STICKMAN'S LETS LEARN CNC THREAD

dmnCrawler

Well-known member
Can you give any recommendations on bits that work well? I am also interested in depth, feed and RPM used with those bits. I would expect it is different for then you are milling out a window vs doing labeling or graphics. Any tips are greatly appreciated.
 

Stickman393

Well-known member
Absolutely!

I've settled on carving at a final depth of 0.1mm using a feed of about 250-300 mm/min using a 0.25mm-0.50mm double fluted solid carbide ball end bit at 12000 RPM.

I set my depth of cut to 0.05mm...but a bit of warning here: you'll either want to depth compensate your Z axis as I did in my last post, or make sure your work surface is completely flat and parallel. A small deviation can ruin your day real fast. If it gets too hard to cut and your spindle starts dragging, you end up getting really ragged edges and your stepper motors start skipping steps...circles turn into lumpy ovals. It's a problem. The nice thing about the program that I mentioned in my previous post is that it offers a feed override...you can speed things up to 200% of the programmed value, or slow them down significantly with a couple of taps.

Part of that is specific to my setup, though. The biggest issue right now is that my Z axis has SIGNIFICANT play along the X axis. The spindle holder is not particularly well designed. So as soon as it encounters resistance on the X axis it starts to drag and jump, so some kind of cutting lubricant is ABSOLUTELY necessary. I'm in the process of upgrading my spindle mount though...we'll see how the 300 watt motor handles the work. I'll try increasing to a 0.1mm depth of cut at that point.

I've mostly been using the CNC for engraving, including marking locations for manual drilling. I'd love to eventually get it to a place where I can carve out the holes though. The little window was accomplished with the same 0.50mm ball tip bit...but I don't recommend this. The taper on the bit makes this a real slow process.

In fact, I'd recommend using a single flute bit on a machine like this for actually CUTTING the aluminum. The biggest problem on a 3018 is that the spindles tend to spin too fast and the feeds tend to run too slow for cutting aluminum with a 2-4 flute bit. A single flute 1/8" bit will work best on these to maintain consistent chip formation without rubbing.

I'll be trying out a 1/4" 60⁰ V bit soon too...doing my homework on potentially swapping to a brushless 500-600 watt motor as well.

This thing has NO issue cutting through HDPE at a .25mm cut. Probably plenty of headroom there.
 

~nick~

Member
I really appreciate this thread, Stickman! I'm actually looking into a CNC. I'm debating throwing down 900+ on a 32" by 32" working range CNC from Vevor, called the Evolution 4. i want to be able to attach an A5 laser to it, though, and I'm not sure the mounting would allow it. I have seen some portable laser engraving stuff. spray paint black over aluminum and laser engrave it to make fine indentations and fill with white paint? What do you think?

Anyway, I dig this thread. Subscribed, Liked, Watched, and hitting the bell :cool:(y)

I'm glad i read your issues with the motor. Hence the going straight to upgrade to a 32"x32" mill. if you lay it out diagonally, you could even mill a one piece headless guitar/bass! Imagine all the multiscale fretboard slots with machine accuracy.. Imagine the extreme carve tops..

But yeah, PCBs! haha. Might be better to just buy the extrusions and stuff and build it myself? 900-1000 is a lot of scratch. :unsure:😱

Have you experimented with different bits? finer bits? Or does the motor need to spin faster for the smaller bits? So much to learn. What about upgrading the frame and the motor?

Are there any resources you'd recommend for beginners to check out?

I wish you well in your CNC endeavors!

You could make pcbs, enclosures, enclosure engraving plates like Dan Drive does, make SMD solder paste templates, maybe even custom knobs out of wood and swirled glitter epoxy! dang, gonna have to write that one down. The downside is the mill time for a single pcb probably doesn't merit a CNC strictly for profit. But perhaps just for fast prototyping turnaround of your own ideas.

Cheers Y'all!
 

Stickman393

Well-known member
Truthfully, anytime I've found a resource that has helped me I've tried to post it in this thread. Theres a lot of information out there...and only so much or it applies to the 2.5D work of engraving.

