Smaller Footprint
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Just thinking out loud and in reference to a discussion occurring on google deltabots group, if some sort of Can bus type system was employed could not the stepper drivers be mounted on the motors? This would make the controller much smaller, and we can all find space for a stepstick sized board on the side of our motors.
We're planning to use CAN bus in the future.
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kelchm, just looking at the X5, for a smaller board would loosing the second extruder stepper, the expansion connector, dropping down to a lower number of microsteps (say 64 or 128 rather than 256) and a lower max current be fine? So for example it would be great for a single extruder desktop size printer but not for a multi extruder large format printer that some are building
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Just thinking out loud and in reference to a discussion occurring on google deltabots group, if some sort of Can bus type system was employed could not the stepper drivers be mounted on the motors? This would make the controller much smaller, and we can all find space for a stepstick sized board on the side of our motors.
So instead of 4 wires you want to carry at least 6 of them to each motor? Let's not talk about enable, TMC SPI and so on. Using a serial connection (SPI, CAN) to the "stepstick" will still need "logic" voltage and ground, protocol wires AND motor voltage wires. I think the printers as they are today are a big mess of wires anyway. Doing the stepstick remote will just increase this mess.
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So instead of 4 wires you want to carry at least 6 of them to each motor? Let's not talk about enable, TMC SPI and so on. Using a serial connection (SPI, CAN) to the "stepstick" will still need "logic" voltage and ground, protocol wires AND motor voltage wires. I think the printers as they are today are a big mess of wires anyway. Doing the stepstick remote will just increase this mess.
This is some way in the future, but we're looking at using one RJ11 or RJ45 connector to connect 2 twisted pairs, plus a 2 core power cable to carry VIN power. A typical slave board would drive something like 2 motors, 2 heaters, 2 fans, 2 temperature sensors, and 2 inputs for endstops or other devices. Daisy chaining slave boards would be supported. Users who need to drive a lot of motors would benefit most.
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Just thinking out loud and in reference to a discussion occurring on google deltabots group, if some sort of Can bus type system was employed could not the stepper drivers be mounted on the motors? This would make the controller much smaller, and we can all find space for a stepstick sized board on the side of our motors.
So instead of 4 wires you want to carry at least 6 of them to each motor? Let's not talk about enable, TMC SPI and so on. Using a serial connection (SPI, CAN) to the "stepstick" will still need "logic" voltage and ground, protocol wires AND motor voltage wires. I think the printers as they are today are a big mess of wires anyway. Doing the stepstick remote will just increase this mess.
That's a fair comment but 3d printers have a lot of wires as they have a lot of electronics in them. I could very happily have an rj45 with cat6 cable to each motor, it would look much less messy than it does now with 4 loose wires to each motor. But what you do get is potentially a controller board of around half the size. A lot of space is taken up by driver chips, capacitors etc..
A lot of duetwifi users seem to be using bigger more expensive printers where fitting the controller into the machine is no problem at all. My compartment under my delta's bed holds a psu, duetwifi, 2 buck converters, and an ssr with room to spare. But my micro delta printer can only fit a ramps/mega board in it with cutouts in the electronics compartment.
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Have you considered turning your micro delta upside down, i.e. stepper motors and electronics at the top instead of the bottom? You can avoid running heavy power wires up the towers by using a cheap 5-terminal bed heater SSR in the bottom.
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Hi David, it's designed so that either the electronics or steppers can be at the top or bottom but not both. It really is micro sized the bed is just 100mm diameter and 3x nema 14 motors only just fit into the base, as I have it configured with electronics at the top, motors at the bottom. The bed is heated by a silicone heater at only 40w on 12v so I won't need any ssr's.
http://www.thingiverse.com/thing:1874766
The duetwifi board is physically larger than the electronics compartment. I could use one externally if I wanted to switch over.
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Maybe turn the board 90 degrees in that case and mount it vertically,
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Sounds like a custom triangular board with 4 drivers would be perfect! Also for such small motors you don't need TMC2660 drivers, the smaller TMC2130 would be a better match.
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This would probably add $10-20 to the cost for everyone, since it would mean doing two PCB fab/assembly processes instead of one. Also it would mean introducing a failure point at the stack's connectors. It would also mean the board is taller for everyone, for some printer designs height is the limiting factor. Not saying it isn't possible, but there would be some drawbacks to consider. Cost is probably the biggest one.
Agreed. The Duet Wifi is already expensive, the price being even higher would be a difficult sell.
Basically I'm just envisioning that the main board would have no integrated stepper drivers. It sounds like that sort of design could work well with multiple CAN bus driver boards that are located very close to the stepper motors. This could also have some big benefits in terms of EMI since the stepper motor wires could be much shorter.
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Basically I'm just envisioning that the main board would have no integrated stepper drivers. It sounds like that sort of design could work well with multiple CAN bus driver boards that are located very close to the stepper motors. This could also have some big benefits in terms of EMI since the stepper motor wires could be much shorter.
Yes, you could do it that way, but the costs would be higher. Each slave board would need a PCB, processor, CAN transceiver, power regulator and connectors, in addition to the stepper driver(s) and any other components moved off the main PCB.
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There is no one size fits all, We tried to make the DuetWifi be suitible for a wide range of printers, and be easily extendable for a much larger range through the large expansion header.
If only small form factor is important then a minimal board with daughter boards on each stepper driver and a hotend carriage mounted hotend controller board would be the way to go, but it would not be cheaper.
If a lower cost controller is important (while retaining core functionality) then a single extruder board with minimal expand-ability is the way to go.
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I think it is what it is and is a very well positioned offering. Smaller boards are available though as you say they're either older tech or less expandable. Electronics though always get smaller, and I'm sure 3d printer controllers will do too, some type of standardisation of wiring and connectors would help.
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John Lydgate said it first (brain teaser for today).
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Needs must as the devil drives?
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Needs must as the devil drives?
Nah. The one I was thinking about was "You can please all of the people some of the time, some of the people all of the time but you can never please all of the people all of the time".
So with the Duet some people want more features, others don't want to pay for features they don't need, others want a smaller footprint, some want more features and a smaller footprint, and we'd all like it to do everything and cost nothing.
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Yeah fair enough I didn't know that was one of his too, but that's what I mean, its a well positioned offering, if it weren't people wouldn't be buying them, or they would be selling them on ebay, which they aren't.
