Optimum
Posts: 3
Joined: Fri May 31, 2019 11:03 am

Raft Infill Pattern Setting

Fri May 31, 2019 11:32 am

Hello all,

Like many on these forums I have been having trouble getting rafts to separate easily from my PLA prints. I looked at a few threads and just went with making a secondary raft process that prints at a lower temp and slower speed with max cooling to set the raft nice and solid so that there's less of a thermal interface for the print to amalgam with.

So far, my results haven't been great (adjusting separation distance seems to be useless as well), but I think what could benefit raft removal the most is the option to set the raft infill pattern to something other than rectilinear. I couldn't find a way to do this in S3D, though. I thought at least that setting the external fill option for a concentric pattern would work, but that sadly does not affect the raft's infill layers. Ideally, I think Wiggle or Triangular would work best.

Has anyone figured out a way to do this? Is there a way already in S3D that I missed? If not, should this be a feature?

Optimum
Posts: 3
Joined: Fri May 31, 2019 11:03 am

Re: Raft Infill Pattern Setting

Mon Jun 03, 2019 2:17 pm

Decided to follow this up with pictures to illustrate what I am talking about.
They were huge so I just uploaded them to a gallery: https://imgur.com/a/O2SWH4P

The first two pictures are the aftermath of separating a rectilinear raft from a print with rectilinear bottom layers. I spent a a few minutes wrestling it off with just my thumbs, barely got any separation. Switched to using pliers, but it left the ugly mess seen in pictures.

The last two pictures show a print with a rectilinear raft, no bottom/top layers, and honeycomb infill. I fiddled with the raft for ~15 seconds just using my fingers and it came off clean. Relatively speaking, of course. (dat separation tho)

** Note: These two prints were not printed at exact same temps and speeds, but the values are close. Will re-do if anyone cares.

The raft settings are the same. However, the first one printed out at:
50mm/min
210C Extruder
60C bed
100% Above Raft speed

While the honeycomb printed out at:
60mm/min
215C Extruder
70C bed
50% Above Raft speed (And yet it came off better. I bet a faster above raft speed would have given better results)

What I want is to be able to change the infill pattern of the Raft to anything we can use for the primary infill. I think I'm gonna test some wiggle/triangle infill at 100%, no bottom/top layers, and with overall settings matching the failed raft (pics 1 and 2). I think the preliminary results suggest that having more control over the infill patterns at the interface between raft and print are really promising, though.

And honestly I probably should have put this in "Feature Requests", so... sorry 'bout that.
I would really like to hear the community's thoughts on this idea, though.

User avatar
dkightley
Posts: 2045
Joined: Tue Mar 10, 2015 4:09 pm

Re: Raft Infill Pattern Setting

Tue Jun 04, 2019 12:03 pm

I think you just have to do some tuning of your print settings rather than request more settings to have to adjust!!

I would kill the bed temperature for a start. PLA doesn't need a heated bed. I'd also suggest:
* reduce first layer after raft speed down to say 30 - 40%
* Set the raft for no base layers and a single top layer
* Set the top layer infill to say 40 - 50%
* start with a separation distance of say 0.3mm and adjust by testing separation ease.

You should be able to pull 80 - 90% of the raft off with your fingers....and use a modelling knife to gently urge the rest to fall off by sliding the blade along the base surface.

Increase the separation distance to lessen the attachment. If the part curls at the edges, you've gone too far and need to adjust back again.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

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