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rear tool head mount fastener will not align with insert
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Description

During MER's build of 5 betas we had one tool head that was a bit cumbersome to mount, we had to loosen the X Carriage cover and use a straight tipped driver to pitch the screw in order to thread into the insert on the tool head mount.
We had hoped it was a fluke, as the other 4 did not have this issue.
The assembler doing redgum finals has run into this twice.
I had a look at it and had extreme difficulty mounting one to an X carriage assembly that wasn't mounted to the printer, with everything loose.
The fastener is resting about a millimeter higher than the insert, which looks centered on the mount as far as I can tell.
@west I have instructed the assembler to set any with this issue aside so that we can look into the issue. Would you be able to come take a look?
I cant see anything obviously wrong with either the insert or the carriage assembly in this case, so I am unable to resolve this properly through assembly.

Event Timeline

logan created this task.Jun 6 2019, 10:34 AM
logan triaged this task as Unbreak Now! priority.
logan created this object with edit policy "LulzBot Hardware Products (Project)".
west added a comment.Jun 6 2019, 10:57 AM

@logan I can swing by sometime today to look at it. Is this specific to the printer or is it only on the x carriage. Can you put a x carriage that is exhibiting this issue on any printer and it still shows the problem?

west added a comment.Jun 6 2019, 11:05 AM

I think because the x carriage has 2 slotted holes (left and right) to allow difference in rod spacing, but the x double bearing holder doesnt have a slotted hole in the center (green circle), the rods could be slightly further apart causing the center screw to sit at an angle

logan added a comment.Jun 6 2019, 11:19 AM

He is going to try swapping the carriage on one of these machines. He did try multiple tool heads with no success.
I had tried mounting one to a carriage not mounted to the machine, with everything loose, and the screw was just not aligning.

west added a comment.Jun 6 2019, 1:09 PM

I mounted a toolhead i had on the x carriage that i brought back and there isnt the gap that we saw, so theres the issue of the triangle alignment spots on the toolhead being slightly undersized and not allowing the toolhead to sit fully on the x carriage. After tightening the 2x front m3x8 bhcs that attach the double bearing holder, the toolhead didnt mount like it should. I loosened those screws and shifted the x double bearing holder down, re-tightened and attached the toolhead fine. So I believe the issue we are seing is the rod spacing on the x is outside the range of the x carriage assembly. To fix this, the x double bearing holder will need to have a slot where the mounting screw goes to allow for a higher variance in rod spacing. While doing that I will also make the alignment triangle posts slightly smaller to allow for variance in the toolhead mount.

logan added a comment.Jun 6 2019, 1:51 PM

Thanks @west, this sounds like a good path forward

west moved this task from Report Issues Here to Beta on the Redgum board.Jun 11 2019, 7:07 AM
west added a comment.Jun 11 2019, 8:38 AM

@logan, the one double bearing holder i printed worked on the x carriage assembly that was exhibiting this issue. I was able to position the double bearing holder at both ends of the adjustment and still be able to fasten the toolhead down . I have a slice request in T7684

logan added a comment.Jun 18 2019, 9:33 AM

So, it is better maybe, because I was eventually able to get the tool head to mount but still not perfect.
I installed the X-Carriage following the OHAI, first adjusting bearing compression and then tightening the screws that attach the X-Carriage to the X Double Bearing by sliding to the ends of travel when tightening the corresponding fastener (slide left - tighten left, slide right - tighten right).
I then attempted to mount the tool head and could not align with the rear insert so I loosened the X-Carriage cover some more and attempted some more, no luck.

Then I loosened both of the fasteners that attach the X-Carriage to the X Double Bearing, moved to the middle of X-Axis travel and re-tightened.
I was then able to mount the tool head, but there is a visible bow to the tool head mount when viewed from above (T7669)

west added a comment.Jun 18 2019, 9:36 AM

And the bow was from the issue in T7669?

logan added a comment.Jun 18 2019, 9:37 AM

@west I believe so, before threading any fasteners I could kinda rock it around on that alignment feature, didn't want to sit flat.

west added a comment.Jun 18 2019, 9:44 AM

Fingers crossed that if we fix T7669 all the rest of the changes will align

adam added a comment.Jun 26 2019, 10:13 AM

@logan @west is this ready for merge to master?

@adam The old version is still in this branch also and will need removed.

v0.1 model and gcodes present, part passed fit test and had no issues mounting the tool head.

logan moved this task from Beta to Needs Review on the Redgum board.Jun 28 2019, 1:17 PM
logan reassigned this task from west to Steven.
logan added a comment.Jul 2 2019, 1:25 PM

Drop test passed, full report:

Steven closed this task as Resolved.Jul 2 2019, 3:32 PM

This is now merged into master.