I love MakerBot and I love Bre, and I think he and his team have done an amazing service to the world.
Recently, I purchased five MakerBots (actually Thing-O-Matics, factory-assembled and tested), which was one for each our current TechShop locations (Menlo Park CA, Raleigh Durham NC, San Francisco CA, San Jose CA, and Detroit MI). I also picked up a Replicator for myself. Research, you know. ;)
After becoming very frustrated with ABS plastic objects warping when the bottom corners would pull loose from the build platform, I started searching for a new solution. No matter what I tried, including using raft versus no raft, increasing the temperature of the HBP (heated build platform), cleaning the Kapton tape with acetone, putting shields around the openings in the MakerBot's housing to keep the heat in, increasing and decreasing the nozzle temperature, nothing would prevent the object or even the raft from popping loose and lifting up on the corners. This happened with all six of the MakerBot variants that I had access to, including Replicator.
Previous solutions that have been created by others and adopted as supposed solutions included the HBP (heated build platform) which comes standard on all late-model Thing-O-Matics and Replicators, Kapton tape on the build platform, using a glass sheet, creating a vacuum table, using painters tape and other tapes, and countless other ideas. But none of these seem to work.
So I thought of my own solution.
My solution has proven to be cheap, fast, simple, and 100% dependable.
Would you like to know what it is? Then read on to the next step!
(I'll try to take better pictures the next time I print a nice large object. Hopefully you can see enough from these photos to be able to follow these steps.)
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Step 1: Put ABS Scraps and Acetone in a Jar
The first step is to make a thin slurry of acetone and ABS plastic scraps (raft and support, and rejected objects you've printed). We all generate lots of scraps on our MakerBots. You can probably make a similar slurry with PLA and acetone, but I haven't tried it yet. Plus, PLA doesn't seem to have as bad of a problem with lifting and curing and warping as ABS does. I personally find PLA to be too brittle for my projects, since I usually make structural objects. Let the ABS scraps and acetone sit in the covered jar for several hours, and the ABS pieces should completely dissolve. You want to have a very thin watery solution.
Step 2: Paint a Thin Layer of ABS Slurry on the Build Platform
I use a Q-Tip to apply a very sketchy application of the ABS slurry to the build platform right on top of the Kapton tape just where the model is going to be built. It does not need to be a solid coat. In fact, if you apply a solid coat, it will actually be very difficult to remove your object from the build platform!
Step 3: Print Your Object
Print your object with NO RAFT, directly onto the ABS slurry-slathered build platform.
Now when you print your object, you will find that it DOES NOT WARP as it grows in thickness. SIMPLY AMAZING!
The ABS slurry creates a thin layer of ABS, sort of like the raft that ReplicatorG creates, which causes the ABS to adhere completely to the build platform. Even very long and very tall objects will build with no warping or curling at all!
Step 4: Remove Your Object (This Can Be Tricky)
The ABS slurry causes the object to stick to the build platform like a barnacle, so you will almost certainly need to pry it off. With large objects, you may need to peel off the Kapton tape. Be careful not to break your object!
Step 5: There You Have It...100% Warp-Free and Curl-Free Free 3D Printing!
It is hard to tell from this image, but I tried to show a view looking straight along the bottom edge of this long, thick object. Believe me, it is 100% straight with no curling, bowing or warping! Without this method, this object would have warped at least 1/4 of an inch on or more corners.
I hope you find this Instructable useful! Let me know if it works for you.