Well, I finally have success printing slightly modified version of the extruder - I added the "output shaft" for the ball bearing and it works OK. I glued the magnet holder using superglue and left a hole in the middle for the screw that holds the bearing in place. The grip is finally sufficient - I am unable to stop the filament when the motor is powered by 12V. Now I have to glue the magnet inby rklauco - General
I'd also bet on the hall sensors - if you have 3 of them, you can calculate at minimum 6 positions. With gearbox 1:100 you actually have 600 positions per revolution - 0.6 degrees. Sounds reasonable. My only problem is that the hall sensors would have to be read by something like analogRead, which can only work on 15kHz as far as I remember from Arduino. Combine it with 3 inputs, you are at 5kHzby rklauco - General
I disassembled the micro I have from China - labeled as N20-12V-100rpm. It has carbon brushes. Unfortunately, due to my crappy printer, my 3 last prints of the extruder did not have sufficient grip (the ball bearing distance was slightly big and the grip was insufficient. I am printing one right now. As soon as it is printed, I'll do a simple experiment. I'll mount the extruder on top of my wardrby rklauco - General
The pololu one is exactly the one we are testing, however I am not sure it's the same one as the one with the burned brushes. There is a great video on YouTube from HomoFaciens on how to identify the quadrature encoder pins - I can't provide a link as youtube is not working from my office. I've read somewhere about the Faulhaber motor (although it's difficult to say if it was the same type) and tby rklauco - General
QuotenebbianIt's a Faulhaber motor with gearbox and encoder, and it has about the right amount of torque. It's also about the right size. Should do the job. I don't have access to ebay Can you, please, share some schematics/wiring of the motor? It looks interesting although it's way heavier then the original target of 30 gramsby rklauco - General
Current resolution (due to low-res strip) is 23 steps per mm. And yes, you can check the code yourself - I'm only using step and direction as inputs. I was thinking about using enable signal to home the axis, but I had slight problem with that for now...by rklauco - General
This is an excellent point! However, my original motivation was a bit different - I am looking for something much quieter then my NEMA17 printer - that is seriously loud. My wife cannot sleep in the next room when I print something. And, I can already tell you, that the DC motors, although still having some issues, are WAY quieter than this. The other motivation was price - but, as I found out,by rklauco - General
QuoteVDX ... for a cheap lightweight encoder you can source/salvage an old PC-mice - it has two optical wheels and the sensors ... there are several projects showing, how to connect to an Arduino ... This is MUCH harder then it sounds - I am not able to get my hands on so old mouse. And I was working with computers for more than 2 decades, for last 10+ years I haven't got in sight of mouse withouby rklauco - General
While looking at the ESC I noticed it has a "regular" Atmel ATmega48 onboard - so potentially we can directly program all the servo code into it and connect the optical encoder to it directly without significant issues (we'd need to grab 3 additional IO ports out of it). Also, providing holding torque should not be that difficult as you can simply power one coil using PWM and hold it in place. Thby rklauco - General
Quoteo_lampeI could advertise some motors from my employer, but I'm sure everyone knows the best german RC-motor manufacturer Last I checked this was not the forum of RC enthusiasts, but I may be wrong... Quoteo_lampeWe also don't have an internet shop, there are too many different features available. Sounds like the exact opposite - the best opportunity to have web shop. But yeah - ho wants toby rklauco - General
Quoteo_lampeYes, but also the higher pole count and the special SPS winding work like a 7:1 gearbox. Can you share a link to some shop or product?by rklauco - General
QuoteipcalitAnother idea is to use a flanged bearing and just glue a plastic adapter for the magnet to the flange. Then the filament runs on the plain bearing and you have no issues with the ABS sleeve being compressed by the filament. It might work even without a flange with the proper glue as the magnet. I'm trying to do a real-life design here and I have a problem - how to ensure the bearing wby rklauco - General
I love the glue approach! This might be the final trick. For now I am focusing on optical encoders as my experience with AS5600 is not 100% smooth I'll give it another try after tomorrow's test of my approach - can't run the printer in the night as I am not looking for divorceby rklauco - General
And keep in mind, that even now the code for the controller has a protection code implemented - should the bearing receive no movement (e.g. filament out or jammed), I'll know about it right then. However, I run out of pins, so I don't know how to get the information back to the RAMPS board. But I have already an idea that may be directly supported by Repetier firmware...by rklauco - General
