Milling a pocket in Aluminum or Steel with clean sharp edges

[Boswell]

I have milled a bunch of pockets in 6061. I found a finish pass at full depth but only a 5 or 10 thousands of material removal is essential for accuracy and surface finish. I use GWizard as well and stay in the conservative end of the slider , typically.

 

[JimDawson]

That cut has the look of a very dull endmill.

Go to Home Depot and pick up a couple of Diablo 1/4'' spiral cut, solid carbide, router bits. (make sure you don't grab down cut by mistake) They do a fine job in aluminum (and steel). I keep a few of them in stock. Be advised, the router bits tend to run a bit on the small side, so a 1/4'' cutter might measure more like 0.245. Not a big deal, but when working with a CNC you have to plug in the actual tool diameter into the CAM setup if you want accuracy.

WD-40 is good, but you need to keep the chips cleared out of the cut, so a spray mist coolant is best.

2400 RPM and 5 IPM is not a bad place to be, maybe 6 IPM would be more in the ballpark at that speed.

 

[cbellanca]

Looks like you have a dull low cost end mill. Take Jim's advice and get a quality sharp end mill from one of the industrial suppliers.

 

[T Bredehoft]

, but its a lot more programming that I would like to avoid.

Forget lots of programing, reduce the tool diameter by .005 and climb cut the finish.

 

[mikey]

I would have used a coarse pitch roughing end mill and finished with a high helix 3-flute to get cleaner edges.

 

[Mercedes107]

OK, here is a 50% rough cut calculation from Gwizard. High speed goes up to 11-12 IPM. Bye the way, you can try Gwizard for free for a time.
View attachment 317795

Thanks. I will see if I can get the forge (my maker space) to get it, they might be able to get it free as they are an educational non profit. I'm kind of leaning towards the calculator so I don't have to walk back and forth to my computer and its a 1 time purchase.

 

[Mercedes107]

I have milled a bunch of pockets in 6061. I found a finish pass at full depth but only a 5 or 10 thousands of material removal is essential for accuracy and surface finish. I use GWizard as well and stay in the conservative end of the slider , typically.

I may give that a try on the pocket. That pretty easy to add into the program.

 

[Mercedes107]

That cut has the look of a very dull endmill.

Go to Home Depot and pick up a couple of Diablo 1/4'' spiral cut, solid carbide, router bits. (make sure you don't grab down cut by mistake) They do a fine job in aluminum (and steel). I keep a few of them in stock. Be advised, the router bits tend to run a bit on the small side, so a 1/4'' cutter might measure more like 0.245. Not a big deal, but when working with a CNC you have to plug in the actual tool diameter into the CAM setup if you want accuracy.

WD-40 is good, but you need to keep the chips cleared out of the cut, so a spray mist coolant is best.

2400 RPM and 5 IPM is not a bad place to be, maybe 6 IPM would be more in the ballpark at that speed.

Thanks for the reply

Will I be able to plunge with the router bits, are they center cut. The ones I see in stock are carbide. I dont have a mister or even compressed air at the moment but I was thinking of holding a vacuum to it.

 

[Mercedes107]

Forget lots of programing, reduce the tool diameter by .005 and climb cut the finish.

That's a bit too costly for me. But I thought of something similar. I could use a 3/16" end mill and then lie to the machine and say it's 0.193" diameter for the first pass so it stays about 0.005" away. Then just change it to 0.1875" for the final pass with a climb cut. Do the same for the outer edge. That would be much simpler programming task.

 

[Mercedes107]

I would have used a coarse pitch roughing end mill and finished with a high helix 3-flute to get cleaner edges.

Thanks for the reply.

I'm trying not to go too crazy with it as I cant afford a set of roughing and high helix end mills. So I'm really trying to find the main problem here just to get to a point where a simple slot looks reasonably presentable. I concur that these end mills may be just too poor a quality and stepping up to a better set might be required or maybe finishing passes.