Multi-color Printing

Remember that project I was working on one blog post ago that we pretended like was yesterday?  When I was first interested in 3D printing it seemed to be a disappointment that models were printed in one color.   You start with a model, give the printer rules on how to extrude filament and in the end, you have a completed print.   

That process happens in a single color though.  And that was sort of sad to me.   Why couldn't models be printed in multiple colors?  Well, it turns out they can, only it's complicated.   Models are printed one flat layer at a time and if you're printing a bear with white paws and a light brown face while the remainder of the model is dark brown, there are different points at each layer that you might need different colors. 

There are several ways this can be accomplished but the current way I'm working on it is via a secondary machine that looks at what colors you need when and splices together bits of filament so that when the printer needs white filament, it's just arrived in the extruder.   When the white is no longer needed and you're back to the dark brown, that color has already been prepared, spliced, and has arrived at the extruder to be melted and added to the model. 

It does all this in a single unbroken length of filament.   Sometimes that length of filament is tens of meters long for complex models.   Crafting the "recipe" of what filaments are needed when and then being able to splice up to four colors together is impressive technology. 

There is an interesting handshake that happens between the machine that's making this chain of filament splices and the printer that's printing the model.   They're not connected electronically.   One has no idea where the other one is aside from the fact that they started at the same point.   How fast the printer prints, if there are pauses by the operator don't affect the device splicing the filament.  The connection is a physical one.   The printer pulls for more filament and the splicer takes that as the message to produce the next segment. 

I'm so impressed.   It's not perfect and there is a lot of tuning that needs to be done to get the filament splices solid as different filaments have different properties.   Alignment is important so that the bear's paws will be white and not the paws and lower legs.   Even if it's not always perfect, the output is so interesting to see, after all this time printing with a single color on one spool

The Big Boy Tiny Girl S'Mores Dessert:  We had a fire in the fire pit we inherited from our neighbors that moved again tonight.  Last nights was fun and my husband was up for doing it again.   My son and he stayed out much longer than my daughter and I did.  She got cold so I went in with her for a bath.   He wanted to stay out and see what types of sticks he could put into the fire and how they'd burn.