AnyCubic i3 Mega Design Notes by jrmoserbaltimore

Last crawled date: 3 years, 1 month ago

These are notes and modifications for the AnyCubic i3 Mega series, including the Mega, Mega S, and Mega Pro; the Mega X is a bit different. AnyCubic could ship the i3 with these upgrades with little to no added cost.
Recommended modifications for the next hardware revision:
Trianglelab E3D V6 Volcano clone, 0.4mm hotend
1.9mm Bowden tube
Fix the linear rod deflection
BLTouch compatibility: Run D11 to the unused pin in the print head, add 5 pins exposing D2 (already run), D11, GND×2, 5V for plugging in a BLTouch (user-supplied)
Aluminum tensioner carriages for the 3D printed tensioner mods
Flexible couplers
Total added cost to ship: $1.35-$3.55
Value propositions:
Much better and more consistent flow (Volcano)
Better retraction, less stringing and blobbing (1.9mm tube)
Fix warped bed (fix Y-axis linear rods)
Auto-leveling can be added easily (BLTouch pins)
Belt change and maintenance is easier (tensioners)
Z screw less sensitive to misalignment (flexible couplers)
Hotend
The hotend is an E3D V5 clone which costs about $8.
The E3D V6 is slightly shorter; however, an E3D V6 with the Volcano block is exactly the correct size, to the mm. A Trianglelab E3D V6 costs $10-$12 off the shelf (without the fan, which isn't included in a replacement $10 stock hotend), In bulk, $8 is a likely negotiated price. This is a huge upgrade.
Added cost: $0-$2
Mod cost: $12
1.9mm Bowden Tube
Trianglelab sells a 1.9mm PTFE Bowden tube at $3/meter. it costs about the same as any other PTFE Bowden tube. This improves retraction distance and flexible filament printing.
Added cost: 10¢
Mod cost: $3
Y axis linear rods
The Y axis rods face deflection because of where they're mounted on the case. A slight modification to the design would fix this, but it's a little complex: the end mounts are inserted from inside, and screwed in from above.
One potential approach is to extend the footprint inside the chassis, and install a screw above ahead of the mount. The mounts bend forward toward the bed; a screw would lift from the forward position, tilting the mount backwards, with its natural tendency to tilt forward being the counterbalance.
Another option is to shim up underneath—the provided STL does so, but this is inferior to the screw calibration approach.
This would involve slightly more material; machining would likely cost $0.
Added cost: 25¢
Mod cost: Good luck?
BLTouch compatibility
The D11 wire can be run to the hotend. The D2 wire is already run, and appears directly next to an unused signal cable that is run to the port in the chassis. Wiring that pin to the servo pin is just a single wire inside the case, no chassis modifications.
There are two unused pin spaces, and an additional three can be added to the board inside (spacious). The change in cost for the board is literally zero (due to PCB manufacturing being such that a board roughly the same size costs the same amount to manufacture with or without the extra header pins).
This would allow mounting a BLTouch inside the print head (a common mod) and plugging it in directly, no wires running anywhere.
Added cost: $0
Mod cost: $0, soldering, and some time
3DTouch still has to be purchased for $12 either way.
Tensioners
The 3D printed Y Tensioner is nice. Let the end user add that. A strip of carbon fiber epoxied to the inside width would prevent the part from flexing when put under tension, too.
The 3D printed X tensioner is annoying to install. Changing the belt will also still be a problem, although it's easy to work around that and change the belt by threading it in place. The bracket takes minimum load and is The 3D printed bracket is printed in the strong orientation and backed up by the metal part.
AnyCubic should include the carriage and screw in metal for the mod, although the carriages can be 3D printed in the strong direction. The mount can be 3D printed for cheap enough.
Added cost: 30¢-50¢ of cheap aluminum
Mod cost: $1
Flexible couplers
Replacing the collar with flexible couplers costs little. A coupler can cost 50¢; the collar costs $15¢. Flexible couplers (with a bearing, which costs a penny) protect the quality when the motor is not exactly aligned to where the shaft belongs.
Added cost: 70¢
Mod cost: $1
Belts
The belts are upgradable to polyurethane and steel on the 20T pulley (16T would be too small). No change to the pulleys required.
AnyCubic i3 uses tie wraps instead of some kind of clip to hold the belt in place. Squeezing the belt folded over itself locks the teeth in place. A reusable clamp would be nice.
Added cost: ?
Mod cost: depends on the 3D printed part.
Cable chain
A cable chain for the i3 provides better fit and finished, and helps keep the cable straight and away from the frame at the top. Print one yourself; they'd add more cost to ship.