Head crashes into model

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Zephyr
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Joined: Sun Mar 25, 2018 5:37 pm

Head crashes into model

Post by Zephyr » Sun Mar 25, 2018 5:51 pm

I need some help please!

I am using an M2 with V4 head, run by Simplify3D software and with PLA filament. I've have a lot of print time on this machine and am fairly familiar with some basic maintenance issues.

My problem is that even after a very careful bed leveling, the hot extruder head will crash into the print model after it reaches about 5 inches in height from the bed. Sometimes, it works just fine. But lately, I've had 5 models in a row that were ruined as the head knocked the models off the raft.

I've added a .5 mm vertical retraction lift as well as preventing a track line through the model outline for travel movements through the software settings. But still no luck. What can I do? Thanks!

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ednisley
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Re: Head crashes into model

Post by ednisley » Mon Mar 26, 2018 2:53 pm

Zephyr wrote:ruined as the head knocked the models off the raft
Show the models so we can see what's going on.

It sounds like this is a case where the geometry is not in your favor and no amount of fiddly tuning will solve the problem.

In particular, thin flanges and perimeter cusps tend to bow upward as the plastic cools. A raised lip at the top of a tall model provides a long lever arm against the platform, so you have an irresistible force meeting an immovable object.

My rule of thumb: if there's any upward bowing, find another orientation or redesign the part.

Zephyr
Posts: 2
Joined: Sun Mar 25, 2018 5:37 pm

Re: Head crashes into model

Post by Zephyr » Mon Mar 26, 2018 5:30 pm

Ed,

Thanks so much! That sounds like a very plausible explanation. Much appreciated!

Sorry, don't see how to load a pic of the model. But it could well be the problem you describe.

I was wondering if the narrow base, required by specs, might also lead to some oscillations, even though the long axis is along the direction of translation, Y axis.

All the best,

Zephyr

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