Stepper motor makes strange sound

alexp · March 16, 2019, 10:20am

HI all

I just started testing the electrical parts.

I used Ramps 1.4 on mega 2560 and DRV8825 driver modules.

Steppers: hanpose 17HS8401-S 48mm Nema17.

According to the datasheet current max is 1.7A -> I was pnaling to use (1.7/2)*0.9 = 0.765V

I was starting a bit lower.

I got the firmware flashed, and repetier host connecting to the board. Then (everything disconnected) I connected one stepper motor. I’m able to step the motor, however it sometimes starts making strange noise and looses commands. And the driver module gets quite hot. I tested everything from 0.3V to 0.8V.

So the questions are:

is it usual that the heat sink gets quite hot?
is it ok to connect only one driver to one stepper? I also tested the dual endstop firmware where every stepper has a dedicated driver
what is the safe direction regarding voltage?
at the moment as soon as i try to step for the first time, Volatge drops from 12 to 7V, the motors make a sound but nothing happens - did I fry it already?

alexp · March 16, 2019, 11:11am

What I did in the meantime:
I disconnected the stepper from the board / bower.

Can easily be turned. Closing any of the outer pairs (shot circuit them) -> much harder to turn. So this test seems OK.

I then used my lab power supply at 0.7V. One cable of a pair connected to (-) and then touching the other with (+) gives one? step in a direction.

Inverting + and - gives one step in the other direction.

For both pairs.

But no more than one step - so its always the same position one clockwise, one back. If I hit the same configuration a second time nothing happens.

Is there a sequence that I could use to get it turn further?

Alex

Edit:
Here are details to the stepper motors. I tried to simulate the sequence shown in the figure ‘wiring diagram’.

I simulated the 4 parts of the sequence individually (diconnected wires in between).

However just one step in one, and then at the overnext configuration a step in the other direction.

Might be that one needs to hold those wires at (+) and (-) not changing polarity while switching to the next phase

billsey · March 16, 2019, 8:37pm

Show us closeup pictures of your RAMPS and the wiring going in and out. Do you have all three jumpers installed under the DRV8825s?

alexp · March 17, 2019, 12:10am

Hi Bill,

here is the close-up:

[attachment file=93422]
The lower cable (blue) is Gnd, the brown +12V.

I removed the two upper DRVs to show that I have all 3 jumpers below every 5 DRVs.

alexp · March 17, 2019, 1:35am

I guess I fried one of the boards already: either the ramps (which I read should be quite robust) or the arduino (see below for more details).

The most important question for the moment is (after getting a new mega/ramps/driver kit):

How to securely test one motor? Is this procedure Ok:

flash the MPCNC_Ramps_T8_16T_LCD_32step firmware
add 3jumpers for 3 DRV’s (lower row)
add only the x DRVs (or all 3)
no resistor / no thermistor
+12V to the green connector of the ramps as shown in the pictures, check to preset the DRVs voltage to 0.7V
disconnect
connect only one stepper motor to the pins right above X DRV as shown here (but only the left most) using the sequence of cables as they come from the stepper.
+12V power up again
plug USB to the computer, in repetier host connect, after connect in the manual control:
do I have to configure Feedrate / Fan / Bed Temp / Extruder Temp?
send 1mm step in X

Is this correct?

I followed this sequence, however

a) I used the dual endstop firmware

b) hat all 5 DRVs installed

c) had the stepper connected to the 4 pins right above X2 as shown in the picture

[attachment file=93427]

Did I do something wrong?

The first minutes, the motor was following the commands in the correct direction (+x / -x) as expected, however it did not execute each command send from the repetier host and the motor made some strange noise.

After a while I guess something got to hot / fried, because now, I can connect from repetier. But as soon as I’m sending the first step command, voltage drops from 12V to 7V (as my lab power supply indicates). The motor still makes a strange sound. This is the same for a second motor. I checked the motors as described in the previous posts, they seem to be OK.

Any idea what got fried?

I can flash different software (blink, fimrware), can connect via repetier. Only when I send a command to a connected motor the voltage drops.

Should I now order the same kit again (with the DRV8825) or could it be that the motors don’t work well with these and I should order a set with A4988?

ponydevil · March 17, 2019, 5:38am

You check current on stepstick?

alexp · March 17, 2019, 5:59am

what is stepstick?

i can see the current on the lab power supply.

at the beginning it was about 2A - 3A with engaged motor - which i think is way to much.

now - since voltage drops its below 1A.

when i connect a pair of the stepper cable directly to the lab supply it consumes only 0.3A

ponydevil · March 17, 2019, 6:28am

Current limiting

for nema17 that we normaly use for mpcnc its about 0,8

alexp · March 17, 2019, 8:12am

Ah, and the strange sound was also present in standstill with motor engaged. I thought it should have steady supply in standstill or is it pulsed somehow?

