Multi Material Printing Purge Blocks


In the world of multi material 3D printing purge blocks are seen as at worst a necessary evil but we are a community. We must be able to come up with a shape that would print a purge block in a shape that would interlock.

I know some have discussed printing a Lego shape on the top but 3D printing means you can make any shape If we could establish a standard interlock shape something simple like a Dovetail in woodwork. If we build to a standard that has a height that’s always a multiple of mm or half mm increments.

We could have standard shapes as walls and corners.

The one thing we would need is a standard interlock shape and personally like the idea of a Male/Female dovetail side. :wink:



The best method is when the model allows ist to use the infill to purge and prime the noozle
but that is harder to implement.



It is not any harder to implement at all. I’ve done it with a post-processing script.

Here is a demo gcode preivew of the post-processed gcode in action.

The real problem with the implementation is the physical translucency of the plastic. With only 3 walls (the usual print parameters for most people, or at least for me) the colours of the infill will bleed through the thin walls. causing two or more colours to affect the surface colour.

Yes, you can increase the walls to reduce or eliminate the effect but it is also kind of defeating the purpose (saving plastic) in the first place.



thats actually really interesting. You could use that to add a bit of variaty to the print. A specked effect for example.
Would you mind sharing your post-processing script for me to have a look at\play with?




There you go but don’t expect it to work without modification. It was a proof of concept thingy but eventually, I’ve lost interest with it.

Frankly, it was inspired by one of Tom’s video.



Hi this is indeed really interesting. There is one problem with this idea if you are trying to print with materials that have different properties - not only different colours. If there would be a possibility of using different models as Purge blocks. You know - something you wanted to print but it’s only mechanical part and how it looks like doesn’t matter that much. Then we would have like almost zero material waste.