@garyd9 Sure! The final result is admittedly more "cobbled" than I usually prefer as a result of the RobotDigg carriages having a 40mm distance between the flats compared to the 35mm on the printed effector of the D300VS+, but here goes any way:
- Purchase 3x 700mm MGN12H rails and carriages from Iverntech on Amazon.
- I started with the ones from RobotDigg, but they were really terrible quality, so I wound up using the rails from Iverntec.
- I found that carefully pulling the carriages off of the rails, cleaning with isopropyl alcohol and re-lubricating with Slick 50 Supercharged One Lube is really worth the effort because they move completely smoothly now
- Purchase a set of RobotDigg carriages MGN12H-OP-BLACK
- Carefully chase the threaded holes with an M3 tap as deep as you can go because the anodize inside the threaded holes really gums the threads up
- Again carefully, file off 0.5mm from the faces that each ball stud will mount to for a total distance of 39mm between the faces (this will make more sense later)
- Thread the ball studs in as deep as they will go on each carriage by hand and note that one side has a shallower hole than the other. Remove that ball stud and shorten those threads by that amount and re-install the ball studs on to the carriages so that they are fully seated.
- Get ahold of some NO snap acting microswitches with a lever arm and replace the ones that came with the printer because without the lever the switch will not activate on the top of the MGN12H carriages (the screws for the wipers are taller than the switch plunger)
- While you are doing this, re-route the wires for the switches to the sides of the towers because you will be using the inner-most face of the towers to mount the rails.
- Go ahead and slide the switch mounts up as high as they will go and tighten the mount back down there
- Get some M3 x 8 screws and some 2020 T-slot "hammer-head" M3 nuts and install the rails on to each tower, facing inward.
- I did this by putting bolts in the holes of the rail at even spacings (I think I started one hole from each end and left 4 holes between bolts on my rails) and loosely starting the nuts on the threads.
- When you put the rail against the tower and start to tighten the bolts, the nuts should center the rail on the tower nicely.
- Place the top of the rails just beneath the lever arm of the end stop switch so that when the carriage comes to the end of the rail, it will hit the endstop switch before balls start to fall out of the carriages.
- Assemble the RobotDigg carriages to the linear rail carriages with the tensioning screws pointed down, install the belts and tension them
- If you watch the video on their website, they show wrapping the belt around the tensioning blocks and pressing them into the carriage. Save yourself the headache, it doesn't fit like that. Just run the belt down one side and get some slightly larger washers to pinch the belt in place when you tighten the tensioning blocks in place.
- Purchase some 1m thick shim washers from McMaster (PN 98055A099) and place two between each ball stud and the effector. Now both the carriages and the effector have 39mm between the ball studs.
- I originally planned to shim the effector to the full 40mm of the carriages, but I couldn't get the nuts for the ball studs in the effector to catch. With the 39mm spacing, the nuts just catch on the ball studs in the effector and you can tighten them to the point that they start to compress the plastic in the effector.
- After all of this work you'll frustratingly notice that the springs between the carbon rods don't fit over the carriages anymore. For a moment I thought that was game over myself, but then I just decided to try getting some zip ties and strapping the springs slightly down the rods, away from the carriage so that there would be clearance. To my surprise, this actually works very well.
- The zip ties do walk around on the rods a little, so I may add a little epoxy to hold them in place at some point. For now, however, periodically moving the zip ties back to where they should be seems to be working ok.
Now, after ALL of that work, you should have a rock solid, smooth moving delta carriage system that will eliminate what appears to have been the source of all of my problems. Run the auto delta calibraion a few times, upload the values to your config file and smile at how nice your prints come out all of the sudden!
Happy printing!