22 septembre 2017

Extruder tuning

After many test and trials, and with the help of Bondtech, I finally found the problem that was causing me some headaches....

Problem was this:

Then after I fixed it, the result was this:

Muuuuch better :)

The reason: My printer is using rails HIWIN. They are very good , but they bring more friction than wheels or long bearings.  So initially I got shift problems due to stepper missing steps. So I increased the power on all my stepper driver, from ~0.7v to 1.2v, including the Extruder driver... That was my   mistake....
The problem you see above come from a too high voltage of  the extruder (Nema 17/25mm) causing the bands with holes. The stepper was given for 700mA, and with 1.2v voltage on the stepper, current is over the limit.

Tha's set. For the pikachu Orange, now the voltage is set at 0.9v and result is far much better.

18 septembre 2017

Cutting Aluminum

Last weekend, I tried to cut an aluminum sheet 2mm thickness. This was my first test with CNC to cut aluminum, as I used to cut carbon sheet and fiberglass mainly .

Result is good so far, next trial will be with a 4mm sheet. It needs to add some oil spraying during the milling.

My settings:
- drillMill: 1 tooth, M2x8
- cutting speed of the Kress: between 5 and 6 (RPM?)
- cut advance: 200mm/sec
- layer: 0.2mm

10 septembre 2017

Tests to improve print quality

This week I made several progresses which improve the print quality, especially regarding retract and ghosting.
First, I installed and test the BondTech BMG extruder. It is a must, compact, very efficient , light, it has only adavantages. With it, and the mirror on bed, I could make my best first layer.  I did first calibrate the width of the line. Once done, this line is very clean. Retract has been set at 3mm. There is still somme stringing (oozing), but it is reasonable.

Then, I tried  to  remove the ghosting effect (aka ripple or vibration). I split it in two: first part appears when the print head accelerate, second part is all over the wall, I 'll call it woobles.


To reduce the wooble  I added   TL-smoother (2) between the TMC2100 driver and the stepper (on X and Y) . Picture show a comparison before (left) and after(right).
We can see that the right one has less woobles. So the TL-smoother seems to have some effect on the TMC2100, however the TMC2100 becomes much more noisy...

Second, to reduce the ghosting, people on forum always says: "reduce acceleration, reduce speed".  So, that what I finally  did because I could 'nt find any vibration problems on my printer mechanic.   But, this time, instead of changing in the Marlin firmware for all movement, I changed it in Slic3R. The last version (2.7.0)  allows to set an acceleration for each movement type. So I set the acceleration for perimeters to 100 (instead of 500). And the result is better, left=before, right=after