Supports get knocked over

[thedoble]

Hi folks

I've been avoiding supports for ages because I always seem to have problems with them. Now I'm doing some prints that require them!

I've tried supports generated by slic3r and also making them in Meshmixer. I've tried making them super thick (8mm diam) with really wide bases for better adhesion.

Eventually the supports fall over. I've never seen it happen, but I have to assume it's from the hotend knocking them down as it travels from one spot to the next. I have heard the hot end scraping against the previous layer as it moves around.

Any thoughts on how to fix this? I have my travel speed set to 250mm/s. Is this too high?

Thanks

[IMBoring25]

250 might be enough to start missing steps, especially around the edge of the print bed. After steps are missed the head could go anywhere.

Aside from that, setting up a z hop is a popular solution for nozzle drag during travel moves.

[thedoble]

250 might be enough to start missing steps, especially around the edge of the print bed. After steps are missed the head could go anywhere.

Aside from that, setting up a z hop is a popular solution for nozzle drag during travel moves.

Thanks, I had considered z-hop as well. What's a reasonable amount? 1mm?

I'll try lowering the travel speed to 200mm/s as well.

[Outsider]

I have my travel speed set to 150mm/sec.

[thedoble]

OK, so it seems like I'm just going too fast. I'll change my settings and see if that improves things.

Here's a picture from my most recent support fail:

[img]http://i.imgur.com/1C1o67h.jpg[/img]

[img]http://i.imgur.com/Z485fPP.jpg[/img]

[thedoble]

Well damn ... my print failed at 93%

The extruder couldn't push the filament down the bowden, ended up burring a divet into the filament and that was that. I'm guessing the additional friction from the bowden tube being coiled up was the cause?

Anyone else have any thoughts?

[Windshadow]

A few tubes of XXXX brew? it must be awful to have a huge print like that fail so close to the end. can you pause the print and then substitute a shorter bowden for the last 10% if you can identify the layer it fails it it might be possible to restart this last one...
Commiserations my friend.

[Glacian22]

I've never had good luck with those long supports from meshmixer, they always fall over. I'd try a slicer that lets you customize where you're putting supports, either simplify3d (if you have cash burning a hole in your pocket) or craftware. Print the hole thing on a raft, put the supports where you need them (while having enough that they interlock on the big vertical sections), that's worked well for me.

[thedoble]

Thanks, I'm pretty gutted. Mainly because it's not obvious why this would happen, and secondly because it was going so well until the failure!

I havent had much luck with pausing prints. Every time I have done it in the past, I end up with a nasty 'ridge' line visible in the print at the pause layer.

[Glacian22]

I caught a minute of your stream of it printing, and then when I read that it failed at over 90% I literally winced...totally been there!

[jmpreuss]

I second the dump the meshmixer support structures. They seem great in theory but I have a 0% success rate with them, even on printers that have a 98% success rate otherwise.

[LiccaDollhouse]

You might want to model a raft just underneath the supports (not necessarily underneath the actual piece themselves).

I had to deal with a similar problem, in this case approximately 9 hours into a print, when the support moved just enough that it caused backpressure problems and a nozzle clog. Having the raft underneath just the support allowed me to finish the print.

[thedoble]

This ought to be a good test of Z-Lift!

[img]http://i.imgur.com/V1oLvqV.jpg[/img]

[thedoble]

I set the supports to a deliberately difficult setting and they seem to be working nicely! Looks like z-hop might be the answer.

[img]http://i.imgur.com/SR3Jzv6.jpg[/img]

[img]http://i.imgur.com/GPxhNwV.jpg[/img]

[thedoble]

Last pics before bed -

[img]http://i.imgur.com/OJg5ThG.jpg[/img]

[img]http://i.imgur.com/4IJIqNZ.jpg[/img]

[thedoble]

Well the supports worked a treat, none of them fell over this time!

I did notice a lot more stringing though, maybe I need to increase the retraction? Before I added z-lift I wouldn't get any, but I'm guessing with the nozzle being lifted, a little bit of plastic oozes out.

[thedoble]

Here's the finished print, the supports were SUPER easy to remove. I just ran a screwdriver up and down the inside of the print and they all popped off.

Also, timelapse video here: https://youtu.be/Ne5_gHyNtB8

[img]http://i.imgur.com/RWkFnBi.jpg[/img]

[img]http://i.imgur.com/YouM6oU.jpg[/img]

[img]http://i.imgur.com/Eu3UkJ1.jpg[/img]

[Xenocrates]

That looks so much like a part for a Tidewall Gunrig that I had to actually get up and dig one out to compare. I take it that it's a piece of terrain for WH40K?

[thedoble]

I'm actually not sure, it definitely seems to have the Tau emblem on it. It's for a customer on 3dhubs.