The best tips and tricks for the best outcomes with DOBOT MOOZ
DOBOT MOOZ – a 3 in 1 3D printer, laser engraver, and CNC carver. Originally crowdfunded on Kickstarter, it is now being used by hundreds of makers. Even though it is shipped with a detailed manual (https://download.dobot.cc/product-manual/dobot-mooz/pdf/en/MOOZ-User-Manual.pdf), there are lots of tips and tricks gained by experience. In this paper, the most important ones are described – in order to prevent damages on the machine and improve the print results.
As I, the author, am a backer myself, I know how it is when assembling the Mooz: Quick, I finally want to see a print! Oh, a footnote? Don’t need that, if it was important, it wouldn’t be a footnote. Unfortunately, that’s absolutely wrong. There are some very important instructions which have to be followed in order to prevent damages.
In the manual, there are two different sections for Mooz-1 and Mooz-2 (1.1 and 1.2). The major difference is the X-axis (1.1.5/1.2.5): Considered from the back, its cable has to be on the right side for Mooz-1 and on the left side for Mooz-2. Not following this instruction can lead to major problems: For some positions of the print head, the cable might not be long enough – leading to an unpleasant incident.
Another tiny but important annotation can be seen on the right-hand side: Despite the other screws, the one in the middle of the linear actuator has to be an M3x6 instead of M3x8. If you use an M3x8, your linear actuator will be frozen, and trying to move certainly won’t be pleasant for the motor.
Installing the heated bed does not sound like a problem at first. Though, there is a little detail which has to be considered. Did you notice the little hex key in the picture? I didn't. I didn't notice that the 4 holes in the base plate were for mounting the heated bed either – and I had to learn it painfully. If you don't use these holes, you have to mount the screws with the short side of the hex key – leading to a much higher leverage effect. Since the heated bed is made of Phenolic, a rather soft material, this can cause the screws to get over-tightened. In the following, the screw threads will be worn, so you won't be able to fix your heated bed well anymore. Hence, mount the heated bed like it is shown in the image, and you won't have any problems.
I will come to a more detailed instruction of setting the zero point later. By now, I just want to draw your attention to the fact that setting the zero point comes before installing the filament in the manual. The reason for this is that the nozzle must not be hot when setting the zero point! It might be self-explaining, but one (including me) sometimes forgets that the nozzle is still hot when re-setting the zero point – after a failed print, for example.
There are two main procedures to calibrate the Mooz: 3-Point-Levelling and setting the zero point. Both are extremely important for precise printing results.
It is very rare that the heated bed is totally even, hence this procedure helps to compensate for that. It is a software-only technique – that means that your bed won't get even, but Mooz will know the slope of your bed and adjust all movements according to it automatically.
3-Point-leveling is only required after (re-)mounting the heated bed. How to do so is described in section 3.2 of the manual. I have 2 tips for you though:
In this procedure, it is very important that the distance between the nozzle and the bed is equal at all 3 points. The manual recommends moving an A4 paper beneath the nozzle to feel how close the nozzle is to the bed. Though, it is hard to reproduce the same movability of an A4 paper thrice. Hence, I use a bill made out of thermal paper you get in every supermarket for it. This has the advantage that it is very thin and thereby very sensitive. As soon as you can't move the bill under the nozzle anymore, you are done.
You have probably recognized that there are 3 buttons in the " motion control" -a section on the touchpad: moving 0.1mm, 1mm and 10mm. Though, it is possible to move your axis’ in 0.02mm steps. This is enabled by the automatic heated bed protection: When the nozzle is already close to the bed, and move the Z-axis down with the 10-button selected, it will not move 10 millimeters, but 1 millimeter if the nozzle is more than 2 centimeters away from the heated bed and 0.06 millimeters if it is less.
This enables a cool trick: Moving 0,1mm up, then switching to the 10button and moving 0.06mm down twice sums up to -0,02mm (0,10−2∗ 0,06=−0,02). Using this technique, you are able to set the points extremely precisely.
