Delta arm rods broke off (disconnected) Now with Pictures

[barbosa.rmv]

Hi Folks,

Something odd happened today.

I was doing a very large print (37+ hours in draft) and this morning, when I checked how it was going, I found the extruder block hanging from 2 rods.

The other 4 rods were broken off, i.e. disconnected, from the cheapskates.

I suspect the mesh loom got entagled between the clip on the left axis. Its curvature kind of pushes it on this direction depending on the height of the print.

I'll post some photos later today but was wondering if this has happened to anyone and if so how to solve it.

Moving the mesh away seems to be dificult.

any feed back appreciated

Thanks

[Jimustanguitar]

By broken off do you mean that they just unsnapped from the carriages, or did they actually break?

Might be fortuitous timing with the new ball-socket arms and new injection molded cheapskates.

[barbosa.rmv]

Correct, they just un snapped...

Can't imagine the force needed for this in multiple axis

[barbosa.rmv]

[img]https://lh3.googleusercontent.com/-Tl4q ... G_0186.JPG[/img]

[img]https://lh3.googleusercontent.com/-RlcZ ... G_0187.JPG[/img]

[img]https://lh3.googleusercontent.com/-3guq ... G_0188.JPG[/img]

[img]https://lh3.googleusercontent.com/-KWZH ... G_0189.JPG[/img]

Note I put the mesh in there, I was NOT able to see this happening it is just a possibility

[img]https://lh3.googleusercontent.com/-GFhf ... G_0191.JPG[/img]

[img]https://lh3.googleusercontent.com/-jzjw ... G_0192.JPG[/img]

For size

[img]https://lh3.googleusercontent.com/-QT3j ... G_0193.JPG[/img]

Any help is appreciated

Thanks

[crocky]

Wow!!!

Never seen that happen, your drive belts must have been working well...

[Tincho85]

Yeah, and that print stuck there really well!
Luckily no permanent damage was done.

[barbosa.rmv]

Hi Folks,

I finally found out what happened to my printer. Or at least I did somethign which fixed it.

Such a catastrophic failure had to be a combination of things.

I kept trying to understand what happened and 3 more prints snapped the rods from their carriages.

All about 80% print, all more or less at the same place.

Every new try I tested a new theory. I even tried to rotate the part on the bed thinking about the angle of the rods but it still happened.

On the 3rd print I actually saw it happen.

Here is the sequence of the fixes:

Removed the feeding boden tube from withing the mesh, this made a softer curvature of the boden tube and make it less likely to get tangled in the carriages, perhaps I should have cut its lenght a bit).
Adjusted the belt tension on all axys (one of them was really loose and in one of the non printing movements it slipped/skidded making everything come appart)
Reduced the non printing move speed from 300mm/s (default in matter controll) to 100 mm/s.

After breaking the printer so many times I actually had to replace the thermistor and re do all the printer head wiring, this forced me to adjust the z height and slightly adjust the height of each axys.

After this I have already printed 3 times the same problematic part and on my way to a 4th print, almost non stop.

All seems good now!

Cheers

[crocky]

Thank heaven for that...

Bowden tube length would appear to be the culprit, glad it is sorted now...

[Mihelich]

I actually just had this exact issue happen to me last night on a 15 hour print.
The loom caught on one of the upper arm pin ends and ripped the arm off.
Just snapped back on with no damage done.
Need to recalibrate tonight and check the length of the bowden tube clearances more closely through its entire travel envelope.
It just must have happen to find a troublesome sweet spot.
I might also look at using the plastic wiring spiral wrap instead of the mesh loom.
It would then be less likely to snag on any if the parts.
Thanks for the heads up on this potential failure mode.

[U.S. Water Rockets]

I've have the arms come off the effector on very long prints because the axles would walk their way out of the u-joints.
It only started doing this recently, so I suspect that thousands of print hours on the axles has worn things out somehow.


I have purchased the new ball socket arms and that should fix it.

[Eaglezsoar]

Very good troubleshooting to find something that only occurs after many hours.
Thanks also for posting exactly what was happening. Many people could be helped by this.