The actual build size of the UP! mini is 120 x 120mm in the X &Y plane, even you calibrate the platform level with the software. That is same like the specification says. In the Z direction, the printing size is 120mm or even higher, some printer will be larger than the specification said. Raft is bigger than the print, then it sticks to the perfboard tightly. The raft is very necessary, it is used for preventing the warping, especially for large models. See this photo, when the ABS becomes cold, the shrink or say the warping strength is very large. It even bends the perfboard. It makes me have to use some clips in the front of the platform when I print the second big model.
If you printed a ball shape model or the model has a smaller bottom, then it can achieve 120 x 120mm build size in the upper. Please see this big model that I printed.
This model was printed last night in a very cold room. The temperature was about 10 degrees or lower, that makes the model break in some places. I watched it print the raft and the smaller place, the room temperature was about 18 degrees that time. The raft didn’t warp even the mini have a lower platform temperature than the UP! plus. This temperature for the UP! mini build size is enough for preventing warping.
If this model is printed in a high temperature, andl with a loose inner fill structure, the break on the model will be minimized or reduced. If printed a small model, this will lessly happen.
Perfboard lifted in some corner is not due to the platform temperature not high enough, it is largely due to the ABS warping strength is too large. Even the temperature comes to 100 degrees, the corner will still lift.
How does the software calibrate the platform level and not affect the printing quality? It is not mesh up the first few layers and make the raft heavy adhesion. Please see three photos below. They are showing the first few layers of the raft thickness. There are some difference in each corner. The plaform level calibration program has 9 positions for measuring the variation, for the large variation some thicker layers will be printed, and for a smaller variation a few thinner layers will be printer.
Now the software only allows platform level variation within 1mm. We will soon upgrade the software which will allows platform level calibration for within 1.5mm variation. Also we will have software upgrade on support no raft printing.
We are working on improving the tolerances on new UP! minis, will make sure the platform much more level. But we never ever forgot the existing UP users, we are always support them, like offering very cheap UP! plus printer upgrade kit to allow the old printers to have the initialize witch, power on switch, LED light and more features; upgrade the layer thickness for both UP! plus and UP! mini free of charge and so on. For existing UP! mini users who have platform unlevel issue, we come out a mechanical adjustment.
Above pictures will show you the instructions for mechanical adjustment. For the unlevel platform, most are in left and right direction, not forth and back direction or say very small variation in forth and back direction.
In pic 1, you can see there are two screws that be marked in green circle. They are used to fix the platform arm on the structure. By loosing one of the screw and put something beneath it can lift one side of the platform, left side or right side.
Firstly, lift the platform to until the gap between the platform and nozzle is 0.1mm or something like that. Move the platform and nozzle position by clicking FR, NR, FL and NL to find out which side on the platform (left and right side) is larger than 0.1mm. Record the variation between the left side and right side. For example, if the left side of the platform is 0.5mm lower than the right side of the platform, then get something that is 0.5mm thickness ( several pieces of paper or metal sheet). Loose the screw A and put the metal sheet (I used that) under the platform arm, see pic 2. Last step is to fasten the Screw A. Then move the platform and nozzle position, you will find the platform is much level.
If any users are still unsatisfied with the UP! mini platform level, you can contact the vendor for support, replace parts or return the printer.
We think software calibration is easier, and users don’t need to tinker with the printer by hand. Platform level calibration can be saved into the SD card. So even you reset the nozzle height, it doesn’t affect the platform level. We are working on Mac software, sorry for coming out the Mac software late. For Mac users, you can calibrate the platform level using a PC, and the data will be saved in the SD card. Then you can still use the Mac software and not affect your usage.