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markwal

Cura 15.06.03: strange very high feedrate motions generated

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Machine: Ultimaker 2

Mode: Advanced

Settings: default

(Sorry, I use youmagine too, but this one is from thingiverse:)

Model: http://www.thingiverse.com/download:907145

from this thing: http://www.thingiverse.com/thing:555242

Generated the gcode here: https://www.dropbox.com/s/1du7l2719pxkgyz/right_knee.gcode?dl=0

Lot's of weird zigzag jerky highspeed motion just inside the innermost perimeter on many layers.  For example:

From approx line 12590:

G11

G1 F3000 X109.306 Y110.671 E269.34268

G1 X109.306 Y110.450 E269.35152

G1 X109.052 Y110.585 E269.36303

G1 F144720 X109.224 Y110.496 E269.37077

G1 F3000 X109.533 Y110.747 E269.38670

G10

F144720!  Really?

Of course, the firmware acceleration and max caps kick in and it doesn't go that fast, but seems pretty random.  The zigzaggy doesn't seem to be necessary except to make the machine load. But perhaps there is a purpose or good reason for generating the zigzags?  It's pretty interesting to look at that gcode in http://gcode.ws too.  Nice neat layers with a string of rapid/random motion changes just inside the perimiter.

Anybody else seen this?  It doesn't seem to happen on every model.  Perhaps ones with sloping outer perimeters?

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CURA 15.06.x is beta, buggy, and limited in functionality at the moment.

Download 15.04.2 if you just want good gcode and no adventures. Not sure why the insistence on not letting people know about the state of the new cura, maybe they just want as many beta testers as possible.

Also they want bugs reported on the github site, since that's the best way to track issues and let them fix them.

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@peetersm Indeed this seems like a pretty serious bug. I've been working to make the next (real) release bugless. The beta of the next release will be released in a day or two.

I'm going to do my best to correct the bug before the new beta release.

For the next time: please submit a github issue at https://github.com/Ultimaker/CuraEngine/issues/ (or https://github.com/Ultimaker/Cura/issues/ if you don't know whether it's a fronet-end bug). Posting a bug on the forum is unlikely to get me working on it.

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Not sure why the insistence on not letting people know about the state of the new cura, maybe they just want as many beta testers as possible.

 

Well, I've been pretty straight forward with regards to what the new version of cura is; A beta.

 

Search the word 'beta' on https://ultimaker.com/en/stories/view/16750-cura-150603-release-notes = 0 Found

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Not sure why the insistence on not letting people know about the state of the new cura, maybe they just want as many beta testers as possible.

 

Well, I've been pretty straight forward with regards to what the new version of cura is; A beta.

 

Yes and I applaud you and the great work you're doing in this forum, thank you, thank you, thank you!!!

BUT still would like to point out respectfully :

1. The Beta is the only link that is listed on the CURA download page.

2. All other software developers usually label the name of the download as beta. i.e Cura-15.06.X-BETA

3. Nowhere in the cura download page does it say beta.

4. Nowhere on the "which cura is right for me" page does it mention a beta status OR even a list of known issues, just raves about how great it is.

5. Nowhere in the initial fan fair forum posts about the new cura was the beta status mentioned.

6. Users would download what they thought was the best version, and them be shocked about the lack of even basic functionality and they would get answers like "oh yeah, we're working on that" or "yep you found another bug, thanks".

7. Users who UN-knowingly download beta software are not happy since they lose time, and possibly plastic, and lose trust for the brand.

8. Users who knowingly download beta software and happy to help debug and improve the product.

I am trying to respectfully and constructively point out the recent (last year) direction that UM has been choosing for their communication about products and upgrades. I've mentioned this before in other posts that I love UM and am a huge advocate for them in my area, BUT I fear for the future since they (knowingly or not) are eroding their brand's name and reputation for quality.

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As to the issue on the 15.06 release being beta: indeed we were wrong to communicate it as being a normal release.

The old Cura was never released in stages. With the new Cura we moved to a system in which we first do a beta release before we do the real release. This went wrong on the first release of the new software. When we first released the new interface we were too eager and changed the download link to the new release, while we shouldn't have been so eager.

The 15.10 beta release should be downloadable this weekend, though it will not be the one directed to by the main download link. There will be a link in a forum post soon.

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You're preaching to the choir. I fully agree that we should (and should have) marked the 15.06 release as beta. But it's not my call to make and there is no sense in crying over spilt milk.

Like bagel-orb already mentioned, the next release will have a beta state (+- 1 month). During this time no new features will be introduced (feature freeze). This means we will have a lot of time to fix stuff.

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@markwal, as you can see the bug is fixed but the why the bug occurred is also important to understand I think.

