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The bottom surface is not smooth compare to the top surface

Hi,

I print my file by using Spot-HT resin. The result come out is great, but just the bottom of it is not smooth.

Does anyone know what is the problem?

Sorry for my bad english.

Thank you
Melvin

This is caused by the instability of the supports, shrinking and warping. You may want to make the supports stronger by increasing the exposure time or making them thicker. Always overexpose the first 0.5mm layers connecting to the tips of the supports to reduce sagging for a flat structure like this. Doing this would also help maintaining the flatness of large area layers connected to the tips to reduce vacuum force caused by the warping of thin layers.

The supports should be at least 3mm long, depending on the viscosity of the resin. Thicker resin You might also want to increase the delay time to 1 second so there is enough time for the resin to stabilize. Slow down the lifting speed for the first 0.5mm layers connecting to the tips to reduce the force on those layers. Once the foundation is sturdy, layers on top of it will be normal. For this model, the foundation is formed by the supports and the first 0.5mm connecting to the tips. The printing process is like build a house. In addition to the gravity, you also have separation force and shrinking force to deal with.

<img src="/uploads/default/original/1X/bf017e07fe9bb8d9ad6fed380abf29455de3aba5.jpg" width=“666” height=“499”,

Thanks for the reply, I had follow your instruction in setting the exposure time. The situation had improve, but there is still some blurry on the surface which attach the support.

This time I try to print a same model in 2 orientation, but the result came out inconsistent. Refer the picture above , i put vertical orientation when printing the left side model, the ride side model is in horizontal orientation. hte right side model was what I export in STL.

I had attach my setting in printing those model, please check.

Thank you!

https://www.dropbox.com/sh/8glaerxtsk559rn/AABcwtvbAKpF94suDybPKd81a?dl=0

here is the link for the STL file and my setting.

Thank you