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torch vibrates when moving slow

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cruz
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torch vibrates when moving slow

Postby cruz » Mon May 28, 2018 2:45 pm

hi everyone,

i've noticed something with my plasma table,
when cutting something with a "lower" speed the torch and torch mount vibrate.
this is only noticeable when it's moving in both (x and y) directions.
if i bump the speed up it gets way less worse.
with a speed of 3000mm/min it vibrates alot (small fast vibrations)
when i go up to 5500mm/min it's noticeable less

this may sound weird but i'm not sure if it has servo or stepper motor,
if needed i could take picture of the motor setup.

is this something in the motor tuning or is it in the machine build up (not rigid enough)?
or does anyone have a idea where the problem lies and could be solved

thank you!

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WyoGreen
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Re: torch vibrates when moving slow

Postby WyoGreen » Mon May 28, 2018 4:16 pm

It would help if we knew more about your table and plasma cutter.
Precision Plasma gantry
CommandCNC Linux controller w/Feather Touch & PN200 hand controller
HT-45 plasma cutter
Plate Marker
CNC Router table

cruz
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Re: torch vibrates when moving slow

Postby cruz » Mon May 28, 2018 5:05 pm

well i'm from europe, belgium so my machine/brand may not be known with you guys.
its a 5x10 water table with a floating head plasma cutter is a hypertherm powermax105.
i'm using inventor 2017 pro for cad sheetcam and mach3 for post processing and controlling the machine.
it has double motors for the y-axis i'm pretty sure they are stepper motors.
torch is mounted with a break away magnet.

hope this helps

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tcaudle
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Re: torch vibrates when moving slow

Postby tcaudle » Mon May 28, 2018 6:00 pm

Put your hand on the taorch as it moving slow and see if you can feel the vibration. Touch the gantry and also the cross carriage. What is your Step per unit setting in MACH for the XY axis? If the drivers are not microstepping at low RPM they "cog". The Steps per unit will tell us what the gearing looks like.

cruz
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Re: torch vibrates when moving slow

Postby cruz » Mon May 28, 2018 6:24 pm

i already put my hand on the torch that's how i knew it.
the vibration is the worst at the torch and the torch mount.
i'll check the step per unit tomorrow, it's a little bit late now here (00:20) :).
i'll aslo take pics of the motors maybe someone here can do something with it.

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steel 35
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Re: torch vibrates when moving slow

Postby steel 35 » Mon May 28, 2018 7:11 pm

The guy that can has already asked you Questions :mrgreen:
PPL HDG 4X8
Hyp 65 duramax's
C&CNC 620-5 Ethernet
Inkscape, Solid Edge, Sheetcam, Autocad 2K
Corel X7 Student NO DXF!

cruz
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Re: torch vibrates when moving slow

Postby cruz » Tue May 29, 2018 12:47 pm

here's a link to a video a took while the machine was moving.
https://mega.nz/#!GPJwwSIb!Bv8JHZdQeZlQ ... rmypSnujMI

here are some pics of the step per unit setting in mach3 and some pics of the motors.

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tcaudle
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Re: torch vibrates when moving slow

Postby tcaudle » Tue May 29, 2018 6:27 pm

May be time to contact the table vendor. I don't see anything in the tuning that would indicate its a really course interface (like direct drive. In mm its pretty fine reoslution so it should run pretty smooth at 1500 mm/min or more. Just for fun tunr on the motors so they are locked and try (hard) to move each axis back and forth. It should not have any slop .
So has it always been rough at low speeds?

If none of that works it may be time to start puling motors off and runnign them on the bench to see if they are rough off the table so you are not runnign in circles. When you ahve them off move the axis by hand . Should be nice and smooth.

cruz
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Re: torch vibrates when moving slow

Postby cruz » Tue May 29, 2018 6:41 pm

by turning on the motors you mean to just start the machine and the pc with mach3?
one thing i forget to mention is that the machine has no limit stop.
i have had few oops moment where i went to for in one of the axis (x and y).
but the machine was still accurate after that.
do you guys thinks the noise that the machine makes whens running is normal?
is it not way too noisy and vibrating?

cruz
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Re: torch vibrates when moving slow

Postby cruz » Wed May 30, 2018 2:17 pm

okay had some time today to look at the motor and drive mechanism.
y-axis is a belt from the motor to the rack and pinion, also it has 2 motor for y-axis which are connected with a solid axle to prevent distortion.
x-axis is now the main problem i think it's a direct rack and pinion connection.
the x-axis is giving the most if not all the vibration when moving at "slower" speeds.
had the x-axis motor of the gantry and checked for any roughness, but it was all good to me.
i know someone said the motor setting in mach3 looked good, but is there something i could change in those settings to help with the vibration??

cruz
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Re: torch vibrates when moving slow

Postby cruz » Thu Jun 07, 2018 8:20 pm

i'm at a lost here, i only notice the vibration when;
- mach3 is running a G-code (no vibrations when jogging the machine)
- when it's moving the y and x axis at the same time
- only really noticeable at the speed of around 3000mm/min

the motors are okay, no play in them.

here's the G-code.
i read somewhere it could be that some line are segmented instead of arc?

