Show all posts by user

Re: Convert SCAD to Solidworks? - 9 years ago

Current version of FreeCAD (v0.15) will import SCAD files happily. If you have no $fn references, cylinders and circles will be treated like that and you will get facet-free cylinders/circles on FreeCAD. You can later export to STEP format to spread the joy to Solid Works or other CAD software.

Re: Patent Infringement on new CLIP technology - 9 years ago

With that wording it seems designing a new version is not forbidden nor protected, only the making is. Whether you build your design or not, tell no one and you might be safe. On the other hand, making your design public seems, again, not being restricted by the law.

Re: Did anyone used linear hall sensors on BLDCs for position sensing? - 9 years ago

Hi LarsK, QuoteLarsK Misan, I do not understand why missed steps is a concern. I don't say this out of arrogance but I am fairly late to the 3d printing world - SO what I would say is that, if your 3d printer is missing steps, it is because it is not designed properly or is in need of maintenance. The only time I see my printers (Delta and a CoreXY) missing steps is when something is terribly of

Re: Did anyone used linear hall sensors on BLDCs for position sensing? - 9 years ago

The advantage of using a closed-loop system is to compensate for potential errors, that means no more missed steps. Cost reduction is not a goal, but we are trying to get this working within a similar cost range as steppers. This solution space has been explored, tested and discarded in the past for RepRap mostly because of its high cost. That is why I am so conscious about its potential cost.

Re: Did anyone used linear hall sensors on BLDCs for position sensing? - 9 years ago

Good catch AndrewBCN, These chips cost around $4 each and they can provide an alternative to optical encoders. It is a cool technology slightly more expensive than optical but dust proof.

Re: Did anyone used linear hall sensors on BLDCs for position sensing? - 9 years ago

Hi AndrewBCN, Thank you for your kind words. I have tested three motors I think could be used. The cheapest one was $5 but it was a MABUCHI 370 brushed motor with 448 CPR incremental encoder. And included a 14-tooth MXL pulley. It seemed to be a bit short of torque at 12V but considering I was using an L298 for the drive electronics I guess that could be improved with more efficient drive. W

Re: Did anyone used linear hall sensors on BLDCs for position sensing? - 9 years ago

HI AndrewBCN, Good points, let me elaborate on them. QuoteAndrewBCN 1. The price of adding the many required linear hall effect sensors to any brushless DC motor assembly is not negligible. First, quite a few sensors are required, second, they must be precisely positioned, and third, each additional sensor requires wires which have to connect to the closed loop control circuit. And of course, e

Did anyone used linear hall sensors on BLDCs for position sensing? - 9 years ago

I am searching for a suitable solution for using DC motors (actually BLDC) to create closed-loop position controls that could replace/improve over the steppers we use in most of our 3D printers. While I do have several motors running successfully with my code: one key part of this quest is to get the price right. Not many are going to buy a $100 motor just to keep their printers from skipping a

Re: New free parametric cad - 9 years ago

oops, I just posted a similar thing starting a new thread :-(

OnShape rocks! - 9 years ago

I have been testing this web-based platform for a while, think of a merge between Solid Works and TinkerCAD. Free with certain limitations. Simple export to STL. It can import/export to/from several popular CAD formats. Still in beta, they say, but I guess that's more PR than lack of stability or availability. Invites seem to be granted effortlessly. oops, almost forgot: They have a nice

Re: RepRap using DC Motors! - 9 years ago

I have tested the motors from what I gather is Ricoh's Smart Position Motor System: that can be found on eBay and Aliexpress (google for 20w brushless encoder). But I have not yet being able to obtain a datasheet (help me out here if you can). These are brushless motors with built-in power driver and encoder that can be controlled from three digital outputs (PWM/direction/brake). Quadrature enc

Re: RepRap iTopie - A Prusa i3 evolution - Development discussion - 9 years ago

Thanks Skarab. It looks very nice and sturdy. It is great to use the space in the bottom for power supply and electronics (smoothieboard looks great).

Re: RepRap iTopie - A Prusa i3 evolution - Development discussion - 9 years ago

Hi Skarab, Can you give us a ballpark of the machining time with a large ShapeOko? What milling bit do you recommend? Thanks.

