[free_matrex2010]

hi all ,

my first try in making pcb in egypt . i am using bit that i bought from here locally , i used it but result is so bad . in picture which i take the result the trace not smooth and having edges too not smooth .

picture have result and tools used too
sorry for bad english.

[kennl]

Try and brush the board with a tooth brush. Looks like it will clean up a bit. Hard to tell from the picture if its jagged cuts or debris.

[free_matrex2010]

Try and brush the board with a tooth brush..
sorry for bad resolution but it`s not debris.i brush the board after cutting but it`s not remove it it too hard my be it will hurt u if u scratch it with ur hand.
the cut is not clean and make boards

[lwill]

What were your spindle speed, feed, and depth of cut?

[free_matrex2010]

spindle speed,12000
feed sorry dont know but it too fast
and depth of cut 0.10 cm

[Joe S.]

I would use some coolant/oil to cut. Copper is like machining bubble gum. It wants to gall & ball up on the cutter, then tears instead of shearing. 1 important fact re: oils, sulfur in cutting oil will give the copper a nice brown patina which is tough to clean off, so choose your oil with that in mind.

[neilw20]

I use broken PCB drills, with just a tiny bit of flute remaining. One single gash at the correct angle, about 5-7 degrees, and a flat just to center works fine.
I end up with a square end ended cut. Not much burring. I often use a 0.3mm bit.
I have a tiny polishing wheel on my dremmel, that is some sort of of soft stuff, that will polish off the burrs without wrecking the copper.
I have just done a 28 pin SMD IC with 0.65mm pitch. That is 0.35mm wide pads, with 0.1mm thick copper. 1/3 cutter diameter depth of cut.

[Jay C]

You meant 0.1mm right? You are tearing the copper, not cutting it. Your tool is too dull, and you depth of cut may need to be reduced as well. Also, what type of spindle, runout can cause some similar results (like using a Dremel). Using some fine sandpaper (400 grit) will help knock off the sharp bits and any the patina/corrosion.

[free_matrex2010]

no i mean 1 mm,is this tool is good for pcb?? and what the spindle speed must be??
my spindle just made in china router apt crown 1050W.

[Jay C]

The smaller the tool the faster it needs to spin. 16K to 20K RPM. Have you tried running 2 passes? The second on is used to clean up the edges.

[free_matrex2010]

iam little confused what the different between ENd mill ,Vshape and my bits??

[neilw20]

This is a 0.3mm carbide drill sharpened for PCB routing.
Bit hard to get a good picture with my phone!! Can get a better shot later, if you need it.
Attachment 205048
It has a flat to half the diameter, and clearance towards the back, and on the right.
It only has to cut to 0.12mm deep. Quite strong, in this form. Leaves burrs sometimes depending on direction of cut.

[blinkenlight]

First off, you're using a rather wide angle V-shaped milling bit: 30 degree tips are commonly used (and even some with 15 deg. exist), yours looks like a 60 degree one - it can still be used to mill PCB, but the deeper you cut the wider the removed strip of copper becomes, making fine PCB milling much harder. Second, feed speed is crucial - since your RPM is fairly low (20000 and higher are better, you can go faster), you really have to be careful not to go too fast or risk breaking off the tip (you might not even notice, just a tiny bit off the tip breaks off usually, the damage is only visible under a magnifying glass) and that would completely ruin the PCB - I don't really go faster than 4 inches per minute with my 10000 RPM right now, your experience might be different. Third, your cutting depth sound completely weird - a normal thickness 1 oz. copper PCB has a 0.036 mm thick layer of copper on it - which means I don't normally go deeper than 0.06 mm - that's 6 _hundredths_ of a millimeter. Alternatively, something like 0.1 mm has to be enough. If you're really cutting 0.1cm (=1mm) deep, that's really, really, _really_ much more than you should. The entire PCB is supposed to be only 1.5mm thick!

Regarding mill bit types - the "V" ones (sometimes also called "engraving" tips) simply end in a sharp point effectively the way the letter "V" looks like, while the typical "end mills" (even if very thin) are usually cylindrical with a flat end - they have the advantage of not increasing cut width as you go cutting deeper (unlike the "V"-bits), but they are also much more fragile because of their shape for the same cutting width as a "V"-bit. Strictly speaking, "V"-bits don't end in a perfect needle-point either - they do have a really, really small flat tip, which is one of their characteristics - it's why you might see listings like "30 degree / 0.1mm V-tip". Unfortunately, in my experience the unmarked wide "V"-bits like in your picture often seem to have a tip of around 0.5mm, which is huge for PCB work; 0.1mm snaps off quite easily (obviously more fragile), so my favorites are the 0.2mm / 30 degree ones.

Lastly, I admit even my PCBs milled under a thin film of oil come out a little not-quite-smooth (besides lubricating, the oil has the added advantage of keeping the copper dust in place), but a quick pass with an abrasive kitchen pad (google "scotch brite" to see what I mean, the brand is not important) cleans them up immediately, without harming the remaining copper traces too much.

[JRock]

Like blinkenlight said, just touch it up with some chore-boy and you'll be fine.

I find the more oxidized the copper is, the more likely it is to tear as well.

I like to shine them up before I cut them to prevent so many jagged edges.