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IndustryArena Forum > Other Machines > PCB milling > Which bits to use for PCB milling?
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  1. #181
    Join Date
    Feb 2013

    Re: Which bits to use for PCB milling?

    Quote Originally Posted by joeavaerage View Post
    di-boride is as slippery in aluminum as it gets.

    You may have noticed that many specialist carbide tools for aluminum are uncoated.

    The normal coatings on carbide tools are TiN or TiAlN, both are tri-valent in nature. Guess what....aluminum is a tri-valent metal and
    so the aluminum has an 'affinity' with a tri-valent coating. Enter di-boride, a quad-valent (four-valent??.....one-more-than-three-valent??
    ...two-less-than-hex-valent??) and its 'as greasy as a butchers prick' as my grandmother used to say!

    I tend to use flood-cooling. I'm not convinced that the oil is as significant as the flood washing the chips out of the cutzone. Having said that
    I have still had Built-Up-Edge in 5083 aluminum with flood cooling. Thats why I tried di-boride...and was impressed.

    Hi Craig,

    I thought this thread is in connection with Re: Which bits to use for PCB milling? so newbies don't get the short end of the thread


  2. #182
    Join Date
    May 2018

    Re: Which bits to use for PCB milling?

    Quote Originally Posted by CitizenOfDreams View Post
    Wow. What are you making, high power strip filters? RF amplifiers?

    A 10-degree V-cutter may work, but definitely not in one pass. Probably not even in five passes.

    I have not tried cutting such thick copper, but I would try a stub 0.2mm mill like this one:

    I tried the 0.6mm version of this bit for etching a PCB, and it worked great! Just set the depth to "more than enough" and you're done in one pass. IMHO, works much easier than a v-bit or a pyramid bit, simply because the width of the isolation cut is (obviously) much easier to manage.

  3. #183
    Join Date
    Jun 2010

    Re: Which bits to use for PCB milling?

    A 10-degree V-cutter may work, but definitely not in one pass. Probably not even in five passes.
    Been there, used that, worked OK.
    Attachment 446998
    Not as low as 10 degrees, but it is what I had at the time.

    Um - the cheap Chinese 10 degree taper cutters do tend to be a bit brittle, but if the tip snaps off just reface the end to be a shade wider.


  4. #184

    I’ve not been at the process of milling PCB’s for long, however I’m happy to share my experience.

    A 1oz copper PCB has 35uM copper on it, which equates to 0.35mm in copper depth.
    Lumps and bumps.

    I’ve used various V bits, including 0.1mm 20 degree, and 0.2mm 30 degree bits, and to be honest, I’ve settled on a 20 degree 0.1mm bit as it produces better results.

    The 30 degree bits although are stronger, will eat into your copper layer with a greater depth, and they will burr your tracks and pads.

    I still snap the tip off the odd 0.1mm 20 degree, and they don’t last long, but it’s all about going slow and shallow.

    I’ve given up with Candle, it’s homing sequence doesn’t work, and it’s so complicated, that if you forget to re-home before doing a Z probe, then it drives your v bit into your PCB, and it’s just very clunky.
    It’s very manual, and has a procedure.

    I use UGS/ FlatCAM and here are my settings

    Tool dia (0.1mm 20) 0.13527
    Cut Z -0.05
    Travel Z 2.0
    Feed Rate 80

    Spindle speed 10,000 although I have a Cronos CNC 3018 pro which switches a 500Watt motor upgrade via 24V relay, and it runs at 13,000 RPM

    10,000 means it triggers my relay full throttle

    Multi depth

    Any deeper / any increase in speed, you will snap the top off your 0.1mm v bit.

    A 20 degree will do at least 1 PCB, not more than that.
    Works out about the same as etching really cost wise.

    UGS doesn’t have Z probe, so I either use a multi meter in contact mode, or switch my feed rate down to 50, and 0.1 steps, and just tweak so it’s just touching, or microns away.
    Sight and tweak

    Set Zero

    I’ve built a clamp jig out of ply wood which sits on my bed, and I’ve screwed a 1mm aluminium plate to it, so my PCB sits on it hard and nice.

    Slow and steady wins the race.

    To be perfectly honest, I’m probably going to spray my PCB’s in Matt black cellulose, and either laser, or mill very shallow.

    Working on a design for a bubble etch tank, which will have a small 7” 12V immersion heater in a small plastic storage box, and I’ll rig up a small manifold with a fish tank pump to generate some bubbles.
    I’ll regulate it with a opto triac / TRIAC circuit, Arduino, and a thermistor.
    Only need 40-60 degree heat for ferric chloride.

    I’m lead to believe it does create a perfect PCB.

    The process cuts out the shadowing effect when doubling up transparency with a 300DPI laser printer.
    Toner sticks to transparency like the school bog roll.

    Much better effort.

    Pretty corrosive stuff, so be sure to get SS wire, or SS immersion heaters.
    Build a coil

    Rinse PCB in recycled cheap sh*t thinners.

    To be honest

    Let me know how you get on.

  5. #185
    Join Date
    Jun 2010

    Re: Which bits to use for PCB milling?

    Standard PCB has 35 micron copper, but that is 0.035 mm, not 0.35 mm.

    I started engraving PCBs with very finely tapered cutters, but I soon found that does not work. Whiskers of copper got left behind while engraving, and they made bridges and short circuits. I found I needed to engrave a larger width to get a reliable PCB, so I now use tips with a bigger angle, or even tiny end mills from the likes of PreciseBits.
    I also found I needed to use a vacuum hold-down to keep the PCB flat.


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