Some Form 2 prints directly on the table in various resins

Printing directly on the table with the Form 2 is far more doable than with the Form 1+, and you can make some pretty interesting things that require nearly zero cleanup. There are several limitations, including extreme difficulty in removing Tough resin parts from the table without using so much force that you destroy them.

None of these are work prints, but I like to experiment with random models from friends and places like Thingiverse when I have idle time on the printer, so here goes. Clear resin first. This shoe model was scaled to a bit over 100mm in length and the heel and toe areas beveled slightly where they meet the table to ensure it would be removable:

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Tough resin uses a lot of compression and multiple passes for early layers so adhesion is very strong. This strong adhesion means you can print parts with orientations that would require divine intervention on the Form 1+. It’s a good idea to try to orient or modify models to provide a way to get the prying tool underneath them or you’re going to be chiseling off smashed tough resin parts and then cleaning kerf off of the table.

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I never used flexible resin on the Form 1+, though I ordered a small bottle of it right before the Form 2 was released, so I just waited for the Form 2 to arrive. I anticipated it was going to be more fiddly than the Tough so I figured the heated resin tray and more uniform shear would save me some trouble. So I did a couple test prints earlier this week, and then decided to go for glory by printing on the table. This bracelet was printed at 100 micron, and I was able to peel it off of the table by hand. Sadly I can’t post the video that shows it expanding and contracting.

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Many thanks to @Justin_Cordesman for these inspiring posts! I was beginning to think that support posts were sometimes just a way to sell more resin.

It looks like a model that can be printed on a FDM printer without supports can be printed direct from the bed on the Form 2. I don’t suppose there’s a way to add supports only where they’re absolutely needed, but have the model placed directly on the build platform?

When I print direct-to-bed on my Form1+ the Z-axis gets crushed about 250 microns. Any idea if the same thing happens with the Form2?

Care should be taken to assure the model won’t come off the bed and fall into the tank. There’s another post by @Stormtrooperguy that describes the negative-outcome when the model falls off and into the path of the wiper arm…

You can probably print most things that don’t require supports on an FDM (and may things that do) as long as they have an appropriate surface to interface with the table. By this I mean enough and appropriately distributed surface area to provide good adhesion, with a profile that makes it possible to get tools under the edges to pry it loose. I’ve found that many openings (as long as they not not present parallel surfaces to the build area, so most circular openings) that would require supports on an FDM are possible without them on the Form 1+ and the Form 2. I do spend time on orientation of parts that I’m printing with supports to try to avoid putting supports into openings with profiles that can get away with it, and will manually remove supports from those openings if I think they are unnecessary. I find this very worthwhile for parts that have internal passages that are difficult to clean up in post processing, and where cleaning up support marks on the outside is far more manageable. I’m inclined to believe that this results in stronger functional parts as well, because the tiny little nicks and bumps from removing supports kind of have to create funky little unpredictable stress risers.

There is no way I know of in PreForm to selectively use supports under only part of a model. This would be a handy feature with some parts. I’d also like the ability to just stick release tabs onto the side of a model that I was printing directly on the table.

I have not printed anything directly on the table with the Form 2 where I cared enough about the Z axis dimension on the base to put calipers on it. Often if I am printing directly on the table it is because I care a lot more about having a very flat base and good crisp corners coming up from it than other factors. I know that there will be a density shift a few mm up from the table and just won’t print directly on the table if I think it will affect assembly of a larger part, or if the aesthetic impact is harder to manage than cleanup of support marks.

I’m not kidding about the difficult of removing large objects if they do not have a point of entry around the edges to get them started. If you print things that have a large surface directly coupled to the table and no obvious means of getting a tool under them, they can basically be impossible to remove without breaking them. With the Tough resin this is problem because even when it is not post-cured, it is in fact Tough, so you eventually use enough force trying to remove a part that you break it, and then you’ve got a bunch of very resilient chunks of plastic welded to the table. The good news is that usually once you do get them started, they tend to very quickly pop right off.

The shoe I already mentioned had its interfaces with the table beveled slightly, so I put the new removal tool under the edge of the heel and just popped the whole part right off, it was super easy. The finger printed in Tough I grabbed and pried across the thinnest axis on the table. A lot more surface area than that and tough parts become hard to remove by hand. For that flexible part, I released it in the first spot by pinching a section with my fingers, taking advantage of its flexibility. Once I pinched the adjacent links to the first one, I was able to carefully peel it up from the table.

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Cool stuff. The downside of printing flat on the bed is that the layers of certain parts are always in the same spot. I noticed that problem the hard way after a 2000 layer print left a nice mark on the resin tray.

I’m picturing a modified build platform with a base material that has a high thermal expansion coefficient (e.g. PEI) and an integrated bed heater. Remove the finished direct-to-bed print, plug into a power supply, and the part pops off as the platform heats up. The components needed are already available, thanks to the 3D FDM industry. Thoughts?

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I am so glad to see this. I sold my Form1+ to buy a Form2 figuring that the new peel method would require that the printers be better calibrated and that therefore they would print to the platform well. It was just a shot in the dark and a lot to invest on a hunch. Seeing this post is a huge relief. I hope that my other problems with the inaccuracy and poor calibration of the Form1+ will be similarly improved.

I did a few prints directly on the bed and it worked very well. Just make sure the object has enough surface area for the first layer

I think there’s a lot we can leverage from the FDM/FFF community on how to manage bed adhesion and removal. For example, parts with small footprints can have removable pads added, which can also incorporate a chamfered edge to facilitate easier removal off the base.

I’m printing direct-to-bed on my Form1+ and I’m finding the adhesion to the brushed aluminum bed is very strong. What is the Form 2 using? It looks like plastic a plastic bed. Also, is the Form 2 base a 2-part assembly like the Form 1+?

The Form 2 bed is multiple pieces, but the metal is machined flat so it provides a more uniform shear load and then very slightly textured presumably to make for a better build surface (thought maybe just appearance). It is sealed to the plastic around the edges so that resin can’t get inside like it can on the Form 1 table.

Do you have any height difference on the parts printing without supports?
On the Form1+, there are compression layers that reduce the models dimensions on the beginning of the print (the area occupied by the supports base).

You can nearly calibrate any model loss out of the form1+ I used 1 cm cubes in the corners untilnone didn’t stick then backed up a bit.

We print directly on the bed quite a bit. There is .012-.026" loss of height.

With a few prints you can tweak your model to accommodate the compression.
There is also usually a small lip around the edges that is easy to trim away.

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I do quite a bit of flat work on my Form 1+ and was printing flat but I had some blowouts on some of the models and also found it hard to compensate for the thickness differences. Are blowouts an issue with the new machine for items such as coins with rimmed edges?

there shouldn’t be any issues with blowouts. But I’ve had some issues where at about 4mm or 4.5mm there’s always a line on the print, sometimes holes. You don’t notice it always, but on some thin parts it causes some big issues.

This happened to me too. I thought it was a failure from my printer but now I understand why it happened.

Thanks for sharing this info Zach :slight_smile:

I think the line has to be something with the printer, not like a mechanical issue, but something in the software that causes an issue at that point. Maybe it changes exposure times at that height or something like that.

The form 1 would “over expose” the first layers for better base adhesion. The Form 2 probably has a similar operation.
On our printer it has been 4.5mm on every one we measured.

@KenCitron The Form 2 is a lot better in terms of blowouts from ‘cups’ that compress/decompress over every peel/print cycle. It’s presumably a different scale of part than your coins, but here’s a photo of a large part that has two hollow cavities and has no vent holes, printed directly on the build platform.

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