[trubleshtr]

Not sure what you mean but I don't think I am side loading the acme screws.

What is a centralizing acme screw and nut assembly?

Only air cutting at the moment have not cut anything therefore the tool sharpness is not relevent.

Well I have gone from mechanical to electrical back to mechanical trying to troubleshoot.

hi david, At first i was unaware that you guys were air cutting so please ignore my comments on tool sharpness.
A centralizing screw is just a tighter clearance between the nut and screw esentially, A general acme screw and nut tends to have more "slop" in it and can therefore bind much easier when shock loaded or side loaded.
Side load is just that, a force acting on the side of the screw and nut assembly (perpindicular to the way it is moving).
If you try to move a acme screw to fast right from rest it is possable that the initial shock loading can bind your assembly.

Resonance on the other hand is a fancy word for electrical vibration. You never want your amps and voltage to be at a point in the phase where they resonate, it will cause heat and ruin your drives or motors. This is why volt ref(vref) and gain adjustments exsist in drives, to tune out the amp and voltage phase I believe (correct me if I am wrong) that you do not want your amp and voltage to be converging at the sametime, normally one is ahead of the other by 90 degrees. adjusting the vref shifts the phase so they dont converage at the sametime.
What fixitt is saying is not only are you experienceing this resonace electrically, your acme screw itself, when turning is adding more mechanical vibration which amplifies the condition, causing miss steps and stalling.

Perhaps an upgrade to rolled ball screws would also help?

[David Da Costa]

THanks for the explanation. Does anyone know where can you order such centralizing acme threaded rod and nuts?

Thanks again

[trubleshtr]

xxx.nookindustries.com/acme/AcmeGlossary.cfm#ScrewCritical

if mechancial vibration is bad from the acme screw, why not spend a little more and up grade to cheap rolled ballscrews from misumi or Roton or Nook?

You could verify first this is the case, before laying out the cash, by doing what the others have done and place some rubber mounts between your motor mount and install a spider type love joy to aid in absorbing mechanical vibrations?

cheers

[Fixittt]

that is with a pitch screw of 10 is that correct?

Looks very very good! Sounds good as well. now why cant mine do that? at least at 50 IPM?

[Fixittt]

hi david, At first i was unaware that you guys were air cutting so please ignore my comments on tool sharpness.
A centralizing screw is just a tighter clearance between the nut and screw esentially, A general acme screw and nut tends to have more "slop" in it and can therefore bind much easier when shock loaded or side loaded.
Side load is just that, a force acting on the side of the screw and nut assembly (perpindicular to the way it is moving).
If you try to move a acme screw to fast right from rest it is possable that the initial shock loading can bind your assembly.

Resonance on the other hand is a fancy word for electrical vibration. You never want your amps and voltage to be at a point in the phase where they resonate, it will cause heat and ruin your drives or motors. This is why volt ref(vref) and gain adjustments exsist in drives, to tune out the amp and voltage phase I believe (correct me if I am wrong) that you do not want your amp and voltage to be converging at the sametime, normally one is ahead of the other by 90 degrees. adjusting the vref shifts the phase so they dont converage at the sametime.
What fixitt is saying is not only are you experienceing this resonace electrically, your acme screw itself, when turning is adding more mechanical vibration which amplifies the condition, causing miss steps and stalling.

Perhaps an upgrade to rolled ball screws would also help?

Glad i got someone around to translate my idiot ramblings. In other words "Yeah what he said!"



now as for upgrading to ball screws. Dont I wish! I just dont have the funds right now for that. Not after throwing all the money at it to get the machine back in a working state. Plus I am out of work right now due to a motorcycle wreck. Tinkering with this and learning the jewlery side of CAD/CAM is what is keeping me sain.

[David Da Costa]

xxx.nookindustries.com/acme/AcmeGlossary.cfm#ScrewCritical

if mechancial vibration is bad from the acme screw, why not spend a little more and up grade to cheap rolled ballscrews from misumi or Roton or Nook?

You could verify first this is the case, before laying out the cash, by doing what the others have done and place some rubber mounts between your motor mount and install a spider type love joy to aid in absorbing mechanical vibrations?

cheers

I think we are cross-posting. Joe's design calls for lovejoys which I have had installed all along. I have just installed rubber grommets - see video.

THanks

[David Da Costa]

that is with a pitch screw of 10 is that correct?

Looks very very good! Sounds good as well. now why cant mine do that? at least at 50 IPM?

Yes 10.

Now to put everything back together and see if I can still get similar results.

[Fixittt]

xxx.nookindustries.com/acme/AcmeGlossary.cfm#ScrewCritical

if mechancial vibration is bad from the acme screw, why not spend a little more and up grade to cheap rolled ballscrews from misumi or Roton or Nook?

You could verify first this is the case, before laying out the cash, by doing what the others have done and place some rubber mounts between your motor mount and install a spider type love joy to aid in absorbing mechanical vibrations?

cheers

here is an older video I did on my maxnc it shows exaclty what I (And several others) are up agaisnt.
Vref settings are 2.83
and as you can see and mostly hear. Resonence is a problem!

