[dck]

Hello,
I'm working on a retrofit project for a plasma cutting machine.
In the retrofit I am using 50Kgf stepper motor, 5: 1 planetary reducer, 35mm pinion.
However I have a problem the machine presents vibration follows the photos of the machine where it is possible to see the structure of the whole machine in aluminum.
I put a damper on the step motors, the vibration slows down a bit but still has vibration.

I would like to know if anyone has any tips on how I can remove this vibration.

Thank you!!!

[romanos1983]

hello
1 did you set a bigger microsteps on steper drive?
2 did you check to move the axis without motor attached to se if you have vibration?
3 what kind of vibration you have? consistent or random?
4 how much steps/mm you have?
5 are you using mach3? if yes with what connection USB or LPT?
6 if you have conection with LPT port what is your karnel speed ?
7 disasamble the motors to se if they vibrating

inform me and than maby i can help you

[dck]

1 did you set a bigger microsteps on steper drive? The driver is set to 1/10

2 did you check to move the axis without motor attached to se if you have vibration? The motor vibrates even without being connected to the machine.

3 what kind of vibration you have? consistent or random? The vibration is random only arises in low volocidades.

4 how much steps/mm you have? I'm using 103.93 steps / mm

5 are you using mach3? if yes with what connection USB or LPT? Yes I am using Mach3 with LPT

6 if you have conection with LPT port what is your karnel speed ?The kernel speed is 35000Hz

7 disasamble the motors to se if they vibratingwa? If the motors are disabled or stopped, there is no vibration.

[romanos1983]

1 The driver is set to 1/10
103.93 steps/mm?
without the reduction 5:1 its only 20,786 steps/mm it way too low for smooth motion you need at least 120 steps/mm(600steps/mm with 5/1 reduction) for smooth motion set your drivers to atleast 1/128 or maby 1/256.
I know it will be too slow but try it. If the vibration disappeared and the speed is too low and you want more speed buy smooth stepper or a usb board with at least 400 KHz

2 The motor vibrates even without being connected to the machine. (low resolution)

3 The vibration is random only arises in low volocidades. It vibrating at high speed too it just doing it so fast that you cant feal it (low resolution)

5 Make sure to ground everything steper drives PC ect.

6 The kernel speed is 35000Hz Make it 25000Hz if needed just to check

7 go to motor tuning in mach3 and try to raise step pulse to 5 and dir pulse to 5 (read the stepper driver manual for correct time)

8 Disable CV control in mach3 (just to check)

If after all this you still have vibration than try other PC and other BBoard

let me know if it worked cheers

[dck]

Hello,
I did the following tests:

I changed the driver configuration from 1/10 to 1/128.
The motor vibrates without being connected to the rack.
Vibration is random seed surge at low speeds, but critical at 1500mm / min
I changed the kernel configuration to 25000Hz.
I changed the dir setting and press to 5.
I disabled the CV setting on mach3.

Here is the link of two videos I made to see the problem better:

Link 1: https://drive.google.com/open?id=0Bx...GZDd1FyR3ZqSms
In this video the motor is stuck in the rack.

Link 2: https://drive.google.com/open?id=0Bx...VMzMG5HQnRfOEE
In this video the motor is not stuck in the rack.

I am grateful if you can give me some more tips.

[romanos1983]

i cant se any vibration in the video
if you mean the noice you can lower it by lowering the amperage for example if it is at 4 amp make it 1.5amp
you can change the amps from stepper drives just read the manual
Do not expect steppers to work like servos, stepper are noisy

[Beefy]

Something is definitely wrong and those motors should not be making that noise.

The problem is between the PC and the stepper motor.

Microstepping of 10 is quite normal and will not cause vibration. You do not need to go changing it to higher than that. A higher microstepping value will cause a loss of torque (Google microstepping and torque). It will also require Mach to give out a much higher step pulse frequency. Leave your microstepping at 10.

Steppers are not noisy. Yes you can hear them compared to servo motors but they do not make the sound that yours is making. I use Gecko G203V drives and at rest my steppers are extremely quiet. As they speed up you can hear them but it is not noisy.

