Question PCB engraving with VFD spindle

Hi,

For general interest.

Some pcb engraving/etching done recently using Eagle 8.1.0 and pcb to gcode ulp. Track widths and isolation set to 0.012" and engraved with single pas. Minimum hole size is 0.7mm. Tracks engraved using a 30degree carbide engraving bit set to cut to 0.008" deep. Spindle set to 18000rpm and 600mm/min for engraving and milling board cutout.







I think the engraving speed could safely be increased to nearer 1000mm/min without sacrificing quality - something to try on the next boards.

Peter

PCB engraving uses VFD spindle for high speed, where VFD stands for Variable Frequency Drives. VFD are commonly seen on bigger budget CNC machines. The PCB engraver is ideal for cutting and engraving a range of resistant materials, including copper board, plastic, and acrylic. It's a powerful operating system which is simple to use and allows multiple designs to be made at once.

Hi Peter.

A quick question if I may.

Suppose I wished to engrave lettering or indeed a fancy pattern into the surface of a chromed brass guitar pickup. How easy would this be to do? Obviously, I have the same kit as you. Do I just buy a carbide engraving bit and set an appropriate depth and spin it as normal? I would have guess an XY feed rate in the low to mid hundreds and I see you went for 600 mm/min. I also see you went for a depth of 0.2 mm. This would probably be correct for what I want to do.

I can screw the pickups to the spoil board using their own mounting tabs.

The reason I ask is that it is possible to buy unbranded guitar pickups at nearly 1/3 the price of the branded ones made in the same factory. They lack the correct etching, but are electromagnetically the same. [Obviously I'm not attempting to counterfeit them and other markings would have to be added on the base plate to distinguish them from the 'correct' ones.]

Doug

Hello Doug, I use www.sorotec.de/shop/Zerspanungswerkzeuge/sorotec-werkzeuge/Gravurwerkzeuge/Gravierfraeser/ with 8mm/sec and 0.2mm deep. Doing an extra pass of 0.01 mm will remove all burrs.

Make sure the surface is absolutely flat, otherwise your tool will break or the result will be uneven.

Erik.

Hi Doug,

Hmmmm!! Engraving chromium is going to be difficult because of its extreme hardness - I would think that engraving on the pick offs is done before plating. The settings and tools I use on copper clad glass fibre laminate are going to be of little relevance to your problem IMHO.

I did a quick on line search to get some views on the matter and came up with this forum discussion that might assist you.

www.cnczone.com/forums/general-material-machining-solutions/108089-machining-chromium-cobalt.html

To quote one post on this forum - "chrome, nickel/chrome are in the same machinablity zone ( bloody hard )" - I think this says it all!! Perhaps an alternative method is laser engraving, though I know very little about this to be honest.

One really stupid thought, if the cover of the pick off is removable, strip off the existing chrome plating, engrave the underlying brass, and then rechrome the part.

Sorry I can't be more helpful - but good luck with it, this guitar is going to be an awesome instrument when it is finally complete. I really admire your dedication and resourcefulness in tackling such a project.

Best wishes,

Peter

Thanks chaps.

The engraving is definitely done in the chrome. This is an interesting sideline and not part of my main guitar build.

I think a solid carbide V-groove engraving bit will be fine at 0.2 mm depth and 40-600 mm/min feed rate. I acknowledge your point about the workpiece (pickup) being completely flat Erik.

I worked out tonight that the font used looks very much like Rockwell italic which is a standard windows font.

Doug

I use the big 840 here for milling my pcb's i use altium and eagle spit them into flatcam do the copper removal set up and then get extra fine pcb mills done.

just got a 420 for better tolerances.


also for engraving text into aluminum cases.

0.1 vbit
pcb cut depth -39 micron so just the copper is coming away

fr4 copper clad is multi point probed in uccnc then the g-code appended before running.

Break points for the auto-changer to change tools

i have had the mill go down to 0.5 pitch quite happily.