[David Da Costa]

Sounds familliar

[Fixittt]

WELL?????? does it work?!?!?!?!?!?!?! Or did the bald spot get bigger?

[David Da Costa]

Still putting it back together Taking the time to make sure everything is in perfect alingment

[Buzz9075]

I am back, got more rubber washers for my Y axis, glad to hear they are working for you as well David. So if you do implement them you will need to ensure that any back pressure from you cutter can NOT be transfered to the motor or the motor will push on the washers and you accuracy is out the window.

For example on my lead screw I plan on putting a nut and bearing assembly on the far side of the wood that the lead screw goes through to from the motor to the Z axis. This way when you apply pressure down on your cut the force will stop there and not make it back ot the motor... so you really should be able to loosely mount the motor and keep the accuracy.

Will get back to you gusy after I complete my Y axis testing with both a rubber and some lovejoy

[Buzz9075]

Just remembered I forgot to indicate, the gear ratio is 1:1 and the motor drives to leadsrews on the same belt. Check out my web link I list before it has lots of pictures of the entire machine.

[HayTay]

Will get back to you gusy after I complete my Y axis testing with both a rubber and some lovejoy

Is that legal in Canada? Better safe than sorry. Don't forget to clean up any mess when you're finished.

Seriously, though, you've got everyone watching this thread, and the others, to see how this issue with the Xylotex controller and the 425+ oz-in stepper motors is resolved. If I stay away for a couple of hours I find that I'm several thread pages behind. Glad to see you're making progress no matter how slow it may seem.

Keep up the good work.

[Buzz9075]

While I still have lots more tests to run. I think I have a winner... the Y axis appears to be purring like a kitten with the lovejoy and a rubber. The machine is moving through the pattern no on its fourth pass and I have yet to hear even a sign of a moan from either the Y or Z axis. As a matter of fact I have heard some rather cool sounds as the system transfer directions.
Setting X 52/4 Y 52/2 Y 40/1

And I just notice my Y axis mount is not even on straight... I bet I put it on at a -10Degree angle from straight.

Next round of test is going to need to make sure it is coming back to where I sent it away from (back to the same 0,0,0)

I'll be back...

[joecnc2006]

I am back, got more rubber washers for my Y axis, glad to hear they are working for you as well David. So if you do implement them you will need to ensure that any back pressure from you cutter can NOT be transfered to the motor or the motor will push on the washers and you accuracy is out the window.

For example on my lead screw I plan on putting a nut and bearing assembly on the far side of the wood that the lead screw goes through to from the motor to the Z axis. This way when you apply pressure down on your cut the force will stop there and not make it back ot the motor... so you really should be able to loosely mount the motor and keep the accuracy.

Will get back to you gusy after I complete my Y axis testing with both a rubber and some lovejoy

the leadscrew is installed and locked into place at both ends with nuts against the bearings, so the movement of the motor will not affect the placement or accuracy of the machine.

[Buzz9075]

Success.... well today anyway.

For a setup I attached two lazer to the z axis carage so that I could confirm the machine was returning to the exact same point all the time.

My goal was to complete the task 5 times with out issue... only ever seen it do one or two before and that would be rare.

The first pass was perfect.
Second pass the axis stalled on me so I realigned it as the motors (remember I noticed it out of line).

Five more passes were run each one the lasers return to the same position each time.

So for now I am sastisfied I have found my solution to the problem and will be making adjustment to stop the push back on the motors.

To review the solution. For each motor I place a rubber washer on each side of the motor mounting plate and then I clamped down reasonable well. I also used lovejob couplers to ensure the misalignment of the axis are not a problem as well. I also encased the rubber washers in metal washers.

Thanks everyone for your help.

My estimates on the amount of work to figure this out since Xmas is about 40 to 50 hours of testing which does not include all the time I spent reading everyones posts.

[joecnc2006]

David I feel really bad you have had so much trouble with the Z-Axis, wish i knew about the Xylotex board better, I think you ordered the HobbyCNC Board, maybe you can try that later on with the 425oz motors, and run them
unipolar at 305 oz.

Joe

[xscsime]

Hello David,

I was just checking the motor specs and the Xylotex manual and wanted to check with you and see if this is how you have the motor wired to the Xylotex board.

blue/white and red/white to ZA
Blue and Red to ZA#

green/white and black/white to ZB
Black and Green to ZB#

This set up would require your Vref setting at test point TPZ to be 3.6 volts.

What Voltage did you set the Vrefs to?

Rick

[Fixittt]

I have my steppers wired exactly how XYLOTEX recomends as my whole PSU, 4 axis driver and motors (269`s) came from Xylotex.

To make mine run without loosing steps I have to run with Vrefs
X 1.72V Vel. 20.67 Accel 1.03
Y 2.36V 21.65 2.57
Z 2.03V 30 3.84


These settings are after months of unting and searching for the sweet spot.
This is not on the router table, but a MAXNC 15 mini mill with 20 TPI screws