Re: Servo motors on Prusa i3 - 9 years ago

I am in the process of migrating to a powerful 32-bit platform that will integrate motion planning and control loops. Most likely, control loops will take into account position and speed control, with acceleration feedforward to take into account the physics of moving mass. I have found quite a lot of interesting information here:

Re: Servo motors on Prusa i3 - 9 years ago

I have just tested it and I realized I was provided wrong information. The seller claimed the encoder had 888 lines but it turns out this is wrong. I guess it is something around 450. Anyway, the question about accuracy is problematic: at the end of a movement, I get zero error, meaning it is right on the spot. During motion, I have posted a live capture from an analyzer that may help answer th

Re: Servo motors on Prusa i3 - 9 years ago

I started my tests having just 2x encoder resolution and that turned out to be 31.189 steps/mm. It does not sound like much, but I reckon these values are actually accurate, while microsteps do no always correspond to real positions (there is a bit of lag between real and commanded position at the microstep level) . I am moving to 4x encoder resolution which should hopefully double that.

Servo motors on Prusa i3 - 9 years ago

I have done a proof of concept modifying some of the available code and writing some new one so each servo motor mimics the motion of a stepper and reacts to the step and direction signals of Marlin firmware. For the moment only X and Y axis are changed: Additional software Parts for i3: and Please note my approach uses a new Arduino Pro Mini per axis for the closed-loop logic (encoder and

Re: Cómo empezar en Sevilla - 9 years ago

Las piezas son una muy pequeña parte del coste total. Las puedes conseguir en eBay por unos 30€. Aunque si preguntas en la lista de Clone Wars es posible que te alguien te las pueda donar. En cualquier caso lo que buscas es una Prusa i3 (no Mendel).

Re: Servo Driver compatible with RAMPS (STEP/DIR) - 9 years ago

Another take on the same matter

Re: una ayuda con la construcion de la prusa i3 single frame - 9 years ago

Para la primera impresora tendrás mejores probabilidades de éxito si montas algo estándar.

Re: Best mechanical strength among biocomposites for bone tissue scaffolds - 9 years ago

Why don't you consider porous sintered titanium mesh-like structures? These can be implanted and will be populated by patient's bone cells while providing load-support functionality. Not that I can provide an answer to your question but I reckon beyond the material itself, it is the form factor what will make a difference.

Re: Are HA/PLA and HA/PLGA filaments possible to prepare? - 9 years ago

These are usually created by electrospinning but there are some ideas for joining FDM and electrospinning like "Electrospinning and additive manufacturing: converging technologies" Paul D. Dalton,* Cédryck Vaquette, Brooke L. Farrugia, Tim R. Dargaville, Toby D. Brown and Dietmar W. Hutmacher* in Biomaterials Science (free access to that article after free registration)

Re: Recalentamiento de cable USB al conectar impresora - 9 years ago

Tanto la fuente del PC como la Meanwell disponen de filtros que derivan una pequeña corriente a tierra (que no debe de calentar ningún cable en condiciones normales). El problema reside en que normalmente el terminal GND de las fuentes (V-) también va conectado a tierra. En ausencia de tierra este terminal tiene una componente AC además del valor de 0V DC. No te recomiendo trabajar en esas condic

Re: Recalentamiento de cable USB al conectar impresora - 9 years ago

Todo indica que tienes un problema eléctrico. En ningún caso el cable USB se debería calentar. ¿Tienes toma de tierra en tu instalación?

Re: Good, Fast, or Cheap? Pick Two - 9 years ago

I have bought several tens of units from Brian. Not a single problem (as far as you keep the temperature within bounds). It is my hotend of choice for ABS and PLA. And if bought in bulk Brian can beat most clones price-wise too. And Brian always included some spare resistors and thermistors just in case. Once (due to a short deadline) I bought some clones made/sold by reprapworld: not anymore

Re: Impresora 3D usando TB6560 4 ejes? - 9 years ago

Re: Impresora 3D usando TB6560 4 ejes? - 9 years ago

Si no has tenido problema, ignora mi comentario. Si lo pruebas y no se mueve, ya sabes por qué es: los pulsos de "step" que hacen avanzar el motor son demasiado cortos (duran poco tiempo) y el driver no los detecta con lo que no mueve el motor.

Re: Impresora 3D usando TB6560 4 ejes? - 9 years ago

Vas a tener problemas con el firmware porque suelen dar un pulso más corto en la señal de paso de lo que necesitan esos drivers.

Re: software recomendado para mi cnc casera (arduino + easy driver) - 9 years ago

El Mach3 te permite hacer pequeños trabajos en el modo demo sin pagar una licencia (creo que hasta 500 lineas de gcode). Es un programa para Windows. Para Linux tienes el EMC2 que es libre. Lo puedes descargar con una instalación completa en CD desde linuxcnc.org edit: se me olvidaba, puedes emplear grbl en tu arduino e Inkscape con las gcode tools (tambien te puede interesar webgrbl y jscut)

Re: Atfer Hbot, go to CoreXY. - 9 years ago

Damn Pololus!! they die so easily