QuoteipcalitIs this what you a have in mind? oO| - where "o" is the Mk8, O is the bearing, and | is the shaft for the encoder? I'm wondering whether having the encoder so far from the motor creates troubles for the PID loop. If I recall correctly most recommendations are to get the encoder as close as possible to the motor (generally on the motor itself), but here we are not dealing with high speby rklauco - General
To continue the original thread - I decided to go in a bit different direction. I'll make a tiny (2-3 mm) shaft with heatshrink that will be measuring the bearing movement by simply touching it. As there is virtualy no load, the added friction will be minimal. Yesterday I tested the MK8 and it is much smaller and has way better grip as the groove is bigger then MK7. So MK8 is a clear winner for mby rklauco - General
Wow, that looks FUNNY! Have you tested it already?by rklauco - General
QuoteipcalitFor now, it is just an experiment and if it turns out that it fails, we could always try brass or aluminum. Heh, you are 100% right - I almost forgot I have rapid prototyping machine on my hands I'll work on it tomorrow afternoon and try to come up with a sample - we'll see...by rklauco - General
So, if I understand it correctly, the actual push on the filament is done using the sleeve, not the bearing, right? Not that I have anything against it, I am just wondering if the fit will be stable over time - at least ABS would wore out quite fast due to the friction of resisting filament (my opinion only).by rklauco - General
I have a problem with the "just attach the encoder disk or magnet to the idler bearing" part of the sentence. As the idler bearing has to push the filament, I can't imagine something reliably be attached while not obstructing: the idler itself shaft for the bearing I thought about some mechanism to do it reliably, but I was not able to come up with something - limits of my imagination, I thinkby rklauco - General
OK. I am too slow for this I understand the driving frequency - and based on my ATtiny85 timer set-up, I should operate somewhere within 32kHz. The only other electronics I am using is 2 caps - 470uF and 100nF. Wiring: Pin1 - GND Pin2 - input1 Pin3 - input2 Pin4 - VCC (5V) Pin5 - VBB (12V) Pin6 - output to motor 1 Pin7 - GND Pin8 - output to motor 2 I am not using anything special here - one ofby rklauco - General
My problem with any of the gears like MK7/8 etc. is the diameter. To explain - for reasonable price I am able to get encoder with ~50-100 steps. By using the quadrupling code, I am able to get resolution of 400 impulses per revolution. Now, if I select my preferred width of 3mm shaft and add ~1mm of heat-shrink-like sleeve, I'll end up with 4mm diameter. That means 1 revolution will move 4*3.1415by rklauco - General
So, for those interested, I made a small video demo. I am missing an extruder for now (working on it), but the rest works 100% with precision beyond my expectation. A this is what I love about closed loop.by rklauco - General
6MHz? I thought you are using 74595 for that - if you make a simple resistor-based voltage shift, you can use clock with 595 at cca. 31MHz. But still, 185kHz is plenty even for PWM signal!!! I have to try this at home - I have few ESPs lying around. Just not sure if a breadboard can handle 6MHz signalby rklauco - Developers
Wow, this looks amazing. One stupid question - what's the possible frequency you can achieve with this DMA approach when just setting one pin on and off using the 595?by rklauco - Developers
QuotemisanYour steel rod for filament motion sensing may have some teeth too, as we know this increases the grip, though in this case filament will be forcing rod rotation and not the other way around. I wanted to ensure the grip by shrink wrapping the rod using regular shrink tube for electrical isolation I don't like teeth on the rod, but if the shrink wrap will not work, I'll try this approacby rklauco - General
Is there any progress here? For me this is still very interesting...by rklauco - Developers
QuoteLoboCNCHow much current are you running through the motor? The total on resistance of the A4953 is about 1 ohm, so I'd guess that with no connection to the thermal pad, it'll get pretty hot even if you are drawing less than 1amp. Thanks for the hint. Normally the motor takes less then 150mA, but with problems during movement (e.g. start or hitting a minimum/maximum position) it can take almby rklauco - General
I am thinking about some different approach. The idea of measuring the actual movement of the filament stuck in my head. What I am thinking of is a solution like this: do not measure the motor movement instead measure the movement of the filament introduce a "spring-like" mechanism to push the filament string against a steel rod the rod would be covered with heat-shrinking sleeve where the filamby rklauco - General
So. I received on Friday the geared motors with extended shaft and encoders. First of them has some strange encoder - it does work, but the output seems to be very strange - floats somewhere at 2.5V and spikes to 5V and 0V like when there is a capacitor in the way. Therefore it is not working with my Arduino code as the spikes are too short and are not detected by the chip. I'd have to add additiby rklauco - General