We recently had a project where the client needed an exceedingly smooth finish in order to apply a reflective finish. We print in PLA so there is no truly reliable chemical method for smoothing the surface of a print. However, PLA smooths beautifully with a little heat. So we developed a method to smooth PLA prints using heat without warping the print. Here was the result. Does this look smooth to you?
When we work with clients on their products there is generally one misconception that comes up consistently. That misconception is the one of Quality. Basically how precise can the parts be? Most people believe that FDM printers create rough parts that need a lot of finishing. This is a misconception brought on by consumer 3D printers. The Printers we use at Slant can print as finely as a human hair.
There are two types of 3D printers commonly found FDM (filament deposition) and SLA (Stereolithography). FDM printers use a nozzle expelling hot plastic to build up a part. SLA use light moving over a thin layer of resin to create a layer. Due to the fact that SLA uses light, it has the potential for almost infinite precision. But what about FDM?
The standards for FDM are very loose and change from one printer to the next. The main value is vertical resolution, or how thick the layers are as they are put down. Most printers can go to .2 mm in that respect. This is really not very good. The layers are visible and a human can feel the texture.
When we designed the printers for our Farm we ensured that they could print as small as .1 mm resolution. This is the width of a human hair. This resolution makes parts almost perfectly smooth.
But now one must contend with horizontal resolution. The size of the nozzle on most FDM printers is .4 mm. Which means that that is minimum width of some part of the part. But this too can be reduced. It is possible to fit a .1 mm nozzle so that very fine details can be created. But this does require that the printer be capable of moving the heavy printer head very precisely. Again this is why we designed our own printers. The SlantBox has a full metal frame and highly tensioned belt system that ensures the head is moving precisely. We are able to create very small gears that are as precise as machined or molded parts.
The primary issue is that many people believe that FDM is an inferior process. This is mainly due to the experience that people have with consumer 3D printers that do provide very poor quality. But in reality FDM printers can be extremely precise and provide very good results. But few people have the time, means and expertise to create that precision consistently.