Update 9/2/2017 part 1
I made a mistake with the design (again), I forgot to stagger the idlers on the Y axis to make up for the loop of the belt that hits the servos. A new design was made to save time and parts to keep track of I extended the arms out and added a second set of screw holes. I added some additional stiffness on the lower arm also.
Belt binding from V2
I had also noticed at this point that I seemed to still be playing with tolerances that where to tight. So I opened up the clearances on either side of the channel again. Thinking this would solve things.
While the new parts where printing I finally uploaded marlin to the arduino and set about configuring that. I also realized I needed to get some barrel connectors for the MKS TFT2.8 I picked up to use as a display/controller. I also starting making the Cables for the stepper motors and endstops.
Next I went through the process of removing the old parts and installing the new ones. Clearances where much better this time seemed like I was going to be good. Set about making sure everything was moving on the correct plane then went about Installing the Y axis channel and test carriage.
Unfortunately it seems as if the Y axis’s are still binding, further more the parts have warped enough during printing that they are several degrees off on the alignment between the two. I spent a bunch of time checking alignments and squareness. I also decided to fire things up and see how the first moves went. The carriage moves great in the X axis but there is no Y axis movement, the steppers just skip steps or jump the semi loose belts. After alot of checking stuff I decided to walk away for a bit and come up with a new plan of attack. After all you need to stumble a bit in the process of experimenting, I wasn’t ready to just give up yet.
I decided to try lubricating the Channels after testing it with some scrap and previous revisions of parts. This did help some but not enough to allow the steppers to move things in the Y direction . After investigating more it appears that the channels might be binding in the corners. I also had incorporated a small step in certain places to make it easier to align the size of tape a bought (the tight varied in size quite a bit larger than it was advertised at (I am glad i didn’t buy the larger size).
This also brought to my attention another flaw in my design. That its a pain in the ass to swap parts for the Y axis. As it requires the disassembly of top section of the frame, and removal of the stepper motors and idler assemblies each time. So Version 4 of the Y axis slider will likely be a multiple piece assembly. To allow for changes without that level of disassembly and realignment. I also know that the tape will wear over time. How quickly i am not sure. So it would be wise to address this sooner than later if this proves to be a working method of design. This should me remove the few degrees that the X axis is off due to warpage.
My other thought is that i am possibly adding an additional twisting force to my design with the current X axis placement in the design. Since the Bar sits above the Y axis. 23mm or so. When you look at the deign specs on Corexy.com you see that he does a much better job of keeping the forces in line better, when it comes to the carriage and Y axis’s. So i might need to investigate that method of doing things. (i have known about the twisting issues in the hypercube design. However I had hope the Tslot extrusions would counter this issue.
I still think Tslot is the better/more affordable option when it comes to accessibility. So I am not ready to give up on it anytime soon. The idea of paying 65$-100$ per ground 12mm rods in suitable lengths for larger format FDM printers is painful on the wallet. Compared to 25-35$ I payed for annodized 2020 Tslot from McMasterCarr in 8’ Lengths.
I will try to post a video later of the current movments.