Pibot & Repetier-Host
Posted by liquidnyquiz
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Pibot & Repetier-Host June 23, 2014 02:05AM |
Registered: 10 years ago Posts: 17 |
Hi! I am in the process of building my mendel90. I am at the last step choosing electronics. I am really interested in running Repetier for firmware so I can use Repetier-Host. I was looking at Pibot ( www.pibot.com ). Does anyone have any other suggestions for boards that will run repetier firmware?
Edited 1 time(s). Last edit at 06/23/2014 02:29AM by liquidnyquiz.
Edited 1 time(s). Last edit at 06/23/2014 02:29AM by liquidnyquiz.
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Re: Pibot & Repetier-Host June 23, 2014 05:27AM |
Admin Registered: 17 years ago Posts: 7,879 |
I think Repetier firmware will run on any Reprap board. I haven't tried it yet myself.
[www.hydraraptor.blogspot.com]
[www.hydraraptor.blogspot.com]
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Re: Pibot & Repetier-Host June 23, 2014 07:05AM |
Admin Registered: 17 years ago Posts: 7,879 |
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Re: Pibot & Repetier-Host June 23, 2014 09:33AM |
Registered: 10 years ago Posts: 17 |
Ah yes I had forgot that Repetier-Host supports a few firmwares. Thank you.
My concern is, how do you go about powering the 2 z motors of the same driver? Parallel will devide the amperes. What are the dangers with running the stepper motor at lower amperes than rated for? Skip steps?
I guess I am confused on how you would use a board setup for 3 axis motors and run an extra one with no consequences?
My concern is, how do you go about powering the 2 z motors of the same driver? Parallel will devide the amperes. What are the dangers with running the stepper motor at lower amperes than rated for? Skip steps?
I guess I am confused on how you would use a board setup for 3 axis motors and run an extra one with no consequences?
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Re: Pibot & Repetier-Host June 23, 2014 11:09AM |
Registered: 9 years ago Posts: 41 |
The Mendel 90 instructions suggest you run the Z steppers in series. That way the steppers see the same current as they would normally and the drivers deliver a little more voltage than they would normally. Works well with the kind of NEMA17 steppers we use for repraps.
Edited 1 time(s). Last edit at 06/23/2014 11:09AM by ElectroWomble.
Edited 1 time(s). Last edit at 06/23/2014 11:09AM by ElectroWomble.
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Re: Pibot & Repetier-Host June 23, 2014 04:36PM |
Registered: 10 years ago Posts: 541 |
Quote
ElectroWomble
The Mendel 90 instructions suggest you run the Z steppers in series. That way the steppers see the same current as they would normally and the drivers deliver a little more voltage than they would normally. Works well with the kind of NEMA17 steppers we use for repraps.
Driving the two stepper motors in series reduces the voltage applied to the motor (compared to driving a single motor). This reduces the torque capability of the motor but there is sufficient for the Z-axis even with 6V applied.
Regards,
Neil Darlow
I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.
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Re: Pibot & Repetier-Host June 23, 2014 06:38PM |
Admin Registered: 17 years ago Posts: 7,879 |
No it doesn't reduce the torque as that is proportional to the current, not the voltage. And current is set by the stepper driver at 1.25A. It does theoretically reduce the maximum speed but I actually think that is actually limited by mid band resonance on the Z drive.
[www.hydraraptor.blogspot.com]
[www.hydraraptor.blogspot.com]
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Re: Pibot & Repetier-Host June 23, 2014 06:47PM |
Registered: 9 years ago Posts: 41 |
As i understand it (sombody correct me if im wrong) the drivers deliver a set current as determined by the current setting trim pot. If you wire the two stepers in series then that doubles the total resistance (double the impeadance to be totaly corect) so the the driver must supply double the voltage across boath motors (across the output of the driver) to achive the same current as if there were only one motor. The voltage seen across one of the seares conected motors will be exactly the same as it was when there was only one motor in the circuit. Hope that makes some kind off since. [it's late :-)]
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Re: Pibot & Repetier-Host June 23, 2014 10:25PM |
Registered: 10 years ago Posts: 17 |
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Re: Pibot & Repetier-Host June 24, 2014 04:54AM |
Admin Registered: 17 years ago Posts: 7,879 |
Yes that is how most RepRap machines work. Obviously the motors need to be low voltage high torque types. NEMA17 is only the specification of the face plate.
