RUG/Pennsylvania/State College/Printers/PSU Wallace

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Unit Wallace small.png
Unit Wallace small.png
Wallace
Color: White
Extruder: 0.35 mm
Temperature: TBD

3D printer codename: Wallace is a unit that is currently in progress. Construction began during the 2nd week of the Spring semester (January 2014). The effort is headed by Brandon Tunkel and Alex Marcireau. The design is a modification of the RepRap Wallace printer, dubbed the 3DM1. The build is slated to reach completion by the end of the Spring semester.

The decision to switch to the Wallace design was based on several advantages over the Open Hybrid Mendel printers. First off, this style of printer is intended to be as simple as possible. This is accomplished by utilizing as few parts as necessary. This results in a lower cost and assembly effort. Additionally, it allows for a more robust printer. Fewer joints and points of attachment result in fewer places for unwanted motion or "play". Secondly, the Wallace design allows for a large print volume. The nature of the design permits a large range of motion in each axial direction. The printer bed is considerably large at 20" x 14.5", and the Z-axis can accommodate a print approximately 11" in height.

Other improvements with this printer that are not exclusive to the 3DM1 design are the Bowden extruder and linear bearings. This extruder type allows for less weight and thus less mass to move in all axial directions. This will reduce shaking of the extruder and allow for faster movement when not extruding. The motors will also be under a smaller load in comparison to that experienced in moving a conventional extruder. Linear bearings make part of the simplicity of the Wallace design possible. A single linear bearing will stay fixed to a shaft, whereas at least 2 ball bearings would be required to do the same job (also requiring a system to fix the bearings to the carriage).

Log

Date Modification / Problem
7/25/2014 Fully operational with auto-bed leveling! Currently trying to find a good place to mount the extruder.
4/8/2014 Mechanical components are assembled and nearly ready for function. Electronic components are in hand, but have not been attached to the printer. All wiring has yet to be completed. The Bowden extruder is assembled but still needs a hot tip and wiring.
4/24/2014 The electronics have been tested and attached to the printer. The hot tip has been obtained and the extruder is undergoing its final assembly.

Operating Specifications

Design 3DM1
Electronics RAMPS 1.4
Firmware Marlin
Extruder 0.35mm
Heated Bed No

PSU Unit Wallace - Current Condition

Basic Printer Operation

This printer has a few unique things you need to do before printing. First of all, there are some specific print settings needed for Slic3r.

- I use a 0.735 extrusion multiplier

- Layer heigts must be low, I use 0.15mm (this is to reduce bowden pressure)

- I also use a 0.3mm extrusion width for all of the available settings (again, to reduce bowden pressure)

- Printing is done at 220C and MUST HAVE the fan on. It will become extremely difficult to use without it.

- Finally, I have 1mm of wiped retraction and 1mm of extrusion on restart. I am not set on these values, so feel free to edit them, however this seems to be working O.K..

Now onto the other random stuff. Changing filament is hard. Enough said. When you heat the filament to remove it, some filament expands in the chamber and is impossible to pull through the coupling on the hot tip side of the bowden. I suggest you remove the tube from the connector, heat the extruder, pull out the filament by hand and cut the swollen portion. Then you can change filament much easier. The same goes for loading. I suggest you feed the filament all the way through the tube without the end of the tube inserted into the quick fit coupling. Then, with about 5 cm of filament protruding from the tube, insert the filament into the connector and work the filament down into the extruder until the tube is once again secured in the coupling.

As for print operation, this printer has (semi-) auto bed leveling, which is handy because its large bed is nearly impossible to keep level. There is no servo (at the moment) to move the switch in position, however there is an arm that can be flipped down manually. Upon starting up the printer, flip the switch down and send a G28 command. It should home and move somewhere towards the right-middle of the print bed. Then send a G29 command. This probes the bed 9 times to get an accurate reading. Next, put the probe in the up position (so its out of the way) and run your print!

Good luck and happy printing!

7/25/2014 462RUG

Video - Current Condition

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Assorted Prints

...soon

Operators

This machine is currently being assembled by:


State College RepRap Users Group
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