Hi, Im trying to make my own pcb engraving cnc machine, at a low budget with my own 3d printed parts and design.
The only cnc machine i have ever owned and used is a 3d printer, so i would love to hear some advice and improvements from people on my janky design.
As you can see, it is still a work in progress and needs a bed for the pcb to be placed on, possibly leveling knobs for this bed too?
Another thing you might notice with my strange design is that im using two mg995 stepper motors to lift the 775 spindle motor up or down. This was to keep cost low, and also because i feel that i wont need much accuracy on the “z” axis as i only need to lift the motor for passovers.
The blurry picture is taken from below the spindle, i used steel ball bearings to create a linear slide rail so the motor can be lifted up and down on.
Am i correct in using a “v bit” for pcb engraving?
Going onto the circuitry, i am using two a4988 motor drivers to power the x and y axis nema 17 motors with their 350mm lead screws. The drivers are connected to an esp8266 wemos d1 mini.
I haven’t thought much about the programming side where i will need to convert g code into stepper movement.
On to the structure, my 3d printer area is limited, so parts have to slot together. Each corner of the design is connecting using dovetail joints, with the funky angular covers sloted over the top. Is there a better 3d printable corner joint than dovetail joint considering i want maximum rigidity?
Thanks
Edit, quick video of the motor lifting mechanism if i explained it badly: Vid.zip (7.1 MB)
I built an engraving machine from bits and pieces from the shop, some 3D printed parts and a Dremel. Runs an Uno, grbl. Does OK for what it is. I did learn an awful lot about CNC machines and software making it.
When you get your bed installed, consider using a g code sender like bCNC that can do bed leveling. I mill the bed level then use bed level to fine tune.
I use 0.3mm end mills as cutters.
I do simple PC boards using Fritzing because Fritz generates the Gerber and drill files for free. Then a CAM program to from Gerber and Exilon to g code. My machine runs grbl as the controller.
If set up carefully I can make some pretty decent PC boards. Though if i have time to wait and need more than one, i would just order them.
Thanks for the reply, with that bed leveling software, would i need to have a probe attached to my machine that goes to different points and reads the height of the bed at that point?
Just wandering what method is used to read the bed heights, and feed the data back to the leveling program.
My method is to attach a sacrificial piece a bit largr than the PC board to the bed. Then i mill that piece flat and attach the PC board blank with clamps.
I connect the PC blank copper to ground and insert my tool in the Z axis. I comnect the tool to the probe input with an alligator clip. Then set up for probing and run the probing program. When that is fininsed the bed level information has been recorded and i run the board file. The level informstion is insered as it goes along.
Ah ok that seems smart milling the bed so its level, with your machine, how is it layed out? Is the bed fixed in place, then the spindle moves in the x and y axis, or is it like mine where the bed moves along the y axis and the head moves along the x axis(like an ender 3 for example)
I only ask because im not sure if my nema 17s can handle the strain of milling a large sacrificial piece, i imagine they can just about handle milling a pc at most.
Sounds like our machines are quite a bit the same. The bed is Y axis and moves back and forth on drawer slides. X axis moves (above) left and right on parallel rods from an old line printer. Z carriage and clamp for spindle (Dremel) are 3D printed.
My controller is an Uno with a CNC shield V3 runninig grbl1.01.
I do very light duty work as my spindle motor is a Dremel. Flattening pass is at most 2mm with a 1/4" bit.
I have had a lot of fun with my machine and have learned an awful lot about CNC machines (which was my goal at the start, along with seeing if I could do it with junk parts).
New update on the peoject, i have massively changed the design and scrapped using servo motors to lift the head, and am instead using another nema 17 to lift the head.
I have noticed that the head wobbles alot, i put a video below.
Could i have bad bearings, im using lm8suu bearings? Maybe longer bearings would be better like standsrd 24mm long lm8UU
Would love any recommendations to try and remove this wobby, i feel like its too bad to be useable
