CNC PCB milling
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Wow, the ER11 collets on Ali Express are incredibly inexpensive--just a little more than $1, with free shipping: https://www.aliexpress.com/item/6MM-SUPER-PRECISION-ER11-COLLET-CNC-CHUCK-MILL-CNC-Workholding-Mill-Lathe-VEC05-P0-25/32795483676.html?spm=2114.search0104.3.44.64385e319AOvIk&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10344_10130_10068_10324_10547_10342_10325_10546_10343_10340_10548_10341_10545_10084_10083_10618_10307_5722320_10313_10059_10534_100031_10103_441_10624_442_10623_10622_10621_10620_10142,searchweb201603_2,ppcSwitch_5&algo_expid=3eb984d6-bba6-4935-8f90-0f6a6da33214-6&algo_pvid=3eb984d6-bba6-4935-8f90-0f6a6da33214&priceBeautifyAB=0
Unless someone here has theory or experience to contraindicate, I guess the only way to answer the question is to buy some end mills and collets and try it out.
@neverdie If you go 6mm or 1/4 inch only to flatten the bed, you might be better off just selecting the collet after buying a plain router bit locally, probably neither will be used for much if anything until you need to replace the bed.... They are pretty cheap usually and ideal for mdf, just keep the cutting rate cautious with the light drive motor, and beware of the dust, it goes everywhere, and you can't spray it as water affects the mdf...
A 1/4" face cutter would put less load on your motor than a 1/2", just take it easy on the milling rate.... -
I'm not sure how to analyze it a priori. If I have to run it at a much lower feedrate to compensate for a light duty motor, then the supposed speed benefits of a larger end-mill might not materialize.
@neverdie said in CNC PCB milling:
a priori
? You mean as earlier, sorry, I didn't use Latin after 60BC, it rather went out of fashion don't you know.... ;)
The power you require to bring the mass up to speed is one thing, the speed of approach and the area to be cut is the greater puzzle I suggest. The bit will not snap for sure, your motor might object if you take big bites though...
If you rip the surface in a 0.5mm top slice and listen to the motor you will get a good idea of how it reacts, then either increase the approach speed or the depth I would suggest.. You are using the device outside it's parameters, better to be cautious, the bits are a lot tougher than the motor... -
I ordered the collets and end-mills that I referenced above, so after they arrive I'll post an update as to how it went.
Meanwhile, now that my CNC is in the garage, it's hard to know when it has finished running. I'm thinking of making a node to monitor it and then sent me a wireless alert when it finishes. So, how best to know when it has finished? I'm presently toying with the idea of monitoring its current consumption, on the theory that if no significant current is flowing, then it is done. However, maybe someone here knows of a better way?
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I ordered the collets and end-mills that I referenced above, so after they arrive I'll post an update as to how it went.
Meanwhile, now that my CNC is in the garage, it's hard to know when it has finished running. I'm thinking of making a node to monitor it and then sent me a wireless alert when it finishes. So, how best to know when it has finished? I'm presently toying with the idea of monitoring its current consumption, on the theory that if no significant current is flowing, then it is done. However, maybe someone here knows of a better way?
@neverdie I find it hard to believe you would just walk away from it with no curiosity or desire for direct observation. Have you considered using the highly technical door to access and use eyes to see and ears to listen ? You are breaking new ground here, or mdf actually, where is that American spirit? Did Galoka think the Ulus were too ugly to save?....
Beyond the giggles, I suggest a strategically placed vacuum cleaner intake as close as you can get taped down and just watch what happens, you are in a better position to cut power than 20m away diverted by Youtube.... -
@neverdie I find it hard to believe you would just walk away from it with no curiosity or desire for direct observation. Have you considered using the highly technical door to access and use eyes to see and ears to listen ? You are breaking new ground here, or mdf actually, where is that American spirit? Did Galoka think the Ulus were too ugly to save?....
