Pcb milling : Do you have more tips and tricks ???

Opbouw en gebruik van de freesmachine

Postby boeingbrown » Tue Mar 10, 2009 12:00 am

Hi Peter,

Many thanks for explaining that !

stabilized by a plasticwheel

Will add that too. The "native"disk" is very irregular in it's surface.

Did you cut the toolpoint in half?

No, I did'nt, because of the simple trial, in a hurry.

Will see what I can "make" in this way ! Great ! Thanks.

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Postby boeingbrown » Wed Mar 11, 2009 12:00 am

Hi All, Peter (K),

Got an interesting addendum / correction on my "college notes", written here before, from Peter (van Grieken), the Colinbus teacher in the course.

1. With a floating head, even fixing the pcb with tape (above or beneath) isn't necessary at all !
The floating head presses the pcb against the layer underneath. We indeed saw that in the course.
The (theoretical possible) shift of the plate in x-y direction was only counteracted by the two pins in the (hardware) mirror line ("Y-axis") and that was all.
Turning around was simply taking it up and turning it upside down and fitting it again via the belonging holes in the pcb over the 2 pins on the table.

2. The 16 micons pcb's I saw / described are used for pcb's which undergo in a later stage a process of metalising (right word ?) holes drilled in it.
So first of all, holes are drilled in this thin pcb. Than it's metalised causing the holes to have metal inside. After this process the inner of the holes has thickened a little bit but also the "general pcb" has grown to slightly more thickness (probably growing to the well known 35 microns). After this step all things can be done which have nothing to do with holes that need to be metalised (other holes, traces, pads etc.).

3. As written : Eagle treads oval pads as traces, and therefore has this visual effect in Coliliner. No other problems either can be expected.

4. A BIB, BIG Flamish -Dutch linguage barrier ... has caused a wrong number for the distance before a pcb milling tool is "dead". I wrote "4 meters". Peter van Grieken (amongst other Peters here...) corrected me: 30 meters !

Interesting was that this distance lifetime is stongly prolonged by the floating head (!) because the sharp point is nearly total outside the very hard and damaging epoxy (FR4 material). He stressed also using the high rpm in this "setup" (but did not give here an explanation for it).

5. He included two interesting pictures attached here.

Good depth and same usage distance.
Wrong depth and same usage distance.
The difference is striking.

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