RatRig V-Core 3.1 & 4 Caster Mounts

This enables you to mount heavier duty M12 Stud feet or leveling casters to your V-Core 3.1 & 4 printers while strengthening the frame and still allowing for it to be leveled on the floor.

I disliked the idea of using the stock M8 threaded holes in the upright extrusions of the V-Core with M8 Stud casters as it puts the entire weight of the printer on those extrusions/threads that aren't even a full M8 thread (as the cutouts in the center hole mean you don't have a continuous M8 thread).  Additionally, the M8 casters tend to be smaller (harder to roll), have less leveling height adjustment, and have the risk of skewing your frame when rolling it (since the caster is bolted to just one upright extrusion in the corner - risk forcing this extrusion up with a hard bump from the caster).  Furthermore, once those M8 threads in the corner extrusions are damaged, there is no way to continue using them without replacing the aluminum extrusion and thus having to re-square your frame.

Hence this mod.  The thick metal corner mount plate ties together the 3 extrusions that meet in each corner, adding to the rigidity of the machine while also distributing the force of the leveling casters/feet into all three of these now reinforced extrusions. It also allows for the use of the heavier duty, easier to roll, and larger leveling height adjustments of the M12 style casters.

BOM:

CNC/Laser/Plasma Cut Aluminum 6061 Plates - 4x

1. VC4: Requires at least 20mm thick so casters fully clear the motors on the VC4 (otherwise the casters can hit the front Z motors when you turn the printer).
   1. I found 25mm was essentially the same price as 20mm, so went with that. 30mm was dramatically more expensive.
2. VC3.1: Recommend the plate is thick enough for adequate thread engagement by the caster/foot stud.  Likely at least 12-20mm, although there is no issue with thicker mounts.
3. Either have these CNC milled to have 90 degree chamfers for metric FHSC bolts or countersink them yourself afterwards (will need a chamfer tool that can do M6 and M8 FHSC 90 degree chamfers).  Bolts must be recessed otherwise casters will hit the bolt heads when installed.
4. The included Step Files for CNC services DO NOT have the M12 threads that the caster bolts into modeled into the Step file.  This is because almost all CNC services require you to specify tapped threads with a separate drawing you submit, and not include those threads modeled into your Step file.  Be aware you will need to specify you want the 10.2mm hole tapped to M12x1.75 or be prepared to tap this yourself.

Bolts:

1. 16x M6 FHSC that are 5-8mm longer than your caster mount plate you have cut
   1. e.g. 25mm Plate needs M6x30MM FHCS
2. 16x M6 3030 T Nuts
3. 4x M8 FHSC that are 30mm longer than your caster mount plate you have cut
   1. e.g. 25mm Plate needs M8x55 FHCS
4. Casters:

M12 Caster

1. There are many different M12 Chinese leveling casters that work with this, but the type that tends to be best usually has an “80S” in the model number, 2.5 inch wheels, and a 65mm Hex on the top.  The 65mm hex on top will not stick out past the edges of the printer, but casters with larger hexes on top may stick out.
2. I do not recommend the ratcheting leveling casters.  The ratchet mechanisms are unreliable and prone to failure.  The ones you have to screw in/out by hand are more reliable, even though they are more inconvenient to use.
   1. The exception is the Foot Master ratcheting casters, but these are $60 a corner ($240 for a full machine!) - a Chinese set of 4 is ~$50-$80.
3. Many of these Chinese leveling casters use a hard plastic foot.  Under high acceleration/high speed moves, your printer can slide around.  Get a caster that uses a soft rubber foot instead of hard plastic.  Many unfortunately advertise themselves as rubber but come as plastic, so this can be difficult. 
4. Example of what I Used:
   1. https://www.amazon.com/dp/B0CNRS3H9R?ref=ppx_yo2ov_dt_b_fed_asin_title 
      1. This has an upgraded wheel with a bearing in it and a soft rubber foot.
5. Depending on how thick of a mount plate you get cut for your use you may have to cut down the M12 stud in the caster or get a shorter stud as there is no room for the stud to extend out past the mount plate.

Install Instructions:

1. Tap Corner Upright Extrusions to M8x1.25.  At least 30mm of threads should be tapped into the extrusion (which will likely be the max most standard length taps can do)
   1. V-Core 4 - these extrusions should already be tapped to M8x1.25
2. Tap the 10.2mm hole on each Caster Mount to M12x1.75 
3. Screw in M12 caster stud to the M12x1.75 hole you just tapped in the Caster Mount
   1. Trim off any part of the M12 stud that extends through the plate.  The stud will hit the extrusion when installed and make you unable to tighten the caster mount plate to the frame.
4. Install M6 FHSC bolts with M6 3030 T Nuts into mount plate
5. Install caster mount and caster to the frame by bolting down the M6 FHSC and Nuts and  the M8 bolt into the corner extrusion.
6. Level your machine and enjoy the leveling casters.