Beyond the giggles, I suggest a strategically placed vacuum cleaner intake as close as you can get taped down and just watch what happens, you are in a better position to cut power than 20m away diverted by Youtube....@zboblamont
Watching it do an auto-level on 300 points is pretty boring.... I have better things to do than watch paint dry. -
@zboblamont
Watching it do an auto-level on 300 points is pretty boring.... I have better things to do than watch paint dry. -
I ordered the collets and end-mills that I referenced above, so after they arrive I'll post an update as to how it went.
Meanwhile, now that my CNC is in the garage, it's hard to know when it has finished running. I'm thinking of making a node to monitor it and then sent me a wireless alert when it finishes. So, how best to know when it has finished? I'm presently toying with the idea of monitoring its current consumption, on the theory that if no significant current is flowing, then it is done. However, maybe someone here knows of a better way?
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@neverdie Hey, your choice, your motor.....
Watching paint dry is most under-rated really, except when you are on the other end of the brush...@zboblamont I think maybe you're misunderstanding. I would watch it do the bed-level (well, at the beginning anyway), to monitor drain on the motor. However, with all the auto-leveling and etching and milling and drilling I just let it run and come back when it's finished. That's really where I want to go with this in the end anyway. As far as protecting the motor, there should be (but maybe isn't?) something to shut it down if the current jumps above a certain limit. I should think that would be all the protection that's needed. So, maybe that's yet another reason to task an arduino with monitoring the current flow. One reason would be to alert me when the present job is done. The other reason would be to shut it all down if the current got too high (indicating a failure situation of some kind).
In fact, the beauty of having it in the garage is that it can run in the background without being noticed. If I were to run it in the house, the noise is rather overwhelming, and it would be hard to ignore it.
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@neverdie why not put a webcam/ipcam at it, like many people do with a 3d printer?
Will show you when it's finished and when something goes wrong.@yveaux said in CNC PCB milling:
@neverdie why not put a webcam/ipcam at it, like many people do with a 3d printer?
Will show you when it's finished and when something goes wrong.I just don't see the allure in that. It requires my polling it, rather than being interrupt driven. To me it's like putting a webcam on your dryer to observe when it's done. I mean, yes, it is faster than walking over to it, but it just seems far from optimal.
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Yesterday I was doing copper removal with a 2mm end-mill, and several times when plunging it brought the motor to a complete stop. The motor recovered and continued in the x-y dimension at the new z.
So, obviously, the z-feedrate was too high. Is there a feedrate specific to the z-axis, or is it just the same as the general feedrate used by the x-y? I know there are velocity and acceleration parameters that can be different for x,y, and z. Do I control it using that instead of the seemingly general purpose "feedrate"?
Also, not sure why I experienced the problem this time and not previous times, as I was running the same g-code as before. Perhaps the end-mill acquired too much plastic gunk clinging to it? What's the best way to clean that stuff off?
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Yesterday I was doing copper removal with a 2mm end-mill, and several times when plunging it brought the motor to a complete stop. The motor recovered and continued in the x-y dimension at the new z.
So, obviously, the z-feedrate was too high. Is there a feedrate specific to the z-axis, or is it just the same as the general feedrate used by the x-y? I know there are velocity and acceleration parameters that can be different for x,y, and z. Do I control it using that instead of the seemingly general purpose "feedrate"?
Also, not sure why I experienced the problem this time and not previous times, as I was running the same g-code as before. Perhaps the end-mill acquired too much plastic gunk clinging to it? What's the best way to clean that stuff off?
@neverdie said in CNC PCB milling:
Is there a feedrate specific to the z-axis, or is it just the same as the general feedrate used by the x-y?
I ran some tests and proved that the general feedrate does apply to the z-axis. However, at the moment, the rest of the answer remains unknown to me.
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So, anyhow, maybe another way to check for job completion would be to monitor the DATA+ line from the USB cable feeding the WoodPecker controller. I'm guessing that if it shows no activity, then the job is done.
@neverdie said in CNC PCB milling:
So, anyhow, maybe another way to check for job completion would be to monitor the DATA+ line from the USB cable feeding the WoodPecker controller. I'm guessing that if it shows no activity, then the job is done.
I tested this, and it won't work. It seems that USB is constantly sending data frames (or something) regardless of whether actual serial data is being transmitted.
