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Stereolithography produces parts by projecting ultraviolet light on the top of a vat of liquid photopolymer, causing it to harden. CLIP produces parts by projecting ultraviolet light through the bottom of a vat of liquid photopolymer, causing it to harden. This seems like a minor difference, yet CLIP is reportedly much faster (I've seen numbers as high as 100x). Why is this?

1 Answer 1

The number of 100x could be true in some situations. I wish I could see the part(s) that they printed to measure this 100x, but that is another story.

Looking at their videos they can move the build plate at a maximum speed of 10mm per minute. You will see the Eiffel tower video where they have to change over to standard speed for flat layers. It is because the flat layers stop resin flow and can't be printed using continuous printing.

Prodways have shown that they can move it at 20mm per minute, but again there are things that are not advertised/mentioned. To achieve higher speeds you need to make the resins more reactive. Making resins more reactive means the resins won't last as long in the vat/bottle. So they expire sooner. It also means they could harden under normal light conditions so it makes it difficult to work with. If you look at the Prodways video you will see resin waste on the build plate. That shows that the projector brightness was set too high.

Gizmo can print between 5 and 25 times faster than a leading brand of SLA printers, also depends on the number of parts and complexity on the build plate. The decision was made to advertise the build plate moving speed, e.g. 3mm per minute, rather than the number of times faster than anything else, because that is a value that doesn't change with the number of items on the build plate, but it does change depending on the projection area size.

Imagine you just have a single line going upwards then most SLA printers could do it at the same speed. B9 Creator (bottom up) users have actually shown they can do continuous printing when printing really tiny items with very thin walls, because they don't have suction problems in those situations.

Now when you add many small objects with small features on the build plate DLP printers will display the full layer in one go where laser based SLA machines need to draw out each part like an FDM machine.

Continuous printing does have limitations. Resin needs to flow from the bottom or you will get resin starvation and cause holes so you might not be able to use it for everything. You should see it as another tool in your printing toolbox rather than the be all and end all.

So after all that, the 100x depends on so many things, you shouldn't get stuck at looking at that number other than knowing it is a way of marketing the printers.