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
On Tuesday the 7th we went to metaallokaal, a metal workshop, to play around with some MIG welders and to get additional information on the welding process. Jeroen, the owner of metaallokaal, gave us some advice on which settings to use. During the instruction our group had a collective eureka moment when Jeroen demonstrated a “wrong” setting for the MIG welder. The feed rate and the power setting were both too low to weld on to the thick plate.
Today we’re going to tell you about our decision for our 3D printer system. The printer built by the Michigan University used a delta system, quite a well-known system for polymer 3D printers. We however, argue that a Cartesian system would be much better suited for our metal printing application. The reason for this is that the main advantages of a delta system, less materials required and a lower weight, implicate a major disadvantage for any MIG welder based metal 3D printer.