z blog

April 2011

Desktop manufacturing begins!

Thing-O-Matic review

I have received and started to use a Thing-o-Matic 3D printer, made by Makerbot Industries, New York. It took me a while to decide between that and a Reprap Mendel, with the Thing-o-Matic finally winning as it looked like the process of getting it ready to print would be less frustrating.


Being UK based, I ordered from UK distributor Robosavvy who delivered good service. I opened the parcel and found several bags of mechanical and electronic parts, a bunch of pre-cut wooden panels, steel rods and a pound of 3mm ABS plastic filament.

Assembly

It took the best part of three days to assemble the machine, following the comprehensive online guide. I found no tricky or really difficult part in the assembly, just had to be careful with the somehow flimsy laser cut plywood panels. Also if you are not confident with soldering you will need help. I took extra care in routing the cables, drilling a couple of holes for small cable ties.

Software installation on a windows xp laptop was smooth: a control software called ReplicatorG, using Skeinforge G-Code generator and Python. G-Code is the language spoken by most computer numerical control (CNC) machines, big family to which the Thing-o-matic belongs. After connecting to the USB port, testing the functions from the convenient Replicatorg's control panel, all that was required was calibrating the Z axis, which involved tweaking some of Skeinforge parameters. Once again, the online manual is very good and it was no hassle at all. It was a joy to see the first ABS test extrude doodle-like dollop landing on the platform.

When the machine was ready. I dowloaded a cube model from the Thingiverse, the open source repository for all home manufacturing things. The print went well, although the base of the cube came out somewhat warped.


Sketchup

I downloaded Google Sketchup and the plug-in required to export stl files (stereolithography) and after some exploration designed a virtual random round thing with blobs. Exported to stl, opened the file in ReplicatorG, started printing.

The nozzle and platform went to their start positions, the machine heated (takes approximately 8 minutes from ambient temperature), then the nozzle move towards the table, and kept going down into the fragile plastic belt. It tore it apart before I had time to stop it. Luckily the machine came with two spares, and the accident had no consequences.

What had happened is that the sketchup model was not centered as Replicatorg required, and the base level of the model was below the 0 z coordinate, hence driving the nozzle into the table. It would be good if the software prevented that from happening, as I can't see why the nozzle would need to go under the platform level at all?

I have now printed a few things, mostly small parts for a small robot, all designed in sketchup. It is probably not the best software around, but it is reasonably intuitive and precise and free.

Replicatorg

After my first platform destruction, I found out that Replicatorg is fitted with positioning functions that make it a breeze to move, centre and place the model on a virtual printing platform, with a useful visual preview. Once I got that, no more trouble with z coordinates, and after a good few prints I am quite relaxed and don't feel like I need to run to the machine when I hear the print start.



Evaluation

The precision of the prints is variable depending on surfaces, and often extra finish and/or trial and error dimensioning are required. The ABS is nicely workable, drillable, file-able, and robust.

All in all, I would say that the Thing-0-Matic is a nice, usable little machine, that works well without endless tweaking. I got my first useful part from it (a 3 parts caster wheel bracket for my robot) 5 days after receiving the box, which I think is good.

Other printed parts on the robot are the infra-red sensor mount, the tail holder, the tail end, and a couple of other bits not visible on the photograph. The plywood base of the robot is cut with a newly purchased CNC router (see below).

The robot, called Minitningy, has had its first appearance on stage on April 19th in the Love and the Machine performance.

CNC 3040 router

As I was into developing my toolbox with contemporary kit, I also went for a CNC router. With my limited budget and space, I bought a small chinese model, which arrived almost fully pre-assembled. I had to find an older PC with a parallel port to drive the control system, and to buy Mach3, a CNC machine control software.

I am still in the early days of using the router, and a technical fault has occurred which I am trying to resolve with the Hong Kong-based seller. A spare part should arrive soon, and I will complete the review once it is in.

The photo below shows a box printed on Thing-o-Matic, then engraved with the router.



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