CNC PCB milling

[NeverDie]

I finished putting together the first frame. It was a bit frustrating, because the T-slot nuts they use can come out of the groove, and so to prevent that I had to keep constant tension on it while I tightened it down. I do think most of the T-slot nuts should have been the kind that don't slip out that way.

[andrew]

@NeverDie
firmware settings: it is stored in the EEPROM, but nothing guarantees that the same location will be used for the same parameters in case of different versions, so the output of "$$" command should be saved, this contains everything which you can manually set up if necessary.

ER11: take extra care during the installation process to not "harm" the motor's axis. usually the ER11 is pretty tight and howtos mention that the motor should be cooled (by the freezer) and the ER11 should be warmed up before putting them together, to help the mounting process and to prevent unwanted distortion.

I put the CNC 2418 assembly guide to my share, for ones it is interesting.

[rmtucker]

@andrew
1000rpm for the spindle seems very slow,is that number correct?

[andrew]

@rmtucker it is not 1000rpm, but the pwm control for the whole spindle speed range. see the details in the official document.
once you use the spindle speed with the value of $30 or above, then the controller will drive the spindle with continuous voltage, without pwm, so it will use its maximum rpm.
compared to bigger cncs with bigger spindles (e.g. what you can see from @executivul's video above) , 2418's is not that fast (in rpm), on the other hand it should not be "very slow". can you show a video on that?

[rmtucker]

@andrew
I see.
So what would be your best guess at your actual spindle rpm when cutting under your feed/depth of cut examples given above.?

[NeverDie]

@andrew said in CNC PCB milling:

I put the CNC 2418 assembly guide to my share, for ones it is interesting.

Yes, those are exactly the same instructions I received with my kit too.

[NeverDie]

@andrew
I tried connecting to the Woodpecker board using the Arduino serial terminal at 115200 baud. It greets me by saying:

Grbl 0.9j ['$' for help]

However, if I send it $ I get no response. If I send it $$, I get no response either.

Is this normal?

How do I send it $$ and get it to respond?

[andrew]

@neverdie no, that is not normal, but this is most probably just a communication issue. which software is used for the terminal connection? try to change the cr/lf settings, or the flow control options.

[andrew]

@rmtucker I did not measure the max rpm for the given spindle, but I use it on "max" (so spindle setting is 1000) for the given jobs.

[NeverDie]

Ah, nevermind. I changed the terminal to send it a carriage return, and now it works. Here is the output from asking it $ and $$:

Grbl 0.9j ['$' for help]
$$ (view Grbl settings)
$# (view # parameters)
$G (view parser state)
$I (view build info)
$N (view startup blocks)
$x=value (save Grbl setting)
$Nx=line (save startup block)
$C (check gcode mode)
$X (kill alarm lock)
$H (run homing cycle)
~ (cycle start)
! (feed hold)
? (current status)
ctrl-x (reset Grbl)
ok
$0=10 (step pulse, usec)
$1=25 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=5 (dir port invert mask:00000101)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=3 (status report mask:00000011)
$11=0.010 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=0 (hard limits, bool)
$22=0 (homing cycle, bool)
$23=0 (homing dir invert mask:00000000)
$24=25.000 (homing feed, mm/min)
$25=500.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$100=800.000 (x, step/mm)
$101=800.000 (y, step/mm)
$102=800.000 (z, step/mm)
$110=5000.000 (x max rate, mm/min)
$111=5000.000 (y max rate, mm/min)
$112=800.000 (z max rate, mm/min)
$120=10.000 (x accel, mm/sec^2)
$121=10.000 (y accel, mm/sec^2)
$122=10.000 (z accel, mm/sec^2)
$130=200.000 (x max travel, mm)
$131=200.000 (y max travel, mm)
$132=200.000 (z max travel, mm)
ok

[NeverDie]

Here's the current build status:

I'm guessing I'm something more than half-way done.

[NeverDie]

@andrew said in CNC PCB milling:

the ER11 should be warmed up

how exactly? Heat gun?

I've put the motor assembly in the freezer....

[NeverDie]

I'll let it freeze overnight and then try it in the morning.

[sundberg84]

@neverdie said in CNC PCB milling:

freeze

Why do you want to freeze the motor? :eyes:

[mfalkvidd]

@sundberg84 see andrew's earlier post.

Freezing the motor axis makes it a bit smaller.

[dbemowsk]

@sundberg84 And heating up the other part makes it expand and get bigger allowing the two to fit together easier. Has to do with tight tolerances.

[NeverDie]

@andrew
Since I probably have only one shot at this, how hot should I heat up the ER11 before trying to fit it onto the frozen spindle? Should it be burning hot, or is luke-warm enough?

[andrew]

@neverdie unfortunately, as I mentioned, I don't have ER11 (yet), and I just read articles and vendor suggestions on the installation method, so I cannot provide experience based suggestions to that. as far as I remember nor concrete temperature was mentioned, so I would say you should not "overheat" it.

[NeverDie]

@andrew said in CNC PCB milling:

@neverdie unfortunately, as I mentioned, I don't have ER11 (yet), and I just read articles and vendor suggestions on the installation method, so I cannot provide experience based suggestions to that. as far as I remember nor concrete temperature was mentioned, so I would say you should not "overheat" it.

I slipped it on, no problem at all. After freezing the motor overnight, what I did was heat the ER11 with my wife's crafting hot air gun. I held it with an insulated glove as I warmed it up. When it started to become uncomfortable to hold with even the insulated glove, I slipped it on without any resistance.

Hopefully this info will help you when you receive yours.

[andrew]

@neverdie :) nice, so your wife saved the project :)))
be patient and do not power the spindle for couple of hours, while it is cold, as it could be wet inside which could cause shorts and other issues.