PCB CNC Machine(s) -- Group Project


#1

Hey All!

Ever since I found out that the Sherline CNC Mill is actually a little CNC lathe that was converted to a mill, I’m supremely interested in getting this back into a lathe to compliment the Taig.

Thanks to @xquared, that machine has been brought to life recently as a PCB mill; but it seemingly has difficult (and expensive) problems that relate to mill operation that might not affect it being a lathe as much (ie x axis backlash)

Therefore

I propose we do a group build of a CNC circuitboard mill.

Doing this would not only get us the circuitboard mill that people have wanted for a long time, but also, once done, freeing the Sherline to be converted back into a small CNC lathe.

There are a number of ~$300 CNC mill kits of this sort on Amazon.ca. Maybe that makes sense, but I suspect that between the membership, we will have a good number of extra parts kicking around to come up with most of what we need.
I, personally, have NEMA 17 stepper motors to offer to the cause.

Is anyone interested in helping build 1 CNC so we can end up with 2? Seems like a good deal to me. Our high profile group builds are great for our community, and given the size of the new mill is pretty small and the force load on it is also small, we could probably do this on the cheap.

Thoughts?
Anyone have parts they’d donate to this cause?


#2

Oh, and I have a Raspberry Pi to offer if that would work well as a host.


#3

I don’t know if I have any useful parts to donate to the cause, but I’d be down to put in my time and some money towards making this a thing.


#4

Can we get a quick survey of the available cheap PCB mills out there? Not directed at anyone specific :slight_smile:

It’ll give an approximate design, and we can roughly spec out parts to see if it’s viable to kit our own. I expect it’ll mostly be a bunch of extruded aluminum.


#5

Good call, a survey of the existing ones along with capabilities would be a great start!


#6

Time (and money) is a very valuable asset! Looking forward to it!


#7

not cheap, the Bantam mills are stuff dreams are made of:


#8

I’m sure the Bantam would be amazing, but I think the scope of this is what would be useful and is there a low barrier to getting there. I doubt we can fundraise to get an Othermill (though I’d be happy to be proven wrong).

Here’s a quick sampling of a few engraving machines I’m seeing on Amazon.

These are just chosen at random near the low-end of the price points. They give us an idea of what sort of variances they have and what minimums.


#9

I posted the bantam link mostly for comparison of specs. i do not expect us getting a bantam, ever. half the price is probably the software anyways.

I’ll extract out the stuff like work surface area, stepper motor precision and spindles speed for comparison with the amazon kits


#10

Thank you @mike for the motivation!
One of the creators of this CNC-Laser Cutter-Plasma Cutter had talked at VHS some time back, it is at http://goodenoughcnc.eu/
Should we do a group build for this CNC?
If more stiffness or better tolerance is needed, stiffen the frame or make it on a Granite Bed (there were some Granite Bed Lathes at Summit tools in 2016-2017).


#11

Could build one or possibly make new gears on the other cnc?


#12

Yes, I think the only way this gets done is people committing to providing parts, material, and labor. If there’s something you will provide for such a venture let us know. A control board, aluminum/steel for a gantry? Acme rods? A spindle? If we know what common parts we have we can start designing around the known elements.


#13

This is what I’m offering, I’m thinking maybe GRBL + LinuxCNC


#14

Are those steppers strong enough? One option is that if Free Geek gets a couple large laser printers for scrap we can strip them down to get stepper motors out of them. Photocopier might also be an option. Get some nice nema 23’s out of them if we get the right one.


#15

That sounds nice! One of them is larger than the others and has a planetary gear. When cutting motor brackets we could make mount holes and holdouts for both NEMA 17 and 23 and adjust as needed. That way we don’t have a blocker and have options.


#16

I’ve never actually found typical NEMA motors of any kind in printers, and we do have a big boxes of assorted oddball stepper sizes. I don’t really recommend we use them.

Don’t know what size those steppers you have are, Mike, but I recommend we use them. We can always upgrade with beefier steppers of the same NEMA standard later if it turns out not to be enough.

Two match motors are important for the X/Y, if we go for a CoreXY design. The geared one might be good for Z axis, depending on the plan for the final design.


#17

Have to go with large business lasers. Yeah your more likely to find the pot steppers. But there are ones have nema’s. Large plotters also are a good bet. Never actually seen a pot stepper in a plotter.


#18

Those are steppers from when I bought a drawbot from @iMakeRobots, so whatever his kit had; I’m not sure of the holding power.

The planetary geared one should be more than enough for a z-axis; it was a drive motor for an extruder in its past life.

Jarrett is going to do an inventory of his hardware to see if we can do a coreXY, we’ll plan on using these steppers, but let’s upgrade if needed. A couple stepper motors aren’t going to break the bank.

I’m looking into GRBL right now with a Raspberry Pi for the driving motor. I don’t know if I’ll get GRBL to run with the stepper drivers I have, but if I can get the hardware I have to drive the motors, I think we are doing well.


#19

Also, the plan is to drive the bed on the corexy; we still need a z axis to control the spindle. For saving money; we should start with the spindle from the sherline.


#20

I might have another pair of steppers of the same vintage as @mike’s, happy to throw them into the pot (will probably be able to confirm tomorrow night)