Backlash problem in X axis on NM-200

[psooley]

I have been successfully operating my NM-200 for over two years now. Just started to recognize some non-repeatability problems in the machine mainly in the X axis direction. I have adjusted the gibbs in both the X and Y axes. Got rid of a side movement in the X axis table that was very apparent. Less so in the Y axis. After adjusting the gibbs, I am still measuring a 0.013" backlash in the X axis direction. Any suggestions as to how to repair this problem? Anyone else experience this problem. Thank-you.

[Dynoray]

I have been successfully operating my NM-200 for over two years now. Just started to recognize some non-repeatability problems in the machine mainly in the X axis direction. I have adjusted the gibbs in both the X and Y axes. Got rid of a side movement in the X axis table that was very apparent. Less so in the Y axis. After adjusting the gibbs, I am still measuring a 0.013" backlash in the X axis direction. Any suggestions as to how to repair this problem? Anyone else experience this problem. Thank-you.

Yes, the ball screw is too short, so they don't bother to tighten the nut on the fixed mount bearing for the ball screw (right hand side of the X axis)
The knob on the left end of the ball screw (which is steel on steel) is controlling the ball screw thrust toward the right side.
Take the knob right off the left side and tighten the ball screw not on the right side mount. While your doing this, you'll probably want to replace the ball screw mount on the left side with a bearing unit or it will evenutually bind as it's steel on steel and no way to lube it without taking it apart.
Having said that, when those cheap balls screws are NEW and setup correctly (far from how they come from the factory) you'll still see 0.0008-0.0012" backlash.
Ray

[ihavenofish]

I have been successfully operating my NM-200 for over two years now. Just started to recognize some non-repeatability problems in the machine mainly in the X axis direction. I have adjusted the gibbs in both the X and Y axes. Got rid of a side movement in the X axis table that was very apparent. Less so in the Y axis. After adjusting the gibbs, I am still measuring a 0.013" backlash in the X axis direction. Any suggestions as to how to repair this problem? Anyone else experience this problem. Thank-you.

you should have a double nut on the drive side. loosen off the first nut (nearest motor) then snug the second, then retighten the fisrt. this should clear up the backlash. there is a usually a little tabbed retainer that holds the nuts from moving on their own in use. youll have to bend this out of the way first to tighten things. when its tightened you should have in around a thou of backlash which comes from general compression in the sytem. dont bother with mach3 compensation, it just makes things worse, as does making the gibs too tight.

the free side isnt steel on steel as mentioned above, its a bearing so you shouldnt have any problems there. the knob on the end ive just taken off and chucked in a box.

you may want to snug up all the axes while your at it, as over time they might come loose. the ball nut itself should be fine after such a short time.

[Dynoray]

you should have a double nut on the drive side. loosen off the first nut (nearest motor) then snug the second, then retighten the fisrt. this should clear up the backlash. there is a usually a little tabbed retainer that holds the nuts from moving on their own in use. youll have to bend this out of the way first to tighten things. when its tightened you should have in around a thou of backlash which comes from general compression in the sytem. dont bother with mach3 compensation, it just makes things worse, as does making the gibs too tight.

the free side isnt steel on steel as mentioned above, its a bearing so you shouldnt have any problems there. the knob on the end ive just taken off and chucked in a box.

you may want to snug up all the axes while your at it, as over time they might come loose. the ball nut itself should be fine after such a short time.

Why would you say it's not steel on steel? Did you go look at his?
Our's was as was anyone that I have talked to that looked or had to fix the same problem this guy is having. When I first got the NM-200 and called Novakoned about it, they said that's how they are and that's it's not a good setup but that's the way it is.

Maybe you got one that was built correctly, most haven't.

[ihavenofish]

mine isnt, i can take pictures of it. jobean HAS pictures of his on the forum, its a bearing. his is the new style like yours.

[newton009]

I guaranty the floating ends on the NM200 V2 do NOT have floating bearings as they should, nor bushings. Nothing but ballscrew to mount. No lube from the one shot oil system. The gibbs also have no lube from the oilier system.

[newton009]

[QUOTE=ihavenofish;971204]you should have a double nut on the drive side. loosen off the first nut (nearest motor) then snug the second, then retighten the fisrt. this should clear up the backlash.

Where can I get a machine like yours?

My NM200 V2 there is no double nut on the drive side of any axis (XYorZ). There is the ballscrew with a shoulder that presses upon a sleeve. It supplies tension to the bearing against the mounting block. The other side has the opposite bearing with a similar sleeve ending with a threaded collar that sets the bearing tension. It's locked in place with three set screws.

[ihavenofish]

im looking at the blow apart diagram in the smithy 1240 manual (same machine). it shows some sort of bushing, though indeed it does seem like its not a rolling bearing by the description. odd. but its not definitely not steel on steel....

http://www.smithy.com/uploads/Smithy...ual%202008.pdf

it also shows the double lock nut arangement on the drive side. if they replaced the lock nuts with a single with set screws on the new machine, i dont see how that would be an issue, it should still tighten up the same way.

i also dont see how the screw could be too short yet have play. if it was too short id imagine it would be too tight no?

[Dynoray]

im looking at the blow apart diagram in the smithy 1240 manual (same machine). it shows some sort of bushing, though indeed it does seem like its not a rolling bearing by the description. odd. but its not definitely not steel on steel....

http://www.smithy.com/uploads/Smithy...ual%202008.pdf

it also shows the double lock nut arangement on the drive side. if they replaced the lock nuts with a single with set screws on the new machine, i dont see how that would be an issue, it should still tighten up the same way.

i also dont see how the screw could be too short yet have play. if it was too short id imagine it would be too tight no?