So, to take the idea any further, I'd have to tap into and monitor the Serial Rx pin on the Woodpecker atmega328p chip itself.
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@neverdie said in CNC PCB milling:
So, anyhow, maybe another way to check for job completion would be to monitor the DATA+ line from the USB cable feeding the WoodPecker controller. I'm guessing that if it shows no activity, then the job is done.
I tested this, and it won't work. It seems that USB is constantly sending data frames (or something) regardless of whether actual serial data is being transmitted.
So, to take the idea any further, I'd have to tap into and monitor the Serial Rx pin on the Woodpecker atmega328p chip itself.
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I tried measuring the current with an INA219, and wow, the current measures much higher than what my bench power supply had been telling me. Doing just auto-leveling consumes about 0.5a at 24v. Turning on the spindle and just carving air consumes over 1a at 24v. So, I'm guessing that actually routing PCB material (not just air) might well exceed the 2a limit of the INA219, at least in worst case scenarios where the bit may bind (or the feedrate too high) enough to slow the motor down.
So, I'll simply slam a couple more shunt resistors in parallel with it, and then it should be good for measuring up to 6 amps.
All this assumes that the Woodpecker contains a proper snubber diode, so that I don't get voltage spikes when turning the spindle off. Indeed, it looks as though the woodpecker does have an SS54 schottky diode installed just below the spindle power plug, and I'm guessing it is intended to serve that purpose.
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Virtually every screw on this CNC has come lose, so I'll be applying Loctite on all of them to hopefully avoid a repeat in the future.
I think there will just inevitably be some amount of vibration during the milling process (which obviously gets worse if there are lose screws). So, beyond Loctiting everything, I wonder if it makes sense to also rest the whole thing on some vibration dampers such as:
https://www.amazon.com/Anti-walk-Silent-Feet-Anti-Vibration-Machines/dp/B00536VQE0/ref=sr_1_8?ie=UTF8&qid=1518798934&sr=8-8&keywords=vibration+laundryI mounted our clothes dryer on these particular feet, and they work fantastic, at least for that purpose. Maybe not the right choice for this CNC though.
In the case of 3D printers, I notice that the Prusa I3 Mk3 sits on rubber feet, presumably for a similar reason.Anyone found good vibration damping feet for their CNC?
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Virtually every screw on this CNC has come lose, so I'll be applying Loctite on all of them to hopefully avoid a repeat in the future.
I think there will just inevitably be some amount of vibration during the milling process (which obviously gets worse if there are lose screws). So, beyond Loctiting everything, I wonder if it makes sense to also rest the whole thing on some vibration dampers such as:
https://www.amazon.com/Anti-walk-Silent-Feet-Anti-Vibration-Machines/dp/B00536VQE0/ref=sr_1_8?ie=UTF8&qid=1518798934&sr=8-8&keywords=vibration+laundryI mounted our clothes dryer on these particular feet, and they work fantastic, at least for that purpose. Maybe not the right choice for this CNC though.
In the case of 3D printers, I notice that the Prusa I3 Mk3 sits on rubber feet, presumably for a similar reason.Anyone found good vibration damping feet for their CNC?
@neverdie Crazy though it may sound, have you considered cheap engine/gearbox mounts (for vehicles) for the base frame onto some baseplate or U-mounts?
All excess energy in a machine has to be dissipated to maintain base accuracy, the more rigid the structure is, the more that undamped energy is transferred to somewhere to dissipate, the base is probably the easiest to resolve... -
@neverdie Crazy though it may sound, have you considered cheap engine/gearbox mounts (for vehicles) for the base frame onto some baseplate or U-mounts?
All excess energy in a machine has to be dissipated to maintain base accuracy, the more rigid the structure is, the more that undamped energy is transferred to somewhere to dissipate, the base is probably the easiest to resolve...@zboblamont
Not sure how that would be setup exactly.I'll try this:
https://www.amazon.com/dp/B00B84FNBS/ref=cm_sw_r_cp_ep_dp_H.1HAbVV7GBAFThat way the aluminum frame will be supported all the way around.
