Replacement motor

Hi I have some motor and wirer questions.
I need to replace x and y motors to stronger motors are they possible to run on the duet without problem with over heating?
I also need to make my cables for my heater cartridge longer about 1400 mm in total I am using 40W 12V, what size of wire should I use 0,75mm2 or 1mm2.
I am using Duet V0.8.5 and Duex4 V0.2 and the Duex has pins instead of screw terminals for the Heaters this means that I have to connect a a fairly thick cable to a dupont connector any tips on how to do that?
Thanks in advance/Joar

It would help to know why you need stronger motors. Do you need more torque in general, or more incremental torque (i.e. torque for a very small angular displacement)?

If you need more torque in general, choose longer motors. Aim for a current rating of 1.3 to 1.5A so that the Duet can drive them up to about 85% of rated current without the drivers overheating. This firm [www.omc-stepperonline.com] does a wide range and their list is worth looking at just to see what is available and how torque increases with length, even if you end up buying motors elsewhere.

Obviously, a longer X axis motor means there will be more weight for the Z motor to lift, and more wear on the threaded rod.

If you need higher incremental torque, choose 0.9deg/step motors for the X and Y axes.

When connecting a 12V hot end heater to header pins on a Duet, use both pairs of pins, just as RepRapPro does in the Ormerod kit. If you use 24V power and a 24V heater instead then the current is halved and a single pair of pins is sufficient.

Edited 1 time(s). Last edit at 10/15/2015 02:49AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi dc42, well my ormerod is not that ormerodish anymore, and I have problem with step missing because of the interia of the design, the motors I linked in my previous post is 1.5 amp so i guess that would be okay and I should run them on 1.275 amp?
On the Duex 4 there is only one set of pins for the heater, or am I wrong?
What cable area is ok for 3,33 amp and 1.2m (it will be up 70 C as well).
If Iam going to run 24 V instead is it correct that I only need:
1. New power supply
2.New heater Cartridge
3. New heated bed
4. 24 V Fans

I run my machine with a E3D kraken style hotend, that means 4x 40W heaters so maybe it would be good to go for 24 V instead?
Thanks/Joar

Yes, that looks like a good motor to me. If you will be running it at 1.275A then I suggest you use a fan to direct cooling air along the line of stepper motors on the Duet. But you may find that 1A is enough.

I am not an expert on cable size vs. current rating.

I believe the screw terminals on the DueX4 are rated at 5A, so connecting a heater to a single pair of screw terminals is OK. It's the header pins that have a lower current rating, around 2A AFAIR.

I upgraded one of my printers to 24V recently and my list of components to replace was the same as yours, except for the heated bed which was already AC mains powered.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I will mount both cards with dual fans so it should be okay, is there a good heat zink that i could use on the drivers as well?
On the new duex4 the screw terminal is removed, only pins.
What was your main goal when switching to 24V was is the advantage?
When you run the bed on AC main do you use the 12V that you normaly connet to the heated bed to run a relay as this one link ?
And the the thermistor is connected as usually of course?
/Joar

Hello,

I use motors with 34mm depth and 1.5A for my Ormerod 2. I am at the office right now, but if you are interested I can provide a datasheet within the next 8-10 hours. These motors are very common at ebay and Aliexpress ans so the price is less then 15€. The original motors are hard to get so I decided to use these ones. I was astonished that they can operate with 1.5A. I tested that already and it works. Maybe the torque is less than your motor, but it is more than the original as I compared both motors.

Regards,

Sven

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Slicer: Simplify3D 4.0; sometimes CraftWare 1.14 or Cura 2.7
Delta with Duet-WiFi, FW: 1.20.1RC2; mini-sensor board by dc42 for auto-leveling
Ormerod common modifications: Mini-sensor board by dc42, aluminum X-arm, 0.4 mm nozzle E3D like, 2nd fan, Z stepper nut M5 x 15, Herringbone gears, Z-axis bearing at top, spring loaded extruder with pneumatic fitting, Y belt axis tensioner
Ormerod 2: FW: 1.19-dc42 on Duet-WiFi. own build, modifications: GT2-belts, silicone heat-bed, different motors and so on. Printed parts: bed support, (PSU holder) and Y-feet.
Ormerod 1: FW: 1.15c-dc42 on 1k Duet-Board. Modifications: Aluminium bed-support, (nearly) all parts reprinted in PLA/ ABS, and so on.

Quote
Joar107
When you run the bed on AC main do you use the 12V that you normaly connet to the heated bed to run a relay as this one link ?
And the the thermistor is connected as usually of course?
/Joar

No, you don't need a timer relay - any relay with a 12V coil and mains rated N.O. contacts can be used - connect the coil to the bed heater output of the Duet (e.g. [uk.rs-online.com]). Don't forget to put a flyback diode across the relay coil. You could also use a solid-state relay or an optically isolated triac [uk.rs-online.com] will switch a bed heater of up to 150W or so.

The thermistor stays exactly the same.

Dave

Edited 2 time(s). Last edit at 10/15/2015 07:37AM by dmould.

Quote
dmould

Quote
Joar107
When you run the bed on AC main do you use the 12V that you normaly connet to the heated bed to run a relay as this one link ?
And the the thermistor is connected as usually of course?
/Joar

No, you don't need a timer relay - any relay with a 12V coil and mains rated N.O. contacts can be used - connect the coil to the bed heater output of the Duet (e.g. [uk.rs-online.com]). Don't forget to put a flyback diode across the relay coil.

The thermistor stays exactly the same.

