On Tuesday the 28th of October the annual science fair at the faculty of industrial design was held. We displayed the printer and most of the testprints we made. We were not allowed to do any welding at the science fair for obvious reasons so we showed a video of the working printer.
Many people were interested in the design of the printer and we’ve got a lot of positive feedback. We received questions on how the printer works. Questions like: “where does the metal come from?” and “What software do you use?”. And some people had suggestions on improving the design. For example, the use of water for cooling.
The printer got the amount of attention that we were hoping for which made the science fair a nice way to end the project.
As the project is being wrapped up, for next year’s minor students to continue on, we can reflect on the progress made and of course list the areas which in our eyes have the highest potential for improvement.
During the initial week of the project progress seemed slow, with a quick visit to a metal workshop to receive some guidance on welding processes and settings. Deciding on which axis system to use and acquiring the right parts took longer than expected, luckily there was a Prusa supplier about 20 minutes away by bike!
After printing a simple wall, simply by stacking bead upon bead of metal is an obvious start. Let’s face it though, it is not the most challenging of structures. To investigate the boundaries of the printer we have first printed an overhanging wall, basically a slanted wall, by offsetting the printerhead slightly per layer we managed to print a wall of similar quality to our vertical wall. The initiation and termination points of the welder were quite problematic resulting in a slightly tapered wall.
This post will feature the BOM of our 3D printer. The base for our printer is a prusa i3 kit. This is a well documented design so we will not name all the parts that it contains. The build manual can be found on http://reprap.org/wiki/Prusa_i3_Build_Manual. The modifications to the original prusa design are quite simple. In place of the print bed we used a box constructed of sheetmetal. This box is isolated on the inside with a material that is normally used in ovens, the material contains vermiculite and is commonly available. The plate on which we weld lies in this box and is connected to the ground cable of the MIG welder by a piece of threaded rod, this rod goes through the box and the isolation material. Make sure to electrically isolate this bolt from the sheetmetal box. We did this by making a small “washer” out of wood.
We used an aluminium extruder carriage which we ordered at reprapworld. It is best to use a metal carriage since a lot of the heat from the welding will go upward and this might damage a plastic carriage over time. The torch holder is made from a small block of aluminium, we used a mill to fabricate this part but it can also be made with a pillar drill and a saw. Continue reading
The software part of a 3D printer can be divided in to two parts; the software on the host computer (slicer), and the software on the printer itself (firmware). In this post we will discuss how you can configure and optimize your software for metal 3D printing (FDM).
Hello dear followers,
Here’s a video of our first autonomous print, that’s the printer doing it all by itself. We finally got the relay switch for the torch working, and you can already see a huge improvement in the quality of the print around the edges.
Enjoy the video!
Having finished assembly and laid down several beads of metal on the plate a series of “scientific” tests were done to tune our setup. The variables include:
- Feed rate MIG welder
- Voltage setting of the MIG welder
- Travel rate of the torch
Results were rated qualitatively and after a day of testing a final setup was chosen which was deemed suitable for our purpose.
The MIG welder is set to feed wire at a rate of 4 [m/min]. The open circuit voltage level is set to 16.9 [V]. Travel rate of the torch will be 330 [mm/min]. Gas flow is set to 9 [L/min].
Using this setup beads were layered on top of each other to form a wall like shape resulting in a surprisingly consistent and strong structure. Grinding off the outer layer and polishing the smooth surface revealed a uniform formation with no visible lines between the layers of welds. A second wall was printed, to be analysed and destructively tested at the 3mE facilities.
The next step in the project will be to print hollow structure. More results to follow.
– The Metalprinters
The day of our first tests has come. We managed to print a few very straight lines and even stack one line on top of another. The control over the welding torch however is still done by a manual switch, since the software is not quite finished yet.
We hope you’ll enjoy this little video of our first few tests.
More tests for quality improvement and printing software will follow soon.
Yesterday we finished the assembling of the metal printer. We have attached the torch to the printer, we have positioned the endstops and connected the first cables. The result looks like this:
Welding over a long period of time generates high amounts of heat (remember steel melts at around 1400 °C). In an earlier post about manual 3D printing it was mentioned that regular breaks must be taken in the welding process to avoid overheating of the both the welding apparatus and the print product. In order to prevent the plastic 3D printed parts on our machine from melting it was decided to re-manufacture critical components out of aluminium.
A heat shielded box will be used to protect the rest of the machine from the heat of the product and to contain most of the molten metal bits which fly around. The box is made by bending a 2 mm sheet of aluminium, it is then lined with slabs of light weight, heat resistant tiles. These tiles were thoroughly tested beforehand by welding right on top of them with varying power settings of the machine (note: for 3d printing only the lowest setting will be used). At low power settings the tiles could be picked up by hand immediately after welding. Damage occurred only when large pools of molten steel came in direct contact with the tiles when welding at with the highest power setting. To protect the MIG torch from sparks and molten metal a simple shield was fabricated from sheet aluminium, this was attached to the torch clamp.
Heat resistant tile after testing, it discolours at high heat but is damaged only when in direct contact with molten steel.
– The Metalprinters