As you might have discerned from my last post, I had no intention to go for a proper 3D-printer straightaway.
More specifically: I wanted to see, what could be archieved with some basic tools (mostly) and standard parts, wrought material or alienated stuff (my favorite).
Smooth rods and linear bearings are good value for money, but I already had seen the “Poor Man’s Linear Motion Guides” of Youtuber alanator25 and the bearing assemblies at buildyourcnc.com.
M8 screws are a good fit for “608ZZ” Skateboard bearings (22mm x 8mm x 7mm, the cheapest ones available according to Lieven Standaert’s excellent “practical prototyping primer” at cccamp15) and the “alfer combitech” profiles you can buy at “toom” have pretty sharp edges – so I took some… no idea what it originally was… cupboard back panel(?) and had a try. In the second attempt the dimensions were already practicable.
Here it is a short video:
So I had really cheap bearings and two meters of affordable square tubing. What about building a CNC machine from that?
The decision was made against an “XY Head / Z Bed” arrangement. I drew some lines in my EDA-tool (Target 3001!) and printed the plan.
Then I had to make sure that all of the holes align. Easy, if you can drill through all parts at once…
…which didn’t work with a cordless drill, freehand, on the old shelfs I used as top and bottom. But in the end it was aligned sufficiently for chipboard and chipboard screws.
Unfortunately I had made a mistake when I ordered the “rudder horns”, planned to serve as joints. One degree of freedom was missing, since I clicked the worng type…
The effector could be mounted, but movements resulted from flexing the M3 threaded rod.
So here is the first workaround to give each joint a second degree of freedom.
After this worked I could order some new parts, rearrange the slides and apply screwlock. Next step was the belts (RPP 3mm profile) with the appropriate HTD3 pulleys. The come with pilot holes, so here I had to use a drill press and a reamer to treat them properly…
Having three metal pulleys was obviously not a bad thing, so I direectly ordered them instead of searching someone to print such parts for me.