[grossmanator]

I am new to CNC and I just bought a K2 2514 router straight from the manufacturer. I have set it up with steppers and a G540. I am happy with it in almost every way. Two concerns though:

First, it makes a weird rumbling noise when I move it in the x direction (longest axis). The noise is most pronounced when I do a G0 jog in the x direction. It also only occurs when the machine is about 2/3 down the x axis. Meaning when the axis is all the way down at either end of the table, I can jog and it moves very quietly. Both other axes move silently. Also, I can stop the rumbling noise simply by pushing on one side of the gantry as it moves. I have to push it in a specific direction though. I think it might be coming from the lead screw as I have gently pushed the lead screw as it is jogging and I can get the noise to stop.... This leads me to my second question:

Every once in a while my CNC makes popping noises. I think I have narrowed the origin of these noises to the kerk lead screw nuts. Is it possible that the anti-backlash mechanism is compressing and then all of the sudden uncompressing? Could it be that they need to be lubricated? Do lead-screws need lubrication?

thanks for any insight,

- Will

[cabnet636]

3in1 oil and lubricate first!!

jim

[grossmanator]

Thanks for the reply but could you be a bit more specific. Do I oil both the linear bearings and the lead screws?

[cabnet636]

my machine has hiwin bearings and when you said ticking i ahd heard that before so i oiled the bearings and the rails, solved my problem

the ticking was odd but it went away

jim

[grossmanator]

I have posted a video of my machine on youtube. Please watch it to listen to the problems I describe below.

[ame="http://www.youtube.com/watch?v=0_29A4UmZ4M"]YouTube - CNC[/ame]

Here is a video of my CNC in action. You can hear the popping noises every once in a while. These popping noises occur on all three axes. I think they are originating from the kerk anti-backlash nuts. The low rumbling noises occur only at certain times and only on the x-axis (left to right in the video). As always, when I went to film it, the axis stopped making the noise on its own. But I am still able to induce the noise simply by gently pulling on the axis. You’ll notice that I pull in the same direction each time and that pulling in the opposite direction (pushing) eliminates the noise. It seems that the rumbling only occurs when the gantry is near the middle of it travel.

Has anyone seen this type of behavior before? If anyone has any ideas about what either of these two noises could be, please let me know. Misalignment? Lubrication? I am new to CNC and so I don’t have a clue. Also, what can I do to fix these problems?

Thanks!

[stevespo]

Have you figured out what the noises are? Called K2 tech support? Did oil/grease help?

Steve

[grossmanator]

Have you figured out what the noises are? Called K2 tech support? Did oil/grease help?

Steve

Allright, I'm pretty sure I figured out what was wrong. I contacted the guys at K2 and they were very prompt in getting back to me. They had me try several things including tightening the lead screw nut (essentially stretches the lead screw) and readjusting the block that holds the kerk nut. But what really helped was while I was doing all this I found that one of the bolts for the kerk nut was completely loose and the other two bolts could have used some tightening as well.

After tightening up the kerk nut, I decided to also tighten the the lead screw nut to put more tension on the lead screw and minimize whipping. After these two tasks, the machine ran much much better. I also tensioned up the y axis lead screw as I could feel it move slightly when i pushed or pulled on it.

moral of the story here is check all your bolts before you go on to more complicated solutions.

It's worth noting that before doing any of the above, I tried lubricating the leadscrew and this reduced the noise a little, but did not eliminate it.

Also, I want to say thanks to the K2 people for responding quickly to my questions and helping me out. All in all I think I have a very good router now.

- Will

[Mangus]

I have the exact same problem, and find that it's worse (read: easier to induce) when moving the long axis faster than 40 ipm. I have my rapids set to about 80 ipm and at that speed the long axis groans away when the nut gets about 1/4 of the way down the screw until about 3/4 down. Lubrication doesn't help.

I'll double check to make sure nothing is loose, including the screw tension, as you suggest. I'm dubious that the screw tension should be increased much, as the end plates probably can't handle too much stress in that regard.

I'm curious to know - in the video, you're moving the gantry quite slowly. If you speed it up a bit (with proprly set, slow accel/decel), can you get it to groan even after your adjustment? I'm betting yes, but hoping no.

-Mark

[grossmanator]

I think I figured out where the problem is coming from. I disconnected the lead screw of the x-axis (long axis) from the gantry such that the gantry could slide freely in the x-direction. I then did a G0 rapid on the x-axis such that if the leadscrew were still attached to the gantry it would go 40 ipm (400 rotations per second for my leadscrew). At this speed, it is easy to watch the leadscrew and see if it is out of true. I found that my leadscrew wabbled a significant amount indicating that it was not straight. This means that the nut is subjected to a sine wave like friction force (as the leadscrew moves further and closer to the true alignement position of the nut). I'm almost positive that this sine way like force is the cause of the noise! I'd be interested to know if you see this behavior as well.

