Spaghetti Supports


#1

I did a Durable print today where I only needed a few touchpoints toward the top of my part. Here’s the lattice Preform generated:

That tall, skinny truss isn’t nearly robust enough. Here’s how it turned out on my Form 3:

I printed a few of these, here are some others:

I’m surprised just how wobbly the lattice got! (I’m tempted to try it on my Form 2 for comparison).

It’s been requested before, but here’s a great example of where it would be nice if some advanced feature let you edit touchpoints on both ends of the supports. There’s no need for the bottom of those supports to touch my model at all - the truss could widen slightly toward the base and straddle my model to make contact with the raft instead. And if their bottom ends don’t touch my model, I’d be happy to see Preform throw in a few more truss columns and bracing to make the lattice more rigid.

I’m going to craft a custom support lattice for my next attempt, but thought I’d share this in case it’s of value for the Preform developers. (If anyone thinks the fault is my printer, let me know and I’d be happy to run other tests).


#2

Ouch…yeah durable can be really soft :frowning:

I second being able to move touchpoint bottoms. Sometimes it sucks to have more support artifacts in your part when it could be avoided.


#3

There are a number of things here.

1/ You have some control over where the base of the supports are placed. By placing the touchpoints on the sides of the model, rather than just the bottom, Preform will throw bases outwards, making a wider support base.

2/ I would be tempted to add two or three touchpoints up the edge of model to bind the support structure to the model, it will also help widen the support bases. You could also think about building this piece directly on the build platform.

3/ Green resin absorbs IPA, and especially DPM/TPM, so if the piece is in the wash too long finer sections, like supports will distort more than the main body of the piece.


Is Preform a good slicer?
#4

These are definitely work around a, but I still agree with OG on some improvements to support placement in preform.

Also, I haven’t seen parts absorb DPM more than IPA. Quite the contrary actually…and I believe formlabs says the same somewhere in their documentation (ie. That parts can be left in tpm without the same concern of swelling as ipa).


#5

Finished a bulked-up, custom support structure. Not the prettiest but should do the job. I used Formware 3D. It’s not bad; certainly quicker than modeling them in my CAD software. Preform could learn a few tricks from it on support editing.

Here are both versions side-by-side in Preform, beside a screenshot from Formware:

I started the print last night. It’s about a third of the way and looking good. Hopefully my resin lasts to the end. The revision takes about 40% more material - no doubt I went a little overboard on the column sizes, but I wanted to be sure. :slight_smile:


@billb Thanks for the suggestions, they are appreciated.

You have some control over where the base of the supports are placed

I did try moving around touchpoints to nudge Preform toward a better lattice, but it was like pushing rope with magnets. Would be a cinch if the software let you “grab” the base of a support and drag it elsewhere. Or paint “no-go” areas for contacts.

I really wanted to minimize contact points, and I couldn’t find an arrangement that supported the areas I needed while reducing/eliminating contacts at the bottom of my model.

add two or three touchpoints up the edge of model to bind the support structure…

That’s a really good idea. Lattices usually support my model, it didn’t occur to me to do it the other way around. But again, I didn’t want to add unnecessary contacts.

building this piece directly on the build platform

My first attempt was directly on the build platform, but the bleed (or “elephants foot”) was bad enough that I decided to lift it and live with sanding that one side. Form 3 really needs something akin to Z Fine Tuning. On my Form 2 I can virtually eliminate bleed on a part like this and use parts straight off the platform.

if the piece is in the wash too long

They came out of the printer hopelessly jagged already. You’re correct the wash probably softened them up some more (I’m doing longer washes since my alcohol is getting a bit saturated and fresh supplies are scarce).


#6

Much better:

For my custom lattice I went with three 0.4mm contacts to support the nub at the top, instead of the single 0.85mm contact (with an extra 0.4mm reinforcement a little ways up).
Turns out that wasn’t quite enough. I think there might be a difference between where the two slicers measure contact points, and the ones I did were a bit too small. Also got a severe layer shift 2/3 of the way up the model, no idea what that was about.

The structure itself is much more solid. Next revision would slightly enlarge the touchpoints and shave some resin off the supports.