Scarring from Support?

I’m sure this has been discussed already but I haven’t been able to find anything.

Does anyone else get surface scarring from support removal? I’m familiar with FDM printing and I understand this is just part of it. But with the beauty and surface finish of the Form SLA printer, those surface blemishes from the support structure are all the more hideous to the eye.

My issue is when I remove the support, I either get a small divot going into the print or I’m left with a little bit of material behind, which I then attempt to remove (usually resulting in an imperfect surface finish).

I know the Formlabs website recommends “sanding” and then using mineral spirits. Personally I have never had good experience with sanding a print (unless I plan to sand the ENTIRE print including non supported areas). It usually ends with different surface finishes which often times does not look any better.

I was wondering what other peoples processes are? I’m currently using the preset support options. Should I play around with the support options? Increase touch point size? decrease? What have other people done?

Also should I be curing my print first before removing supports? I’ve found that if I handle the print to much (such as removing supports) before its fully cured, then the supports dont remove as well and the tackiness of the print can sometimes mess with the surface finish.

In general, what does everyone do to minimize surface scarring?

@Mo3dPrinting: A lot depends on what purpose your printed part has. If it is a figurine, then I believe all surfaces are very visually important. For me, the main purpose of parts that I print are either preliminary functional mechanical prototypes, or metal form tools or fixturing. Sometimes for a metal form tool, I cannot have the support surface come into contact with the metal being formed because the surface imperfection on the 3D printed form tool will mark or damage the metal surface being formed. So when in PreForm, I make sure to orient my part so that no supports will contact visually important surfaces of the part. I typically sand any surfaces after printing…but my parts are either mechanical components or tooling, so whether the surface is a sanded finish or not really does not matter to me. But I know that overall visual appearance is critical to jewelry makers or figurine makers. So if you are making jewelry or figurines, my response is not very applicable to you.

Concerning when to remove supports: I always remove supports after curing, as the print is a bit too tacky and more part damage is possible due to the relative softness of the material when not yet cured. But I also know that the material is more brittle after curing, so the way that the supports trim away after curing is more difficult because sometimes the surface material around the support shatters when trimming away the support. I notice that when supports are contacting the part right at a corner surface, there is more damage to the part than if the support contacts the part on a flat surface.

When in PreForm, I always edit the supports so that I have only a few…as few as I can get away with. Sometimes there are small reddish areas on the part (while in PreForm) which means that there may be trouble with the print, but in my experience my prints have turned out fine even when surfaces have been reddish due to my removing supports.

There are a bunch of tricks for making support removal easier and cleaner and I’m excited to see what other forum users have come up with.

Reducing touch point size will make support removal easier. That said, reducing touch points too much can cause print failures and I’ve found parts floating in the resin tank after getting a bit too ambitious. Iterate down to see what point sizes your prints can reliably handle. The default settings do represent the greatest combination of reliability and ease of cleanup but greater ease of cleanup can be had if you’re willing to experiment a bit.

As for physically removing the supports, I’ve found that it’s easiest shortly after parts come out of the IPA bath. They tend to snap off cleanly and do leave small bumps but not divots. Removing supports becomes much more difficult after UV curing. Some materials like Flexible do need larger point sizes so with those, it might be easiest to cut away supports though removing them right after an IPA bath still works pretty well.

I’ve found that lower grit sand paper does change the surface finish a bit. Wet sanding with higher grits (200-300) seems to go just as quickly as dry sanding with lower grits and produces a much better finish so you might give that a whirl. Mineral oil will remove the white finish from sanded surfaces.

Also, you can fill divots with droplets of resin, cure with a LED or Sunlight, and then sand down. Once the model is in its final sanded state, it can be wiped down with a little resin (which then needs to get cured using post-cure methods) to get the surface smooth again. Mineral oil serves much the same purpose from a raw-surface-finish standpoint. But it’s no good if you intend to paint the model but need to eliminate some minor surface finish imperfections caused by sanding.

1 Like

Thanks for the response. I was leaning towards a lot of what you say, its nice to hear other people thinking the same way to confirm my theories.

I tend to print more very small visual display prototyping pieces or figurines with my Form printer, and I don’t always want to have to prime and paint them. Getting that smooth finish where support was touching on a part thats only a few centimeters big has proven to be tricky for myself. If I’m going for a something I need to physically use then I tend to use my FDM printer and ABS (just my preference as I love the properties of ABS for mechanical use).

Granted yours is a special metal forming application, So your process makes sense.

These are great ideas, just the kind of suggestions I was looking for. I’m going to have to experiment with these. Thanks for the response!

Using a media blaster with a fine glass bead (smooth, not sharp) media is the standard go-to for final finish, after removing supports on SLA’s. This way, you and quickly and easily remove the sanding/file marks from the part and have a beautiful uniform matte finish in seconds.

Tabletop media blasters are a relatively cheap investment for how much time it saves in finishing… you just need a compressor.

Walnut shell media and a vibrating rock tumbler/polisher work well for me. No compressor required. Available for cheap $ at Harbor Freight.

I like the walnut shell idea… so you end up with a satin finish then? Less matte?

The blaster is great for speed. It’s literally seconds added to the process. I’ll have to grab some 24-grit walnut and play with it in the blaster!

Yeah. Softer media means less aggressive abrasion. I also think that just having the particles vibrated against the print vs. blasting media might produce better results. Uniform polishing is more easily achieved I think. You get all sides at once.

Granted, a vibratory application may have some benefit, but if you have to get parts delivered… it’s not really an option.

Again, simply hitting a part in a media blaster takes SECONDS… a fraction of tumbling. But, when tumbling with walnut, does the resulting part texture result in a matte texture, or one that is more satin/polished?

The main reason for the issue with supports is that the resin will accumulate around them and the laser will penetrate the resin beyond the current layer which cures material sticking to the underside of the print (where the supports are).
There’s some possible methods to reduce this effect that could be implemented in SLA printers in the future but it can’t be avoided entirely because of how the print is submerged in the resin. Printers like Polyjet use a print head that deposits small amounts of the resin where it needs to be so it avoids the issue.

For the Form2, getting a good orientation and support placement can improve results. Sometimes it also helps to break up the part into pieces so that you can orient parts so the important details will print better.
Sanding is necessary though to get things smoothed out, it’s unlikely you will get the results you need without it. For me, i do it by hand, I have a lot of small details along with some very thin parts that would likely break using something like a tumbler. It can take a lot of time to sand around all of the small details but I can get very good results.

“Satin” and “Matte” are close to the same thing. I guess I’d call the finish “Matte” more than “Satin”.