Problem- Lots of crunching noise from Z axis ballnut. Normal?

[alexccmeister]

Hi all,

Just installed my cncfusion kit on my x2. After installing the Z axis, I find that there is a lot of crunching noise from the ballnut. And the travel is not smooth and the z axis binds sometimes especially near the top.

Anyone has this problem? Is this misalignment issue? Or just need to wear the bearings down.

Alex

[kawazuki]

Originally Posted by alexccmeister Hi all, Just installed my cncfusion kit on my x2. After installing the Z axis, I find that there is a lot of crunching noise from the ballnut. And the travel is not smooth and the z axis binds sometimes especially near the top. Anyone has this problem? Is this misalignment issue? Or just need to wear the bearings down. Alex

Likewise! I installed mine last week and was appalled at the noise! Heavy thick oil is your friend - trickle it in from the top to lube the balls - makes for a quieter life!

[cyclestart]

Originally Posted by alexccmeister I find that there is a lot of crunching noise from the ballnut.

I remember reading on some supplier's site that crunching noises can be a side effect of preloading (larger ball method) a rolled ballscrew. To be considered "normal" apparently.

the z axis binds sometimes especially near the top.

That's not good. Sounds like something is misaligned if it wasn't tight in that spot pre-cnc.

[Crevice Reamer]

Loosen all the Z axis screws. Run the head up and down a few times. See if the noise/binding gets any better.

Stop the head at full up and tighten the screws.

What Power supply, motors, and drivers are you using?

CR.

[sansbury]

My Roton overloaded nuts do crunch a bit but they crunch a lot worse the farther off the alignment is.

Search around here b/c a month or so ago a fellow found he had to shave off a bit of the Z-axis motor mount in order to get a good fit on his X2/CNCF rig. There is more variation in these mills than is sometimes expected.

[alexccmeister]

Originally Posted by kawazuki Likewise! I installed mine last week and was appalled at the noise! Heavy thick oil is your friend - trickle it in from the top to lube the balls - makes for a quieter life!

Thanks, I am using some M-oil on it.

Originally Posted by cyclestart I remember reading on some supplier's site that crunching noises can be a side effect of preloading (larger ball method) a rolled ballscrew. To be considered "normal" apparently. That's not good. Sounds like something is misaligned if it wasn't tight in that spot pre-cnc.

The kit is from CNCfusion and they are not preloaded. I suspect the crunching is caused by the weight of the head pushing down . The noise is worse when trying to go up. I think there is a slight misalignment as well. I can't adjust the Z axis much as the slot cncfusion provided for the bolt is just the right fit and there isn't much room to play around. I wonder if I should make the hole larger.

Originally Posted by Crevice Reamer Loosen all the Z axis screws. Run the head up and down a few times. See if the noise/binding gets any better. Stop the head at full up and tighten the screws. What Power supply, motors, and drivers are you using? CR.

I am using Keling driver kl5056 and 24volt power unit. Its not enough I know but all I can afford when I first got it. Will upgrade in the future. BTW, I haven't connected the controller to the mill yet. Turns out my HP laptop won't work with Mach3 and I need to set up a desktop pc in my shop now. Will do that tomorrow.

Originally Posted by sansbury My Roton overloaded nuts do crunch a bit but they crunch a lot worse the farther off the alignment is. Search around here b/c a month or so ago a fellow found he had to shave off a bit of the Z-axis motor mount in order to get a good fit on his X2/CNCF rig. There is more variation in these mills than is sometimes expected.

Yup! you are right. They are not as precise as everyone like them to be. I read somewhere here that the tables should be able to move when push. I managed to do that with my X and Y without much noise. I will definitely fix a counter balance to the spindle head to help the motor work less. The stock spring thingy just not good enough.

Thanks guys.

Alex

[bilinghm]

I spent a lot of time fine tuning the alignment of the Z ball screw. It did initially make some "crunchy" noises. Careful measurement is essential. Shims were required to achieve good alignment. With the alignment dialed in, the Z ball screw is very quiet.

Good luck!

Bill

[alexccmeister]

HI Bill,

Thanks for your input. Good to know its just not plug and play (ironic as it may sound) but that would mean its a solvable problem. I did some adjustment for my x and y and they are running smoothly. Albeit a bit of play as I couldn't tighten the gibs too much. Is yours the same?

Alex

[SScnc]

Originally Posted by sansbury My Roton overloaded nuts do crunch a bit but they crunch a lot worse the farther off the alignment is. Search around here b/c a month or so ago a fellow found he had to shave off a bit of the Z-axis motor mount in order to get a good fit on his X2/CNCF rig. There is more variation in these mills than is sometimes expected.

Right, that was me. I had to mill down the mating side of the Z head mount block (the small one) of the CNCFusion kit. That allowed the ballscrew to be vertical and got rid of the binding and most of the noise.

I also drilled a larger hole on the left side of the Z head opposite of the large allen screw that holds the CNCFusion block on so I could use a 3/8" allen wrench to remove that same small block so the gib screws could be adjusted much easier. I saw someone else had done that here.

Without that hole, trying to adjust the gib screws is is a major PIA ! with it, it's easy. Just remember to lock the Z stop block in place.

As for counter weight, I'm using THIS from Keling and don't have any problems with the Z moving.

[alexccmeister]

Hi SScnc,

Do you have any pictures showing your adjustment? Thanks.

Alex

[SScnc]

No specific pictures but here's a couple of things that should help...

Below is a quote from sansbury that helped me allot and makes sense...

Those should work--plenty of people have driven these with 270s. The first thing I'd try is putting a handwheel on the Z and try raising it manually with the power off, and see if it gets a lot harder to move at some point. This would indicate that there is a mechanical binding issue which would most likely be due to slight misalignment of the screw. Are you using a standard ballnut on the Z or is it an overloaded one? The overloaded ones are a bit more sensitive to alignment. If there is no change in the torque needed to raise the head, then I would also try swapping the motor/driver with one from the X or Y. If this works then either the motor or driver are at issue. I don't think this is likely since the Z works for most of its travel but I try to not assume too much!

And I found the post by Regnar about drilling the hole in the left side and he has good pics of that...

http://www.cnczone.com/forums/showpo...94&postcount=7

Originally Posted by Regnar I use full size t handles with ball ends instead of straight ends. The trick is to drill out the other side where the old manual handle screw held it in place to fit a large t handle. Next is you loosen and take out the small screws. Then loosen the large inside screw with keeping pressure against the screw to make sure it doesnt drop into the spindle. Then just raise the z axis by the motors and the mount will move out of the way so that you are able to get to the z gibs. You will notice that the Z mount has a nice milled area that will allow it to just slide up the gib screws. I forgot to mention the first step should be Locking down the head with to stop that you should also modify to be able to come on and off.

HTH,

Steve

[kawazuki]

FYI if it matters - the CNC Fusion z-z ballnut is preloaded as standard, the
x-x and y-y are optional. A 270oz stepper moves my head just fine - no spring, no counterweight!