Wednesday, December 23, 2015

3D Printing 101 Series and an update

Several years ago Bob Warfield of CNCCookbook fame asked me to do a series of posts on 3D printing. There was an introduction and four parts to the series that discussed the basics of the printer, mechanics, electronics and software. These posts have had a lot of reads, so I thought it made sense to link them here for others to find.

These posts are a few years old and a lot has changed. Arduino-based controllers were the norm, now many of us have moved on to more sophisticated electronics and firmware like the Smoothieboard/Smoothieware and Duet/RepRapFirmware combos. Control electronics and firmware are evolving quickly. Hot ends, extruders and even motion control are advancing quickly. The weak link in the chain as I write this at the end of 2015 is the slicing software that converts the model (typically an STL file) into the gcode that instructs the printer on how to print the object. I've used as many slicers - both open source and commercial - as I can get my hands on and as a sweeping generalization, they are still primitive compared to the capabilities of the hardware and the designs and products many of us wish to print.

On the hardware front, there is no one "best" option. I'm a "delta advocate" but I own Cartesian printers too. I've evolved many aspects of my printers over the last few years and I'm currently putting together a new printer with "all the bells and whistles". Let me describe it and I'll be making more posts over the coming weeks as I finish and commission it.

The basic structure is the Metal Max all aluminum Rostock frame from Trick Laser. This is a "drop in" replacement for folks who already own a SeeMeCNC Rostock Max printer. Meaning, all of the parts from the Rostock Max can be migrated to the aluminum frame. I'm building the printer using best-of-breed components.

First up is the motion control. I decided to use linear guides on this machine rather than Delrin-wheeled carriages that roll in the upright extrusion slots. I'm using LM76 SGR10 Speed Demon rails and blocks. More as I put these into service. I'm also using .9° stepper motors rather than the typical 1.8° steppers. This doubles the effective resolution of the motion.

On the "business end" I'll likely run a Cyclops switching extruder or the tried-and-true v6 from E3D-Online. I've spent a lot of time studying and understanding these hot ends and contributed to part of the design that was incorporated in the v6 (search for "hackney") to address some reliability issues.

Recently I came across the amazing Bondtech QR extruder. I've tested many, many combinations of hot ends and extruders over the last few years. Until I met the QR, I was unable to achieve the high reliability I need from demanding hot ends like the Cyclops. The QRs are unique in that they have counter rotating drive gears pushing the filament. This results in noticeably smoother extrusion with a lot more pressure that traditional single gear extruders. I'll be using the QRs on this new build.

For the controller and firmware, my current favorite and what I believe to be state of the art is the Duet and David Crocker's dc42 branch of the RepRapFirmware. The firmware is really the magic ingredient with the this combo. It calculates each point of delta movement, unlike all the others (that I know about) that reduce the movements to short line segments. The dc42 firmware also has very functional and fast delta auto-calibration that takes less than 30 seconds to run and works reliably every time - no muss, no fuss. And the capper is the big PanelDue touch screen controller display. I'm using a 7" touch screen on this machine.

I am using 24V power supplies and other components and decisions will be made as needed.

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