Also, do you get noise from any of the other axes?

[Mangus]

Yeah, all 3 axes make the noise during faster moves. The long axis leadscrew is definitely out of true, but I'm not sure that this would be the direct cause. It may be what starts the resonance, though.

[grossmanator]

Yeah, all 3 axes make the noise during faster moves. The long axis leadscrew is definitely out of true, but I'm not sure that this would be the direct cause. It may be what starts the resonance, though.

I think I said this before, but to reiterate, I found I could eliminate the vibrations/noise if I held onto the leadscrew nut while it was moving. Just a gentle squeeze on the nut was all it took. I have been thinking about potential fixes and I think one solution could be to put a rubber band around the nut. This would squeeze the nut and cause more friction, but might help eliminate the vibrations.

[Mangus]

If I put some pressure on the leadscrew the noise stops as well. I think doing either simply dampens the vibration and breaks the resonant feedback; I'm not sure it's actually doing anything diagnosticly.

[grossmanator]

If I put some pressure on the leadscrew the noise stops as well. I think doing either simply dampens the vibration and breaks the resonant feedback; I'm not sure it's actually doing anything diagnosticly.

I agree. I think the lead screw and nut are resonating at the natural frequency of the system. By putting your finger on the nut, you are changing the natural frequency of the system and thus drastically reducing the vibrations. My rubber band solution would only change the natural frequency of the system and not fix the source of the vibrations.

[Mangus]

The rubber band probably doesn't have enough relative mass to make a measurable change to the resonant frequency of the system.

I think there are other things at play (friction, most likely) that need to be fixed. Fix that, and you've solved the noise problem.

I look forward to digging into the issue. I'm having more fun playing with and perfecting the machine than I am cutting things with it. I suppose that's a luxury of it being a hobby and not a job.

[grossmanator]

Yeah I look forward to it as well. Could you give some specs of your machine: steppers? servos?, what type of drivers?, router tool, mach 3?, etc...

[RedLabel]

Hi, It was an interesting thread, I read it before my purchase hoped that mine would not have the same problem. But at high speeds(Im talking about 100ipm, although my drive and steppers could pass 200ipm with ease this machine is not built for those speeds) the same (even worse).

So I want to join the club of people with noisy 2514's , may i ?


Did you guys solved the resonance problem(That explanation seems logical), or better yet solved the vibration issue.

I'm going to contact K2 tomorrow but it would be nice to hear from you.

[grossmanator]

Welcome to the club.

I never did come to a solution except slowing my machine down to about 35 ipm max speed on each axis. Recently I haven't had time to work on a solution. I haven't heard from Mangus in a while so it will be good to talk to someone who can relate to the problem. I'd be interested to see the specs on your machine (steppers? drivers? software? etc). Can you post?

I think that Mangus and I were correct in our conclusions. The problem stems from frictional vibration at the natural frequency of the system.

Hopefully now that one more person is in the same situation we can all find a good solution.

again, welcome.

[RedLabel]

Thanks grossmanator,

The frame is the same as yours (2514).

I'm using G540 gecko drive with 381oz-in steppers. Using Mach3 to drive them(and it was painfull to adjust simple offsets in mach3, the user interface is just terrible, even for a job that easy I had to play with it). The psu is a 48v 7.3A psu and using a refurb 2.8ghz dell.

Tried all the steppers one by one, and they all worked well(I went above 200ipm(actually this is a bad measure, more then 2000 rev per minute) with ease on the bench).

The first time I set it up it was not noisy(but working at 19ipm), after I tried higher speeds(100ipm) I began to hear that. As I repeat the noise increased so I suppose at each use something gets loose more and more.

[grossmanator]

What kind of leadscrews do you have? Pitch? Also, are you running the G540 at 10 microsteps?

[Mangus]

I'm still here. And I'm still experiencing the problem (and, interesting timing, I spent some time playing around just last night).

I'm still nearly positive this has to do with friction between the nut and the leadscrew.

My Y (long) axis does it above about 40 IPM. My Z axis does it the worst (who would have thought?!) and does it above about 10 IPM.

I still don't know how to solve it, but it almost seems as though the proper lube might help. I haven't had success with either petroleum grease or (after cleaning) lithium grease.

I can wiggle the lead screws in the nuts just a bit (i.e. if I center the long axis to the center of the machine and grab the lead screw and move it a bit, I can see the screw move in the nut). I'm pretty sure this is normal and a result of the anti-backlash mechanism in the nut.

It's a damn annoying problem. Hopefully we can put our minds together to solve it. And perhaps K2 will have some ideas.

-Mark