As the access to the workshop at my university is a total mess and I want to greatly improve my home prototyping capabilities, I'm currently designing and building a CNC that i can use in my room.
to be able to do this project, the entire CNC has to be able to be stored under my bed. this means i have only 20 cm of height available. Width and depth are not such a big problem as i have a pretty large bed.
The end result should preferably be pretty sleek and professional(ish).
If interest is shown, i will make the source of everything freely available and proper build and assembly documentation can be made.
And of course as a disclaimer, with "high performance" I mean high performance in the diy cheap cnc realm ;)
The main goals of this design are:
Design has to be cheap(ish); parts i can get for free through contacts won't be seen as costs, as is stuff like the water-jet cutter i can use for free at my university.
Can fit under my bed for storage when not in use
Minimal disassembly effort and time required for storage
Repair-ability and expand-ability integrated into the design
Can machine at least aluminium parts with acceptable accuracy (0.05mm tolerances are a absolute minimum, higher precision preffered).
3D printed parts only used when it's right for the job, not like pretty much every other build project these days.
A 3D touch probe has to be mountable for indexing and future use as a improvised CMM.
Future upgrades may include BLDC motors for X and Y motion
So, it's been a while since the last update. However it's mostly been waiting for parts to arrive from china. But in the mean time i've made some progress.
firstly, the sides of the gantry plates were awful, the mounting holes are machined, but the outline was done on a plasma cutter to save time. so i spent an entire evening filing and anding the sides clean and flush to make it all seem way nicer to the eye.
so i'm pretty happy with the result after some hard manual work
secondly, all the MGN rails and almost all of the carriages are in. Also some M3 Bolts, M5 bolts, T-slot nuts, spacer plates and 2020 extrusions have been received. So i've been able to start assembling the y-gantry.
pretty happy with the overall fit and finish. The blue printed motor mount plate is just a temporary place holder to check the design.
I designed the gantry plate to be mounted with M5 bolts to the 2020 extrusions. Now did i find out that the extrusions i ordered had a larger inner hole, so i've drilled out the gantry plates and mounted the gantry plates with M6 bolts, however i just had one bolt laying around, so it is temporarily improvised with a threaded rod and a bolt as you can see. But i ordered the right bolts and should be a drop-in replacement once i have those.
after i got my new ER11 collet set in the mail, i designed and printed a nice small box for it to prevent me from losing them.
and lastly i remembered i had a random block of scrap metal laying at my parent's house wich would be perfect for the front and back frame rigidity improvement brackets (i'm not actually sure what to call them, see the last log. those).
i've contacted someone from my uni to check when i can access the workshop to machine this block to finish. But as the other 2020 extrusions are not yet in, there's no real reason to hurry.
For the next few weeks i'll be focussing on my examns so i'll probably post an update as soon as the complete frame is ready for assembly.
It's great to see the interest in my little project!
So after considering Paulvdh's comments, i came to the conclusion that the base did lack rigidity and I wasn't quite happy with the assembly. The design relied too much on proper assembly and tramming and not enough on proper machining. As i'd rather spend an hour or two extra in the workshop so i can just throw the parts together and have them aligned and square and everything.
I've decided to add about 20 euro's of steel and an extra day of workshop time to improve the base.
The width of the base is now determined by a big chunk of precisely machined steel in the front and back instead of waterjet cut sheet steel. This will also greatly improve the rigidity of the base plate, and add some mass to the whole thing.
I've decided that this will be the final design for now, and will start making the drawings and buying the rest of the parts. The MGN rails i ordered this black friday are also in, so progress is coming.
I've uploaded a 3D pdf of the latest version. Interested people can take a look at this. Tips are still welcome and will be considered.
I'll probably be busy and away this christmas, so the next update will probably come somewhere around the half of januari. Happy new year everybody! ;)
So, the side plates are done! My friend did a perfect job, and i will only need to sand the surfaces for aesthetics.
Secondly, the Leadscrews for the Y-gantry are in! they are okay-ish quality, but the nuts have a completely unacceptable amount of play in them. so i will have to find new ones. Although i had a known good quality nut laying around and that worked perfectly without any noticeable play, so the rods themselves are good (enough, for now at least).
i will probably throw them in a lathe for finishing sometime next week.
So i decided to change the Y-axis motor configuration. The design used to use one single NEMA17 Motor with a 600mm closed GT2 belt to drive the two leadscrews synchronously. However to simplify the tramming and tweaking of the physical unit, I decided to change it to two motors each driving it's own leadscrew.
Also, both Y-Gantry side plates are done, i'll post the result later on.
So the project has progressed a bit again. The side plates are in the making and almost finished today, just some cleaning, sanding and finishing up to do.
Secondly i finished the render of the CAD model that shows the folding mechanism. Note: Due to the fact that my trusty dual Xeon e5645 isn't really cutting it anymore these days, i had to remove pretty much all the screws from the model. However the Z-gantry is fixed with four large bolts and aligned with a tolerance fit. the animation doesn't really show this. But the bar linkages that allow the Z-axis to fold down are just for easy folding and reassembly and bear no structural loads at any point during actual use.
I'm currently looking into the Electronics side of things. At first i was planning on using a simple modified 3D printer electronics setup, pretty much like my Kossel 3D printer does. And then throw something like GRBL on it. However i'm not really sure that's the best option for this build (possibly linuxCNC or Mach4?). if anyone has any suggestions, be sure to comment, chat, mail or use carrier pidgeon whatever floats your boat.