Hand showing the remains of a raft on a 3d printed object. Source: WhiteClouds
Hand showing the remains of a raft on a 3d printed object. Source: WhiteClouds

There are a lot of variables that go into a 3D print job. Rafts and supports are meant to help make your object better, but do they always accomplish that?

My 3D Prints Before Using the Raft

When I first started printing with my Cube, I expected that the special glue we use to help prints stick to the glass plate did the trick just fine. I printed a Rook chess piece, a couple bracelets, a pencil protector- all without a hitch. But when I printed my first Sphinx of Hatshepsut I began to wonder. The front corners of its base curled up. Then I printed a silver medallion I designed and its edges peeled too. I’m too much of a perfectionist with my artwork to let this be ok. So I set out to solve the curling problem.

My colleague, Cris, prints with a raft on every single print he puts out on his MakerBot Replicator 2. He seems to get good results from it. When he saw my Sphinx he asked if I was using a raft. Sheepishly, I admitted that I hadn’t been but resolved to try it based on his results.

Printing With a Raft

I printed another medallion, this time with a raft. Much better! No curled edges. For a moment, I was happy. So I printed another Sphinx, also with a raft, just to perfect the first one. To my shock and horror, the edges curled up worse than the first time. The entire raft peeled up with the object at all four corners. Was the raft to blame for an even uglier print? Was it the humidity levels? Temperature? What was I to do?

Time to roll up the sleeves and get “Scientific Process” on this problem.

After a bit of comparison, I realized that all the curling issues were with objects printed in ABS plastic. None of the PLA prints had any issues whatsoever. Interesting observation. So I’m printing another medallion, this time in PLA, with no raft— just standard glue.

Rafts and Post-processing

While we wait for the medallion print to finish, let me tell you what I learned about rafts in post-processing.

I wanted to take the Sphinx off its raft so I got the usual tools of scraper and leather glove. The edges of the raft peeled off a little too easily, leaving the raft firmly embedded in the bottom of my object (see images). The image shows everything I could get off with my bare fingernails and scraper. The sphinx just got demoted from bad to super annoyingly bad. The same issue, only worse, happened with the medallion.

Conclusion

The PLA medallion finished and it’s basically perfect. No raft. No curling. Just glue. There was a small problem but not too severe: The glue was so strong, I had to jam the scraper tool around the edge to get it to come loose. In the process, I knocked off the lower edge of the print. (see image). It might look like a lot of filament but it’s not even noticeable on the object. Next time I’ll keep the glue nice and light.

Conclusion: The Cube’s glue works as good, or better, than its printed raft. PLA needs no raft and ABS is going to curl no matter what. My advice is to use PLA for everything you can. If you must use ABS, don’t use a raft and expect some curling.