Is it for a ac cobra replica?
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Yup.
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Hahaha I was like ohhh that’s a ac cobra 
Keep us updated plz
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Will do
Doug and Eetu, that is a great idea! I never thought to try that… it would really shorten the cut time!
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Yep. A regular drill bit has a different bottom, angled with blades pointing downward, and can penetrate and drill faster than an end mill with a flat bottom. Presumably you’d be using a drill bit with hardened steel and/or some coating on it to increase life span. As @ebbels mentioned, a drill bit can be put right into the CNC router. As I mentioned, you could use an end mill in the CNC to premark where to manually drill. His idea is probably easier. The trick here, the kicker so to speak, is to have those holes drill at the same spots where your later CNC operation (with the linear cutting) would be doing its plunge cuts. You could output the later operation first, so as to make note of those locations. Someone may know a way to tell the CAM software exactly where you want the plunges to happen. That would probably be ideal. I know Fusion 360 allows you to choose where to start a profile cut. I am not sure if ESTLcam allows that. Note: this goal may be achievable in ESTLcam by designing the profile cuts as “not quite complete.” If there were to be a small gap between the start of a profile line and then end of the same profile line, then that small gap might serve as a hint to nudge the ESTLcam software to start profile cut there. The gap should essentially be the center of the predrilled hole’s location. The bottom line is that if the plunge cuts will be happening where material was already removed, you can speed up those plunge cuts greatly. Bear in mind, if you are doing trochoidal milling, by default it makes the plunges trochoidal as well, which increases the size of the plunge cut holes!
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Only note that makita (or others hand routers) rpm ain’t ideal for drilling. Makita dial number 1 is 9.7k rpm?, so it is important to get feeds calculated right. It is in my todo list to test drilling into aluninium by lr3. (quite long list so far and growing every day more xd) I let you know how it goes.
Have the drill be a tool in estlcam and then the milling be a different tool. Manually order it or Estlcam can order it for you so the drill goes first then it pauses for tool change and then it will do the mill operation.
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Works really well. As soon as the LR4 drops I’ll have a video ready. 
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The plan now, I think, is to machine this from a suitable plastic.
I’m assuming that this will be easier to cut, so many of your suggestions to achieve this from aluminium won’t be necessary (I hope, but thanks for all your tips).
I have a friend who can wire-erode - so he will cut the “AC” badge in stainless and that will be glued on.
Partly this decision is for convenience and partly it’s that we want a black rather than aluminium look.
So my question, now, is does anyone have experience of plastics and can suggest a material?
Cutting feeds/speeds guidance would be great, too.
Thanks
Carbon fiber would be pretty slick. You could cut the mold or print it in sections. 
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I installed a rs4 grill and it was some type of pressboard or resin impregnated stuff. I wasn’t happy with the quality but it looked good and did hold up.
Sorry I don’t have more info on the plastic stuff
I know if your going that route research
Extruded and casted there is a big difference apparently for how it machines.
Sorry, what’s an RS4 grill?
It was a grill for a car that someone had copied to sell.
Oh an Audi? Yes that’s a complex design. Not dissimilar in terms of the mesh part.
Thanks
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Looks awesome!