# Specific 3D Printers, Scanners, & Hardware > Peachy Printer Forum >  Back filling printed parts.

## jjmouris

Hi Rylan, the Peachy team and others,


I have been thinking about some stuff and how printing the parts that I would want to print would work out in reality. It seems to me that a greater surface accuracy with minimal warping would come from scribing a thin layer along the critical surface first and then back filling this to the thickness required. Initially with a bit more resin to get a sensible wall thickness (~5mm) and then filling the part with something substantial after the print is finished. Possibly the inside surface should be slightly under cured to ensure a good strong bond with the back filling material. This will require some clever software work with respect to getting from a designed part to driving the printer.


In any case, I came up with the idea of back filling the parts with a mix of the same photosensitive resin mixed with Poraver. Poraver is basically just recycled glass in the shape of little balls and can be had in different grain sizes. You are looking at only about 10-20% resin per volume compared to filling completely with resin. Even less with foaming agent added to the resin before mixing with the Poraver.


http://poraver.com/?q=en/product/granularities


The benefits of this method are plenty. The main advantage is that the Poraver lets through light to some degree and does not warp. With such low resin amounts per volume the warping should be kept to a minimum while a very solid and thick structure can be made. You can cut down on printing time compare to printing an internal structure and you can cure the back filled part with a flood light in a very short time as you see fit. You can simply pour in some Poraver and then some resin over the top and let the resin run through. Any excess can run out through a small hole in the bottom of the print, effectively not wasting any excess resin.


Not to mention, Poraver is an environmentally friendly and already recycled product.


I can see how this type of parts production could be used to create all sorts of consumer parts with interesting properties.


Your thoughts?!  :Smile: 


J

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## Anuvin

I believe that Poraver or a similar product has been tried with success. It is certainly something I will be trying as time goes on. Very good idea J.

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## Anuvin

Upon playing with the peachy for a while, I think you could probably put unwanted or failed prints into a coffee grinder and make them into a good resin filler, but it may not float, so you would have to inject it after the fact. For most parts, this would probably work just fine. I will test this more and report back.

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## Feign

I'm still floored by Rylan's filler suggestion over in this thread.  The thought of using semi-cooked rice as a filler never in a million years would have occured to me.  Doubly for its spongy structure that can absorb some of the stress from the resin shrinkage as it cures (usually a big problem with curing solid parts from the outside inwards).

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## Anuvin

Rice! What a fantastic idea! Good call Feign, I forgot all about that thread. Totally going to try that then I start doing solid prints.

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