Introduction to Thermoform
Hey guys and gals, today I am going to go over how to thermoform your 3D printed parts. This is useful for the 3D printed hands and arms that I do for E-Nable. I will go over some of the benefits to this process, and some ways that you can use it in your designs and prints.
Thermoforming is the process of heating your prints after they are finished printing and then reshaping them. This allows you to create more complex shapes and designs that would typically be possible. Also, let me say… I have only used this process with PLA and was not able to thermoform Nylon in a hot water bath.
All of these parts you are about to see where printed on my venerable Tevo Black Widow. It’s equipped with TMC2100 stepper drivers on the X/Y axis, parts cooling fan, Volcano hotend with Micro Swiss goodies, and a glass bed.
Methods to Thermoform
There are a few different methods to thermoform your prints. The two main methods are a hot water bath or a heat gun. I prefer the hot water bath. I feel it is an excellent way to get the whole part to a stable temperature without the risk of melting it. This method also typically requires nothing extra to be purchased. There are still many houses without a heat gun, come on people. It was in 2018. Kidding!
With that said, these instructions are to be taken at your own risk. Please be safe, as there is a high chance of getting burned. If you intend to try this out, please read these instructions a few times. Be familiar with the process so that you can give it your full attention. After all that… let’s start to thermoform!
The Heat Gun Method
The heat gun thermoform method requires finding a safe space to heat your 3D printed part without the fear of burning your dwelling to the ground. Find a scrap plate, dish or pan that is NOT FLAMMABLE. That part in ‘caps’ is pretty important. I will not be held responsible for any structure fires in the name of 3D printing. Keep the heat and blower speed on the heat gun low and also keep the gun 6-8″ away from your 3D printed parts.
Move the heat gun quickly either left/right or up/down depending on the overall shape of the 3D printed part. Do not keep the heat gun focused on one place for too long. This thermoforming method tends to go from nothing… to a hot drippy print quickly… so be prepared. Once the print is heated, bend it any way that you would like. When the plastic cools, it will retain the shape that you manipulated it to.
Hot Water Bath Method
The hot water bath method requires you to submerge the part into boiling water until it becomes pliable. This is, in my opinion, the superior way to thermoform as opposed to the heat gun. This method allows the whole part to get to the same temperature. The water doesn’t need to be boiling, but it should be able to get around 200F/90c.
You can use a pot on the stove, hot water from a tea kettle into a dish, or even use an electric skillet as I do. The skillet allows me to submerge large parts fully and can heat the water fairly quickly.
After getting the water up to temperature, submerge your part until it becomes pliable. Remove the region from the water with some tongs and cool for a few seconds as to not burn your hands. Once it’s cold enough for you to touch, form it to your heart’s delight safely. If you didn’t get it correct the first time, toss it back in the water, and it will go back to its original shape. Pretty handy, huh?
So you are probably wondering… why go through all this hassle? Why not print the shape I wanted to begin with? Well, what if I told you that this would save you time, money, and filament.. while also strengthening your parts. Buckle up and prepare to be amazed!
The forearm gauntlet and bicep cuff that I print for the E-Nable 3D printed hands now print entirely flat. This wasn’t always the case. Some models printed the forearm gauntlet vertically while some printed along the X or the Y-axis. The problem with this is that the holes for the wrist and elbow pins are set along a layer line. This makes the design prone to breaking and cracking.
The old style gauntlets also suffer from being ill-fitting and less forgiving to flexion. Which, are all terrible compromises for something that is meant to be worn on your arm. The thermoformed gauntlets print faster than the old style because they require no support structure. This saves you money on printer operation and the filament. The thermoformed gauntlets are also much stronger than the old style.
Instead of the pin holes being on a layer line, they go all the way through the layers. This reduces the possibility of cracking during use and improves flexion in the parts. Using the thermoform gauntlets also promotes a better fit for the recipient.
If your measurements weren’t quite right, you now can quickly reheat the part and adjust it for a better fit. You can use the thermoform principles in parts design. Was the design that you were initially working on too challenging to print? Try adjusting it for thermoform!
The Draw Backs
The only downside to this design method is that parts are not ready directly from the print bed; they require post-processing with either of the techniques that I described above. I’ve also noticed that too hot of temperatures can affect the 3D printed parts colour and finish. It would be best to try this on a scrap piece before you dedicate an essential print job to this.
So, today you’ve learned what thermoforming is, what it’s suitable for, and some of its drawbacks. It’s up to you to either wipe your brain of the last 5-10 minutes or thermoform a 3D printed part……right…… now