Mendelmax 2.0 tweaking and adjusting
As the complexity of the part increased from our initial support design study : http://open3dp.me.washington.edu/2014/12/diy-support-study1/, the support we originally made was no longer suitable for use, as it would get trapped within the lattice structure we created, and be impossible to pull out. Now things are getting interesting..
We noticed two things from our prior experiment:
1. We wasted time and filament making solid support. We needed to turn the support into a shell to reduce heat, and wasted material. This will also make it easier to break out later.
2. We needed to add thin sections in the support to make it weak enough there to break apart to get it out.
Here is what the completed part looked like from the bottom:
You can see now that the support was hollowed after it was designed in by using a “shell” command in Solidworks. We used a .5 MM shell thickness, which was a bit overkill. It could have been done with .3 with equal success. The gaps between the part and it’s support was consistent with the last setup. You can see in the foreground that there was a built in stress riser (thin spot about .05 MM thick) up the middle to aid in breakout, and the results were the support came out in two equal pieces. The results were excellent!
I don’t know. But I do know that in practice I’m not all that impressed with the performance of blue painter’s tape either. It doesn’t have a very strong adhesion with the print bed (it’s adhesive was designed to be easily removable), so there are two cases in which I have had issues:
1. Long parts. If you lay down plastic in a straight line on your print bed, a certain percentage of that length will be lost to linear contraction of the material as it cools.
2. Heated build beds. Blue tape was designed to be put on walls and trim around your home as a mask that won’t leave behind a residue. It was not designed to be stuck to a surface, and have that surface heated up to 100 degrees C while maintaining it’s full adhesive properties (common ABS plate temp). Especially with our ABS builds, we have had problems not only with the plastic not sticking to the tape (wrong nozzle zero height setting) but with the part actually pulling the tape off of the bed under contraction.
I set out to find a solution to this problem, and found with a bit of searching, High temperature masking tape (MCMASTER PART # 7627A27).
The tape comes in 3″ X 60′ rolls, and costs about 18.50 a roll. It claims to be stable up to 325 degrees F. It’s not cheap, but it’s also been very durable. Our issues with part adhesion have gone away completely with the use of this tape, as well as the thermal degradation of the tape adhesive when used on a heated build plate.
The nice thing about masking tape, is it is not as sensitive to nozzle Z height adjustments as Kapton tape is. I’m guessing this is due to it’s slightly “fuzzy” texture that the liquid plastic bonds to kind of like velcro, or just the fact that it is not smooth, and therefore has more surface area for the plastic to adhere to. This means with the many, many people who use our printers (with highly varying degrees of…..ehem….ability), we don’t have to re-level the beds constantly.
There are some things to be careful about when using this tape:
1. Don’t heat the build plate above 25 degrees C with PLA!!!!!!!! You will never get your part unstuck without damaging the tape!
2. Consistent with above, you may need to experiment with how close to set your Nozzle Z-zero height to get your desired release strength. The plastics I have used tend to stick better to this tape than the blue tape.
This work is licensed under a Creative Commons Attribution 3.0 Unported.