DC motor replacement for 3D printers May 04, 2016 02:20AM |
Registered: 9 years ago Posts: 181 |
Re: DC motor replacement for 3D printers May 04, 2016 04:44AM |
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Re: DC motor replacement for 3D printers May 04, 2016 11:15AM |
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Re: DC motor replacement for 3D printers May 04, 2016 12:30PM |
Registered: 11 years ago Posts: 564 |
Quote
bobc
I like the idea, but it's hard to find motors from old inkjet printers if you don't have them. Finding a cheap enough motor and encoder with the right specs was always the sticking point for me.
Re: DC motor replacement for 3D printers May 04, 2016 12:42PM |
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Re: DC motor replacement for 3D printers May 04, 2016 01:48PM |
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Re: DC motor replacement for 3D printers May 04, 2016 01:57PM |
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Re: DC motor replacement for 3D printers May 04, 2016 03:45PM |
Registered: 9 years ago Posts: 181 |
My current resolution (calculated and tested) is approximately 0.047mm per reading.Quote
o_lampe
What resolution does the encoder strip provide?
You can really read an absolute position with these or do you have to home the axis before you turn off the printer? ( to start at a known position next time )
Re: DC motor replacement for 3D printers May 04, 2016 03:50PM |
Registered: 9 years ago Posts: 181 |
You are right.Quote
bobc
I like the idea, but it's hard to find motors from old inkjet printers if you don't have them. Finding a cheap enough motor and encoder with the right specs was always the sticking point for me.
Re: DC motor replacement for 3D printers May 04, 2016 04:00PM |
Registered: 9 years ago Posts: 181 |
For now I worked with ATtiny85 from China for less than $2 - that's cheap enough for meQuote
cozmicray
What is your micro-controller?
What code are you using?
That's a bit different - the alignment routine there is to align current position of the ink cartridge with the position of the print gantry holding such cartridge - to ensure the droplets of black colour fall precisely onto the expected spot as the droplets of the colour ones.Quote
cozmicray
One can not say an inkjet printer will never run out of alignment
There are inkjet alignment routines.
I strongly advice to check Miguel's youtube channel - so far he made extruder driven by the cheap RC servo with magnetic encoder inside and here you can see his original arduino based system with encoders on the motors including a demonstration of violent printhead misalignment.Quote
cozmicray
Would like to see a closed loop system running on cheap controller
that can pull around and operate an extruder / hotend
Re: DC motor replacement for 3D printers May 04, 2016 04:27PM |
Registered: 9 years ago Posts: 181 |
Well, if one can get the motor with encoder for, let's say, $4, then add the price of ATtiny85 ($1) and H-bridge (I'm using TB6612FNG capable of driving 2 motors) for $1.4, you have the whole axis done for less then $7.
Re: DC motor replacement for 3D printers May 05, 2016 02:17PM |
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Re: DC motor replacement for 3D printers May 05, 2016 02:35PM |
Registered: 9 years ago Posts: 181 |
Re: DC motor replacement for 3D printers May 05, 2016 03:13PM |
Registered: 11 years ago Posts: 564 |
Quote
bobc
I had a another look on ebay, and I found some interesting cheap motors like this one [www.ebay.co.uk]
Is that the sort of thing we need? I am not quite sure how to read the specs.
I will get a few just to have a play with. I have some applications where this might be really useful.
Re: DC motor replacement for 3D printers May 05, 2016 03:18PM |
Registered: 9 years ago Posts: 181 |
Exactly my experience.Quote
LoboCNC
Reading the specs on motors sold on ebay or aliexpress is really tricky because the people selling them often don't know that they have and fail to give you pertinent details (like encoder resolution, number of channels, etc.)
Re: DC motor replacement for 3D printers May 05, 2016 06:14PM |
Registered: 10 years ago Posts: 483 |
Re: DC motor replacement for 3D printers May 05, 2016 06:25PM |
Registered: 11 years ago Posts: 564 |
Quote
rklauco
Different topic - do you consider it better to have the encoder on the motor?
