Greetings folks,
I’ve noticed many saying they’ve ruled-out the “platform flatness” being part or all of the problems printing with tough resin, by using a straight edge to measure the flatness. If you are not using a $50.00+ piece of stainless steel over 8" which is only used to test your machinists squares are square…then you are not using a straight edge to measure the platform for flatness. And to measure the peaks and valleys, only a stainless steel gauge will do, depending on the humidity, paper will have over 10 noticeable thicknesses throughout a day.
There’s a reason we are not able to print at 25 microns using the Tough or the Flexible resin. I cannot comment on the chemistry involved here, but I do know there is no difference between a 3D printer and a milling machine when talking absolute “0” in the z axis. Both the Form1 and a milling machine must know or set a reference point in the z axis. The z axis reference point of zero on a milling machine is very easy to configure compared to the Form1 3D printer.
Formlabs uses both the silicone layer in the resin tank and the aluminum platform in the support base fabrication process to set a reference point in the z axis, which is not actually required to print, What is required is the last layer of the support base to be flat for that model/part.
For any one given printer, If there are varying degrees of support-base adhesion success based on where the model is printed on the platform, then it’s my guess the flatness of the platform is paramount. The support base is very important, but only because the last layer of the base must be flat. Whether you print with supports or not, there’s a minimum number of compressed layers that must happen to get to “flat”. The silicone surface in the resin tray provides a compressible surface while the printer builds the support base thus creating a flat surface for the accuracy to follow.
Back in Aug 2013 I experienced a few problems, upon tightening the tolerances of the peaks and valleys relating to the flatness of the platform…those problems went away. I’m still using the same platform that came with my Form1 during the Kickstarter campaign.
Again, there are reasons why we’re not able to print Tough or Flexible at 25 microns. It’s all about the layer height in relation to flatness and the chemistry of the resin.
The only accurate fine-tuning available for the Form1 is in the z axis.
If one can determine where on a platform a model prints in Tough resin successfully, then move the model around til it fails, mark the precise area the model failed in relation to the model printed successfully and then use a straight edge (guaranteed and certified) with a tolerance of less than the layer height used over 8 inches…then you will be able to identify the areas of the platform requiring flatness adjustments.
cheers and good journeys,
Brent