N0010 (Filename: test driehoek.tap)
N0020 (Post processor: Mach3 plasma.scpost)
N0030 (Date: 06/06/2018)
N0040 G21 (Units: Metric)
N0050 G53 G90 G91.1 G40
N0060 F1
N0070 S500
N0080 (Part: New part)
N0090 (Operation: Outside Offset, Shape, T11: test)
N0100 M06 T11 F3000.0 (test)
N0110 G00 Z10.0000
N0120 X38.0791 Y-2.3843
N0130 Z2.2500
N0140 M03
N0150 G04 P0.4
N0160 G03 X38.0061 Y-1.6391 Z1.5000 I-3.8400 J0.0000 F500.0
N0170 X34.2391 Y1.4557 I-3.7670 J-0.7452 F3000.0
N0180 G01 X11.0855
N0190 X0.9391 Y11.6022
N0200 Y1002.3093
N0210 X1001.7926 Y1.4557
N0220 X34.2391
N0230 X30.2391
N0240 G03 X27.6791 Y-1.1043 I0.0000 J-2.5600
N0250 M05
N0260 G04 P0.5
N0270 G00 Z10.0000
N0280 M05 M30

tcaudle
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Re: torch vibrates when moving slow

Postby tcaudle » Fri Jun 08, 2018 2:09 pm

The clue is in what you said at first. Jog and different speeds and see. So what is the difference in MACH when its jogging versus running code? well if its a parallel port based system and MACH is generating the steps (not through an external motion card), then when running code it has to do all kinds of math and that puts overhead on the processor . That in turn messes with the pulse train and it "jitters" The slower the PC the worse it gets. The more background processes it has running the worst it is. There is a reason the "Smooth Stepper" card was invented. It took the overhead off MACH3 to generate the motion (steps) in real time and moved into an external processor. So you need to have a look at the system and see how it connects to the controller. If its a thick computer cable (DB25) its a parallel port .

Can it be fixed? well generally Yes. It need s faster PC and/or MACH needs to be optimized for Windows using their white paper.

You may also want to look at the post to reduce the precision if you are running in mm. no plasma machine can hold 4 decimal places in mm. Even two places for mm is pretty tight. you have to do that in the POST where it defines the number of decimal places sent for each line.

Can I assume this machine has no THC? There is nothing in the code for a touch off or a separate pierce height versus cut height, There are only two Z moves. One up to 10mm and one down to 2.25 mm and the torch fires. Maybe its the wrong POST ?

cruz
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Re: torch vibrates when moving slow

Postby cruz » Fri Jun 08, 2018 2:32 pm

tcaudle wrote:The clue is in what you said at first. Jog and different speeds and see. So what is the difference in MACH when its jogging versus running code? well if its a parallel port based system and MACH is generating the steps (not through an external motion card), then when running code it has to do all kinds of math and that puts overhead on the processor . That in turn messes with the pulse train and it "jitters" The slower the PC the worse it gets. The more background processes it has running the worst it is. There is a reason the "Smooth Stepper" card was invented. It took the overhead off MACH3 to generate the motion (steps) in real time and moved into an external processor. So you need to have a look at the system and see how it connects to the controller. If its a thick computer cable (DB25) its a parallel port .

Can it be fixed? well generally Yes. It need s faster PC and/or MACH needs to be optimized for Windows using their white paper.

You may also want to look at the post to reduce the precision if you are running in mm. no plasma machine can hold 4 decimal places in mm. Even two places for mm is pretty tight. you have to do that in the POST where it defines the number of decimal places sent for each line.

Can I assume this machine has no THC? There is nothing in the code for a touch off or a separate pierce height versus cut height, There are only two Z moves. One up to 10mm and one down to 2.25 mm and the torch fires. Maybe its the wrong POST ?


i did the driver test that came with mach3, it came out perfect (if that's relevant).
to be honest i don't think it's the pc, it's a dedicated pc just for sheetcam and mach3.
and sheetcam is closed when running a code also i've done a few thing to help the pc like setting it in the basic theme and turning of background processes that it doesn't need for mach3.
it is a parallel port system.

the table does have THC (Compact THC Controller 150)
but the post processor i was told to use says it's without thc wich sounds weird to me.
i use the mach3 plasma post processor that came with sheetcam.
is that a good one or do i need to use another one?

