I’m working on a 3d print of a bust that has failed twice. I’m uploading a screen shot of the preform bust as well as a photo of the two failures. The object pretty much fills the build platform. This is from a scan that I reduced and then hollowed in Meshmixer. As it currently stands the walls are 2.5mm thick. I’m printing with a Form1+. After hollowing the object I opened up the large underside of the bust so that it is completely open.
The difference between the first print and the somewhat better second one was my increasing the support density to 1.25 and the point size to .8mm.
I’m thinking that the walls are just too thin to print something of this size so I’m considering going back to Meshmixer and redoing the hollowing step. But before I do this I’m wondering if someone with more experience might have some other suggestions.
Wall thickness shouldn’t be a problem at 2.5mm.
Uploading the .form file would give anyone who wants to put in the time the info needed to determine the likely mode/cause.
Didn’t think to upload the .form file. Here’s a link:
I routinely print at 1.5mm with very few issues on my form2, you say it’s hollow, I’m assuming you have vent holes and internal supports?
I do have internal supports.
I’m not entirely clear on vent holes but the entire underside is hollow so as it is printing upside down, there’s always that opening at the “top.” As I understand how these printers work, they should not fill with resin in this situation because with each layer the bed tips away from the previous layer. That should, I think, allow any resin inside to drain away so long as there’s an opening above so no vacuum is formed to hold the resin in.
You are correct in your thinking that the large opening at the “top” prevents and vacuum/suction problems. Also, after looking at your .form file, I see no particular problems with the file. The supports are reasonable. I would actually use much less on my Form 2… there are only a handful of local-minimums that you need to deal with after the initial perimeter is printed and supported.
I can’t state the condition of your tank for the first print, but since the second was a little more successful, I presume you drained, filtered the liquid resin, and removed all solidified resin from the bottom of the tank.
My best guess is that you have hot spots in the silicone layer that are preventing a full cure. Although most tanks can take 2+ liters of resin, I’ve seen some damaged in one print, due to geometry… given that this model consumes a majority of the print area, it’s hard to avoid those hot spots.
Since you are using a Form 1+…
Is it possible that you were low on resin and it simply didn’t flow back to fill an area, therefore leaving nothing for the next layer to bond to? This type of failure would explain the “ever-growing” failure area AND the fact that later local minimums do print.
The bust needs to be angled face up so that the supports are in the back and then limits the supports on the face. This may create a build problem with size.
The way you are building too much force exists on lifting the model from the resin tray surface.
You all have me thinking about several things. I would much prefer to print this face up but it won’t fit in the Form1+ build volume that way. I did have enough resin in the Form1+ tray. Even after the full run, it was still half full.
However, when draining the tray after the second run I noticed a couple of things. There was a small area of cured resin stuck to the bottom. I don’t know if this was from my runs or some in the past. This printer is in a makerspace and is shared by several people. Of greater concern, there was a divot in the surface of the tray and resin was stuck there. That could easily have caused the part to tear between layers.
I’m going to buy a new tray and because I’m overly cautious, a new bottle of resin. I’ll also try increasing the wall thickness of the object, maybe to 4 or 5mm. There’s no practical downside for me in doing that, just the use of additional resin.
Thanks to everyone for the input. If others have thoughts, please continue to post. I won’t be ready to reprint for a week or so.
You can print whatever you want at what ever position you choose. It just won’t always work.
unfortunately printing with a 3D printer is not like printing with a 2D printer.
You need to be concerned with various needs of both the printer and the model you want to print.
Although FL tries to help us figure this out with guides and all; it has taken me 100s of prints to get it!
Believe me, I get it. I’ve printed many, many prints with FDM printers. I’ve printed some but far fewer with the Form1. I’m well aware that learning is incremental. That’s where these forums and other internet resources can be so helpful. Rather than just flailing on our own, we can experiment, share what we’ve learned at the same time learn from those who have walked these paths before. I hope you don’t disapprove of my turning to this forum as a resource.
Here’s an example of a contribution I’ve made to the cause.
If I was printing at a maker space I would purchase my own tray. With the Form 1 clouding and chunking of the PDMS are issues that aren’t easy to deal with. With your own tray it’s possible to resurface the tank at home.
I don’t really see any issues with the print layout either but the fact that it printed better with more supports is a pretty good clue. I would add a lot more supports in the area where the failure starts.
Thanks to all for the help with this. I pretty much did everything people suggested. Thicker walls on the print, new resin and new tray. The results are really excellent.
I see that you had a successful print, finally. That’s great!
One thing I noticed is that, when I had a form1+, is that on warm days I had far more print successes than on cold days. Eventually, others also noticed this correlation. A few individuals placed terrarium heaters along the edge of the printing window in the resin tank. Their success rates went up significantly
The Form2 heats up the resin to about 31C.
I think it helps to keep the resin more like a fluid.