14 août 2017

Vibration, ripple, shadow, ghosting

I have own several printers and the ripple effect always  appears on most of my print.
How to get rid of it ?

The ripple or vibration or shadow effect looks like this:

Look on the surface where it is bright, do you see all this little waves ? They are vertically aligned. The surface should be perfectly flat and clean.
This test has been printed with my last printer, home made, see TevoTarantula in an earlier post.

Thanks to "megablue" who did post this very demonstrative test. You can find it here on thingiverse.

To remove this effect, I tried several things: switch from delta (the worse for ripple effect) to Prusa, change rods on OboXL3D (big ultimaker like), switch from bowden extruder to direct, switch from Direct to the E3D Titan Aero...

Here is the list, mechanical, electronic and settings:
- belt tension
- axis movement softness
- remove any play
- replace motor (Nema 17 1.8° and 0.9° per turn)
- stepper driver (A4988, DRV8825, TMC2100)
- various electronic boards (Mks base 1.3, MKS base 1.5, MKS SBASE, Arduino + Ramps, etc...)
- frame: delta(Kossel XL), ulimatker like, Tarantula Tevo (prusa), Minifab, Anet 3d(prusa), TevoTitan(prusa)
- bowden to Direct extruder
- Direct extruder to Titan Aero
- decrease X, Y acceleration
- decrease X, Y jerk
- Increase E jerk
- increase E acceleration
- reduce X,Y max speed

09 août 2017

Testing a very low cost powerfull chinese servo MG996R...

Well, I am dispointed by this very low cost chinese servo MG996 , which is supposed to provide a 9kgcm torque...
It is less powerfull than a Hitec 5485HB   with 6.5kgcm....

In fact, both servos do not comply specifications announced, even the hitec one. Be warned.
But the Hitec is still better, with less power consumption.

See the videos of the various tests:

MG996 + 2kgcm
MG996 + 4kgcm
HS5485HB + 2kgcm
HS5485HB + 4kgcm
HS5485HB + 6kgcm

06 août 2017

GT2 pulley

After some search I found this way to make a pulley of various size , for a GT2 belt with a 2mm  pitch.

First, you need to know the number of tooth, and the pitch of one tooth (2mm ). Then compute the diameter of a circle which will contain a polygon. The side of the polygon is the pitch, and the number of side of th epolygon is the number of tooth. This site is great  to help that computation:
otherwise this formula:
Inradius r
  • r = (1/2)a cot(π/n) = R cos(π/n)
where r  is the distance between the center of wheel, and the nearest point of the side, and n the numer of sides of the polygon:

Once r value is found, then the wheel can be created under CAO software with this method:

1) make a solid wheel a little bigger than r, thinckness 8mm is fine for GT6
2) extrude draw on the surface , one tooth  like this:

The distance between both extrmimites of the tooth should 2mm. The diameter should be .78.
The center of the circle should be at r distance from the center of the pulley. 
3) do a circular repetition of the function , based on the center of the wheel

31 juillet 2017

TaranTitan: second version

I call it TaranTitan as it is started from ideas of the Tarantula printer and use the E3D Titan extruder.
The TitanAero is a direct extruder (no bowden) small and pretty light. It should bring only benefit to the quality of the print.  Based on my previous design Tarantula++obo, I made the follwing changes:

  • retrofit from 32 bits electronic to 8 bits (mks-sbase) to Mks-base 
  • retrofit the stepper motors from 0.9°/step to classic 1.8°/step
  • remove the external box and fix all electronic and Raspberry to the frame. This save a lot of space on my bench
  • replace the dual head extruder by a Titan Aero from E3D
  • improve the part which fix the Y axis to the frame
  • replace the  TFT32 by a graphic LCD display. It allows to see print progress even if print was launched from the raspberry.... the TFT32 does not
  • add some LEDS on both sides of the frame
  • simplify the Y-motor fix
  • replace power supply by a good meanswell 350w, much more silent that the Amazon power supply at 19$...
  • AND Finally, the most important change, use the new driver TMC2100 which are much more smooth and silent than previous driver used on the mks-sbase (drv8825)

The result is this 3D printer, which now provide very good quality prints  :)

27 juin 2017

Mouse/trackball click on a keyboard

Since several year, I started to feel some pain in my left arm and left shoulder, that's the side of my mouse. So I decided to do something , first I moved the mouse of the right side (I am left handy) , using the right arm instead of the left. But still , it was not enough, so I switched to a trackball. Trackball is much better as it avoid to move the whole arm, so only finger can operate. But the click buttons (left and right) are even more difficult to manipulate without moving the ball.

So, I installed a small application on my PC (neatmouse) , to simulate mouse click using some keyboard keys. First, i configured F1/F2/F3 as left/middle/right button. So far it worked ok.
But for some application it does not work correctly, for instance when using Virtualbox and linux guest. Linux can't be configured good enough so that it behave same as PC when hitting those remapped keyboard keys.

Then I decided to build a mini keyboard to replace those F1/F2/F3 + configuration to make a solution fully portable on any PC.
This is my first prototype of  a mini-keyboard for mouse click. Left/right button behave exactly as left/right mouse or trackball click.  This is much better, now I can use this mini keyboard as a full replacement of my mouse/trackball click button.

The mini keyboard is connected directly inside the trackball, on the left and right switches. It  easy to install but requires some basic soldering. There is no need for any software or configuration in windows/linux, or any change on the PC itself.

A more designed version, with nices buttons  is planned soon  :)

14 avril 2017

Anet A8

Sompe pictures of the Anet A8, very good ratio quaility/prices, I paid it only 162€ transport included...


30 mars 2017

After winter Tarantula cleanup

ok, after one year of use and  improvement, I decided to go for a big cleanup of my Tarantula. So here the result: new corner junction, new dual Z motors , new Z screw for setting, lcd on top...