Hi Guys,
I just got my printer this monday, I’ve been playing around with various settings trying to learn how to optimize my prints, just as an FYI if you havent learned some lessons:
Print at least 2mm of base layer, i tried to print the lowest possible to “save material” however the thing was impossible to scrape off the build platform, took me a few hours to clear all of the littler chunks it kept breaking into.
Now, for my question:
How do you play around with the Base of the build?
I have a part that’s basically a ring-ish piece, hwoever the blob occupies the whole space inside, I think THATs a waste of materal:
I’d start by reading through the support site guide to better understand orientating and supporting prints. This page talks specifically about model orientation:
Flat surfaces with support structures print much more successfully at an angle of at least 10–20º. You will notice that if you use the automatic orientation in PreForm by highlighting your part and clicking “Orient Selected” it will usually position your piece at an angle. After each layer, the printer performs a “peel” process, which literally peels the printed layer off the PDMS surface of the resin tank. The forces involved can distort the extremely thin layer of a flat surface mounted on support structures. If a planar surface is oriented at an angle to the build platform, there is only a little overhang for each new layer. Furthermore, many thin-walled parts present significantly less area in any slice when printed at an angle.
It looks like you are using Tough V3. If so, break out a hair dryer and soften the raft with some heat The model will lift off much easier and not shatter into a million pieces.
Craig’s suggestion trying auto-orient is a good idea.
The Form printer is a lot different from a FDM printer. If you were printing that object with PLA or ABS, you’d be right to want to orient it parallel to the build plate. That’s a mistake for SLA. As Craig says, angled to minimize the cross-sectional area being printed at each layer will yield a better result. It’ll make your base smaller, too, which will make it easier to get off the platform later.
You can also try increasing the Z fine tuning offset a little. My Tough prints needed a chisel to get them off the base and this corrected the problem for me… but it took me a few iterations to get it right.
There is a condition in Preform (bug) that sometimes will generate an entire flat base like you have pictured above. Not only does this waste resin it isn’t very easy to get off the platform. To get this full rafting of the base to go away you need to play with the supports. Try manually clearing the supports from one small area of the part turning the supported area into a giant C shaped section. Preform will see this opening and no longer fill the entire inner section with the base. This saves a ton of material.
The orientation for this part actually can work flat as long as you’re OK with sanding the area around the supports a little more. Large flat areas should not be printed horizontal because the surface finish on the top side (platform side) will be trash. Any large flat area should be oriented as close to vertical as possible for the best finish. Near horizontal will have the most layer lines visible.
Something else worth noting. If you cannot get rid of the large raft in the middle, you can always plop something in the middle. Take a look at the following:
These are two completely different STL’s I have from 2 different projects. I have printed them just like this a couple of times with no issues. Supports can be generated separately or all at the same time.
Preform is smart enough (or dumb enough, I’m not sure which) to know the items are not overlapping but allow the rafts to overlap.
Taking it one step further, you can also put an item under an enclosed item such as this:
You can definitely overlap bases, I’ve done it while trying to squeeze a few more objects on to the build plate. But I’m not sure PreForm is even looking for this. If you overlap two objects (regardless of whether it’s the object geometry or the object base that’s overlapping) seems to me that PreForm is probably still treating these things as two separate objects. So wherever there is overlap the beam will pass that location twice. If so, this would potentially overcure these areas making it even harder to get the print off the platform, and it might also cause problems with peeling…
Not that I know anything about this subject but when I sliced parts for my old FDM machine the slicer would simply slice the print bed, The fact that there looked like two visible parts in one place was actually only one element to the slicer. So the slice at each level would “absorb” and just treat a location as having either part or no part ??
As I say just my guess.
And it’s definitely possible that PreForm accounts for intersections when generating the actual printer download file, and ensures those intersections only get painted once. I have no idea actually, and being an software engineer I could see it going either way depending on the expectations of the design team.
I’ve done the trick with placing a supported object in the center “hollow” of another object and printing worked out just fine. I’ve also overlapped parts and bases where I had overhangs that didn’t need supports and allowed it. These might have been harder to remove except that even a small stand-alone print is hard to remove on my printer for some reason so there was no way for me to tell.