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Re: torch vibrates when moving slow

Postby BTA Plasma » Fri Jun 08, 2018 2:51 pm

If your step is too course or your gear motion is sticky like some profiles you will get a ton of vibration at low speed.

cruz
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Re: torch vibrates when moving slow

Postby cruz » Fri Jun 08, 2018 2:56 pm

BTA Plasma wrote:If your step is too course or your gear motion is sticky like some profiles you will get a ton of vibration at low speed.

you mean "steps per"? these settings is what it came with from the factory.
i also calibrated all the axis with mach3 and came out with the same step per.
what do you mean by sticky gear motion?

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Re: torch vibrates when moving slow

Postby BTA Plasma » Fri Jun 08, 2018 3:32 pm

What are your steps pre. With the power off and the motors unplugged does the carriage move freely without binding?

cruz
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Re: torch vibrates when moving slow

Postby cruz » Fri Jun 08, 2018 3:37 pm

BTA Plasma wrote:What are your steps pre. With the power off and the motors unplugged does the carriage move freely without binding?

i've loaded pictures up of my motor settings, they're at the top of this page.
for y and x axis the step per are 187,25
for the z axis it's 2468.
but look at the pics i uploaded so you can see the other settings.

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Re: torch vibrates when moving slow

Postby BTA Plasma » Fri Jun 08, 2018 3:54 pm

187.25

If it is 187.25 your minimum step is .0053. That is far too course for smooth motion. Must be direct drive with a large gear.

cruz
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Re: torch vibrates when moving slow

Postby cruz » Fri Jun 08, 2018 5:11 pm

huh...?
perhaps we are missing each other here.
i'm from belgium, not the usa those settings are in metric.
or am i not understanding something?
the y and x axis motors are belt connected to a gear rack and pinion.
z axis is directly connected to a rack and pinion.

tcaudle
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Re: torch vibrates when moving slow

Postby tcaudle » Sat Jun 09, 2018 2:33 pm

Its all in mm . Converted to IPM it has plenty of resolution. So if its not the mechanics and not the PC then I guess its not happening.
Parallel port systems had motion issues and they are often subtle. Windows gives priority to communications over other processes. MACH3 grabs the system clock and hijacks it to send lots of pulses per second. Windows can prempt that using a higher priority. Sone things can cause ragged pulse streams. Its more obvious on slower feedrates because you do not have the inertial forces that tend to smooth out in higher RPM's Then there is low speed resonance. Some Stepper drives have anti-resonance tuning that takes care of that at low RPM.

cruz
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Re: torch vibrates when moving slow

Postby cruz » Sat Jun 09, 2018 3:28 pm

that's what i'm confused about
i was thinking it was something in the software mach3 or sheetcam.
i'll try to turn off more processes in windows which are not required.

the reason i don't think it is the machine itself is because it's a new machine that was checked before delivery, and i trust company from where it came.

i'm also beginning to think that i am being too demanding from a machine with stepper motor running on mach and sheetcam.
for now i don't have anything to cut, when i have i'll upload some pics to see if they are within the capabilities of a machine like mine.

thanks alot guys.

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Re: torch vibrates when moving slow

Postby all names have been taken » Mon Jun 11, 2018 10:07 pm

Hello,

I really hope you find the problem. I know it can be frustrating. A couple of observations. Right off the bat, someone told you that you are currently talking to the guru. Yet, you readily dismissed all his recommendations. That is not a viable way to get continued support.

You also stated that you didn't believe it could be your machine nor your pc because you completely trust the people that sold it to you. Yet, you are here looking for tech support instead of the people you trust. The people you trust sold you a system that uses parallel ports and windows. I don't think they did you any favors there.

cruz
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Re: torch vibrates when moving slow

Postby cruz » Mon Jun 11, 2018 10:38 pm

I'm sorry if I am coming across as not willing to take advice, if that was the case I wouldn't be here.
I answered everyone's questions to my best capabilities.

I've not been able to contact the vendor, up until this issue he's been very helpful with aiding me regarding the table.
But now I've been trying to get a hold of him for a week without success.
It's the case where he's taking to much on his plate I think.

To try explaining myself better (remember English isn't my native language :)) :

I've never trusted any part of my cnc plasma system regarding this problem but I do have a list(that is constantly changing) of possible cause of the problem.
I've posted this problem also on a Dutch forum with all the info and help I got I made conclusions.
with the basic or non existing experience I have in this field it might seem like I'm being arrogant or stubborn.
Apologies for that that's not my intention.

I appreciate the help I've been getting from this community.
It's great to have a community where you can get help so easy from people who alot about it.

Thanks again everyone


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