You need CV (constant velocity) for plasma cutting. In any case that would not change the step pulse output stream when your motors are at standstill. Put that back to CV.

I've calculated your steps/mm and they seem correct. This is based on microstepping of 10, the pinion diameter and gear ratio, and assuming your stepper motors have a typical step angle of 1.8 degrees (200 FULL steps/revolution). My plasma table actually has steps/mm of about 104 on one axis and 93 steps/mm on another. My microsteps are at 10. My motors are completely silent at rest.

Try disconnecting the step signal input from your stepper drive. Does the motor still vibrate ?? If the vibration continues you have narrowed the problem to either the stepper drive or the motor.

Is this problem the same on EVERY motor or just this one ?? Can you take a motor which is good, and change it out with the vibrating motor. Do you still get the same problem. If the good motor vibrates, either the wiring to the motor is wrong OR the stepper drive has a problem. If the problem is now gone, then either the motor was bad or it was wired wrong.

You do not need a smoothstepper with a frequency of at least 400 Khz. Mach3 using the parallel port has more than enough speed to drive steppers using 35 Khz. My system has similar specifications to yours and runs my steppers up to 10,000 mm/min. I am just using the parallel port. A smoothstepper is an external motion controller. It buffers the step and direction signals so that there is no interruptions caused by the Windows operating system. When using a parallel port you are relying on Windows not interrupting what Mach3 is doing. So long as you install Mach3 correctly and do not have anything else running on your PC it's normally fine. You do sometimes get a PC which does not work well with Mach3. However, I don't think this has anything to do with your motor vibrating even while it's at rest.

Regarding stepper motor amps. If you reduce your motor amps you are reducing your torque, that is not what you want. If your system does not have enough torque, you could end up with lost steps. Can you find any data for your stepper motors so you know their current rating. Set your stepper drives to the motor rated amperage. Higher amps than rated will not give you much more torque and will cause motor overheating. Less amps than rated and you are reducing motor torque.

[romanos1983]

hello. he didnt say that the motor vibrating at stop position
Steppers ARE noisy, did you even used other than geco steppers? i used more than 4 brands and they are diferend in noise. gecos are very quite
i know why i told him to do what i told him i have my reasons
cv must disabled during trublshoting because cv+low accelaration rate can vidrate running gcode
and also he must increase microsteps because every steps will hit the gears inside the planetary gearbox and make noise because of backlash isnide the gearbox
35khz is not enough with 1/128 microstepping you need far more to have speed at good smooth motion
also lowering the amps make stepper smother
if the amps are too high it steps more violent

those cheap steppers are noisy and 1/10 mean the full stepp of 1.8deg divide. 10=0.18deg and every stepp will hit the gears inside the gearbox
and if you make the amps too high the stepper will go with more torge to hit the gears and the noise will increase
also smoothsteppers and usb are not bufering the steps thay are generating the stepps outside the PC they are converting the gcode to puls. PC sending the gcode to the device and not pulse
its a big diferend, please do not say somthing if you dont know
you say the problem is between the PC and the stepper moto? sure it is, there is nothin left.

also everithing i sey it was wrong for you why is that?
you are draging him to wrong direction

he cant do enything for the noise exept lowering amps and increasing the microsteps or buy better quality steppers or even better servos.
also he must be sure for the ground

[Beefy]

Very interesting reasons Romanos.

So your solution to this problem seems to be to take actions that REDUCE STEPPER TORQUE, good solution.

Increasing microsteps loses torque.
Reducing motor amps loses torque.
The funny thing is a plasma table NEEDS TORQUE for fast direction changes.
You don't get rid of noise symptoms by breaking the table in another way.

Seems there's a few things you don't know too.

If you are saying there is nothing wrong except for the stepper vibration causing gearbox teeth noise, then you should explain that to dck, not give him "solutions" that break his table.

If you think the problem is in the gearboxes then perhaps the solution is changing the gearboxes. Why did you not mention that to the op instead of your table breaking solutions.

