Anyone got any ideas of some good plastics to machine and their feeds and speeds with stock spindle? wiki was a bit sketchy on details…
HDPE, visit your local kitchen stuff shop, look for cutting boards, often cheap and already sized for your CNC
I’ve found harder plastics are easier to machine than softer ones. I really like acetal (aka Delrin). You need to be careful with heat buidup. I’ve found that the softer plastics have a tendency to deform rather than cut when the bit gets warm. Sharp endmills are a must. I’ve purchased most of my delrin off ebay.
okay, single flute or double? how much material can i take off at a time?
I’ve only used double flute (most of my experience is with my Sherline mill). I often machined delrin with 0.050" depth of cut (which is about 1.27mm). I seem to recall going upto 20 IPM (500 mm/min), but I would look at the quality of the cut and the swarf and adjust.
I think that I use similar feeds as I would for aluminum, but bump up the depth of cut. I wasn’t very scientific about feeds and speeds at the time. I’m investigating some tools for doing proper calculations (http://www.cnccookbook.com/CCGWizard.html)
You want good ventilation when cutting any plastic. Some of them give off toxic fumes when heated.
Is that with the stock spindle? I think i am not being confident enough with my cut depth, I do 0.5 mm for plywood at 700mm feed, is this too little?
On my OX (which is very similar to the Shapeoko) I have the 400 watt quiet cut spindle. For MDF, with a 1/8" 2 flute carbide endmill, I’ve been using 1.5mm depth of cut with 800 mm/min feed rates.
Great info. A buddy of mine told me about a book that has all that info. I’ll have to find out what it is and post it on here.