Finally- more progress on the "snowstock" delta bot 3D printer!
I've uploaded the files of all parts shown in this blog post to the "Snowstock" page on Thingiverse.
.STL and solidworks 2013 .prt files are located at: http://www.thingiverse.com/thing:214848
One of the things I learned from using and modifying my MendelMax 1.5 is that a cooling fan really, really helps with part quality- particularly with bridging and small features. So, the snowstock will have a part cooling fan from the start.
|Fan shroud wth 40mm fan mounted and ready to go|
|Mounted and ready to go|
The assembly looks great, but the Traxxas rod ends introduced much more slop than I'd like. Ideally there should be zero backlash / slop in the print head. As assembled, it had at least a quarter inch of total play at the nozzle- unacceptable for a quality print. So, I decided to implement magnetic bearings right away and not as a future upgrade.
Assembling and installing the magnetic bearings
I chose to design and print ABS endcaps to epoxy onto carbon fiber rod to hold the M5x15 SHCS's. Other examples of magnetic bearings I've seen online have glued the 10mm spherical magnets to the ends of the carbon rods. That might work, but it seems less secure and messier than just using two screws per joint, one on each side of the ball magnet. Each screw is then threaded into the respective component.
|Endcap ready for screw installation and epoxying|
|M5x15 SHCS installed- note head was dished out using a 10mm ball end mill for a higher strength joint with the 10mm rare earth magnets|
|Dishing out the M5x15mm SHCSs|
|All 6 rods, assembled and ready to go|
|Carriage mount installed|
|Joint detail shown- the silver ball is a 10mm spherical rare earth magnet from e-bay|
|Magnetic arms assembled|
I have yet to actually power up and run the printer- I still need to design, print and install the extrusion mechanism. But, even so, I think the magnetic bearing upgrade was worth while. The Traxxas rod ends had far too much slop, I'm sure it would have been very difficult to achieve a decent print quality. The magnetic bearings have zero slop, and also very securely hold the mechanism together. As long as there isn't any sort of long term wear issues I'm sure they will work great.