For actual 3D work, I recommend getting a free "personal use only" license for Fusion 360. It's a DENSE program, and I've only begun to use it for fiddling around with other people's designs. It's great for 3d printer type stuff as well....but it looks like the learning curve is going to be a bit more intense than the rest of what I've posted about here.

I haven't gotten around to picking up a laser yet...I may not for a while. Truthfully, it seems like it would be a major pain to swap out a spindle and a laser.

I've done plenty of experimentation with bits.. personally, I like the ultra-fine ball end bits because the actual line thickness can be a problem when engraving text. If the letters or lines are spaced too closely together, I've found that my bits have a tendency towards drifting into the previously milled groove.

As far as my setup goes, I'm getting close to finishing my initial Z-axis spindle mount upgrade. Only problem here is that I need to make a spacer for the x axis lead screw anchor...unfortunately the one I bought doesn't line up perfectly with my existing frame. It is what it is.

IMO, Building one from scratch would require some milling experience. It would be remarkably difficult to cut parts and assemble a square, rigid frame unless you're well versed in how a CNC machine operates. Little unforseen problems arise all the time...I've certainly learned that with my spindle mount upgrade.

Honestly, at this point it probably would have been better if I had just plopped down the extra cash for a better unit...but what I do appreciate about the buy cheap and upgrade path is that you end up learning a lot along the way. What I don't appreciate, though, is not having the time to actually work on the damned thing. So there's that.

Truthfully, my wood knobs I've always done manually, on a lathe. But it's feasible to do one on a CNC too, if one has a 4th rotary axis. The possibilities are indeed endless...hell, one could even make their own guitar and bass hardware if one was so inclined out of brass or aluminum. I plan on doing that myself here for an 8 string...
 

Stickman393

Well-known member
OK: UPGRADED Z AXIS IN THE HOUSE.

HOLY $-@+

WAY better. The added rigidity let's the bits just TEAR through aluminum.

I'll be revising my feeds and speeds over the next few days here methinks. IMG_20210920_205604_copy_2079x1559.jpg
 
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Stickman393

Well-known member
Just got my new PWM controller in...I dig it. Soft start, programmable ramp times, min and max speed, digital interface with one touch control. We'll see how she performs under load.

I'm probably going to add a volt and amp panel meter here too...just to make sure I'm not driving the motor too hard. Probably a good idea to monitor the temp inside the enclosure too, if it gets too hot I can always add more vents: I've got one on top and one on bottom. Hot environments are NOT good for power supplies. This thing is a 350 watter ONLY at design ambient conditions, as is true of most switching power supplies. Raise the temp too high and they derate.

I slapped it all together in a cheap aluminum enclosure from Amazon...it's certainly not the most rigid thing in the world, but it's big and more than adequate for the job.

Oh, and one more thing: WOODWORKERS DOUBLE-SIDED STICKY TAPE.

I forgot to talk about this earlier. For simple engraving and light HSM, and probably laser work, this stuff is AWESOME! No need for a vise: just slap it on the enclosure, make sure it's square, and go.

Just remember...LIGHT passes. Now that my spindle is more rigid I started getting over my skis and found out just how much this stuff could handle. More than you would think.

I'm starting to plan my next CNC builds...I'll likely keep a smaller form factor for anything that has to do with milling metal: it's just MUCH easier to keep a frame stable and rigid when the geometry is smaller. Leverage is the enemy here.

I'm also wondering how difficult it would be to design a 2-axis CNC horizontal step driller for completely automating the power and in/out drilling. That'd be slick.

Wood? I plan on building up something big enough to do guitar shit...but that'll have to be in the future.

IMG_20210925_172251_copy_2302x1726.jpg IMG_20210925_171905_copy_1620x2161.jpg
 

Paradox916

Well-known member
I will admit I haven’t been following this thread, I just don’t have the time or means to get into CNC (although I always wanted to) you have covered some serious ground though! Keep killing it! And I will live vicariously through you.
 