From my perspective the belt still can slip and cause problems by this, so I guess I would opt for a linear encoder on the X and Y gantry itself - seems safer to me.
Re: DC motor replacement for 3D printers May 05, 2016 06:41PM |
Registered: 9 years ago Posts: 181 |
Re: DC motor replacement for 3D printers May 05, 2016 07:04PM |
Registered: 11 years ago Posts: 564 |
Re: DC motor replacement for 3D printers May 05, 2016 07:08PM |
Registered: 9 years ago Posts: 181 |
I am struggling with the Y axis for now. I printed 4 carriages already, none of them fit to the gantryQuote
LoboCNC
How are you testing the servo performance? Is your printer printing yet? A good overall measure is to print something like a GT2 pulley and then seeing how well a GT2 belt fits. Printing pulley teeth produces the sort of small back & forth motion that really tests how well your servos are working dynamically under a load. Could be that your inertial loads are really light as compared to the stiffness of your loose belt and that you won't actually have any trouble positioning through the slop.
Re: DC motor replacement for 3D printers May 06, 2016 05:37AM |
Registered: 9 years ago Posts: 5,232 |
Re: DC motor replacement for 3D printers May 06, 2016 06:02AM |
Registered: 9 years ago Posts: 181 |
Your numbers are correct, confirmed by this siteQuote
o_lampe
How does "51mNm starting torque" translate in Ncm? Is it 5.1Ncm?
Then the "9.8mNm rated load" is only 0.98Ncm, which IMHO is very low.
What is the weight of this motor? We have seen steppers with 50grams and 7Ncm holding torque....
Re: DC motor replacement for 3D printers May 06, 2016 11:24AM |
Registered: 9 years ago Posts: 5,232 |
Re: DC motor replacement for 3D printers May 06, 2016 11:33AM |
Registered: 9 years ago Posts: 181 |
Re: DC motor replacement for 3D printers May 06, 2016 11:39AM |
Registered: 9 years ago Posts: 181 |
My current solution to this is to limit the jerk movement distance, provide safe acceleration and feedrate speeds.Quote
o_lampe
I agree with your torque theory, but in certain moments you need this huge torque ( immediately ). At turning points of a move ( inertia ) or when you start to move you have to deal with more friction.
Re: DC motor replacement for 3D printers May 06, 2016 11:53AM |
Registered: 11 years ago Posts: 564 |
Quote
o_lampe
I agree with your torque theory, but in certain moments you need this huge torque ( immediately ). At turning points of a move ( inertia ) or when you start to move you have to deal with more friction.
The PID is not very helpful then, because it's not part of the planner in firmware. You will reach the desired position eventually, but not necessarily in sync with the other axis/extruder.
Re: DC motor replacement for 3D printers May 07, 2016 03:39AM |
Registered: 9 years ago Posts: 5,232 |
Re: DC motor replacement for 3D printers May 07, 2016 07:39AM |
Registered: 14 years ago Posts: 7,616 |
Quote
rklauco
motors overheated
Generation 7 Electronics | Teacup Firmware | RepRap DIY |
Re: DC motor replacement for 3D printers May 07, 2016 07:43AM |
Registered: 9 years ago Posts: 181 |
Of course I did that first. But the steppers were simply too weak to move the gantry then. I'd suggest you first look at the steppers used within ToyRep to get the ideaQuote
Traumflug
How about reducing motor current? A printer design isn't at fault if you don't adjust such things properly, nor is the concept of having stepper motors.
Re: DC motor replacement for 3D printers May 07, 2016 10:26AM |
Registered: 11 years ago Posts: 564 |
Quote
o_lampe
I made a mental pro/con list and one of the cons was the limited access to dc motors, sensors and strips.
Would it be possible to make my own encoder strip? Say, I have a laser engraver and would like to make a different strip...( longer, more/less signals per mm, UV resistant material, etc...)