Fab Academy

Miguel Lourenco

 


 
 
 

 
 
 Composites

For the build plate of my 3d printer project, I chose to use a carbon fiber sandwich panel due its light weight and strength. Total thickness of each plate = 12mm, with low density inner core (honeycomb) enclosed by two stiff outer skins of laminated carbon fiber with 0,5 mm thickness.

 

The final shape of the table was achieved through CNC cutting.

The tool paths for CNC cutting of carbon fiber sandwich panel, were performed with ArtCam and used a 6 mm diameter end mill.

 

You must be caution with cutting parameters and tool quality because the carbon fiber is hard to cut. Cutting carbon fiber with CNC router easily causes tool wearing, especially on HSS tools.

 

I had used some laminated carbon fiber cloth with epoxy resin (SICOMIN SR1500) plus a hardener (SICOMIN Slow Hardener SD 2503) with 3:1 ratio.

Don't forget to mixing the 2 components until uniform color is achieved.

I made a 2 layers of laminated carbon fiber cloth on a aluminium planar surface matrix. We must be sure the mixture is at least at room temperature (surrounding 20 to 25 Celsius degrees), to be thin enough to penetrate the cloth. furthermore, we should impregnate the cloth by pressing it with the epoxy mixture.

After cured, without any special issues, just dry air and temperature surrounding 20 celsius degrees (2 days), I easily unmolding de composite from the matriz. Next, I cut it with a par of scissors to obtain the composite straps with enough width to cover all the edges that had been cut in CNC router machine.

Note: SICOMIN is a brand from France and we have got it at www.rebelco.pt, in Portugal.

Figure above shows epoxy resin and hardener containers. The aluminum works very nice to use as matrix because it's easy to demolding (although I usually use silicone spray on it before put any compound or carbon fiber).

 

Finally, joined the composite carbon fiber straps to the carbon fiber sandwich panel with epoxy resin plus a hardener (3:1) and waited until it is cured to sanding all the edges.

I remember I used clamps made ​​from threaded spindles (M6) and tighten to hold the strips in the polymerization process, but didn't take any picture, sorry.

For finishing I used a spray varnish to obtain a shiny surface.

 

 

Build plate with 4 adjusting screws (4 helical springs around it). Top plate has level adjustment feature.


 

Images

 

Carbon fiber sandwich panel (honeycomb) - 12 mm thickness.

 

Tool paths with 6mm diameter end mill, performed with ArtCam.

 

Carbon fiber sandwich panel after CNC cutting.

 

Cutting carbon fiber straps. Also a sharp knife (x-acto) is a good tool to do the work.

 

Final result with carbon fiber caps added.