I picked up a Rostock Max 3d printer a few weeks back. I wanted one to gain experience with a bowden hot end setup and a delta arm configuration. The build was pretty straight forward for me as I have built many 3d printers and even designed my own. I found the stock power supply did not provide enough power for me to heat the bed and maintain a constant temp on the hot end. I replaced it with a quality Corsair 600W supply that has a single 12V rail. Other than this and the fans I added the rest of the RMax is stock. If I had to pick one thing about the build that I did not like it would be the fitting of the arms to the aluminum u-joints. This required a lot of sanding, scraping and countless refits to get them to move with minimal friction.
My first prints turned out a lot worse than I was hoping for. However I was expecting more tuning than usual as I had read that Bowdens and delta’s required it to make decent prints. I was starting with PLA instead of ABS so it was even harder to tune the bowden setup. I needed to add a fan to cool the peek part of the hotend to stop the PLA from oozing up and causing a jam. I spent a lot of time on PLA prints and tuning but could just not get a result I was happy with. I decided to switch to ABS as it was supposed to be easier with the Rmax and its Bowden setup. Well I spent an equally frustrating amount of time trying to tweak the settings and not getting acceptable results. I was basing my tuning on the nozzle size of 0.5mm. In order to be sure I confirmed with John at SeeMeCNC that mine was indeed shipped with a 0.5mm nozzle.
Well it turns out my 0.5mm nozzle was not actually a 0.5mm nozzle. It was most likely a 0.7mm or larger. I figured out the nozzle wasn’t 0.5mm by extruding slowly into open air and waiting for it too cool then measuring the diameter. I was between 0.9 and 1mm in diameter. Normally a 0.5mm nozzle would measure about 0.6mm or so.
0.7mm nozzle on the left and 0.??? on the right
The mush was caused because I was using 0.5mm nozzle settings for extrusion and infill width in KISS. If you try and print infill with a width less than the nozzle diameter it won’t work. It makes sense why if you think about it. How can you possibly extrude infill at a diameter less than the nozzle diameter keeping in mind that infill typically bridges itself in open air. Mine would just fall apart as the flow calculation was wrong.
Once I dialed in the correct extrusion width into KISS the results were amazing. Infill was perfectly connected and layered. No more mushy mess!
I’d really like to be printing with a 0.5mm nozzle but I’ll have to wait until SeeMeCNC sends a replacement. For now I put on the 0.35mm nozzle. In this video you can see me printing the golvend tornado. I sliced it with KISS slicer at 0.25mm layer height. Printing at 20mm/s with feedrate at 150% and temp set to 230.
More pics using PLA