Is cncrouterparts ok ?

[SpacedCowboy]

I'm having some difficulties with some of the stepper motors they sent me, and I'm not getting any replies back to emails I've sent them. Here's the first email I sent a few days back:

Hi there,

I recently (1/21) bought 3 motors, the appropriate cables and a PSU from you (order #2230), to use on my K2CNC KT2514 router.

After I attached the motors to my G540, I noticed that jogging the router down any axis would work, but I'd randomly get "clunks" from the router table. There was no visible jerk, but I would always get something. I was jogging at 30ipm, so I tried slowing things down until I could no longer hear them - at 3 ipm there were no detectable clunks doing a (0,0)->(10,0)->(10,10)->(0,10)->(0,0) cycle. At 5ipm I could still detect them.

There's a video showing what I mean at http://0x0000ff.com/video/k2cnc.m4v - you have to wait a little while, but there's 6 or 7 clunks in the video.

So, I called K2CNC, and they suggested a few things. One of them was to run the motors without being attached to the router. This morning I disconnected Z and X and tried running at 30ipm, and I could still hear the "clunks" even without the CNC machine attached - you can see a photo of the motor settings at http://0x0000ff.com/k2cnc/30ipm.jpg and hear the audio at http://0x0000ff.com/k2cnc/30ipm.mp3 - the audio was recorded using my cellphone, so you may have to turn up the volume. The "clunk" is about 20 seconds in.

Just to see if there was a running-too-slow issue, I tried turning up the ipm to 75 (see http://0x0000ff.com/k2cnc/75ipm.jpg) and this time the motor "clicked" (I guess a high-frequency "clunk" is a "click"...) every second or so; finally, about 34 seconds in, the motor stalled. You can hear the audio at http://0x0000ff.com/k2cnc/75ipm.mp3 - same caveats apply, you'll probably have to turn the volume up...

People are reliably running this sort of CNC machine at ~60ipm, and certainly an unloaded motor ought to be able to sustain 75ipm without stalling, so something is up. Over to you...

Simon.

I've not heard bad things about them, so am I just being unlucky or is this typical ? The frustrating thing is that there's no phone number I can find on their site - it's all email-based, and they're ignoring my emails!

Simon

Update Yes, it turns out that they are - see below for their reply, and they followed through in email as promised. Looks like it was just a mixup due to spam filtering.

[hub]

I have no experience with that vendor.
But I think you are experiencing resonance problems. I had/have it too on my steppers.. It seems to be very common.
There are ways to fix it, like adding a damper to the motors for example.

Hub

[ger21]

Clunking steppers can be caused by resonance, or PC issues as well. It's very unlikely that you have defective steppers.

What kind of drives are you using?

[SpacedCowboy]

The driver is a Gecko G540, attached via cncrouterparts' low-AWG 9-way cables to cncrouterparts 380 oz-in steppers. The whole thing is being driven by Mach3 (although it's a demo license at the moment, so the max frequency it'll run at is 25KHz. I wonder if it might perform better at a higher clock...)

The steppers are supposed to have the correct resistors already applied internally, makes for easy wiring...

Gecko suggested it might be the PC as well (which would suck, because I bought the PC specially for this purpose). I'm going to try a different PC (yay!( at the weekend and see if I get the same issues.

As for "damping", how does one go about adding a damper to the motors (as suggested above). What is a 'damper' for a motor - just more mass ?

What's disappointing is the lack of response - even if it was just to say "Nah, doubt it's our stuff". Just being ignored doesn't sit well...

Simon

[ger21]

If it's a dual core PC, try disabling C1E or EIST in the bios.

[ahren]

Simon,

Apologies for not getting back to you -- I saw this post and went back through my email but couldn't find your messages. Turns out they got spam filtered, and I'm not sure why.

Anyhow, I'd agree this is most likely a PC issue. I'll do some more searching as well and send you an email response so we can continue the dialog there.

Best regards,

Ahren
CNCRouterParts

[Bob La Londe]

Ahren has been fairly responsive for me. I've bought two sets of motors and 1 G540 from him as well as a few power supplies.

