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Broaching of igus bushing
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We have an rma that had a bushing that was over reamed causing the x carriage to rotate about the Y thus causing less than par prints

Event Timeline

west created this task.Jun 4 2019, 7:29 AM
DaniAO added a comment.Jun 4 2019, 7:45 AM

We have only seen one case of this correct? and this ticket is just to track what we saw?

oliver added a subscriber: oliver.Jun 4 2019, 7:52 AM

There have been several more incidents of parts being over broached on the production floor. This is one of the reasons we try to only broach if the parts need it and do drag tests on the bushing parts in cluster.

Is this ticket about over reaming for bushing insertion or over broaching and allowing uneven (tilted?) drag?

tutley added a comment.Jun 4 2019, 8:06 AM

@david.hall this is about broaching the igus bushings

I went over the broaching process with my weekend crew this weekend and with our day crew on last Thursday, so we should see less of this problem. Did we also not start a process just recently where they would be broached on the line, so that the assembly was with the part?

tutley added a comment.Jun 4 2019, 8:18 AM

@david.hall yes you are correct, the broaching on the assembly line is only temporary due to the interference in the x double bearing holder (T6933)
once the ECO is complete there should be no need to broach on the line anymore

The broaching on the line is being done by replacing the lower x rod with a rough rod and moving the carriage back and forth, so it is broaching parallel to the axis of travel,
when broaching by hand, there is no guarantee that you are broaching along the axis of travel. I think it is still possible this problem could arise with the assembly broaching method, but i think it is much more likely that it happened when broaching by hand

oliver added a comment.Jun 4 2019, 8:20 AM

@david.hall The only time they should be broaching them on the line is if they're on the machine and it is still seeing too much drag. One of the solutions is too broach the bushings while they are on the machine to ensure that we are not over-broach towards the wrong sides.

That would be what I was referring to. Thanks

DaniAO renamed this task from Over reamed bushing to Broaching of part.Jun 4 2019, 8:22 AM
tutley renamed this task from Broaching of part to Broaching of igus bushing.Jun 4 2019, 8:24 AM
tutley added a subscriber: franklin.Jun 4 2019, 2:30 PM

Im inspecting a machine for high x backlash measurements that @franklin brought over.
I noticed that the xcarriage had a lot of rotational play about the y axis, Upon removing the lower igus bushings, I could see that these bushings were extremely over broached.

The bushing slides on a 12mm rod, and igus has a maximum internal diameter spec at 12.04mm

Bushing A



Bushing B



Prior to swapping the bushings the measured x backlash was about .41mm. This was giving shifted circular edges, like so:

I installed fresh 12mm bushings, with no broaching and the axis was much tighter as this x carriage printed part is prior to T6933, and has the bushing/part interference. Now the x backlash measured .96mm. I then replaced the lower x rod with a rough rod and ran the carriage back and forth ~5-6 times by homing the x, turning motors off, and pushing the carriage to the right (pressing in the middle of the carriage where the belt attaches), then homing x again and repeating. This broached the bushings along the axis of travel. I reinstalled the x lower rod, and now the x backlash measures 0.26mm.

I then re ran the calibration print and got true circles.

Based on this it appears that broaching these by hand is causing excess play in the bushings on the x carriage, that excess play introduces rotational play along the y axis of the x carriage. This then causes high x backlash measurements and will over compensate when printing circular edges or changing direction in X.

I feel that no broaching should be done by and should only be done with the rough rod installed in the machine such that the broaching happens along the axis of travel.

@tutley , I agree with the broaching understanding that you measured out. Can we get the part number of the part you are testing, so that I know if we are dealing with just one part (x carriage). I want to make sure that this is the only part being broached currently. "I feel that no broaching should be done by and should only be done with the rough rod installed in the machine such that the broaching happens along the axis of travel."
We will need to see the volume of bushings requiring broaching and then see how this can be done for current issues.

tutley added a comment.Jun 5 2019, 7:04 AM

@david.hall these are the bushings in AS-PR0141 X double bearing holder

I think once the ECO for T6933 is complete the need for broaching will be minimal

MER, @EricNugent , do we have any word on T6933 being moved forward, so that we can hopefully be finished with this issue?
Also, should we assemble a "jig" X carriage assembly, for broaching the current AS-PR0140 parts that are assembled and will be too tight, due to the old model stl?

@david.hall we are currently at the testing phase. I believe @DaniAO will be able to give you a better time line estimate.

DaniAO added a comment.Jun 5 2019, 8:40 AM

@tutley is correct, we are in testing. TSR is suppose to be getting these installed on printers asap so we have some testing.

@bowman , Rasy, got with me this morning and asked about why parts can't be broached ( en masse). That his work station is getting so slow due to having to do all parts with the method downstairs. I wanted you to know that we will see a slow down in production now due to the method needed to get the parts broached correctly. We need to get the testing phase of this process done quickly, as we have already tested the new parts for drag. We are going to slow final assembly down considerably now.

@david.hall I am currently trying to contact tech support to see where they are with getting these installed. Also I am gonna tag @TyTh and @lisa since tech support is doing this testing.

These have been installed and are currently being tested

@TyTh if it is possible, please record the calibration data from auto-calibration after installing the parts. This will help us determine if this will give a better tolerance for calibration. Thanks.

I have had lots of backlash issues today with tight X carriages and has put a damper on my production numbers. @bowman @wolffchadd

I have also seen an increase in issues with backlash today, it is definitely slowing things down for me as well. We are broaching them on the machine, as is Rasy, but we are still seeing problems.

DaniAO added a subscriber: MikeR.Jun 6 2019, 12:05 PM

@MikeR do we have any more of the PP-GP0392 that were redesigned on the change orders that we can test on these trouble machines at all?

The others were installed on lago machines and installed fine... but they weren't having this problem before so we can't tell if it really fixed the problem or not?

If we don't have and @david.hall can we get some?

Should have tagged @EricNugent as well

If you need more from Cluster, @EricNugent can verify that we have the correct file pushed and just request the amount you would like printed. Then we can fit them in as soon as a printer is open.

david.hall closed this task as Resolved.Jul 2 2019, 5:35 AM

This process has stopped (broaching in Cluster). We currently only broach with rod installed on the printer to be broached. Hopefully this will go away as soon as we install the updated file that has the redesign for the bushing positioning. This ticket should be closed.

DaniAO added a comment.Jul 2 2019, 7:20 AM

Change order isn't complete just yet, but it will be closed once it is.