Yvan's Mostly-Free CNC (Introduction)

Y-van · January 16, 2020, 1:36am

Hi everyone, I’ve been lurking for a while. I’m Yvan (pronounced Why van?) and I’m a Controls Engineer at a self-driving industrial robot company. My wife-unit and I also run a small farm with chickens, goats, ducks, bees, and god knows what else.

I’ve been holding off on posting this until I had a chance to clean up my shop. It was pretty bad. I am pleased to share that my LR2 is 90% complete, and fully functional. I call it the mostly-free CNC because I’ve been pretty good at scrounging parts from all over the place.

The reason I built this is that when I said I wanted a farm sign my wife got quotes in the $700-2000 range, and I figured I could design and build a CNC for $500. Then I found the LR2, and I skipped the design part.

Things I got for free/cheap

table/workbench is made from a 2x4 construction shelving unit that I disassembled from my old house
50 year old Sears router from my late dad
printed on various colours of filament that I had kicking around
Arduino Mega I had kicking around
power supply I had kicking around
metric bolts from work
MDF and plexiglas I found in my shop
small shop vac from my late father-in-law
Raspberry Pi, which I accidentally smoked with 24V
tractor inner tube for router guard/dust barrier

Things I paid for

roller wheels
GT2 gears and belts
stepper motors
cheap RAMPS clone
stepper drivers
limit switches
tubes
casters
miscellaneous electrical panel stuff.

The important details

Workpiece size: 4 ft x 8 ft x 50cm
Table: 2x4 softwood ladder construction
Top/spoilboard: None, I’ve just been screwing into the frame
XZ plates: Crudely sawn 12mm MDF
Router plate: Crudely sawn 6mm plexiglas; design modified to accommodate my router and vacuum
End-stops: One at each end of x-axis at the moment.
Controller: Arduino+RAMPS with DRV8825 (?) drivers
Wiring: X and Z are in series. All connections are broken out to terminal blocks for ease of assembly and upkeep.
Display: None at the moment. I have one of the common ones but need the PCB to convert the two 2x5 connectors to the RAMPS board.
Interface: OctoPrint running on FreeBSD on a nano-size x64 PC
CAD tool of choice: Fusion 360 for personal; Solidworks for work
CAM tool of choice: Fusion 360 for most stuff. Easel is OK for quick and dirty jobs.

On the to-do list

Make the cables, hoses, etc. pretty
7000mW laser is on order
add extruders
a drilling attachment from doner drill
cubbies for all my power hand tools underneath
drawers for mill tools and filament
area for sheet storage and off-cuts
relays for router, vacuum, etc.
motor speed controller for spindle
Maybe one of those 9-axis SKR boards so I can separate X and Z axes and still add extruders.

Handy pegboard at one end

You may have guessed that I’m a function over form guy.

Mini PC and RAMPS

These will be going into a cabinet so they don’t keep getting filled with sawdust.

Things that surprised me

The zip ties are fine. What is everyone bitching about? I didn’t have the dexterity to use the little D-shaped bits though.
I tried mounting the controls to the gantry like most people, but I just found it awkward.

Things that enrage me

When the power is cut, one side of my z-axis falls, making it a pain in the ass to reset. Thankfully my tubes haven’t bent yet. I think I need to add some friction to the one side to avoid this (in addition to having already disabled the M84 timeout.
Until you clean up your cabling, it is really easy to CNC cut your y-axis stepper cable.
Those Dupont connectors are the worst. I’ve gotten pretty good at crimping them and making connectors, but I rage-quit and replaced them all with terminal blocks (except to the board itself)
I have yet to find CAM software that doesn’t choke on my farm logo (or more generally on semi-complex SVG files)

Anyways I hope to actually make something pretty to post here soon.

jeffeb3 · January 16, 2020, 1:49am

That is a great space and a great machine. You win the prize for largest Z. The closer you can get to the table, the more rigid it will be.

Y-van · January 16, 2020, 2:08am

As you can see in the photos, I’ve been using firewood for test stock. I can throw a log up there and cut it without holding it down LOL. I do a test cut and then resurface it… until I run out of stump.

Yes, it is noticably less rigid at full height, but by no means unusable if you have realistic expectations.

vicious1 · January 16, 2020, 3:16am

Welcome! You are just the right kind of mad scientist we need around here. Plenty of custom on there. So glad you like it, and good to hear you got away so cheaply. Reusing stuff from the shelf is the best feeling! Gotta find a way to convince you to add some sort of section that will raise and lower instead of the giraffe you made…you can’t call yours a lowrider anymore we need a new name for that one.

Thanks for the pictures, keep them coming, and welcome to the crew!

scrounge79 · January 16, 2020, 4:46am

I do believe if I had seen your build a year ago about this time, I might have gone lowrider instead of MPCNC. Pretty sure it will happen though sometime. Cool build.

Just ordered a kit and crimper this past weekend, plus some aviation plugs. Mainly because I am getting a serial wiring setup to text out my Linux CNC and my tinyG, but from what I have read, they aren’t that easy to work with. Been watching videos for figuring it out.

jamiek · January 16, 2020, 4:53am

Love it!

With that height (and that stump) it looks like you have a sawmill, which would just be ridiculous. And awesome.

bluff-chuffer · January 16, 2020, 4:55am

What pitch leadscrew are you using? The T8 x 8 (4 start) screws I had would fall under gravity. No problems with T8 x 2 (single start) I later used.

jeffeb3 · January 16, 2020, 5:18am

Just reduce your max Z speed, or you will have skipped steps, and potentially cpu restarts. We used to have a bunch of problems with the allthread screws, which are similar in pitch.

Y-van · January 16, 2020, 5:46pm

It is T8 x 2 https://www.amazon.ca/gp/product/B07CLSJX4M

Y-van · January 16, 2020, 5:53pm

I watched quite a few videos and write-ups, and 80% of them were incorrect, so be careful. The trick is to only strip about 3mm from the end of the wire and only insert 1.5mm of insulation into the bottom ears. If there are any stands visible sticking out the top, start over and strip off less. If you don’t get a satisfying little click when you insert the terminal into the receptacle, cut it off and start over. It may take 20-30 tries before you get it perfect. Be willing to cut them off and start over. If you try to use one that is less than perfect you will quickly regret it when you have to start troubleshooting connections.

niget2002 · January 16, 2020, 6:43pm

I love the DIN mounted power supplies. If I ever build a lowrider I want to go that route too.

turbomacncheese · January 17, 2020, 2:32am

Yup!

bluff-chuffer · January 17, 2020, 4:51am

I see, well that rules the leadsrews out (unless they have mistakenly sent you a wrong leadscrew - its hard to tell from the photo’s, but check them. Just look at the top of the screw and see if you can count more than one start point. Its possible that the Z height changes are not the same, consequently there is a spring action returning the wrong one back to the rest point.

Otherwise I assume the motor must get some feedback from some where, but can’t say why one is affected and not the other.

Y-van · January 2, 2022, 1:57pm

I realized I never update with pics of my electrical panel and beefy parts.