Stepper Motor Replacement

RaymondS

Hi All,

Please advise a newbie here. Sorry for the long post but normally people ask more questions and so I hope I have given enough intent as to why my decision and also what I need to know.

I have taken my lessor spec'd "Creality CR-10S PRO V2" and upgraded it slightly (ok...maybe slightly is a lie because the only thing left of creality is the Frame, Power supply, Stepper Motor's and the sticker on the front..... )

What I have changed is:
New Duet 3 Mini5+
Humera
All rollers removed and now using linear rails (X, Y and Z)
Added strengthening to the frame
Replaced all fans
New screwthread rods and guides (old ones had a slight bend)
Backlash nuts
Distribution boards (for ribbon cable)
Drag chain
FYSETC-Mini-12864-Panel (just to have limited control)
Many new printed parts to hold everything changed

I have been having issues with the stepper motors and have changed Amperage, Jerk, Acceleration, etc... and have decided that I have already overcommitted on the project and so replacing the stepper motors is a small price to pay at this stage to have peace of mind.

The Z Motors are Creality's 42-34 which is supposed to be 1.5A rated but anything above 0.7A and the motors are untouchable from a heat perspective. At 1A they measure about 90 degrees Celcius on a small 10 minute print job.

The X & Y are Creality's 42-40 which when measuring the travel are erratic. With 15, 20, 22, 40mm movements forward and back again mostly landing up in the right positions... but 10, 30 & 50mm are erratic and can be out but 0.04-0.12mm per movement on any of the distance tests (as I mentioned, I have set amps all the way from 0.8 to 1.5 amps with different results all the time).

Not worried about the cost now, I want to replace all 4 motors (Z is dual). I am not really into speed but more into quality. So my dilemma of which motors to go with is a challenge (Living in the UAE, I need to import and need to take this into consideration)

Some points I read:
Duet 3 Mini5+ has TMC 2209 and so max 2A
Duet site says stick to 1.8 instead of 0.9 unless delta printer

I am planning to build a Voron or Ratrig later next year and so could reuse a lot of my investment here.

My thoughts are to go with 0.9 motors but only 1.68A rated as to not push the drivers to the limit. Is this a silly decision?

0.9 vs 1.8? Considering I am not in it for speed and the power supply is 24V
1.68A vs 2A? I know we only run amperage at about 85% and so 2A motor could be run at 1.7A which is below driver amp rating

Any opinions on the above?

These are the options I am looking at from stepperonline:
0.9:
Option 1
Manufacturer Part Number: 17HM19-1684S
Motor Type: Bipolar Stepper
Step Angle: 0.9 deg
Holding Torque: 44Ncm(62.3oz.in)
Rated Current/phase: 1.68A
Voltage: 2.8V
Phase Resistance: 1.65ohms
Inductance: 4.1mH ± 20%(1KHz)

Option 2
Manufacturer Part Number: 17HM19-2004S
Motor Type: Bipolar Stepper
Step Angle: 0.9 deg
Holding Torque: 46Ncm(65.1oz.in)
Rated Current/phase: 2.0A
Voltage: 2.9V
Phase Resistance: 1.45ohms
Inductance: 4.0mH ± 20%(1KHz)

1.8:
Option 3
Manufacturer Part Number: 17HS19-1684S1
Motor Type: Bipolar Stepper
Step Angle: 1.8 deg
Holding Torque: 45Ncm(64oz.in)
Rated Current/phase: 1.68A
Voltage: 2.8V
Phase Resistance: 1.65ohms
Inductance: 2.8mH ± 20%(1KHz)

Option 4
Manufacturer Part Number: 17HS16-2004S1
Motor Type: Bipolar Stepper
Step Angle: 1.8 deg
Holding Torque: 45Ncm(64oz.in)
Rated Current/phase: 2A
Voltage: 2.2V
Phase Resistance: 1.1ohms
Inductance: 2.6mH ± 20%(1KHz)

All thoughts on these stepper motors welcome.

Hope someone can help

T3P3Tony

@raymonds as a start point you can plug your motor options in here:
https://www.reprapfirmware.org/emf.html

That will let you know the max speeds you can reach for the variations on inductance etc

Plan to run the motors at 80% of rated current.

The TMC 2209 data sheet says 2.0A but that must be on a huge heatsink with a lot of cooling. Plan to use 1.4-1.6A max. I see you already have a fan blowing across the electronics in the recommended way which is good.