You are showing you do not understand plasma cutting if your solutions are to decrease motor torque. Sorry but that is a ridiculous solution. You gave an example of reducing amps from 4 to 1.5, in other words reduce the motor torque to 37.5%. And you say I don't know what I'm talking about.
Also considering the fact that increasing the microstep quantity also decreases torque, your "solution" reduce torque to even LESS than 37.5%.
That “solution” would mean the table would need it’s acceleration and rapid speeds drastically reducing to avoid lost steps, not very practical.

I’ve also used several different stepper motors and stepper drives and have never heard any such loud noise as what the op shown in his videos. I’ve also watched plenty Youtube videos and never heard any stepper motor sound really loud. So I don’t know what stepper drives and motors you are used to.

However nitty gritty you want to get with the explanation of the smoothstepper, that's not really relevant, but if you want to argue it OK. Mach3 is a gcode interpreter, it takes gcode and converts it to step/dir pulses. With a normal parallel port system these pulses are generated direct within windows and given to the parallel port. Windows being a multi-tasking system means it can get interrupted by other tasks and the step pulse stream can be interrupted. My understanding was an external motion controller recieved these steps from the PC and buffered them so they could be send out with perfect timing and not be interrupted like can happen with the parallel port. OK so what if I'm wrong and the SS reads gcode and generates the step pulses directly ?? SO WHAT, BIG DEAL. The point I'm making is that the op doesn't have to go and spend hundreds of dollars on an external motion controller when thousands of cnc machines with steppers are running just fine from Mach3 with a parallel port. The problem is obviously somewhere else and the solution is not buying a Smoothstepper.

And when you say you have your reasons, explain them.

For example when you say disable CV, you didn't tell the op why. And even if disable CV helped, what does he do then. This is a plasma cutting table and it must use CV for normal operation. So you need to explain what is achieved by this test and then what must happen when it has to be put back into CV mode.

Solutions:

If the gearboxes are worn and loose and amplify stepper motor vibration, change them.

If the stepper drive is rubbish and causes even a good motor to vibrate excessively change it.

If a rubbish motor vibrates even with a good stepper drive, change it.

If Mach3 / PC is giving out a bad pulse stream, sort that out. Install Mach3 as is recommended in the Mach3 optimisation guide. Disable un-necessary services. Don’t run any other programs. Is the Mach3 driver test showing good results.

But don’t go buying a smoothstepper and reducing torque to 1/3 to “fix” this problem. I think it is you that is dragging him in the wrong direction.

[dck]

I made tests today, reinstalled mach3 and reconfigured all of it and made a cable by directly connecting the drivers to the computer's parallel port.

But the problem remains the same.

As soon as possible I will test with another computer to see if it improves.

[Beefy]

What about what Romanos said, is the gearbox causing the noise. Normally these gearboxes are very low backlash and do not have "looseness" between the gears. Are your gearboxes worn and "rattley". Could be worthwhile disconnecting the motor from the gearbox and see how the vibration is then.

Are any of your motors running good or are they all the same.

As I explained earlier, if you have just one motor running good, you can use the method of elimination, and swap things around to find out which one is causing the problem.

[dck]

I have disconnected the reduction box but the vibration continues.
All engines have the same problem, all are the same.

[romanos1983]

dck increase microsteps and dicrease amp and se if its better
if not, change your PC and Bboard

[Torchhead]

I made tests today, reinstalled mach3 and reconfigured all of it and made a cable by directly connecting the drivers to the computer's parallel port.

But the problem remains the same.

As soon as possible I will test with another computer to see if it improves.

Parallel port will not directly drive any driver card. There has to be a breakout card with buffers. Parallel ports have weak pullups and are made to sink current but at logic levels. If you don't have a buffered break out board (preferably one with output isolated INPUTS) you won't get proper motion from a stepper.

[dck]

I did increase and reduce the microsteps of the driver but the best configuration where it worked best was 1/10.

When I connected the parallel port directly to the driver without the Breakout Board to do a test it worked normally.