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MKS LV8729 , a 128 µStep Driver // Any test?

Posted by epoxi 
MKS LV8729 , a 128 µStep Driver // Any test?
November 18, 2016 08:47PM
Hello!

I recently found this:

[www.aliexpress.com]

Did someone have the chance of test it?

Regards!


ePoxi


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Re: MKS LV8729 , a 128 µStep Driver // Any test?
November 19, 2016 02:53AM
a lot of their advert is accurate information but glosses over important facts

lets hit the highlights shell we?

"Name: MKS LV8729"
Can't fault them on their choose for a name smiling smiley

"Overview
MKS LV8729 is a ultra quiet stepper motor driver, and good for Nema stepper motor whose current is less than 1.5A, which makes motor steady, quiet and precise."

That very low current, and later on they further cover their own butts with
"Default 0.8A,1.5A Max. Advise using 1.3A Max." so 1.3amps max in reality...

"Also, it does good work with MKS ROBIN, MKS GEN,MKS SBASE and RAMPS1.4 controller board on 3d printer, carving machine, CNC, etc."
This is only a half truth... over 1/32 micro stepping all 8 bit controllers like the ramps and MKS GEN cannot generate step pulses fast enough to be useful.
The 32 bit boards like MKS SBASE and MKS ROBIN should be fine with the higher stepper micro stepping rates.

So will it work yes*
*as long as you aren’t using the higher micro stepping features that make their board special, or your not using a 8 bit controller board.

Edited 1 time(s). Last edit at 11/19/2016 02:56AM by Dust.
Re: MKS LV8729 , a 128 µStep Driver // Any test?
November 23, 2016 10:04AM
Has anyone out there used these stepper drivers?
Re: MKS LV8729 , a 128 µStep Driver // Any test?
January 25, 2017 03:29PM
I got some to try. I am using them on my X & y axis @ 16 step with RAMPS

Observations so far:
- Quiet, similar to TMC2100
- Run cooler than A4988 or TMC2100 for similar current
- No problems at all
Re: MKS LV8729 , a 128 µStep Driver // Any test?
January 27, 2017 01:52PM
I believe they are the same chip as used in the THB6128 stepper drivers, but with the thermal pad on the bottom of the package instead of the top.

Edited 1 time(s). Last edit at 01/27/2017 01:53PM by dc42.

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Re: MKS LV8729 , a 128 µStep Driver // Any test?
February 11, 2017 08:18AM
Actually I am trying them right now.

Using 32 steps with RAMPS board on X and Y axis (removed the middle jumper to enable 32 steps and also had to increase the steps from 80 to 160 on both axes).

Quiter than 4988s for sure.

Not quiter than my TMC2100s. More like a very silent 4988. I can't hear the steppers while using TMC2100s, I can definitely hear them with these.

Works cooler than TMCs and probably cooler than 4988s. I have no idea if they are as stable as the 4988s but they definitely are more stable than TMCs.
Re: MKS LV8729 , a 128 µStep Driver // Any test?
March 11, 2017 09:30PM
hello

i have 4 pcs MKS LV8729 Stepper Motor Driver for sale. i never use and do not qnow how silence they are ,
price 25 usd including economical shipping
if you want international tracked shipping will check price
Re: MKS LV8729 , a 128 µStep Driver // Any test?
April 05, 2017 12:24AM
I did manage to find some information on these drivers. lv8729stepperdriverinfo.docx
And a datasheet LV8729steppercontrollerdatasheet.pdf

I've just got 4 of these, attached them to my corexy, set 1/64th microstepping using the jumper settings in the document above (which are correct as it now has 800 steps/mm (0.9 deg motors) and moves 100mm when asked to).

However to move 60mm/s with just x and y in motion will use 96khz step pulses when re-arm is set for around 100khz max. so 1/32 might be more realistic given that I also need to run the extruder and z axis (with grid compensation).

Doing a few tests now.

Edited 3 time(s). Last edit at 04/05/2017 08:41AM by DjDemonD.

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Re: MKS LV8729 , a 128 µStep Driver // Any test?
April 05, 2017 01:12AM
So yes cooler running both at the drivers and the motors than tmc2100, quieter than A4988s but not as much.

Oddly they seem quieter at 1/32 than 1/64 certainly a huge amount quieter than drv8825.

I'm running my extruder on 1/2 stepping (flex3drive with 40:1 gearing) and its still reasonably quiet, so these drivers must do some sort of interpolation.

Prints coming out quite sharp for petg, no layer shifts


Edited 6 time(s). Last edit at 04/05/2017 07:18AM by DjDemonD.

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Re: MKS LV8729 , a 128 µStep Driver // Any test?
April 10, 2017 12:33PM
Also found this info related to LV8729 drviers [www.thanksbuyer.com]

This suggests that the driver automatically goes to half current when there has been no step pulse for 0.5 seconds, this would partially explain why they run cooler in a simplistic sense than other similar units.

Does anyone know how to set fast decay on this driver? I tried to figure it out from the datasheet above but whilst it automatically switches between decay modes no mention of how to set it to fast decay only mode.


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Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 08, 2017 12:30PM
I have just received 4 of these drivers from Aliexpress. I have tried 1/16, 1/32 and 1/64 for my corexy printer's X and Y axis but all of them were very loud as if there is a huge machine in my room. Is there anything I missed?
Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 09, 2017 12:47AM
What motor current/vref are you running, what motor size? How much resonance is there in your frame?h


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Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 09, 2017 01:51AM
Quote
DjDemonD
What motor current/vref are you running, what motor size? How much resonance is there in your frame?h
My motors have 0.85a max current. So I have set the Vref to 0.4V. But I don't have any knowledge about resonance, how can I measure that?
Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 09, 2017 02:48AM
The vref at 0.4v gives 0.8A so you're running those motors at/near their maximum current handling, they will always be noisy when near that level. The document above has values of vref against current. You should always aim to run motors at around 75% of their max current to prevent excess noise, and heating of the motors in use, which can soften/melt printed motor brackets. For your motors reduce vref to 0.3v or even 0.25v. See if that helps with noise.

