CNC PCB milling

[NeverDie]

@neverdie said in CNC PCB milling:

one of them just came loose again

And now the other one did too. Is anyone using a threadlocker on the set screws to keep this from happening?

I think I'll put on some locktite and let it dry overnight and then see if it still happens tomorrow. I'll start with just the threaded rods.

Anyhow, the good news is that the heat sinks plainly did not short out the GRBL controller boards. I guess the adhesive must act as an electrical insulator.

[NeverDie]

Thinking about it now, an alternative might be to grind one side of the threaded rod flat in the region where it fits into the adapter. That would match the concept of the motor rotor, where that has already been done.

Ideally I would notch it in just the region where the set screw makes contact. I suppose I could do that with a Dremel.

Investigating now, I see that the adapter came loose on the motor rotor also. So, I think locktite will be a must.

http://www.loctiteproducts.com/tds/T_LKR_BLUE_tds.pdf

Looking at the datasheet, it takes 24 hours to cure.

[NeverDie]

Well, humbug! I'm all out. Maybe tomorrow I'll buy the red threadlocker, which is even stronger.

[NeverDie]

@rmtucker Which g-code sender is it that you like best?

[dbemowsk]

@neverdie, or anyone else that can answer this with some logic, just because the topic came up. Why does Loctite red come in a blue container and loctite blue come in a red container?

[Yveaux]

@dbemowsk said in CNC PCB milling:

Why does Loctite red come in a blue container and loctite blue come in a red container?

Made in China?

[NeverDie]

Probably historical reasons.

[dbemowsk]

@yveaux LOL

[NeverDie]

Probably a committee decision. Half liked red, and the other half liked blue. They were deadlocked, and this was their compromise decision. :laughing:

[andrew]

@neverdie for the touch sensing you should use A5 connector from the headers, connecting it to the actual tool (bit), then a gnd (header's bottom row) connecting to the pcb's surface.

for the tool connection I use crocodile clamps.

screws: you did not fasten them enough. at the beginning I also missed some endpoints, but since I put the cnc together, I had no issue with any of my screws.

[andrew]

@andrew for first go for a single touch probing instead of a whole autoleveling session.
just for testing purposes, start the touch probing from a higher position and touch the gnd wire directly to the spindle's tool to see whether it stops or not. if not, you should stop it manually from the gui, otherwise it could break the tool.
if everything works well (so you proved that you connections to the pins and the belonging settings are ok), then you can run the simple touch probes or the autoleveling as well.

[sundberg84]

@neverdie said in CNC PCB milling:

Is anyone using a threadlocker on the set screws to keep this from happening?

For one that will probably buy the same CNC could you document how you solve this with a picture?

[rmtucker]

@neverdie said in CNC PCB milling:

@rmtucker Which g-code sender is it that you like best?

I am not using a g-code sender,i am using mach3.
But i have just started playing with grbl and bCNC seems to do most things.

[andrew]

@neverdie one more think I forgot to mention: after I assembled the cnc, I used a little wd40 across each axis and moved each from one end to another. it helped for smooth and "barrier-free" movements.

[NeverDie]

@andrew said in CNC PCB milling:

you should use A5 connector

Does using A5 somehow automagically just work, or does it require additional software configuration?

[NeverDie]

@sundberg84 said in CNC PCB milling:

@neverdie said in CNC PCB milling:

Is anyone using a threadlocker on the set screws to keep this from happening?

For one that will probably buy the same CNC could you document how you solve this with a picture?

OK, here is what I'm doing in pictures. I'm applying blue 242 Loctite:

to the threads of the 4 set screws on the coupler:

That should keep them from loosening up after they are screwed into position. Note, you have at most 10 minutes of working time before it sets.

[NeverDie]

I applied it to the motor set screws first and let it set:

Note: I used rare earth magnets to help secure the set screw to the allen wrench. That insures that the set screw doesn't drop off and disappear somewhere on the floor. Works great.

The couplers are made from anodized aluminum, so I'm not sure how well the loctite will work on them. However, I think it will still work, as the set screws themselves are steel.

[NeverDie]

I found an intro to bCNC:
https://www.youtube.com/watch?v=c-2k48TwU-8

It looks easy and intuitive, so I'll probably go with that.

As usual, it's the software that has the best tutorial that wins.

[zboblamont]

@neverdie I used to use nail varnish on threads as it was just as effective, even though it annoyed the partner whose nail varnish it was. It is not the bond between the metals which is that important, it is adding resistance between the threads to prevent unscrewing, were it to completely bond, you would shear the bolt before it was removed, which is a whole lot of trouble....

[NeverDie]

@zboblamont said in CNC PCB milling:

@neverdie I used to use nail varnish on threads as it was just as effective, even though it annoyed the partner whose nail varnish it was. It is not the bond between the metals which is that important, it is adding resistance between the threads to prevent unscrewing, were it to completely bond, you would shear the bolt before it was removed, which is a whole lot of trouble....

Does nail varnish cure anaerobically in the presence of metal ions? That seems to be much of the theory behind thread lockers.

I thought nail varnish cured by evaporation.

In any case, I wiped off the excess loctite, because it might never dry (or, at least, take a long while to do so).

I think the loctite is likely to work, since Andrew had success without anything but torquing it down hard. On the other hand, maybe his is threaded differently than what came in my kit.