Vibration on drive shaft - is this normal?

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Vibration on drive shaft - is this normal?

Postby pwg » Mon Mar 05, 2018 8:11 pm

I have noticed some vibration/rattling on the threaded shaft that spans the gantry from the left to the right that I don't remember the last time I turned it on. This vibration occurs when moving left to right or right to left floating above the piece. There seems to be a small amount of play at the right edge of the shaft where it enters the gantry. The machine is relatively new (arrived in January) and has been used to cut a couple of signs but has not been used for heavy work. I'd guess its been used for four hours of cutting time. My questions:

* Has anyone else experienced this?
* Is this normal - should just ignore it?
* Is there an adjustment I need to make?
* Should I be contacting New Wave about this?

Thanks,
-Phil

Edits: It is a Shark HD4 Extended bed.
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Re: Vibration on drive shaft - is this normal?

Postby Rando » Mon Mar 05, 2018 11:44 pm

It's not all that unusual for the shaft couplings to need to be tightened rather early in life. It's not entirely clear which end you're talking about, since "right edge" depends on which side of the gantry you're on. If by "where it enters the gantry" you mean at the side where the stepper motor is, then it's likely either that shaft coupling, or possibly (but much less likely) the bolts holding the stepper motor on. If it's the shaft coupler, it's pretty easy to fix with an allen wrench. Easy, especially when compared to the one under the bed...that coupling is a pain to get to.

Anyway, check the coupling; that's usually what the problem is with that kind of thing.

Also, there is also a certain set of movement speeds that will cause unexpectedly loud resonances in the machine. A loose shaft coupler will show as very large backlash; your circles will be flattened. But if you're hearing the rattle and your patterns come out okay, it might just be an issue with that resonant noise. The "medium" jog setting along the length of the bed (moving the whole gantry, my "x" axis, likely your "y" axis) make a horrible noise as it moves, that's not there at other speeds. So, that's a maybe too :D.

Regards, and hope that helps!

Thom
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A proud member of the Pacific Northwest CNC Club (now on Facebook)
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Re: Vibration on drive shaft - is this normal?

Postby pwg » Tue Mar 06, 2018 6:27 pm

Hi Thom,

Thanks for your response. In my attempt to be clear, I guess I was anything but. In referring to left and right, I was trying to refer to them in the same way as the machine moves. So in my case, the right edge is the end opposite the stepper motor. I appreciate your instructions for the end with the stepper motor (i.e tighten the shaft coupler or the bolts holding the motor) and will keep this in mind for the future. Any suggestions for opposite end. I don't see any obvious adjustment at the "motorless" end of the shaft.

Thanks,
-Phil
pwg
 
Posts: 4
Joined: Wed Jan 03, 2018 7:27 pm

Re: Vibration on drive shaft - is this normal?

Postby Rando » Tue Mar 06, 2018 9:56 pm

pwg wrote:Hi Thom,

Thanks for your response. In my attempt to be clear, I guess I was anything but. In referring to left and right, I was trying to refer to them in the same way as the machine moves. So in my case, the right edge is the end opposite the stepper motor. I appreciate your instructions for the end with the stepper motor (i.e tighten the shaft coupler or the bolts holding the motor) and will keep this in mind for the future. Any suggestions for opposite end. I don't see any obvious adjustment at the "motorless" end of the shaft.

Thanks,
-Phil


Phil:

Cool...yeah, being a tech-writer AND an engineer means I usually go through and remove as many of the "it", "that", or anything else that's not precisely and unambiguously discernible from my own posts. Unfortunately, that also means my need for over-specifying everything makes any vagueness in others' writing set of bells and red flashing lights for me :D.

At the far end, check to see if the bearing is somehow not seated properly. While it's physically possible, it would have to be a manufacturing defect for that bearing to be "bad". I suppose it's possible that the gantry's connection to the side-plates might be loose, but that's cray-cray! A mis-cut lead screw?...

One possible thought. The end-panels are hard flat surfaces. There's lots of noises going on usually when it's running. Any chance that noise/roughness you're hearing is actually noise coming from the back-right side of the z-axis carriage, and reflecting off that right-hand side? (Sorry, don't mean to diminish, just trying to pinpoint the source) If there was grunge caught in there that's hidden? I know on my machine I only rarely am far enough toward the wall to really see behind and into that bearing. I suppose check the screws all around the z-axis, gantry and the upright side-plates. For instance, if a single nut on the side-plate-to-angle-iron joint is loose and rattling?

I dunno. That's definitely the side that shouldn't cause ANY problems, that's for sure!

Hmmmm.....

Cheers!

Thom
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)
Rando
 
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