The issue with 0.85A motors is that they may not provide enough torque to move larger/heavier printer axes, especially corexy where one motor has to be able to move the entire corexy mechanism by itself on diagonal head moves. 1.68A motors are more commonly used, as most drivers can deliver 1.2A (vref 0.6v on these drivers) maintaining the 75% recommended setting and will generate at least twice the torque.

Also check the jumpers under the drivers carefully to ensure they are set to the microstepping mode you want i.e. 1/16 is the most common setting or 1/32 if your controller can handle it. If they are set to 1, 1/2, 1/4 or 1/8 they are likely to be noisier. The document linked to there shows you the jumper config you need.

If you are not sure what they are set to, ask for 50mm of movement, if your firmware is using the default steps/mm for example 80 for 20t pulleys and gt2 belt and 1/16 microstepping it will move 50mm, if it moves 100mm then its set to 1/8, if it only moves 25mm then its set to 1/32. Adjust your steps/mm to the correct amount for the microstepping you are using.

I'm not sure I'd "measure" resonance but some frames vibrate at certain frequencies, sometimes its loose tnuts/bolts etc... Though I suspect you are just over driving your motors.

Edited 1 time(s). Last edit at 05/09/2017 02:51AM by DjDemonD.

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Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 09, 2017 09:51AM
Quote
DjDemonD
The vref at 0.4v gives 0.8A so you're running those motors at/near their maximum current handling, they will always be noisy when near that level. The document above has values of vref against current. You should always aim to run motors at around 75% of their max current to prevent excess noise, and heating of the motors in use, which can soften/melt printed motor brackets. For your motors reduce vref to 0.3v or even 0.25v. See if that helps with noise.

The issue with 0.85A motors is that they may not provide enough torque to move larger/heavier printer axes, especially corexy where one motor has to be able to move the entire corexy mechanism by itself on diagonal head moves. 1.68A motors are more commonly used, as most drivers can deliver 1.2A (vref 0.6v on these drivers) maintaining the 75% recommended setting and will generate at least twice the torque.

Also check the jumpers under the drivers carefully to ensure they are set to the microstepping mode you want i.e. 1/16 is the most common setting or 1/32 if your controller can handle it. If they are set to 1, 1/2, 1/4 or 1/8 they are likely to be noisier. The document linked to there shows you the jumper config you need.

If you are not sure what they are set to, ask for 50mm of movement, if your firmware is using the default steps/mm for example 80 for 20t pulleys and gt2 belt and 1/16 microstepping it will move 50mm, if it moves 100mm then its set to 1/8, if it only moves 25mm then its set to 1/32. Adjust your steps/mm to the correct amount for the microstepping you are using.

I'm not sure I'd "measure" resonance but some frames vibrate at certain frequencies, sometimes its loose tnuts/bolts etc... Though I suspect you are just over driving your motors.
Thank you for the reply. I have lowered the Vref to about 0.3V and noise decreased significantly. But still the printer makes noise something closer to drv8825,almost the same. I set jumpers for 1/32 on my mks gen. I am still trying for the best. But I think these drivers are not that good as tmc2100s.
Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 09, 2017 10:56AM
I couldn't get tmc 2100s to work, too low vref skipped steps, too high vref skipped steps, very little window of usability. Motors and drivers very hot. The lv drivers are medium noise, but motors and drivers run cool, easy to setup thus far nice quality prints no skipped steps.

Using 1/32 tried 1/64 but actually found it slightly noisier.

Edited 1 time(s). Last edit at 05/09/2017 10:57AM by DjDemonD.

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Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 09, 2017 07:43PM
There are 3 brands of it that I could find: Original watterott, fysetc brand and mks brand. They all come stealthChop mode which is not suitable for 3d printers because of their low torque. Spreadcycle mode is advised for 3d printers. I tried fysetc and there is no spreadcycle mode for it as the seller declared to me. Mks have that option:
[youtu.be]
I didn't try it yet but now I am using the original one:
[www.filastruder.com]
And I am really satisfied with these drivers. I thought LV8729 can be a cheaper alternative but I couldn't get the same or at least a similar result.

Edited 2 time(s). Last edit at 05/09/2017 07:45PM by s3rkan.
Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 10, 2017 12:08AM
Quote

I tried fysetc and there is no spreadcycle mode for it as the seller declared to me

I'm using fysetc too and was able to change the modes by soldering bridges on the underside. ( see thread about TMC2100 in general forum )
Of course, I don't know they are in spreadcycle now, but they behave different.
Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 10, 2017 12:16AM
Quote
o_lampe
Quote

I tried fysetc and there is no spreadcycle mode for it as the seller declared to me

I'm using fysetc too and was able to change the modes by soldering bridges on the underside. ( see thread about TMC2100 in general forum )
Of course, I don't know they are in spreadcycle now, but they behave different.
Did you solder the tiny CFG1 pad for spreadcycle?
Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 10, 2017 03:31AM
Yes, I also soldered CFG2, but that wasn't useful yet.

Re: MKS LV8729 , a 128 µStep Driver // Any test?
May 10, 2017 12:06PM
I tried both CFG1 solder bridge and CFG2 solder bridge and neither mod resulted in reasonable torque, low noise and no skipped steps.

Does anyone know how to set the LV drivers in fast decay? This is the LV driver thread, there are a couple of other threads on TMC2100.


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