Did anyone try to mill foams, particularly Smooth-On Foam It #8?
@Smooth-On_Inc seems to advertise it for machining but I can’t find any closeups showing the surface finish.
There are only 2 low resolution images that kind of suggest air bubbles (it’s a foam after all) but you can’t judge their size and thus not the level of detail that material would be usable for.
I don’t know this foam, but I already machined different kinds of foam.
For example: extruded polystirene, polyéthylène foam, rubber foam …
What would be the use of your machined parts ?
I machine masters for molds.
Objects are 10-40cm in length and features get as small as 2mm.
The advantage of the CNC is the surface finish and thus little manual work and high level of details compared to a 3D print at the expense of having to deal with stock material and lots of dust/shavings.
If I need to use a ton of putty, filler and manual work to get a smooth surface,
I may as well use the 3D printer instead of the CNC mill in the first place.
Personnaly, and if it is compatible with your application I would suggest to try machining paraffin blocks.
Its advantages are: verry easy to machine, smooth and homogene surface no need of powerful machines.
Here in france we can find it at the tooling suppliers like otelo: http://www.otelo.fr/fr/catalogue/matiere-usinage-prototypes.html
Let me know if it helps.
I used carving wax(melting point >100°C) with great success.
However casting large cylinders for the 4th axis doesn’t work above a certain size due to internal stress when cooling.
Paraffin(melting point 37°C) creates terrible half.molten shavings that fly everywhere and stick to everything, including the object you are currently machining.
Did you try to machine at lower RPM to avoid the semi molten shavings ?
Maybe you should try to use (if possible) air cooling or water cooling via mist type oiler.
I have similar problems when machining some plastics that melt, adding water enence both surface quality and speed when eliminating chips and/or part melting.
We’re talking about a 60°C melting point
while having the same issues as real carving wax.
That paraffin is a bit cheaper then carving wax doesn’t outweight it’s terrible material properties.
It also doesn’t eleminate the issue of internal stress and thus cracks when casting larger cylinders for the 4th axis.
That’s why I’m investigating high density foams.
They don’t require melting, minimum storage space in the workshop, no careful separation of shavings from other dust for re-melting, no issues with making larger size blanks and nearly no cooling time compared to the thermal capacity of 10Kg of molten wax in the same room you try to work in.
Try Sika blocks. It is great for milling application. Denstiy is starting from 0.5g/cm3 t0 1.1g/cm3
http://www.polychem-group.com/en/toolingsysteme/board-materials.html
We do a lot of polystyrene foam milling, large surfaces but not so detailed. Extruded polystyrene was much more picky and it will melt and leave a bad finish. Polyurethane is the best foam material for detailed shapes but it gets very expensive fast (higher densities).
Thanks. This one is a PU foam.
I already used a flexible and a very rigid version of it but did not machine any.
@Marcus_Wolschon you mention machining issues with paraffin. Might I ask if you are hogging out the shape in one pass, or, are you doing one or more roughing passes followed by a finishing pass?
Also, have you sent a message to the manufacturer of the Foam you are asking about to see if they can guide you in your decision? From looking at the images, you may/should get the required resolution you are after, but, that is just my guess.
#8 is 30eur for 1,36Kg = 0.08m3 = 80’000cm3 (130Kg/m^3 as liquid and 8x expansion),
170eur for 11Kg and 777eur for 55Kg
Multiple, shallow passes. Tried fast(little contact time) and slow passes.
Paraffin is just not a good material to work on with any kind of friction.
(Carving wax works perfectly for machining.)
I dont think there could be any issue if you go for cutting speeds as high as 4 metres/second. Try it
No I won’t try Paraffin again. The sticky, half molten shavings where a mess at a tiny fraction of that speed. Why would I? I have better materials already.