Postprocessing 3D prints

[Dr. Mike 195]

A member recently messaged me with a question about a brain she printed from this file. I as posting the response here in the hope that it will help others in the community. 

 

QUESTION
"I came across your 3D printable human brain model and was able to successfully print it. Thank you for sharing it! Now I need to post-process it and am wondering if you can explain how you post-processed your print? I have never done the post-processing before and am not sure the best approach to take. I have attached a picture of our printed brain for your reference. Thank you in advance for insight you can offer!"

 

 

RESPONSE:

Based on the picture you attached, it looks like you used a single extruder printer and printed both the supports and model in the same material, presumably PLA. You need to tear off the supports using pliers. This can be a time-consuming job as getting in every nook and cranny can be difficult. If you find the supports are stuck to much to the model, you may have to adjust some of the settings in your slicer software to compensate. There may be a rough surface where the supports touch the model that you can sand off. If you have a dual extrusion printer, you can print the supports using a water soluble material such as PVA, which makes the supports easy to remove by soaking in water. Dual extruders can be finicky and you will likely have to spend a lot of time trying out different settings to get the supports to work just right, including calibrating the XY offset of the second extruder, determining optimal print temperature for the PLA and support to work together, overhang speed, support infill percentage, etc. This process is very time consuming but gratifying once you get your printer dialed in.

 

If you don't want to deal with the headache, embodi3D has a 3D printing service and can print and ship to you. 

Hope this helps.

 

Dr. Mike

 

[arcadia-ncdl 0]

Dr. Mike,

 

How were you able to hollow out the 3D MRI scan? I've watched your hollowing out CT scan tutorial but wonder if it's a similar process for an MRI scan?

[Dr. Mike 195]

You can use a variety of free tools, including Blender or Meshmixer. Meshmixer is probably easiest. Here is the function shown in this picture. 

 

[valchanov 20]

Removing the support is a really hard and painful job, I almost cut one of my fingers the last time I did it (the bleeding was serious though). This is why I prefer to avoid the 3d printing of brain models and I'm making only visualizations. Anyway, here are some tips how to remove the damn thing without hurting yourself:
1. Use a bit lower extrusion temperature or additional cooling fan. For PLA try to print it at 195 degrees instead of 210. This will keep the details nice and steady, the support - easily removable and will eliminate the stringing. It's a bit risky, the model can deattach from the building platform.
2. Use a raft. A real game changer, when we're talking about support removing from complicated organic models.
3. Silk PLA filament. The supports with those filaments are much easier for removal. And it looks really cool.
4. Use different slide thickness at the interface layers. With most of the slicers, you can control the layer thickness in the different parts of your model. You can use lower slide thickness at the interface layers between the support and higher thickness at the rest of the model. This will keep the printing time acceptable and the support - removable.

5. You can try dual extrusion system with PVA as support, if you're ok with the constant oozing and stringing from the second extruder and the terrible performance of most of the PVA filaments. You can also try BVOH with a such system, if you can afford it.

[kopachini 29]

In Slicer PE, now Prusa Slicer, under Support materials, there is a parameter called Contact Z distance, you can increase it to 0.2 (detachable) which makes removing supports more easily

[valchanov 20]

2 minutes ago, kopachini said:

In Slicer PE, now Prusa Slicer, under Support materials, there is a parameter called Contact Z distance, you can increase it to 0.2 (detachable) which makes removing supports more easily

I'm usually avoiding this option, because I had few really bad cases of support deattachment/falling, which hurts a lot in 24+ hours print (I had to hold the support to the model with duck tape, while the printer was still printing). But for the brain model this option will come handy, because of the density of the scaffolds - they are literally everywhere and can compensate few spots of support deattachment. 

[kopachini 29]

This was eye openning for me, now is so much easier for me to remove suppots... but after this post I will probably have same problems as you  (we from Balkans are very superstitious as yo know   at least I am)

[valchanov 20]

[smithnovel 0]

It's amazing to see that i had the same problem and question. I usually avoid the Contact Z distance. Anyways, I got information from several places regarding any problem in 3d printing.