Setting the zero point is probably the most important procedure before printing. I actually don't know why the instructions for setting the zero point in the manual to appear before the instructions for 3-Point-Levelling, but you have to set the zero point after 3-Point-Levelling. 3-Point-Levelling only detects the slope of your heated bed, but setting the zero point defines where the nozzle should move to at the beginning of every print. If it is too high, your print won't stick to the bed. If it is too low, the filament can’t be extruded from the nozzle. Hence, you have to find the perfect height. As described in 3.1.1, I use a bill for that. Move the head down until the first step at which you can't push the bill under the nozzle away from it anymore. Then, you can consider the nozzle's height to be equal with the heated bed. Now, move it up as much as it turns out to work for your layer height settings. For me, it is between 0.1 and 0.2mm. As seen in 3.1.2, you are able to set the position very precisely. In Cura1, the default initial layer height is 0.3mm. Hence, if your zero height is lower than that, the filament will be pushed to the heated bed and thereby stick to it.
There is a handful of settings which can help you to improve your print results. I personally use Cura2 to slice my models. Hence, I will show you how to configure the values there. I am sure these settings are available in other slicing programs as well, but you will have to find them yourself.
The initial layer is always the most important one. If it does not stick well, the whole print will fail. In addition to a perfect zero point, the Initial Layer Speed significantly influences the stickiness of your print. I usually set mine to a very low value like 15mm/s. Your print will maybe need a minute longer, but it is definitely worth doing. To do so, move your cursor on the "Speed" bar in the settings on the right-hand side in Cura as seen in (1).
A Settings-Symbol will appear. Click on it in order to open the "Settings Visibility" -menu. Type "initial layer speed" in the search bar, and check the field "Initial Layer Speed" as seen in (2).
Close the menu and you will see a new setting as in (3). Change it to a low value, e.g. 15mm/s.
As soon as you customized the Initial Layer Speed, you can easily increase the speed of the rest of your print without much quality loss. Especially when printing models without many details, this is extremely worth doing. Also for small or detailed models, it often is not harmful to be printed at high speed. Though, you have to find a setting which fits your needs yourself. I personally mostly print at 60mm/s at least. It is not recommended to print at more than 80mm/s.
Especially higher speeds can harm the linear actuators. Though what is harmful is not the fast speed, but the fast acceleration. Hence, you can configure "Print Jerk" and "Travel Jerk" – the maximum instant velocity change or the derivative of the maximum acceleration per second. To do so, make the setting "Enable Jerk Control" visible as seen in 4.1 and tick the newly appeared setting. Then, you can configure two values. 20mm/s and 30mm/s turned out to be good for me, but you may optimize them. If you hear the linear actuators rattling, you definitely have to lower the Print/Travel Jerk.
Sometimes it happens that, even though your zero points set perfectly, the print does not start at the wanted height. This might be because the printing head moved down too quickly – together with the weight of the X-linear-actuator, this can cause the stepper motors to lose a step – leading to an inaccurate Z-height. Fortunately, this can be prevented easily by configuring the "Maximum Z Speed" setting in Cura. Make it visible as seen in 4.1 and set it to a low value. I use 15mm/s to make sure it is not too fast.
This might be overkill, but it nearly does not affect the print time since the Z-axis only significantly moves at the beginning – during the print it is always less than a millimeter. In combination with a high print speed, configuring this setting can also improve the Z-movements' accuracy in general.
Even though the default setting of the Infill Density is 20% in Cura, if your print won’t be burdened, it is most absolutely fine to set it to 5%. It will make your print lighter and decrease your material cost and print time significantly. The setting should be visible by default. If not, make it visible as seen in 4.1.
The default filament spool holder works perfectly – though, not for all types of filament rolls. Especially for bigger roles, e.g. most 1kg rolls, you probably won’t be able to use the included filament holder. Hence, I created my own one. You can download it on Thingiverse: https://www.thingiverse.com/thing:2733708.I recommend printing it as it is, without rotating the model, since the direction of the layers significantly improves stability.
When using the default filament holder or the one introduced in section 5.1, the filament is not being unwound from the spool straightly, but laterally. Hence, it often happens that it jumps off the spool and gets tangled. To prevent that, I align it as seen on the image.
If you have any other questions or extensions to our list of tips and tricks, feel free to join our Facebook group: https://www.facebook.com/groups/242934739571669/