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Frame Assembly: Trouble attaching the Z-lowers to frame assembly
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Description

Assembly has brought it to our attention that they are struggling with getting the M5 screws as it requires the driver to be at a non-perpendicular angle.

We had a case on the betas where one of the t-slot nuts were cross threaded and stripped out the screw.

I was able to save the part by using a EZ out at a odd angle but I'm afraid that this may be a common occurrence.

Event Timeline

oliver created this task.Feb 19 2019, 9:24 AM
oliver triaged this task as High priority.
oliver created this object with edit policy "LulzBot Hardware Products (Project)".
west added a subscriber: west.Feb 19 2019, 10:01 AM

@oliver what did we do on TAZ 6? The z lowers on TAZ 6 are similar where you cant get a driver perpendicular

They are also damaging the paint on the motors when trying to put them in.

@west From comparing TAZ6 to TAZ Pro, it looks like the TAZ6 had just a bit more clearance to get those screws in, as we didn't have a large motor in the way to have to navigate around.

tutley added subscribers: kent, tutley.EditedFeb 19 2019, 10:51 AM

@oliver @kent Taz 6 z lowers are also installed in the frame before the z motors. We may need to change the assembly flow for quiver if assemblers are going to be damaging the motors like this

logan added a subscriber: logan.Feb 22 2019, 7:46 AM

@tutley The big obstacle there is that the belt is the only thing that holds the X-Ends together as a sub-assembly, if the motor isn't installed, frame assemblers would have to wrestle with more loose parts as they assemble the frame. With blind holes for the smooth rods and no set screws, without the belt there isn't anything holding the Z lower up as the frame is being squared, which I can see being a pain.
If the damage to the motors is avoidable by any means other than leaving them off until after the frame is squared, that would be best.

We could print some flexy sleeves for the drivers so that a hard steel edge isn't rubbing against the motors. Currently one of the frame assemblers is using some of the blue painting tape as a barrier between the hardened steel and motor. The big issue is this is gonna cause is the driver will be at a greater angle and more prone to cross threading if the frame assemblers aren't careful.

logan lowered the priority of this task from High to Low.Apr 15 2019, 2:28 PM

Anyone have a path forward for this?
Leaving the motors off until after the frame is squared is not a viable option at this time as it would require major rework of the OHAI and BOM.

logan closed this task as Wontfix.May 31 2019, 8:37 AM
logan claimed this task.

Have not been hearing complaints about this lately, and without a path forward I am closing this ticket for now.

logan reopened this task as Open.Mon, Jun 24, 3:23 PM
logan raised the priority of this task from Low to Normal.
logan added a subscriber: cmerot.

We have recurring issues on the production floor regarding stripping these fasteners as well as the damage caused by the driver against the motor.
We're going to try out some hex head fasteners with a ratchet end combination wrench to tighten them.
I have requested these:
https://www.mcmaster.com/98093A310
The flanges will make the washers unnecessary.
I have ordered one of these wrenches to try these out with:
https://www.mcmaster.com/5163a24

Just a cautionary note:
since we dont supply a tool for this in the tool bag, customers will have to find their own wrench to work on their machine if they need to get to these screws

@tutley It may already be impossible for the customer to have to adjust the z lower screws based on what we are seeing on the floor. They are wearing through the ball jointed drivers extremely fast trying to properly assemble this part and damaging the motor in the process.

logan added a comment.Mon, Jun 24, 3:54 PM

Dually noted, we could add a cheap wrench to the tool kit. Hopefully they shouldn't need to loosen the fasteners that ensure their frame is square.

The flanged hex head fasteners worked well here.
A few small printed part changes would make it perfect:

  1. recess for screw washer needs to be wider since the flange of the bolt is wider than a washer
  2. the top rear fastener needs more clearance for the wrench

We can also get an 8mm crow's foot for a torque wrench and actually (for the first time) be able to torque these fasteners to the spec and check them :-O

T8316 is Change Order Request for this change