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POST PRINT PROCESSING - A 3D PRINTING GUIDE

Written by: SailorZCreations

There is a range of techniques you can use on 3d prints depending on what you are trying to do - but the most important thing to do before you try any of the techniques is to make sure you are wearing adequate PPE for it!

When you have printed on any printer there is no way to 100% eliminate layer lines. My best advice is to start with the positioning of the model to work with the layer lines wherever possible. This is the easiest way to minimise the amount


a 3d printer
Image from Pixabay

Getting layer lines out on FDM - sanding

What will you need?

  • Sandpaper - I usually start between 300 - 400 grit

  • Water

  • Precision files

Seems basic, but good rough sanding is one of the best ways to remove print lines from your FDM prints. One thing to bear in mind here is that you need to weigh up the level of sanding needed vs the level of detail. If it is a highly detailed model then use precision sanding files to smooth without losing too much detail.

Start at a lower grit and work your way up to a grit that suits your needs. I use water when sanding as it reduces the amount of dust. Then continue as you normally would, apply primer or paint that adheres to the plastic.


Getting print lines out on FDM - Lacquer/filler and primer

What will you need?

  • Spray lacquer or Spray Filler (if you can get 2 in 1 spray filler/primer then bonus)

  • Spray primer in chosen colour (must bond to plastic)

  • sandpaper

Angle the model where you won’t get pooling, gravity isn’t always your friend. Spray alternating thin layers of primer and lacquer/filler, letting them dry thoroughly between each layer until the lines are no longer visible.

If needed, sand down any drips or edges that aren’t perfect. As long as you finish on primer you are good to go.


Getting deep defects out on FDM - Quick Dry Putty

What will you need?

  • Quick Dry Putty (either air or UV)

  • If using UV will need UV light

  • Sandpaper

Definitely, a dirty job, rub the putty over the model with your fingers so it is covered in a thin layer, once warm it should be quite easy. Be careful with the depth and make sure you avoid any details that you wouldn't want lost. Let it dry/cure it and then sand it back to the print. When finished you should have filler in all the layers and can look like stripes with the print material


a 3d printed tiny boat
Image from Pixabay


Getting print lines out on FDM - UV resin

What will you need?

  • UV resin

  • UV light

  • Brush or sponge

  • Silicone sheet to catch drips

In a darker room, with as little UV light as possible. Mount or hold the print, remember gravity will not necessarily be your friend during this process. Pour a small pool of resin on the item and begin to brush or sponge the resin around to fill the layer lines. When it looks right, get the UV light on it as fast as you can. This technique can lose details quickly so make sure you have removed all the resin from where you don’t want it before putting the light on it. Use a lighter to quickly remove bubbles, a heat gun has more chance of pushing the resin.

If you are happy with the level of detail and you managed to get a layer you are happy with then you can leave it here and move onto the priming stage.

If not you can sand it back to the print material and use it as a filler, prime and carry on.


Getting print lines out on SLA - sanding

What will you need?

  • Sandpaper - I usually start between 300 - 400 grit

  • Water

  • Precision files

A good rough sand is one of the best ways to remove print lines from your resin prints. One thing to bear in mind here is that you need to weigh up the level of sanding needed vs the level of detail. If it is a highly detailed model then use precision sanding files to smooth without losing too much detail.

Start at a lower grit and work your way up to a grit that suits your needs. I use water when sanding as it reduces the amount of dust. Then continue as you normally would, apply primer or paint or leave shiny.


Fixing small holes on sla prints - UV resin

What will you need?

  • UV resin

  • UV lamp

  • Toothpick (silicone or wooden)

  • Silicone mat

When using UV resin it is important to remember to use small layers as thicker ones may not cure properly causing issues later down the line. Put a small blob of UV resin on your mat. Using the toothpick slowly fill the hole layer by layer, making sure each layer is 100% cured. When the hole is filled, you can tidy up any bumps by sanding them down.

TIP! If the hole is small but deep, put a toothpick sized drop on the edge of the hole, tilt the item slightly so the drop can use gravity to assist,IE the drop should be at the highest point, and add drop by drop until the weight of the drop pulls itself into the hole. If you try and push the resin in then you will be more likely to end up with bubbles.


Fixing oversanding - UV resin

What will you need?

  • UV resin

  • UV lamp

  • Toothpick (silicone or wooden)

  • Silicone mat

When using UV resin it is important to remember to use small layers as thicker ones may not cure properly causing issues later down the line. Put a small blob of UV resin on your mat. Using the toothpick slowly build back what you removed layer by layer, ensuring each layer is 100% cured. You can tidy up any bumps by sanding them down. If it is a corner you are building back up, on something like a die, I have found it easier to build up a blob on the corner and sand it back to a point.


Plugging drain holes - SLA - with plugs printed

What will you need?

  • UV resin - preferably the one you printed it in

  • UV light

  • Silicone stick

  • IPA + brush/wipe/cottonwool (if water washable use water)

  • Plugs printed and any supports/bumps removed

Start by making sure the plugs fit in the holes but be careful not to drop them into the item. You may need to slim them down a bit depending on shrinkage etc. When they fit and are ready, put a small layer of UV resin around the plug, insert it into the hole, wipe off any excess, use IPA if needed, and let it dry. Once all the liquid has evaporated then cure the plug in place.


Plugging drain holes - SLA - with clay/putty and UV resin

What will you need?

  • UV resin - preferably the one you printed it in

  • UV light

  • Silicone stick

  • Clay/putty/substitute

If the hole is narrow you may not need to use clay, but can just go ahead and build up uv resin using the sides of the hole to narrow it layer by layer. If the hole is wide or has very little depth you can use clay to fill the hole, make sure there is at least a small gap for the resin to adhere all the way around the hole and then add a layer of resin. Build it up, curing layer by layer until it is level or just above and tidy back. If you get resin where you don’t want it you can clean it off before you cure.


For those 3d printing at home, let us know in the comments what questions or problems you have and we can bring you the answers!






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