First mould making attempt. Aluminium (6061) billet, for hand injection of cold 2 pack polyurethane resin charged with glass powder. Did a trial run with a 3D printer and it plays ok, trial run milling soft pine worked ok but the pine mould tore to bits trying to get the part out.
Exhibit A - go on, have a laugh (I know I did when I came back to it this morning, in between the "start again..." tears). The bottom half of the mould still needs to be milled.
Off the mill, finished with 2mm ball nose set with 0.05mm (0.002") scallop height:
After a couple of hours with SIEG X2 driving an umbilical with die grinders and then a Dremel with assorted grinders, wire wheels and brushes and then polish.
There are a few drag marks in there because I stuffed the CAM settings on a couple of operations and didn't set the retract plane high enough. The general level of sheen and thumbnail roughness seems ok but all that pitting and distortion is a product of my crappy workmanship and possibly tool selection.
Give an idea of scale, those holes are 6mm aka 1/4". There's not a lot of room to get sandpaper or stones in there.
I'm ok with writing this one off as a learning experience. It looks generally flattish but with too many little gouges, I'm guessing from one of the wire wheels. I don't really want to oversize the part so chasing those gouges is probably going to wreck the mould.
Help please
I'd like the next attempt to be a little better!
Any advice on how fine I should be shooting that final mill pass and what common hardware shop stuff I can use to clean up the tooling marks without pitting the soft aluminium surface?