Build log: 3D printer Anycubic Predator Height mod

Here I describe my steps on extending the delta 3D printer ‘Predator’ by Anycubic to 950mm z height. I built this mod in April 2019 and the printer is still currently in use.

General information about this build
The build volume for the Anycubic Predator is originally 450mm z height, and 370mm diameter for the round build plate.
The printer itself is well over 1 meter tall due to the fact it is a delta printer: the rods need atleast half a meter of space to be able to reach all corners in the build plate due to the type of movement of a delta printer. With the height mod, this printer is about 152cm tall.

The reason why I choose the Anycubic Predator for my height mod: Delta 3D printers are more suitable for height mods. Their triangular structure and fixed build plate makes them more stable at larger heights, and they print a lot faster due to the combined effort of 3 stepper motors to move the extruder. The Predator is also standard equipped with a floating extruder drive, which makes the bowden tube a lot shorter and no need to extend it to immense lengths at height mods which would stress the bowden system a lot. The Predator also does not require any firmware or board changes to do the height mod.
My other option for the height mod, which has been done before, is the Tevo Little Monster. Similar specs and similar price, but much harder to obtain for me in the Netherlands. The Predator is also a new 2019 model which is important to get recent models since 3d printers develop so quickly.

Information about the gantry carriages and the aluminium extrusions (the pillars)
The Predator uses custom 1000mm long aluminium extrusions as the core of the 3 pillar frame. These are very similar to the standard aluminium 4080 ‘C-beam’ extrusion which have a 40mm gantry gap, but sport a wider 42mm gap for the gantry plates. I didn’t know the dimensions of the Predator frame and instead winged it, which worked out for me after filing down 2mm of the gantry plates drilled holes, so the gantry carriage would fit in the 40mm gap. It would have been much easier if i bought a couple standard openbuild gantry carriages instead (but more expensive). You can take apart the carriages for the predator and install the rod mounts on the new openbuild carriages.

Hardware
3x 1500mm Aluminium 4080 extrusions ‘C-beam’
3x 3000mm GT2 6mm reinforced belts
Some electrical wire to extend the wires for the heated bed and hot-end (speaker wire for example will do)

Tools
Centerpunch and hammer
Drill with HSV drills (M5, M6, M10-12)
Tap and die set
Metal files
Voltmeter + soldering equipment

Steps
I had to disassemble the entire 3d printer back to the ‘starting’ point, that is, how you get the printer with the frame disassembled to the 3 beams and the top/bottom plates.
I took off all the gantry carriages and belts, noted the dimension and placement of the drill holes in the original beams, and marked these in the new c-beams i bought.

Using my centerpunch I punched some holes at the markings, this is used so your drill doesn’t run away from the markings.
I measured the dimensions of the original screws that go into the frame and make sure the drilled holes matched those. I had to use some M10-M12 drills to drill away the outer shell of the aluminium extrusions, so the bolts had better surface to be fastened (it’s similar to the original extrusions so I just imitated that)

Then on the inside of the c-beams I had to drill some smaller holes, (use one mm smaller drill than the screws) for the stepper motor mounts. These need to be tapped with the tap and die set, so you create threading for the screws to be fixed to. I had to make sure the stepper motor mounts fit well on there and keep the 2mm gap difference with the new beams in mind. I also took this opportunity to fit the stepper motors with dampers, to eliminate a ton of sound on this printer.

After mounting the stepper motor mounts and drilling the holes, i had to fit the gantry plates with the wheels in place. You can actually disassemble the rod mounts from the gantry plates and use standard openbuild gantry plates, but I had no time for that and decided to file down the holes that fit the wheels in place, so the wheels would fit into a 40mm gap instead of 42mm gap. This took a couple hours, but in the end it worked out great.

I had to file down the gantry plates for the idler mount as well. Then i could fit the gantry plates in place and span the belts between them. I used about 2750mm belts for each.

I mounted the new 1500mm C-beams to the hotbed and the top of the predator, made sure everything was stable and parallel too.

Last part was to extend the wires with an extra 50cm to be able to fit the extra height, since wires need to go down all the way from the top (where the electronics are), to the heated bed below, and also from the top, to the floating extruder. I kept some of the quick connectors and securely used heatshrink with every extra wire I had to add, to make sure you dont get any short circuit. I used a voltmeter to make sure that each wire was properly connected.
The bundle of cables was suspended using a card holder reel, this would suspend the cables when it’s homed, and reel out when the extra length is necessary, without getting in the way of the printer head.

Then turned it on, homed it, and did a new level. The Anycubic Predator does not need any firmware changes to support the extra height. During leveling/homing however it does slow down when it reaches the original z-height, and it’ll take a bit longer to do those operations, but that’s only a very small inconvenience.

It can print small models in proper detail, and large models up to 950mm (in the middle). Keep in mind that a large model will have more ‘skyscraper’ effect, meaning it will sway due to the pressure of the extruder or even break loose from the bed.
This may lead to excessive layer banding and waves in the print unless accommodated using a special print mode (vase mode, zero infill), low speed, z hop, extra wide support structure at the base, etc etc. You can experiment with several means like these mentioned, to fix it.


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