Posts made by OG3D

@mrehorstdmd yes I knew its gonna happen but didn't thick it would be bad for the belt.

For BLDC motor I'm still figuring how much steeps per revolution I could get out of it.
If you'll watch this Youtube video link text
It looks there are issues when traveling at low speed with resonance frequency but he claimed that it could be solved in firmware update. This is all new to me so I'm learning as I go.

@Blv I'm impressed with your documentation, Great Job.

@mrehorstdmd odrive supports the step/dir interface. I'm not sure if I will have enough torque at low speeds so this will be like an experiment for me. I know the odrive creator had good results using odrive to control his Pick and Place Machine link text.

The reason for leaning toward BLDC motors is to decrease the tool change time during the printing as this printer will have a tool changer similar to E3Ds approach.

After Several revision, I think I'm happy with this design.
Thanks for the help at @mrehorstdmd and @Surgikill

@Surgikill I am stacking the belts to avoid the twisting. Fabtotum style dose look simpler. My goal is to make the XY belt path in such a way that the brackets for the pulley can be easily machined. As this will be a all metal machine, trying to avoid plastic as much as possible.

@mrehorstdmd hope you don't mind me using your photo as reference.
So do the position of the idlers P1/P2/P3/P4 have effect on the precision of the XY Motion?

For the BLDC motor I will be using odrive to drive the two motors.
Think ill be going with D5065 270kv Motor and a CUI AMT102 "8196 CPR capacitive encoder", haven't decide on the motor type 100%.

Thanks guys for the info and the links

This is what I came up with, any comments appreciated.

Here is an ISO View.

There are several different design on the belt path and keeping it tension, could you guys shear your experience.

Thanks,
Oleg

@dc42 Yes they aren't cheap. I have been think about DRO for quit time similar to this.
https://www.igagingstore.com/6-Absolute-Digital-Readout-DRO-Stainless-Steel-Su-p/205470.htm

I know the DROs aren't fast enough to keep up with the motion but it could be used a reference to pull the positions when requested, like during boot up. What do you think?

To my best knowledge absolute encoder will know its position after power cycle, I think its due to absolute encoders are providing a unique position values.

The place that I work they have a machine that has absolute encoders in its servo motor. It does not require homing sequence at startups.

Well on average the printers usual do not get close to 300mm/s, so on CoreXY using a .9 deg I wont see much improvement vs a 1.8deg motor, since by design CoreXY is geared down. Just making sure I understood it correctly.

I have a delta but at speeds 100mm/s quality is not good and seeing Rail Core II print results at 100mm/s got me inspired to build a CoreXY for my second printer.

@dc42 so with steps and direction inputs the absolute position would not be known to duet? my thought towards absolute position encoder is that the printer will always know it position thus with a well build print no need for homing or mesh grid compensation between every prints.

@dc42 are you taking into account of adding a closed loop stepper control with an absolute encoders? I seen talks about it in the past but was curious if your taking this into account for next gen duet. Any replies would be appreciated.

Thanks,
OG

@rcarlyle " That’s one little-appreciated reason why CoreXY tends to produce nicer prints than an equivalent Cartesian — you’ve effectively geared down the motors. "

So is it worth it running at .9deg motor?

I stumbled in to this article

Fast Desktop-Scale Extrusion Additive Manufacturing by MIT
https://arxiv.org/ftp/arxiv/papers/1709/1709.05918.pdf

They used a 50 W Laser Assisted Heater Cartridge.

@dc42 said in Duet hardware actually makes it into Thomas Salanderer's videos:

@og3d said in Duet hardware actually makes it into Thomas Salanderer's videos:

@dc42
What do you think about them?
https://hackaday.io/project/11583-odrive-high-performance-motor-control

It looks good, but way overpowered and too expensive for ordinary 3D printers. It might be good if you wanted to print a house though!

Agree, but image how fast the speeds can become.

@dc42 said in Duet hardware actually makes it into Thomas Salanderer's videos:

@og3d said in Duet hardware actually makes it into Thomas Salanderer's videos:

@dc42
Is implementing closed loop support in hardware and software by an encoders on your radar for next version of duet?

We've been keeping an eye on developments in this area, with a view to doing an alternative DueX expansion board that would drive BLDC motors instead of stepper motors. The main problem so far is the lack of suitable inexpensive BLDC motors. The cheap ones used in quadcopters have no gearbox and no sensors, which is OK when you only run the motors at high speeds, but no good for 3D printers. When we need is a BLDC motor with built-in commutation sensors (so that we can run the motor at low speeds), a reduction gearbox (because BLDCs are only efficient at high speeds), and that gearbox must either have very low backlash or else we also need an encoder on the output shaft with a resolution of at least 5000 counts/rev.

@dc42
What do you think about them?
https://hackaday.io/project/11583-odrive-high-performance-motor-control

I was more think of adding support for encoders.
Something like this one.
https://www.cui.com/product/product-resources/amt100-series-modular-encoders.pdf

@dc42
Is implementing closed loop support in hardware and software by an encoders on your radar for next version of duet?

oh ok, I misunderstood the drops-off values,
my stepper motor part # is 17HS19-2004S

This is what I got
Approximate peak back EMF due to rotation per motor: 8.2 V at 200.0 mm/s
Approximate peak back EMF due to inductance per motor: 1.6 V at 200.0 mm/s
Step pulse frequency: 20.0 kHz at 200.0 mm/s
Speed at which torque starts to drop (low slip angle): 152.5 mm/s @ 25.9 kHz
Speed at which torque starts to drop (high slip angle): 208.9 mm/s @ 35.5 kHz

This is with 1.7A current.

If lower my current to 1.5
I get this
Speed at which torque starts to drop (low slip angle): 163.4 mm/s @ 27.8 kHz
Speed at which torque starts to drop (high slip angle): 224.4 mm/s @ 38.1 kHz

Am I better off with lowering my current?

Also my printer build area is 200mm wide with 450 mm Hight.

Here is what I have
• Printer is Delta style with cross bracing to limit the bending of the towers
• With Huntley Carriage, effector and magnetic arms
• 9mm GT2 belt with 16 teeth pully
• Motors are:
For XYZ: Nema 17 1.8deg 2A 59Ncm
Extruder: Nema 17 1.8deg 1.5A bowben drive Type
• XYZ Motors are installed with Rubber Stepper Motor Vibration Damper
• Duet WIFI v1.02
• 24v power supply

Currently my config.g settings are
M350 X32 Y32 Z32 E16 I1 ; Configure micro stepping with interpolation
M92 X200 Y200 Z200 E663 ; Set steps per mm
M566 X1200 Y1200 Z1200 E1200 ; Set maximum instantaneous speed changes (mm/min)
M203 X18000 Y18000 Z18000 E18000 ; Set maximum speeds (mm/min)
M201 X3000 Y3000 Z3000 E3000 ; Set accelerations (mm/s^2)
M906 X1700 Y1700 Z1700 E1200 I30 ; Set motor currents (mA) and motor idle factor in per cent

Can my acceleration, speed and Inst. speed setting be increased? Am I better off with 16 micro stepping?
I’m new to this, any help is appreciated?