Dave

Think of me like a child that know nothing
I understand that I dont need a timer I just googled and found that one.
The flyback diod puzzles me could you explain a little bit more.
Thanks /Joar

Quote
Treito
Hello,

I use motors with 34mm depth and 1.5A for my Ormerod 2. I am at the office right now, but if you are interested I can provide a datasheet within the next 8-10 hours. These motors are very common at ebay and Aliexpress ans so the price is less then 15€. The original motors are hard to get so I decided to use these ones. I was astonished that they can operate with 1.5A. I tested that already and it works. Maybe the torque is less than your motor, but it is more than the original as I compared both motors.

Regards,

Sven

Hi Sven what torque do you have on that one?
I can get 10 pcs Nema 17 1.2A 54 N.cm directly from wantai for 103 Euro

/Joar

Quote
Joar107
The flyback diod puzzles me could you explain a little bit more.
Thanks /Joar

When voltage is removed from an electromagnet (such as the coil of a relay), the sudden drop in magnetic field will induce a very high voltage across the coil. This can blow a semiconductor such as the switching FET on the Duet. The induced voltage is however of the opposite polarity to the original energising voltage, so it can be shorted out by connecting a diode across the relay that conducts when the voltage is reversed. In this case one side of the coil will be connected directly to +12V, and the other side to the bed heater output of the Duet, so you connect a diode straight across the coil with the cathode of the diode connected to the +12V side of the coil. (The cathode is the end of the diode that is marked). A suitable diode would be a 1N4005 (e.g. [uk.rs-online.com]). Make very sure it is the right way around otherwise it will short out the coil when energised (which will draw excessive current and also blow the FET!)

A side-effect is that the current through the diode slows down the decay of the magnetic field, which means that the relay remains on for a while (there is a small time-delay after coil voltage is removed before the relay contacts open). In this application the short delay will not cause problems, but in other applications where the relay must open immediately, other arrangements have to be made for dealing with the flyback voltage.

Dave

Quote
dmould

Quote
Joar107
The flyback diod puzzles me could you explain a little bit more.
Thanks /Joar

When voltage is removed from an electromagnet (such as the coil of a relay), the sudden drop in magnetic field will induce a very high voltage across the coil. This can blow a semiconductor such as the switching FET on the Duet. The induced voltage is however of the opposite polarity to the original energising voltage, so it can be shorted out by connecting a diode across the relay that conducts when the voltage is reversed. In this case one side of the coil will be connected directly to +12V, and the other side to the bed heater output of the Duet, so you connect a diode straight across the coil with the cathode of the diode connected to the +12V side of the coil. (The cathode is the end of the diode that is marked). A suitable diode would be a 1N4005 (e.g. [uk.rs-online.com]). Make very sure it is the right way around otherwise it will short out the coil when energised (which will draw excessive current and also blow the FET!)

A side-effect is that the current through the diode slows down the decay of the magnetic field, which means that the relay remains on for a while (there is a small time-delay after coil voltage is removed before the relay contacts open). In this application the short delay will not cause problems, but in other applications where the relay must open immediately, other arrangements have to be made for dealing with the flyback voltage.

Dave

Excellent Thanks, this will happen, this is so much better than school
I will check back with you with a photo before I put on the power.
/Joar

Edited 1 time(s). Last edit at 10/15/2015 09:21AM by Joar107.

Don't put heatsinks on the stepper drivers, they are not effective because the driver chips are designed to be cooled via the PCB. Position the fan to blow air over both sides of the PCB, along the line of driver chips.

I would never use a mechanical relay to switch a mains voltage heated bed. DC-AC SSRs are inexpensive, reliable, don't generate interference, don't need flyback diodes, and can even be used with slow PWM. They generally work with anything between 3V and 32V on the control input. Mine is connected to the heated bed output terminal block.

My main motivation for changing to 24V was to get higher maximum speeds after changing to 0.9deg/step motors on my delta printer. A more common reason for using 24V is to drive a larger heated bed without using AC mains voltage.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Don't put heatsinks on the stepper drivers, they are not effective because the driver chips are designed to be cooled via the PCB. Position the fan to blow air over both sides of the PCB, along the line of driver chips.

I would never use a mechanical relay to switch a mains voltage heated bed. DC-AC SSRs are inexpensive, reliable, don't generate interference, don't need flyback diodes, and can even be used with slow PWM. They generally work with anything between 3V and 32V on the control input. Mine is connected to the heated bed output terminal block.

My main motivation for changing to 24V was to get higher maximum speeds after changing to 0.9deg/step motors on my delta printer. A more common reason for using 24V is to drive a larger heated bed without using AC mains voltage.

Could you give me a link to a product that would suit my needs.
Thanks /Joar

Quote
Joar107

Quote
dc42
Don't put heatsinks on the stepper drivers, they are not effective because the driver chips are designed to be cooled via the PCB. Position the fan to blow air over both sides of the PCB, along the line of driver chips.

I would never use a mechanical relay to switch a mains voltage heated bed. DC-AC SSRs are inexpensive, reliable, don't generate interference, don't need flyback diodes, and can even be used with slow PWM. They generally work with anything between 3V and 32V on the control input. Mine is connected to the heated bed output terminal block.

My main motivation for changing to 24V was to get higher maximum speeds after changing to 0.9deg/step motors on my delta printer. A more common reason for using 24V is to drive a larger heated bed without using AC mains voltage.

Could you give me a link to a product that would suit my needs.
Thanks /Joar

Something like DC - AC SSR

Yes, SSR-25DA would be suitable for driving a mains voltage bed heater and is widely available. But if you go this route, you must connect all the metal parts of the bed and printer to mains ground, and for the bed cables you must use highly flexible cable with strain relief at both ends. Also, use of a RCD in the incoming power circuit is recommended.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I am now running with the SSR-25DA and 220V 500W heated bed, it is amazing, thanks all for the help.
/Joar