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Woah! Very clever!
Do you designed it in FreeCAD? If so, can you share the .fcstd file too? I would love to incorporate your design for future versions of Thor!Thanks for sharing 🙂
Hi Mohamed!
Sorry, I have been busy these weeks and I just read your question.
I think that the problem could be related with the homing process. As you don’t have sensors to home the motors, GRBL doesn’t have a reference to start the motion. I think you can do a manual homing by placing the robot in the fully stretched upward position and sending the “Kill alarm lock” command ($X).
Here you have the documentation of GRBL commands in case you need it: https://github.com/gnea/grbl/blob/master/doc/markdown/commands.md
Hi Mendy!
The 0.4A is the current drawn by each phase of the stepper. As we are using bipolar (2 poles) stepper motors, there are 2 phases. So the total current drawn by the stepper should be around 0.8A at 12V.
Let me know if it helps!
Hi Mendy! Thanks for noticing it!
The 3D viewer on angellm.github.io/ThorAssembly was an early version of Thor v2 and I think is now deprecated, but I’ll check it anyway!
I’ll review every point you mentioned.
Thanks for the help 🙂
Yes, that’s it!
I wanted the Shield to be easy to plug, but I screwed it up with the design of the PCB, assigning the pin 41 for the tool servo before realizing that the port 41 is not PWM… So, as a hotfix, a jumper wire should be connected to a free PWM pin and I used the number 7.
Woah, Thor manipulating a 3D scanner looks impressive!
I’m glad you got articulation 2 to work well. Sometimes printing tolerances are a bit tricky 🙂
Hi AliSintax!
Welcome to the Thor community! Do not hesitate to share your progress and ask your questions! 🙂
Hi Claudio!
What a great investigation you have done!
From what you say, everything points to the fuse.ITrip current is the minimum current required to interrupt current flow through the circuit at +23 °C. At this current level, the PTC resettable fuse is heated sufficiently to switch into a high-resistance state.
IHold current is the maximum current the PTC fuse can sustain for long periods of time (4 hours or longer) at +23 °C without tripping.Your fuse is setting the motors power circuit to 5A maximum instead of 7A. If you used the Stepper Online motors, each one draws slightly less than 1Amp. As the robot has 7 motors, the circuit that powers the motors need about 7Amps. These are all approximations, depending on the model of motor you have used there may be slight variations in the total amperage needed.
If you don’t find a PTC resettable fuse of 7A you can use a normal fuse of 7A. It would be harder to change if it breaks, but will do the job.
Hope it helps!
Hi AliSintax,
Thanks for noticing it! It seems like StepperOnline has stopped selling that model in Aliexpress at this time, but they are still selling it in their website.
What problem do you have with the StepperOnline link? I just tried (I’m also from Spain) and it allowed me to order it to Spain (at least to add it to the cart and proceed with the checkout).
I may be wrong, but maybe are you confusing the warehouse country (China/US/Germany/UK) with the delivery address? hahahaBest regards!
Hi Claudio, let’s see if we can solve the problem together!
First of all, you say that your PCB version is the v1.0, do you mean the two-sided PCB or the one-side PCB? It’s my fault for naming them both the same, sorry for the confusion!
Looking at your case, I think that the problem could be one of the following four:
- Broken Stepper Motor: Not very likely but sometimes happen. If you already have tested that motor switching it with another one and worked, you can discard this possibility.
- PCB traces fault: Highly Unlikely in the two-sided PCB, but likely in the one-sided one. Maybe the power traces that send the signals to the 5th motor are short-circuited or cut. You can test it with a multimeter in continuity mode.
- Bad component welding. Likely. If any component has not been properly welded to the PCB it may cause issues. In your case, you should check only the weldings related to the 5th motor (pins, resistor, capacitor).
- Misconfigured/Faulty Stepper driver. Very likely, the problem is almost certainly to be found here. Switch the stepper driver of the 5th motor with another one of the PCB which you know that works. If that is the problem, the driver could be broken or misconfigured. Drivers usually have a potentiometer build in the top which regulates the amount of current supplied to the motor. If it’s set too low, the motor will not receive enough energy to move (but it won’t cause other motors to stop, so I guess is not your case).
Regarding the motors overheating, it’s related to point 4. When the robot is Idle, it has to hold the motors position, blocking them. If it didn’t, it would fall under its own weight. This lockout causes the motor to consume energy, warming up in the process. There are two things that you can do to try to avoid them to overheat: Cooling (that’s why I placed fans in the design) and tuning the stepper drivers to provide enough current to move the motors but not more.
Keep us posted on your progress! 🙂
Hi Tolga!
I just registered your Thor in the Worldwide Section
It’s the number #24 and the first one of Turkey! 🙂Welcome to the Thor family!
The arm rest piece is a clever solution! How the robot not slide when it powers off? Rubber/foam material?
It would be awesome if you can share with us a video of an scan using Thor! Sounds cool!
I’m happy to know that the 4th articulation is now homing perfectly, I’ll be watching your videos to see what applications you find for the robot!
How could I not like your workshop?! It’s like a dream come true for any maker! hahaha
My 5th articulation also has a homing issue. It always homes to a different (sometimes 20-30 degrees off) angle. I believe it might be because of the wiggling that causes the optic endstop disk to give false positives, would this be a correct guess? I’m trying to hotfix this to finish the video, for now I just manually move it after homing.
Do you mean the 4th Articulation? I had some issues with optic endstops until I painted the optic disks using black nail polish. These pieces were so thin that even though I printed them with black filament, at some points the light beam of the sensor managed to pass through the piece, causing some bad hommings. I think this issue is documented somewhere… Could be your case maybe?
About the 5th and 6th articulation, I started imagining about a system where we could simply switch to a single stepper for the 5th (using a 10 to 20 pulley maybe?) and smack a servo to the middle of the Art56MotorCoverRing for 6th. This way 5th would be more stable and still can home, and you wouldn’t need to home the 6th since it’s now a servo. It would also decrease weight from the tip of the arm. It would only require changing a few of the parts in that module, so I might try this design at some point. If it works I’ll just fork the github and add all of the mods with the name Fat Thor.
Sounds like a good solution! I hope to see that design done someday! 🙂