[www.hydraraptor.blogspot.com]
[www.hydraraptor.blogspot.com]
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Re: Pibot & Repetier-Host June 24, 2014 04:59AM |
Registered: 9 years ago Posts: 41 |
Current determines the torque (both for holding and accelerating the motor). The voltage has nothing directly to do with the speed of the motor. As long as you have stepper motors which conform to the recommendations in the wiki: [reprap.org] (which boils down to low resistance) the stepper drivers will have sufficient spare voltage from a 12 volt supply to create the current you wont even if the motors are wired in series. So you will still get your maximum torque.
The driver basically monitors the current going to the motor... if it dose not see sufficient current it cranks up the voltage a bit until it dose (and viser versa).
The driver basically monitors the current going to the motor... if it dose not see sufficient current it cranks up the voltage a bit until it dose (and viser versa).
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Re: Pibot & Repetier-Host June 24, 2014 05:01AM |
Registered: 10 years ago Posts: 541 |
Quote
nophead
No it doesn't reduce the torque as that is proportional to the current, not the voltage. And current is set by the stepper driver at 1.25A. It does theoretically reduce the maximum speed but I actually think that is actually limited by mid band resonance on the Z drive.
There is an indirect effect on achievable torque which varies with the applied voltage.
Quoting this article:
Other benefits of an increased rise time include higher operating torque and higher mechanical power output. As the rise time improves, the winding will spend longer periods of time at its rated current, therefore producing a higher time averaged torque.
But, of course, your are correct that the factor affecting torque is the operating current.
Regards,
Neil Darlow
I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.
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Re: Pibot & Repetier-Host June 24, 2014 05:09AM |
Registered: 9 years ago Posts: 41 |
Yes you will get faster rise time in the inductive winding so you will hit the max current quicker... but if nophead is correct (he usually is :-) ) then that wont matter much as the max speed is limited by the point at which the system goes into mechanical resonance. The point is that that limit is a lot higher speed than we need on a reprap.
So for all practical points of view it will just work.
Edited 1 time(s). Last edit at 06/24/2014 05:10AM by ElectroWomble.
So for all practical points of view it will just work.
Edited 1 time(s). Last edit at 06/24/2014 05:10AM by ElectroWomble.
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Re: Pibot & Repetier-Host June 24, 2014 06:45AM |
Admin Registered: 17 years ago Posts: 7,879 |
Yes the voltage affects the rise time and the ability to overcome the back EMF, so it affects how the torque falls with speed. It doesn't affect the holding torque or the torque when moving slowly. That is why I said the current sets the torque and the voltage determines the maximum speed. Stepper torque falls with speed and the max speed is simply when the torque has fallen below that required by the load.
[www.hydraraptor.blogspot.com]
[www.hydraraptor.blogspot.com]
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Re: Pibot & Repetier-Host June 24, 2014 08:44AM |
Admin Registered: 17 years ago Posts: 7,879 |
However, if you have to accelerate past the mid band resonance the motor will stall before it runs out of torque due to lack of voltage.
[www.hydraraptor.blogspot.com]
[www.hydraraptor.blogspot.com]
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Re: Pibot & Repetier-Host June 25, 2014 12:17AM |
Registered: 10 years ago Posts: 17 |
Thank you all for your answers. I have decided to go with the Pibot setup. They are out of stock for a month! =( . I shall wait. It has taken me 2 months to gather the parts and put it all together, whats 1 more month for electronics.
On a side note, Nophead I found it very time/expensive sourcing all the bolts/nuts. Any chance you will provide a kit for this? Or change the design to use more of the same bolts/nuts.
Edited 1 time(s). Last edit at 06/25/2014 12:19AM by liquidnyquiz.
On a side note, Nophead I found it very time/expensive sourcing all the bolts/nuts. Any chance you will provide a kit for this? Or change the design to use more of the same bolts/nuts.
Edited 1 time(s). Last edit at 06/25/2014 12:19AM by liquidnyquiz.
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Re: Pibot & Repetier-Host June 25, 2014 04:31AM |
Admin Registered: 17 years ago Posts: 7,879 |
We do sell fastener kits, see [forums.reprap.org] for the list of things we sell.
Each fastener has a reason for being the type it is so there isn't much scope for reducing the number of types unless you compromise.
[www.hydraraptor.blogspot.com]
Each fastener has a reason for being the type it is so there isn't much scope for reducing the number of types unless you compromise.
[www.hydraraptor.blogspot.com]
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