billsey · March 17, 2019, 11:10am

It’s normal for an activated stepper to have a buzz or whine even when not moving. I don’t see any obvious problem with your setup and you shouldn’t need to bring it up one at a time. Normally for a dual end stop build I’d put all five drivers on, connect all five steppers and test movements. If a motor was moving backwards I’d power down fully and reverse the wires. The drivers should be set to 0.7V and they will get warm, but not hot enough to burn fingers. I’m betting your RAMPS had a soldering or component problem. You should never see a voltage drop from 12V to 7V even with all steppers moving at once. It could have been a power supply issue but the RAMPS and Megas have been problematic the last couple of years. The Chinese cloners have been cutting quality in order to get the prices lower.

alexp · March 17, 2019, 11:33am

Ok,

thanks. I ordered a new set. I would really have liked to one of the better boards, but this seems not possible for germany.

Is there any fine tuning necessary for some steppers (in the marlin software)?

Could it be that I ordered ‘critical’ steppers?

And how about the feedrate and other setttings in repetier: do I need to adapt these before sending the first command?

vicious1 · March 18, 2019, 4:54am

No, follow the crown tutorial for some good basics.

https://www.v1engineering.com/assembly/software/

alexp · March 18, 2019, 11:45am

Hi Ryan,

thank you. I overlooked the link to the settings of repetier. It’s all so much information…

I hope to get the second control set tomorrow.

Just to be sure:

In order to check the motor safely, can I start with a small voltage setting at the DRV or might I be damaging anything doing so?

I could also limit the Amps delivered by my power supply (and it indicates if limit is active). So I would start with lets say max current delivered to the board limited to 1A and start wit a setting of 0.4V…

And I should be able to quickly disengage all steppers using M17 - right?

I’m afraid to fry the next set in a second (by the way i must say that I did lots of microcontroller things a few years ago, and never ever killed a single chip; so this ‘new experience’ irritates me quite a bit)

Alex

vicious1 · March 18, 2019, 11:50am

Do not touch or unplug anything while powered up, when adjusting the pots use the utmost care not to short anything. Setting them at 0.7V is probably what you need.

alexp · March 18, 2019, 12:32pm

OK. So I’ll start with 0.7V. The voltage has been quite stable (between setting without motor plugged and engaged motor).

Lets hope it was all due to an already disfunctional part on one of the boards…

alexp · March 19, 2019, 9:30am

Hey guys,

you will not belive it: I received a new controller set today, set-up everything carefully, activated the steppe -> same problems again.

~

After checking if its the lab power supply, the laptop, different stepper motors (of the same series) etc. I made the following test:

configure the DRV Voltage to extremely low value (below 0.1V)
activate the stepper motor, check current drawn by the board (which is dominated by the stepper motor)
increase voltage slightly up until current is about 0.4A

=> the motor does what it should without standstill noise / with little noise (depending on the board i use).

The voltage at the DRV I measure is really small (about 0.13V - 0.2V). So the default 0.7V is just way to much.

~

As stated above, I’m not a newbie to electronics, know how to measure current and voltage, my equipment is good.

So can you believe this?

edit:

The steppers seem to work well at 200mA. When I configure it to have 600mA, the heat sink gets quite hot -> I think I will use a lower value. Will I get some problems with such a low current? Steps lost?

alexp · March 20, 2019, 10:15am

No feedback on my findings?

I would suggest to propably add a text to the assembly instructions of the form:

If you are unsure about the motor Voltage settings do the following:

connect a current meter between the power supply and the controller board
configure the Voltage of the drivers to a very low value
connect one stepper at a time
power up, engage one stepper
carefully increase voltage of the related driver module until the measured current is about (what do the experts mean?)

You should end up at ~0.7V, but for some steppers, much lower values might be resulting

Something like that would have saved me lots of time ,worries and money (for the second controller board)

What do you think?

billsey · March 20, 2019, 1:43pm

Alex, is there any chance you are measuring the driver voltage wrong? It just seems weird that you would find it working at 0.13-0.20V when everyone else is at 0.7V. Can you fire us off a picture of you measuring the voltage? Show both the + and - leads.

alexp · March 21, 2019, 8:55am

Hi Bill,

my approach should be fine. Following some pictures (sorry for the blur):

My voltmeter at 0.7V and 9V lab power supply and voltmeter show ~ the same value:

[attachment file=94052]

[attachment file=94053]
Stepper not yet engaged, however connected: 12V at the lab power supply, small current 0.03A

0.24V between potentiometer and Gnd

[attachment file=94054]

Stepper engaged, 0.4A

[attachment file=94055]

Still 0.24V

[attachment file=94056]

At the moment I have the current set to 0.5A (0.26V), as above the heat sinks of the DRV gets quite hot.
What is the current you others allow for when using DRV8825?