Stickman393

Well-known member
Appreciate the kind words y'all.

One fantastic resource that I've been digging into recently: openbuids.com.

They've got prebuilt machines, parts, example DIY builds, and I'm probably going to pick up their black box motion controller at some point here.

There's a WEALTH of knowledge there.
 

Stickman393

Well-known member
At this point in time I've worked out most of the kinks and can achieve repeatable results in both engraving and milling holes in enclosures. The z-probe height mapping functionality in open CNC pro works wonderfully, and I've been able to get around the non-conductive surface of a painted enclosure by carefully laying a sheet of aluminum or copper tape on top of the enclosure and adjusting the final depth by about .1 or so to account for the thickness of the tape and the paint. Something interesting that I've observed, though, is that I'm not quite using my spindle to it's full potential.

II'm using less than 1/3rd of my FLA with typical operations : I.E. what the machine can handle. So...that means that I'm operating my 300 watt motor at about 85 watts under load. That's about a 15 watt increase from when the motor is unloaded.

Why? Part of it is I'm using small bits and shallow cuts that require less power to perform. Once again...the real issue I'm running into here is RIGIDITY.

IF THE MACHINE WAS MORE RIGID, I would easily be able to make .25mm cuts per pass in aluminum. As the machine flexes, though it causes the motor to tilt and skip. Not because of the power of the steppers or the spindle, but because the force required to do so exceed what the actual chassis can withstand.

Honestly, as I've been making little tweaks I've discovered that some of my fixes have led to unforseen issues. My new z axis is indeed more rigid, but it ALSO places the spindle motor further away from the Y-axis slide. It's a longer lever, and that is limiting the new z-axis' structural advantage.

Truthfully, that's the disadvantage of most of these 3018 machines. Linear rods only supported on the edges, short bearings that have to be located and supported a fixed distance from the platform they support...there are little fixes, and certainly better and worse implementations, but the fact remains that 90% of the cheaper models are going to struggle to push enough to take advantage of a 300 watt motor like mine.

That said...I'm liking the design that OpenBuilds adopted, a gantry plate, a low profile lead screw nut and simple wheels on bearings. Sure...you won't be milling cold rolled steel or titanium on something like this with any real efficiency, but I'm probably going to be slowly building up another machine using parts like the photo attached.

That's all for today, cheers.

cbeam_i2_w_1__87373.1510602321.png
 

Travis

Active member
Hi everyone,!

Can someone recomend some better option than 3018 CNC?

I wanna make some PCBs and engraving my pedals :)
 

Stickman393

Well-known member
The 3018 is mostly just a form factor definition, roughly 300mmx180mm...but they generally all have similar features.

That said: you may benefit from choosing a smaller unit, for instance, a 1310 will benefit from the fact that it's working area is much smaller, thus a build similar to mine would end up being FAR more rigid. Levers increase force on an exponential scale the longer they get, and the inverse is also true.

Otherwise, for something that is a pick-up-and-go machine, look for machines that have fully supported linear rails. I had posted a good example of this earlier, the OpenBuilds C-beam. I picked up a 20mm rail recently, and after a little fiddling it's solid as a rock. I'll attach some other examples at the bottom.

Just from looking at it...this one MIGHT work out for some basic PCB and pedal work. I dunno about the height clearance or the ability to use it for super sized enclosures...but it looks pretty solidly designed, might be a good platform for learning GRBL.


But as things get larger, you really need to be mindful of the frame. Aluminum is soft and relatively easy to mill, but it's still metal, and it's gonna push back against the cutter.

I would say there are two paths here:

For those like myself who are remarkably stubborn, it's OK to go a little cheaper and gather experience.

For those that will ultimately abandon the machine if it doesn't do what they want it to the first time they power it up...don't buy a machine off Amazon. Save money, get a carbide 3d nomad, or an openbuilds.com machine.

61VPM1MmqfL._SL1001_.jpg 61iQoa0cITL._SL1376_.jpg
 
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