More Z axis issues

DarkApollo
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Re: More Z axis issues

Post by DarkApollo » Thu Oct 09, 2014 6:22 pm

Improbable Construct wrote:
DarkApollo wrote: 'upgraded' the threaded rod to a 12" rod and added a second carrier bearing to the bottom.
I bet this is your problem. Try taking that bottom bearing off. Threaded rod is not a "precision" screw. You have probably over constrained your Z axis causing to it bind randomly.
It was stalling and acting up (as you see in the video in the first post) on the 8" rod in standard SO2 set up.

Improbable Construct
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Re: More Z axis issues

Post by Improbable Construct » Thu Oct 09, 2014 6:52 pm

Is it possible that the M8 nuts that sandwich the bearing are not tapped straight? I know some others have had that problem.

The only other thing that I can think of is that it looks like your controller can take up to 60v. Maybe is just needs more voltage to run the Z axis properly.
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DarkApollo
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Re: More Z axis issues

Post by DarkApollo » Thu Oct 09, 2014 7:02 pm

Improbable Construct wrote:Is it possible that the M8 nuts that sandwich the bearing are not tapped straight? I know some others have had that problem.

The only other thing that I can think of is that it looks like your controller can take up to 60v. Maybe is just needs more voltage to run the Z axis properly.
I never thought of the nuts not being straight.. that.. that actually makes some sense. I was watching the axis very closely last night and the top nut did not run true (it looked very wobbly when it was spinning)
I am going to remove the nuts and try again.

Also, didnt think about the voltage. That makes some good sense too. I wanted the 48v PSU but Inventables either stopped carrying it or is out of stock on it so I had to settle for the 24v (my spindle hates it.. although at full speed it is turning just slow enough to not melt acrylic and make pretty little chips) If removing the nuts fails, I will look into more power. :tup: :D

WillAdams
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Re: More Z axis issues

Post by WillAdams » Thu Oct 09, 2014 7:20 pm

from: http://docs.shapeoko.com/zaxis.html
**Note** the nuts are commodity / off-the-shelf parts and have a fairly wide manufacturing tolerance. If your threaded rod wobbles unduly after assembly, mark the nuts so as to indicate their orientation and try swapping them around in terms of orientation and positioning, keeping notes on which you have tried --- you should hit upon an arrangement which allows the rod to run fairly true, or at worst case, not hit any other parts (some whipping is inevitable --- one simply wants to achieve a state where nothing will be damaged by the rod end). If nothing works, contact Inventables customer service, or try sourcing new nuts (one option is to take the bearing and threaded rod into a hardware store and try different nuts until you find a pair which works).
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DarkApollo
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Location: Carlisle PA

Re: More Z axis issues

Post by DarkApollo » Fri Oct 10, 2014 11:53 am

:fingers crossed:
I may have fixed it.
The motor was stalling even when removed from the axis so the root of the problem was before the lead screw.

After swapping the plugs to a different axis, I noticed that the motor was turning a lot slower even though the speed and acceleration numbers were a lot higher.
I looked at the screen a bit and on the X axis, the cycle per second was about 2,000, on the Z axis it was 16,000! The speed and acceleration was 1"/s 2"/s respectively. I turned it down to .2"/s and 1"/s acceleration and the cycles dropped to 1800. For good measure I set it to .1"/s which dropped it to 850 and ran the motor for an hour +-15" and it did not stall once. Time to reassemble and see!

I feel like an idiot for not noticing the cycle per second in the days that I have been trouble shooting this thing..

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