1419 cnc spindle upgrade

Hello,
Couple month ago I bought 1419 machine. I really like how it's built. Just out of the box I was able to achieve pretty good results (flatend mill 0.3-0.5mm).
But there are two problems I have:
1) Spindle is noisy. It's Chinese 775 engine.
2) Collet accuracy is far from to be perfect. Every time I spend 15-20 minutes locking, unlocking, rotating collet, etc. to get rid of runout.
I tried to replace OOTB spindle with 20k rpm version from genmitsu -- not a lot of difference (just less noisy when running at 10-12k rpm)

Now I'm looking to try brushless 104W spindle: https://www.ebay.pl/itm/115475403851...dgZlh#shpCntId

Maybe someone has experience with this one?

Why 104W only? I need CNC for two operations which do not require a lot of power: pcb milling and guitar pedal enclosure engraving. Milling and engraving speed is not really important. I can wait 20-30 minutes without any problems. This spindle is equipped with ER8 collet. I expect it will have better runout than on my 775 spindles.
Machine itself is pretty compact, I don't think I need large heavy spindle. Wegstr machine uses 26W spindle and they even cut aluminium(I think they do that very slowly, with small diameter bits, but... looks like it's possible if really needed)

Hi,
I think those DC spindles are not up to the task.

They are just DC motors with deep-groove ballbearings and a ER tool holder clamped on the end. They have crazy high runout.

You need a spindle that has angular contact bearings. Angular contact bearings need to occur in matched pairs. So a low power spindles, say 800W,
will have 'four bearings' arranged in 'two pairs'.

I have been making PCB for eight years and with just one spindle....its been absolutely superb:

https://www.mechatron-gmbh.de/en/

It is a German made spindle, and so is not cheap, but its proven its worth many MANY times over.

Craig

I agree with Craig get a 800W water cooled spindle which is very quiet and accurate with very little runout

Hi,
my one is the cheaper air-cooled one....still has been superb. I use it daily, maybe two PCBs a day and have done for two-three years. More on a hobby basis prior
to that, but still I would guess the spindle has 2000 run hours. Never missed a beat.

I have checked a lot of PCB milling videos and the best result are those who use a fairly heavy (800W +) router. That probably is caused by the bearing quality heavy routers have. There is a pcb milling project (the ant) https://www.youtube.com/watch?v=O7gI6XYmP2o that has a decent PCB milling router and they inspired me to make my own.
I am going to build a small (pcb and steel) milling router. I have made a (prototype) spindle from a ER11 collet holder and 2 7000AC bearings. The runout measured at the collet holder is 0.015 mm.
I have bought a BLDC motor 57BLR70-24-02 (BLDC), DBLS-01S controller and a 24V PSU.
The motor and controller supports HAL, the spindle RPM is constant (within limits) and there is plenty of torque for milling steel. The motor runs at 3500 RPM (absolutely quit) and it will drive the spindle using a 1:2 ratio for PCB milling and 1:1 ratio for milling.
I think a smaller motor (Nema17) would also do the job but that isn't available at the moment.
If 3500 RPM where enough for PCB milling, I think the bearing quality of the 57BLR70-24-02 motor is good enough to just press a ER11 collet holder on the 8mm shaft.

Hi,
if you are using engraving tools of 0.1mm to 0.2mm tip diameter you should aim for runout of less than 10um, 5um preferred.


Matched P4 grade angular contact bearings are required to get that level of performance. Ideally you would spin the tools at 30,000 to 40,000 rpm.
The downside of running the spindle that fast is that the bearing life is shortened. It can be counteracted by using matched P4 ceramic bearings but
they cost even more!

Craig

Quote:

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Originally Posted by joeavaerage

Hi,
if you are using engraving tools of 0.1mm to 0.2mm tip diameter you should aim for runout of less than 10um, 5um preferred.
Craig

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That would require more than just a top quality bearing. Your spindle and collet should also be better than 5um and that is not achievable price wise and not using my hobby tools.

Quote:

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Originally Posted by joeavaerage

Hi,
Ideally you would spin the tools at 30,000 to 40,000 rpm
Craig

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I want to do the PCB milling in a water bath to ovoid the unhealthy dust. I expect that running at 30.000 RPM, the PCB (tool tip) will not be covered with water all the time so I aim at 7000 RPM. That will also keep the noise down and increase bearing life.
That it will take longer to mill the PCB's is not a real problem. It will probably still be faster then the toner transfer procedure I now use and I can do other things (drink coffee).
I am also trying to use "cheap" 6009 bearings at a very small preload. If that doesn't work well enough, I only have to adapt the bearing housing for 7000AC bearings. For me that is worth a try.

Hi,

Quote:

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That would require more than just a top quality bearing. Your spindle and collet should also be better than 5um

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Correct, you need P4 bearings AND precision ground spindle and collet.

Quote:

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I want to do the PCB milling in a water bath to ovoid the unhealthy dust.

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What a load of twaddle....unless you poke your head in there and deliberately breathe the stuff then there is zero risk. The real deal is to control the cutting depth to within 10um
or so that you don't produce fiberglass dust in the first place. Controlling the depth of cut is, and always will be, the biggest challenge to using isolation routing.

My spindle maxes out, or actually rather my VFD maxes out at 24000 rpm. When eventually I have to replace the bearings I'll go for ceramic P4's and get a 600Hz VFD to
push the spindle out to 30,000rpm.

Quote:

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I am also trying to use "cheap" 6009 bearings at a very small preload.

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All of the 6000 series ball bearings are deep groove types and will have something like 0.01mm-0.02mm clearance, a very poor choice if you want low runout.

Craig

He picked up a Bantam Tools Desktop PCB Mill and made a video about the results car games