cast it some day when I have more money, student life The resin came up beautifully clear. It's a shame I couldn't cut accurately enough to get the shapes right

Pics in order:

Test cast with PCB - Although it looks like there are bubbles in it it's just dust. It come up gorgeously clear & bubble free. No vacuum chamber used. Just lucky!

Test shapes

More Test shapes

Casting motherboard (after removing headers & most through hole components)

CNC routing design

Awww yiss, looking great

Aww no I f'ed up

Well...