Making An Object Hollow, My First Print on Form 1+

I printed at the standard 0.1mm resolution. I didn’t want to get to wild the first time around.

wonderful! IS the model share-able?

I added the thin-shell version of the model the the Thingiverse page. You can download it here

Great job. Sounds like you have the fundamentals down well. Just a couple comments. 1mm thick walls are a little on the thin side, they will warp and may as the object cures more over days / weeks start to crack. 2mm is better in practice. Also the internal supports are probably not necessary, if you turn them off you can scan through the layers looking for unsupported areas if there aren’t any you are probably fine, the form1+ is really good at overhangs.

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thanks. I think also 2mm is probably better against warping.

This Model would be quite interesting to print in separate but assembled form. This was done with the Crab Brian Chan creates in this Formlabs video. http://youtu.be/p_4EwIE3hIM

You might even leave channels to run stiff wire through and make the model pose-able.

I agree; 2mm wall thickness is my default setting for shelling parts while keeping them strong.

The guideline I made, Designing for the Form 1, has wall thickness descriptions as such:

**WALL THICKNESS
**
• Strong: 2 mm
• Flexible: 1 mm
• Delicate: 0.5 mm

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This is a very valuable post and discussion! I would really like to see more of these. I think Formlabs could benefit greatly from a series based on prints like this (I know I would!).

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Absolutely. I agree with @Nick_Eide. It is great to see FormLabs staff printing and sharing. It is a whole different side of FormLabs than we typically see here. While the typical post is professional, it is usually defensive. I can’t even express how surprised and impressed I was to see a printing project on the forum that came from the staff.

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I’ve continued to mess with thin walled prints. The general consensus seems to be for slightly thicker shell, so this time I made the walls 1.5mm thick. As to @RocusHalbasch 's advice, I turned off internal supports on these models.

There are some sections that look like they need a little support from the inside. With the supports already computed, I enabled internal supports and went into ‘edit selected’ mode.

And this is where I got stuck for a while. How do I put supports on the inside of the model if I can’t see inside it?

It turns out the answer is non-obvious.

On the right side of the Preform window is a slider that lets you scrub up and down through layers. In ‘edit selected’ mode, the behavior of the slider reverses, and you can see from the selected layer up, instead of the selected layer down.

With the model sliced open like this I can rotate around to see inside the inside and place internal supports as needed.

This took me an embarrassingly long time to figure out.

The original non-hollow model is available for download here

Nicely done Sir. The slider in supports mode interface definitely gets poor scores in the discoverability and principle of least astonishment categories. How did it come out? Also how did you handle drainage? The reason for the second question is I’ve noticed a lot of new users get this wrong for a while and run into blowouts and don’t understand why so stepping through how you handle that and check for it would also probably be an awesome thing to share with people.

Lastly this is something you pick up as you use the printer over time and really analyze a lot of prints, but it is worth mentioning here. The red coloring can not always be trusted. It will sometimes not appear when parts of your print are not supported, and other times will appear even though supports are adequate, it’s useful to help you get most cases done quick, but it’s no substitute for thinking about and analyzing the print yourself.

The part came out great!

I added 4 drain holes on the underside of the base, and a single drain hole in the top. My operating theory is more based on getting the IPA to flow through the inside of the model while keeping drain holes on visible surfaces to a minimum. In general I’m trying to err on the side of caution by adding lots of holes

A discussion of drain holes would be awesome. It seems like something that is really non-intuitive for a new users, especially users not use to producing physical prototypes.

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There are also specific additional considerations for platform up SLA machines life the Form1+. This in a nutshell boils down to for every region of your model that has it’s own closed off region of hollow space at some point in the print you need a drain hole positioned at or near the hollow portin nearest to the platform. This is something I have described my method for working out but I’ve not seen anyone step through visually. Currently I don’t have time to do so either.

I’d love for preform to have a way to add drain holes! I tried hollowing with meshmixer which adds the holes but it keeps mixing up the mesh. I hollow out with Geomagic and it works amazingly well but I haven’t figured out how to add drain holes. I’ve been drilling holes in the base of my models to drain the trapped resin out and to prevent cracking.

That looks fantastic! Thanks for the detailed walk through of your process.

G.

@Michael_Curry, Huh, don’t be too embarrassed, I never did figure that out. That’s neat.

@Michael_Curry , another great print!

From your pictures I would guess that you printed it an 0.1mm layer heights.

@JasonLivingston gives some valuable guidelines for the relationship between thickness & strength.I was wondering if there are any relationship between wall thickness and print layer heights we should also be consider when designing or using Preform.

I agree, The Formlabs users would benefit greatly from a person like Michael working on shareable process improvements and in return, Formlabs would benefit from a happier user base

Would love to see more examples from formulas staff.
Anyhow, I also printed the tachikoma and it has been a great success … now waiting for some paint!

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Great discussion. I would also like to learn more about drain holes. Here are a few questions off the top of my head:

  • What is the minimum diameter that resin will free-flow through?
  • Placement, how to visualize the optimal placement, etc.
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