15 days ago •
So I worked on assembling one full side of the Z-axis today and ran into a few issues. The first is that our NEMA 14 steppers that were purchased from Pololu have a slightly longer shaft than the original batch from an alternative supplier. I should have measured them prior to any machining but didn't think to do so. The model has been updated to reflect the new shaft length, the only major change is that the X-axis square drive has a slightly shorter engagement with the coupler. Once the parts are modified I can install the last bearing and begin assembling the clamshell prototype.
Here is the full assembly with the backpane, the top bearing mount appears to be floating in this image because I had not yet opened up the dowel pin locating holes to the right dimension.
And here you can see the dowel pins inserted. This backplate is the original one I cut which is why it does not have holes to provide access to the guide rod clamping set screws from the back. I hate wasting material so I'll be adding these tomorrow on the drill press, the model has already been adjusted.
I plan on uploading the following parts to GrabCAD this week since they have been prototyped and are unlikely to change:
1. Z-Axis Guide rods
2. Lower Motor Mount
3. Upper Bearing Mount
4. NEMA 14 Coupler
5. NEMA 8 Coupler
6. Spectraline Pully
The Z-axis clamshell still needs to be modified and prototyped before it will be ready for release.
17 days ago •
Preliminary prototype parts for the Z-axis (X-axis drive side) were completed today. I need to swap out the upper bearing mount and lower motor mounts as they were modified since the initial print. The goal for tomorrow is to have this side of the Z-axis running back and forth, with the ability to also run the X-axis spectra line pulley.
Progress has been slower the past few days than I was hoping, family and work tends to get in the way of projects. I'm hoping to have the opposing side of the Z-axis finished this weekend so that I can focus on the Y-axis truss that is causing so much controversy.
This weekend I will also be cleaning up this project, I think we have been doing a decent job of posting build/design updates. However I think the overall project description needs to be dramatically expanded, the BOM needs updating with all of the new parts.
Please post any comments and let us know what we can do to make this project better!
18 days ago •
So my self-imposed deadline of ordering Shapeways parts for the Z and X axis by 7/11 looks like it will be met! There is still clearly a ton of design work to be done, but I'll be purchasing the spectra line pulleys and Z-axis carriage to get a full side operational and run some preliminary testing.
There have been a few comments about injection molding in relation to this project. To be clear the parts WILL be injection molded if we choose to do a kickstarter, they are being 3D printed currently to expedite the build process. I have personally designed 34 injection molds to date, some of which were complex multi-part molds with collapsing internal mandrels (Worked in electronics packaging for a well known corp). Low run production is quite accessible for hobbyists in relation to injection molding, a Morgan press [ http://www.morganindustriesinc.com/ ] can provide more than enough pressure and injection volume to produce any of the parts for the TOME, I believe Techshop is equipped with a similar injection molding machine. We will be utilizing professional injection molding equipment with molds produced on our CNC machinery.
Here you can see the Z-axis clamshell complete, I'm happy with the current design and I'll be reproducing this on the opposing side with a few tweaks to fit the Y-axis control hardware. I hope to begin work on the Y-axis gantry in order to clarify the design intent and validity. I have received several comments about the potential problems with a cantilever design but I am confident the FEA will support my current design. I will post the results for the FEA study when it is complete.
I still need to draw up the anti-backlash nut holder, but this is a simply part that can be FDM printed without degrading performance of the piece.
Corey was able to get most of the Z-axis hardware machined, just waiting on two metric drills to properly size the coupler holes for our stepper motors. Should have a prototype Z-axis running soon!