The 1.8 vs 0.9 degrees is more nuanced. You will get better positioning accuracy with 0.9 degrees and that makes much more of a difference on a delta (where in some arm orientations a small change in motor postion leads to a large change in effector position) than a Cartesian machine. Alternatively you will get higher speeds and more torque out of the 1.8 degree motors.

@raymonds said in Stepper Motor Replacement:

I am planning to build a Voron or Ratrig later next year and so could reuse a lot of my investment here.

I would look at recommended motors for those designs as well then because I know that the Voron community has done a lot of work in specifying motors that work well with there design.

RaymondS

@t3p3tony

Thanks for the reply and advice.

Running the 2A stepper at 80% is 1.6A and so will most likely work. Both Voron and RatRig go with 2A on the Duet, but they mostly focused on speed and so recommend 1.8 degrees

Option 1: I should just stick to this and only change later to 0.9 degrees if I still see the need later.

Option 2: Maybe by 2 of each and play. If I need speed I can place 1.8 on X & Y and the 0.9 on Z (Dual) as Z does not need much speed. (I think the Torque on both is overkill for what I do.) Then swap at a stage and see if there is a difference.

So the last question would be, would it make a difference if on Z is on 0.9 (dual motors) and "X & Y" is on 1.8 degrees? (Or visa versa?)

RaymondS

Any opinions on mixing the motors as mentioned above?

T3P3Tony

@raymonds said in Stepper Motor Replacement:

the last question would be, would it make a difference if on Z is on 0.9 (dual motors) and "X & Y" is on 1.8 degrees? (Or visa versa?)

What is your Z gearing? If you work out what layer height are valid full steps and 1/16 microsteps then compare between 0.9 and 1.8 degree motors.

Experimenting with both is fine if you want to get real world comparisons on your hardware but the simplest option is pick the voron motors.

gloomyandy

@raymonds My experience of 0.9 degree steppers has been pretty mixed. I've found they tend to be louder and harder to tune. I'm not sure that I've really gained any advantage from the extra steps/mm.

dc42

@raymonds I suggest you choose the 1.68A motors, as you are not trying to achieve maximum speed. 17HM19-1684S is what I use on my delta printer. On a Cartesian printer it's fine to have 1.8deg on some axes and 0.9deg on others.

RaymondS

Thanks for all the feedback.

After the feedback, I decide to continue with 1.8 degrees motors. Will play with 0.9 later once I have more experience (not too expensive)

Voron Configurator actually recommends as part of the BOM to go with 2A. Ratrig have a 2.5A option only in thier configurator even though you have selected the DUET 3 Mini5+. 2.5A Motors I think is a little high demand from 2209 based on what I now understand.

The 1.68 seems like a safe move but might not be so great on the 500 x 500 size machine I plane to build.

So I will go down the middle with this for now and run 2A motors somewhere in the 1.4-1.7A range and see how it goes. If needed I will add small heatsinks to the drivers (already have a fan blowing over them. Pitty there is now temp sensor in them).

Good to see all the support here. Made the right choice to go with DUET and loving the experience. Hopefully will build the bigger printer soon.

dc42

@raymonds said in Stepper Motor Replacement:

The 1.68 seems like a safe move but might not be so great on the 500 x 500 size machine I plane to build.

1.68A 1.8deg motors will be just fine. For the Duet 3 Mini, 1.68A would be a better match than 2A.

@raymonds said in Stepper Motor Replacement:

Pitty there is now temp sensor in them

There is an over temperature warning sensor in them, which we configure to kick in at 100C (the lowest available setting). You will see warning messages if this temperature is reached.

Gixxerfast

@raymonds I have been running the Duet 3 mini 5+ with three different A/B-motor setups now:

1. LDO-42STH40-2004MAC 0.9 - I could not get these to work without layer shifting with the Duet board.
1. OMC/Stepperonline 17HS19-2004S1 - These are great affordable stepper motors and worked perfectly IMHO. Still got four of them on Z. Ran them at 1200 - 1600 mA
1. LDO-42STH48-2504AC - Had to see what the hype was all about. I run these at 1600 mA and they are OK but quite noisy. Probably for the speed freaks running 48V stepper drivers. As #1 on my list they have the JST connector so I got neater cabling with these than with #2. Nothing wrong with these so far so they'll stay on.

Disclaimer: These are my subjective opinions not based on any calculations and they may work for me but not for anyone else.

I might add that I have two Sanyo high flow 60 mm fans cooling the controller bay which is quite airy. I haven't noticed any temp warnings from the stepper drivers.