I don't know about the Smithy, but the NM-200 Pro 2 has no bearing on the floating ends. It has a block/mount that looks the same as a bearing unit but it's just a holed bored in the steel the the ball screw end goes in. I called Novakoned as soon as I seen that (thinking someone screwed up at install) but they said they are all like that. It doesn't cause any problems for at least a hour of run time though, LOL
What I was talking about with the X ball screw being too short, when it was assembled, the ball screw was all the way in the non bearing mount (floating end) and the little "hand wheel" tightened. Then the nut on the fixed bearing mount was tightened. The nut was up against the bearing but the ball screw wasn't on the back side, about 0.500" away actually. The "hand wheel" was holding thrust to the right and the bearing to the left. So basically if you took the 5mm screw out of the nob on the left side, the ball screw could move back and forth 0.500".
Mine also has the single not with set screws, great untill you need to remove it, LOL
By the way, I found one of the problems with geckos faulting, looks like a bad stepper motor on the X killing the geckos.
Ray

[newton009]

I don't know about the Smithy, but the NM-200 Pro 2 has no bearing on the floating ends. It has a block/mount that looks the same as a bearing unit but it's just a holed bored in the steel the the ball screw end goes in. I called Novakoned as soon as I seen that (thinking someone screwed up at install) but they said they are all like that. It doesn't cause any problems for at least a hour of run time though, LOL
What I was talking about with the X ball screw being too short, when it was assembled, the ball screw was all the way in the non bearing mount (floating end) and the little "hand wheel" tightened. Then the nut on the fixed bearing mount was tightened. The nut was up against the bearing but the ball screw wasn't on the back side, about 0.500" away actually. The "hand wheel" was holding thrust to the right and the bearing to the left. So basically if you took the 5mm screw out of the nob on the left side, the ball screw could move back and forth 0.500".
Mine also has the single not with set screws, great untill you need to remove it, LOL
By the way, I found one of the problems with geckos faulting, looks like a bad stepper motor on the X killing the geckos.
Ray

Remove the hand wheel assembly by removing the screw in the end and slide the parts off. Its on a key way and a little snug so a little encouragement will be necessary. Wrap a piece of copper around the floating end of the ball screw to protect it and clamp down with a pair of vice grips. While a friend holds the vice grips stationary. Loosen the three setscrews from the bearing retaining nut use a brass drift to tap the nut around. (or you could make a collet type wrench for the nut) The nut has three brass plugs in the setscrew holes. The setscrews drive the brass plugs in to the ball screw threads to clamp it in place. The brass plugs are tight in the hole so the retaining nut will always feel kind of tight. To adjust the retaining nut I use a large flat blade screwdriver as leverage on the slots. The nut doesn't have to be very tight. I would place a test indicator on the axial end of the ball screw to see when it stops sloping back and forth Then tighten a little more, maybe an 8th of a turn.

To fix the floating end requires a washer or sleeve to make up the distance between the ball screw and hand wheel. The washer should only touch the shoulder on the ball screw and back of the hand wheel. This prevents the hand wheel from touching the mounting block that was causing your problem. In no way should the hand wheel be touching the mounting block.

I would think that your stepper faulting might be caused by the ball screw binding. Try the above fix before replacing any parts, unless they are already dead.

Hope this helps.

Regards,

[Dynoray]

Remove the hand wheel assembly by removing the screw in the end and slide the parts off. Its on a key way and a little snug so a little encouragement will be necessary. Wrap a piece of copper around the floating end of the ball screw to protect it and clamp down with a pair of vice grips. While a friend holds the vice grips stationary. Loosen the three setscrews from the bearing retaining nut use a brass drift to tap the nut around. (or you could make a collet type wrench for the nut) The nut has three brass plugs in the setscrew holes. The setscrews drive the brass plugs in to the ball screw threads to clamp it in place. The brass plugs are tight in the hole so the retaining nut will always feel kind of tight. To adjust the retaining nut I use a large flat blade screwdriver as leverage on the slots. The nut doesn't have to be very tight. I would place a test indicator on the axial end of the ball screw to see when it stops sloping back and forth Then tighten a little more, maybe an 8th of a turn.

To fix the floating end requires a washer or sleeve to make up the distance between the ball screw and hand wheel. The washer should only touch the shoulder on the ball screw and back of the hand wheel. This prevents the hand wheel from touching the mounting block that was causing your problem. In no way should the hand wheel be touching the mounting block.

I would think that your stepper faulting might be caused by the ball screw binding. Try the above fix before replacing any parts, unless they are already dead.

Hope this helps.

Regards,

Thanks Newton, I already fixed mine as soon as I recieved it about a year ago (ball screw problem that is) as well as replaced the floating end supports with bearing units. I posted the problems with the ball screws as that is probably what is causing the originator of this threads back lash problems.
I now, after completely giving up hope of any type of support/warranty from Novakoned, have also purchased and changed, the spindle motor, VFD, fixing the electronics and a lot of other little tweeks. Ran it all weekend at 250in/min rapids and cutting at 70-120 in/min with 3-4mm DOC, with 1/2" 2 FT endmill and it's still going, LOL. The 3HP Vector drive spindle setup I have on it now is SO MUCH btter then the original "so called 3HP brushless"
Compaired to the 65in/min rapids and cutting at 30-40in/min with 1mm DOC with 1/2" end mill with the Novakoned system and only getting 30min to 1 hour at that.

[ihavenofish]

Compaired to the 65in/min rapids and cutting at 30-40in/min with 1mm DOC with 1/2" end mill with the Novakoned system and only getting 30min to 1 hour at that.

O_o

its supposed to ship stick at 135ipm. mine runs 170ipm actually, but i keep it at 100 because of mach 3's stupid ass countouring bugs. my 145 runs at 225ipm with the same geckos, but smaller nema34 motors.