[SpacedCowboy]

Ahren got back to me as promised, and sent a very useful document via email. I'll see if I can tune the PC to stop screwing up the movement. Its a Windows-7 PC, so there may be newer reasons (the document deals with XP/Vista) but it'll give me somewhere to start.

I also modified the first post to suit, in case people don't read this far...

Simon

[hub]

The driver is a Gecko G540, attached via cncrouterparts' low-AWG 9-way cables to cncrouterparts 380 oz-in steppers. The whole thing is being driven by Mach3 (although it's a demo license at the moment, so the max frequency it'll run at is 25KHz. I wonder if it might perform better at a higher clock...)

The steppers are supposed to have the correct resistors already applied internally, makes for easy wiring...

Gecko suggested it might be the PC as well (which would suck, because I bought the PC specially for this purpose). I'm going to try a different PC (yay!( at the weekend and see if I get the same issues.

As for "damping", how does one go about adding a damper to the motors (as suggested above). What is a 'damper' for a motor - just more mass ?

What's disappointing is the lack of response - even if it was just to say "Nah, doubt it's our stuff". Just being ignored doesn't sit well...

Simon

If your problem turns out to be resonance, read this for example: http://www.cnczone.com/forums/steppe...er_damper.html

Also during my tests, if I used high microstepping @ 64 or more the steppers started to "clunk" & make weird noises.

[SpacedCowboy]

If your problem turns out to be resonance, read this for example: http://www.cnczone.com/forums/steppe...er_damper.html

Also during my tests, if I used high microstepping @ 64 or more the steppers started to "clunk" & make weird noises.

Thanks - that's very interesting

Cheers
Simon.

[SpacedCowboy]

I'm now pretty sure it's Windows 7 that's causing me grief.

After trying all the things in the Probotix note Ahren sent, but still not getting anywhere, I was playing around with the frequency of the clock in Mach3 (it appears you can change the clock frequency from 25kHz, even though the manual says you can't) - I was thinking that using a different frequency might influence any resonance issues I had...

Changing it to a higher frequency (I tried all the way to 100kHz) did seem to have an effect - the clunks on the unloaded steppers got farther apart even at higher ipm speeds. Encouraged, I tried playing with other things in the motor tuning section (different clock/direction pulse widths etc.) but I couldn't get rid of that 'clunk' every few seconds.

That's when I noticed the disk drive light would blip on pretty much every time there was a clunk. Sometimes it blipped on and there wasn't a clunk but pretty much every time it did clunk, the drive-access light was lit. Sometimes it seemed to be +/- 1/10 of a second or so (which is odd) but the coincidence seems to strong to ignore. Certainly it was suspicious enough to investigate. What makes it seem more likely was that when the motor stalled, there was normally significantly more disk activity than usual. Again, not a 100% match-up, but this would be pushing coincidence to ludicrous levels.

So I tried turning off everything I can find on Windows-7, but I can't find the elusive app/service that's tickling the disk every 2 seconds or so.

At this point, I'm thinking I have a few options:

• Ditch Windows, install Linux and try using EMC2 or LinuxCNC. I've heard EMC2 is complex to use, but at least I'll probably understand the backround processes a lot more than under Windows - I come from a Unix heritage.
• Try to find out what [insert your favourite curse word] process is causing me so much grief under Windows. I've already tried switching everything off I can find though...
• Try going back to the simpler Win-XP or [shudder] Vista, and see if they have the same problem

I can't be the first person to try Mach3 with Windows-7, so I'll try looking on their support pages for hints, but at the moment, I'm pretty down on Microsoft...

Simon

[P.Passuello]

If your problem turns out to be resonance, read this for example: http://www.cnczone.com/forums/steppe...er_damper.html
.

The beauty of the G540 is that you don't need mechanical solutions to combat midband resonance. The Gecko has adjustments for each stepper to fix that problem.

Hope you find the cause of your problem. I recently saw a similar issue to yours with the machine making a clunking noise as you described. The solution was as Ger21 suggested.

Ger21 If it's a dual core PC, try disabling C1E or EIST in the bios.

Will be interested to see what you find.

Cheers
Peter