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drag specifications needed
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Description

Apparently the z left compression bushing drag must be set before the chassis is installed.
We need the drag specification in order to incorporate this adjustment into the sub assembly process.

If other drag specifications are required, please post the drag spec here.

Event Timeline

logan created this task.Feb 26 2019, 11:50 AM
logan triaged this task as Normal priority.
logan created this object with edit policy "LulzBot Hardware Products (Project)".
logan added subscribers: west, Steven, tutley.
west added a comment.Feb 26 2019, 12:16 PM

We will need to find out what the minimum is before there is too much rotation in the axis. Then we should use the max drag spec we have on mini 2 which I believe is 15N so <15N

Sounds good, let us know what you find out and we'll get the process written and implemented.

logan raised the priority of this task from Normal to High.Feb 27 2019, 10:36 AM
west closed this task as Resolved.Feb 27 2019, 12:20 PM
west added a subscriber: kent.

I talked with @kent about this. The drag is max 15N min 5N and it can be checked in final assembly before the chassis is installed

logan reopened this task as Open.Feb 27 2019, 12:23 PM

We still need to get these implemented in the OHAI, and how do they check drag on the completed assembly? By doing so would add the drag of the motor/gearing and would certainly be over 15N. We need the drag specifications for individual bearing sets, so that drag measurements can be taken from them before installing in the assembly. Thanks

And for one double bearing set alone 15N is too high, that spec used on Mini 2 refers to the drag of the assembled axis; must be less than 15N

west added a comment.Feb 27 2019, 12:39 PM

remove the belt clamps on z and install in final

max- 15N min- 5N

west added a comment.Feb 27 2019, 12:42 PM

Or test drag in the sub - z left z right then attach the belt mount. This is a manufacturing process on when the test needs to be implemented

logan added a comment.EditedFeb 27 2019, 12:54 PM

Why can we not get a drag spec for one double bearing holder?
Then the process is simple; set drag with smooth rod attached to force gauge > install part (to sub assembly) > done

west added a comment.Feb 27 2019, 1:01 PM

The axis doesn't run on a only a double bearing holder, for the x ends what you reccomend is doable but for the x carriage it needs to be assembled to ensure the double and single bearing holder have a drag that is in spec together

logan added a comment.Feb 27 2019, 1:05 PM

That is the double bearing holder I am asking about; not concerned with X axis until T5033 is fixed and final assembly OHAI hasn't even been started yet.

logan added a comment.Feb 27 2019, 1:10 PM

But if 15N is the max acceptable carriage drag for X that is fine, we can come up with a way to measure it and include that in the OHAI whenever it gets started. Y axis is pretty straight forward as well; not really concerned there with a 15N carriage drag spec. This ticket requests the drag specification for Z double bearing holders.

west added a comment.Feb 27 2019, 1:29 PM

In T5876 you were concerned with not being able to access the screws for the xmotor mount. The only reason you would need to get to those screws is to set drag, so I assumed you wanted to set drag during final. My apologies for the mis interpretation

west moved this task from Report Issues Here to OHAI Content on the Quiver board.Mar 5 2019, 11:13 AM
logan added a comment.Apr 15 2019, 3:38 PM

@west
Any determination made on this?
We need to get this into the OHAI

west added a comment.Apr 22 2019, 3:29 PM

@kent and I talked about it and decided to "tighten until there is just a tiny pinch on the rod, that way it is as good at positioning as possible" @kent is going to show techs how to achieve this. This was decided since we havent seen an issue in the z

@kent do you have a quick write up or video you can log demonstrating this process so we might be able to implement it into the ohai?

Rough interpretations are essentially:

  1. Tighten top compression of assembly until the nut and screw no longer move back and forth. Repeat for lower compression.
  2. Attempt to rotate the z axis perpendicular to the smooth rods towards the front or back of the machine when installed.

If the part is rotating beyond acceptable ranges, loop back to step one.

logan closed this task as Resolved.Apr 29 2019, 4:26 PM

Yes, my apologies, I forgot to resolve this ticket when I completed implementation of this into the OHAI as described above.
It is also covered for X-End Right, step 3 here: https://ohai.lulzbot.com/project/x-end-right-assembly/quiver/