The bowden system and with high pressure in the nozzle this causes a kind of delay between when you try to speed up or slow down the extruder motor and when the flow out of the nozzle actually changes - because you have to build up pressure in the nozzle before the flow increases. This is a low pass filter meaning quick changes in the head don't translate to quick changes in the extrusion meaning idealy you want to keep the flow at a constant rate.

So what I think bagel-orb tried to do is to make a (hopeless?) attempt at keeping that slightly more constant - for very short moves where the head was expected to slow down due to acceleration issues and where the feeder is expected to therefore also slow down by a factor of 2 he would double the feedrate and so on. Some moves were so slow he had to 1000X the feedrate. This is kind of a vain attempt since due to acceleration limits and since this is for very short moves (think 0.1mm) there's no way it can get up to speed anyway. So bagel-orb limited the max speed to 150mm/sec for this kind of operation.

Hopefully that won't keep Cura from printing up to 300mm/sec. I may have misunderstood the "bug" but I think this is it.

I don't think any of this is going to affect the "weird zigzag jerky" moves you experienced as those are I believe infill to support the layer above or below and occur on sloped sides.

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As to the issue on the 15.06 release being beta: indeed we were wrong to communicate it as being a normal release.

 

Ok..so...what's the reasoning in continuing to leave your mistake up for over two months now?

Honestly are you telling me it's too hard to do any or all of the following:

1. Change the link on the Cura main page back to the stable 15.04.2

2. Put a notice right on the page for the cura download saying something like "15.06.x is still in beta, see older versions link for the stable version"

3. Put some notice on the "which cura is right for me" page that explains the status, and while I'm mentioning that page.....really shouldn't that page cover more that one version?? the title seems to indicate you're sharing info about different versions and informing people as to which version to choose, BUT it only talks about 15.06.x as it fails to mention known issues. This page basically add insult to injury, by continuing to hold up the facade that 15.06.x is a trust worthy good thing that everyone should be using.

As so wonderfully described here ....(paraphrase) when you make a mistake say so and fix it. That video should be mandatory and compulsory viewing for every one at UM.

Doesn't anyone at UM understand the damage that's being done every single day that page stays that way?

Just looking for an answer I can understand from my beloved UM, at least someone help us out with that much.

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You make some valid points, I've also asked about what the difference in between versions.

When you go to the software version list, you see the different versions fine.  Then you go thru CAPTCHA and it downloads.  Prior to that, and in that list, should be some direction on what is changed between versions.

The reason I point this out is that as an Ultimaker Original owner, we are frequently told to download 15.02.1 for the latest firmware for our printer.  If I did not follow the forums, I would not know this!  

Please take this as constructive criticism to make  it easier for all level of Ultimaker owners to find the correct software for their model printer.  :)

Edited by Guest

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Ok..so...what's the reasoning in continuing to leave your mistake up for over two months now?

 

Because my focus is fixing issues, which we've been doing the past month ;) I do give advice about this, but that is the bane of larger companies; Communication takes a lot longer.

 

Doesn't anyone at UM understand the damage that's being done every single day that page stays that way?

 

Yes, yes people do. But we're not with 15 people in a basement anymore. Back in those days it was easy to convince the right people that this was an issue (and easier to find time to fight these kind of battles). R&D is swamped in work, so I (nor any of the people on software) can put energy in all these battles. I try to put energy where my strengths are; improving the software and talking to you people.

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I think Ultimaker, since the forum change, it's more on the hands of the Marketing department than the guys that know how to actually use a 3d printer. They avoid 'beta' 'working-in', they rush updates to publish press notes. It's a bad mojo.

 

Sorry but that isn't really the case. I have heard accusations about this quite a few times but for once I want to make a reply, not aiming to start a discusion but just to clarify how things are done. For one, everyone at Ultimaker knows how to use an Ultimaker, we have all had some training and experience, and especially passion for 3D printing. Otherwise you never even start. You'll see with the next Cura-release that it will be labeled as beta. So no fear there. At Ultimaker we do everything together as a team, nothing is solely up to one department, or in particular 'the marketing department'.

Don't really like the sound of that either.

Edited by Guest
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If everyone is responsible nobody is responsible....

fact is on Ultimaker.com/products/cura customer are pointed in the direction of 'new cura', most people will go directly to download without ever knowing they are using a beta version...

and even though it's late it's never to late to correct it, knowing that it will at least be weeks before there is a stable 'new cura'.

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@gr5 thanks for the follow up. Yes, it does seem to be designed to support the upper layer. I saw this also on an exterior sloping perimeter (not the zigzag, just the short interleaving segments of different speeds. My guess is that at certain slopes and extrusion widths there is a computed extrusion amount that is smaller than the nozzle width and it attempts to achieve this by either filling with a dashed segment or interleaves speeds in an attempt to pull a thinner extrusion alongside the neighbor.

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