There are two popular ways to get plastic pushed into a hotend, bowden and direct extruders:
Bowden: while a “light extruder” might initially seem like a good idea in rl it plays out exactly the other way around:
- Its almost impossible to dial in pressure advance with a bowden system which is a basic need for going fast with a printer.
- Ultra high retracts in the 3mm range severly slow down print speeds as a lot of time is spent on waiting for retracts.
- From 100mm/s onwards print defects like blobbing and inconsistent extrusion in corners start to really show.
- Get a light, geared extruder like the E3d Titan for example, the gearing allows for small “pancake” style nemas, reducing overshoot on x significantly.
- With a light direct extruder and a light bed its possible to reach equilibrium between them, resulting in an easy to tune / fast to drive motion system
- A direct extruder allows for ultra fast / ultra small retracts ( 0.4mm / 2k accel / 75mms is enough with pressure advance ) significantly reducing print times again.
The bed is a rather simple affair as there are only very few options to build it:
Phenolic resin bound sheet at 1mm, common product names are: Pertinax, Hartpapier etc.
As we are printing on the phenolic resin surface the exact type of fibre bound within doesnt really matter.
Its compatible with pretty much any material extrudable, Dry sand the surface with 400grid, attach it to the aluminium bed with 3M 468MP.
Again there are no other options than exhaust insulation, comes in slightly under a mm, one side aluminium foil, sandwiched glassfibre in the middle, self adhesive high temp resisting sheet on the other.
Dont use aluminium ones, way to heavy, printed holder are perfectly fine here.
There are a lot of different ways one can set up his z rods on an I3 style printer, only few are feasible for fast printing though, before installing the z rods one needs to make absolutely sure they are dead straight ( Roll on a flat surface ) If they are not theres pretty much no remedy, so exchange them for straight ones.
Stepper – Rod coupling:
Either get rigid couplings or stepper with inbuild TR Rods, reason is simple: we need to kill any play possible in the z rods to get the extrusions as evenly layered as possible.
Either get pretensioned nuts like shown in the picture or make sure theres absolutely no play in any direction. Upward play is bad as during fast printing there are numerous situations in which the extruder gets pushed up more than his own weight pushes down / the hotend tip melts in short timeframes. ( Extrusional force, crossing slightly overextruded print parts, step upward bending overhangs etc etc )
Top loose bearing:
As we are moving fast the top of the rod need an radial support, otherwise it starts to severely bounce around, a simple remedy are 8mm bore skate bearings ( 608 ) in an printed holder.
Forget everything you think you know about 3D printers.
Throw away your shitty bowden setup, it wont go much over 100mm / s without severe blobbing / insanely long retracts holding back total print speed.
Uninstall Arduino IDE, wipe marlin of your hard drive and regret you ever learned about it.
Roll up your sleeves and get to work – awesomeness awaits.