I’m printing a long and straight part.
When it’s finished, there’s a definite skew from one long side to the other.
I just looked back at all prior prints of the same part and they have skew also.
Some have skew at the bottom only…close to the supports, and some have skew at both ends.
Are there process methods that will reduce or eliminate this skew?
Am I doing something wrong?
Is this an artifact of the way I am taking the part off the platform?
I start at one end and push the putty knife under it until it pops off.
I swish the print around then let it set 2 or 3 times, for a total of 10 minutes in the first vat.
Then I repeat this process in the 2nd vat.
Then I expose the part to UV for an hour while the supports are still intact and the part is standing on the supports.
Could I hang the part upside down by the supports?
What else can I try?
Do you have a screen shot of the part in Preform and a photo of the actual part?
I have a hunch that it might be the orientation and supports if this is the only part that has that problem. If all parts no matter what have the same problem then it might be something else.
It might be better to angle the part so that the curved surface is facing downwards more, and then place supports in a more even pattern along the surface. When placing supports, first start with the areas that simply need support to print at all, and then place support points on areas to keep the print stable while printing. If there isn’t a stable structure then the layers may not align due to the print flexing.
By putting the supports on that curved surface it’ll be easier to clean off since there’s no detail there.
That’s exactly the type of guidance I needed.
I re-oriented, curved side down (at an incline), then re-generated supports at density 1.25.
(previous prints have all been density 1.00)
I’ll have more support contacts to clean up, but print accuracy is my priority, as it should be.
Cleanup will be easy, since these surfaces are all straight in 1 dimension.
I’ll also attempt to peel the part from the platform at the side that has the most supports, hoping to limit deformation.
Printing…Done.
Where the added supports were located, the print came out straighter,
I need to add more supports to the long side…I need to learn how to add individual supports manually.
Also, I think I’m introducing deformation when I snap it off the platform…if I had more supports, it would probably not do that.
The wider the base, the more it sticks to the platform.
You can also rotate the print so it peels at more perpendicular to the part. I typically try to avoid printing perfectly perpendicular or parallel to the tank.
you can get better results by manually placing supports, the automatic system doesn’t care much where the supports go so you can arrange them in a way that they’re easier to remove and that you can get better stability with fewer supports than the automatic system might use.
Out of curiosity, how much deformation are we talking about here ? Did you measure it, or could you take a photo with the skewed part against a flat surface to see the curve better ?
With the part you showed, 1.25 support density and the orientation that you describe I wouldn’t expect the deformation to be over a few 1/10th or a milimeter over a few centimeter of length.
I also wonder if the 0.1 layer size influence negatively the precision of the part due to each layer being more exposer to the laser and thus adhering more strongly to the PDMS layer… But that’s merely a wild guess, maybe @Frew has some more information regarding this ?
The deformation is roughly .8 mm skew over a 130 mm length.
This is a little deceiving because the part was printed with the long dimension at 40 degree incline from the platform, where zero degree incline would be parallel to the platform. It was also printed with the width at roughly 30 degrees from the platform.
Sorry if my terminology is not consistent with yours…I’ve only been printing in quantity for about a month.
Can you upload your .form file so that we can take a look? Experimenting with different support densities is a great first step but for parts that are oriented on their side like this one, it might not be possible to fully brace the part regardless of density. A different angle might help out with this and 0.8mm of deviation is more than we’d expect across a surface like this.
@JohnHue I wouldn’t expect any notable differences in accuracy across different layer heights. 50 micron layers may have slightly less exposure compared to 100 micron layers, but also has twice the number of layers overall. A neat idea nonetheless.
I have had similar problems with a square corner, I added a few extra supports at the problem edge. That helped. I then tried reorienting without the support, by rotating opposite direction same side up and that also solved the problem.
