How To Hot Iron Finish a Rough 3D Print Using a Clothing Iron

Hot iron finishing
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How To Hot Iron Finish a Rough 3D Print Using a Clothing Iron
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3D printers like to think that the print comes clean off the build plate of their printer. After a couple long and complex prints, the reality of 3D printing hits hard.

Brims, rafts and support material leave sharp jagged edges around the print. Supports create rough bumpy points on flat surfaces. Overhanging and bridging surfaces still droop and curl on the print. Other overhangs do not lay down right for a clean flat layer.

While some of this can be potentially fixed by playing with the support settings, who has the time or material to 3D print multiple attempts?

If you have a large item that took 8 or more hours to 3D print, you do not want to reprint it. It is better and faster sometimes to process it with some elbow grease instead.

Tools used in hot iron finishing

Tools used in hot iron finishing. Tin foil, Sealing iron, IR thermometer.

For this blog I’ll show you how to use a clothing iron and soldering pen to quickly smooth out all the rough spots on a 3D print.

With all tools, please read the safety instructions. Because this involves melting plastic, consider using this in a well ventilated area.

Tools

  • Aluminum Foil: This keeps the 3D print from melting and sticking to your iron.
  • Clothing Iron / Sealing Iron: The black iron pictured in this blog is a sealing iron, designed to seal plastic bags in butcher shops. It is smaller and easier to use compared to a large clothing iron. You can find them in hobby shops or online.
  • Soldering iron: Find a quality one that you can control the temperature with. Avoid cheap ones that are designed for wood burning. Also consider an soldering iron with changeable points. I use a blunt point in this blog.
  • Thermometer: I used a IR thermometer to check the temperature, but you can use a meat thermometer as well.

Some of the parts that I show in this blog are for an upcoming 3D printed gun project.

Hot Iron Finishing

  1. Get your iron to a temperature that is just low enough to make the plastic gooey.
The frame of a 3D printed gun with loose layers.

The frame of a 3D printed gun with loose layers.

  1. Place the Aluminum foil over the 3D print that you want to smooth out. Keep the foil as smooth as possible to keep the wrinkles from imprinting into the 3D print.
Use tin foil to cover the part.

Use tin foil to cover the part.

  1. Apply even pressure as you slowly move the iron over the part. Watch the foil for tears as you move.
  2. Check the part frequently. You will feel the 3D print change as the plastic melts.
Using the sealing iron to melt the loose plastic down.

Using the sealing iron to melt the loose plastic down.

  1. Remove the foil to let the part cool.

Soldering Finishing

Soldering irons are good for the small crevices and holes that need to be cleaned out in your 3D print. You can also fix small flaws and edges with this process. If you have loops or ragged edges, this is a great way to smooth them out.
1. Chose the point that you want to use for your job. A blunt point is good for general purpose soldering, but flat points are good for scars created from support materials. Make sure the point is screwed snugly into the soldering iron.

Rough edge to smooth down.

Rough edge to smooth down.

  1. Turn it on and let it come to temperature. If you have a cheap iron, have a wet sponge nearby that you can use to lower the temperature as needed.
  2. Lightly pass the soldering iron over the area to fix. Move smoothly to melt a thin layer at time. Don’t stop or press down, as you will burn the spot.
Using the soldering iron to melt down a rough edge

Using the soldering iron to melt down a rough edge

  1. You can keep melting the plastic down, but let it cool after a couple passes. If it gets too gooey the plastic will ooze and flow in ways you don’t want.

Both of these methods are a quick way to process 3D prints. They will take some practice to master, but I have found that they are a great way to smooth and polish a rough 3D print.

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