Ways to speed up milling of 80% lower

[Term]

you wont have issues with a 4 flute on a manual machine taking light cuts. infact..i would suggest you use a 4 flute since there will be less chatter.

I am a Machinist. Respectfully this advice is absolutely wrong. You should never use a 4 flute endmill on aluminum,always use a 2 flute. The 4 flutes tend to load up and break.

[Targets From Us]

[kcstott]

I am a Machinist. Respectfully this advice is absolutely wrong. You should never use a 4 flute endmill on aluminum,always use a 2 flute. The 4 flutes tend to load up and break.

Here's the thing I've tried giving advice like that. I'm not suggesting it in this post but some people post a question just to hear there own voice so to speak. They refuse to listen to any reasonable advice. and then you have a joke come in behind you and completely contradict what you said "because he's done it for years that way with no problems"

There was a guy here that wanted to use a bench grinder for a case trimmer. I tried to advise him that 3600 RPM was a bit much. Well no dice he insisted he knows what he's doing. So you know what? screw him if he wants to loose a finger or a hand not my problem I warned him so I can sleep good at night.

[kcstott]

Finished #1 this morning. Have 2 more on the way.

Looks like my old set up when I had a small south bend on my apartment patio. Thank god I live in California so I could use the machine year round.

[darthnugget]

The best cutting tool so far has been an accupro 2 flute center cutting end mill. I've tried a few others and haven't been all that impressed with them.

I too have found that the 2 flutes are great for removing bulk material. Much faster than even the high-end 4 flutes. My method is to drill out as much material with drill press, then go to the mill and use a 2 flute end mill to remove what the drill press cannot but leave 1mm of material around pocket, then clean up with a nice 4 flute end mill.

Using the above technique I was able to complete an AR15 lower this weekend in about an hour, but I had everything setup from the night before when I did another AR15 lower. The time eater is the setup and end mill changes, if I had multiple mills I could setup one machine for each function and probably be done in 30 minutes.

I am a Machinist. Respectfully this advice is absolutely wrong. You should never use a 4 flute endmill on aluminum,always use a 2 flute. The 4 flutes tend to load up and break.

^^^ Agreed, however I like the look of the 4 flute for cleanup and since I use it for just 1mm of material it does really well.

[goober]

I am a Machinist. Respectfully this advice is absolutely wrong. You should never use a 4 flute endmill on aluminum,always use a 2 flute. The 4 flutes tend to load up and break.

Respectfully, isn't the unconditional and absolute prohibition against using a 4-flute EM on aluminum a bit extreme?
I mean "right tool for the job" and everything, but its not like were talking about driving screws with a hammer, or tightening nuts with pliers here.
Yes, 2 flute EMs are more appropriate than 4 flutes for aluminum, especially on "real" machines with plenty of hp and much higher feeds, cutter sizes, and rates of material removal.
But on these benchtop mini mills, where the power and rigidity limitations force the user to go much much slower, the arguments against using 4 flutes tend to be much less relevant.
I'll admit I am not a trained machinist. In my personal opinion I'm a total hack. But I've got enough hours on these smaller machines to know that not every single rule or item on the do/don't list is necessarily universal.

[Intimid8tor]

I'm looking forward to trying my 3 flute end mill tonight to see how it works. Fixed my 2nd lower one and moving on to my 3rd one tonight.

Plan is to lay it out, do my outline with end mill then drill out the cavity to within .05" of the final depth dimensions. Then I'll use the mill to finish it up.

I would like to have all my lowers completed by the time we go to the 10/22 build party so I can then get them all anodized together.

[Tom Slick]

I like what FADAL programming tech support told me "push the feed and speed until the tool, part, or machine seems like it is going to break, then back off a little. If it's not scaring you, it's not fast enough."

[kcstott]

I like what FADAL programming tech support told me "push the feed and speed until the tool, part, or machine seems like it is going to break, then back off a little. If it's not scaring you, it's not fast enough."

That's the absolute truth!!!!
And if your chips aren't blue you ain't taking enough.

[Targets From Us]

i want to see these blue aluminum chips you speak of

[Cali-V]

You guys are a funny bunch...

[Intimid8tor]

Just thought I would update this thread as I have completed #'s 3,4 and 5.

Drilling out the pocket first really is the way to go. Perhaps using a different type of end mill would negate this, but it is pretty quick to drill some holes in the pocket to within .10" of the final depth then come back through with a roughing end mill followed by finishing cuts.

I really don't use the jig much anymore. I use it to mill out the first outline and set the starting point of the trigger slot. Other than that the calipers and micrometers guide me.

I drill 4 1/2" holes in the FCG pocket, 1 3/8" hole in the narrower part of the deep pocket and 2 holes in the shelf. No plunging which seems to be easier on the machine and bits.

[itisagoodname]

Looks like i need to pick up a 1/2" bit. Doing #3 this weekend. The last one took me around 4 hours start to finish.

[goober]

Just thought I would update this thread as I have completed #'s 3,4 and 5.

Drilling out the pocket first really is the way to go. Perhaps using a different type of end mill would negate this, but it is pretty quick to drill some holes in the pocket to within .10" of the final depth then come back through with a roughing end mill followed by finishing cuts.

I really don't use the jog much anymore. I use it to mill out the first outline and set the starting point of the trigger slot. Other than that the calipers and micrometers guide me.

I drill 4 1/2" holes in the FCG pocket, 1 3/8" hole in the narrower part of the deep pocket and 2 holes in the shelf. No plunging which seems to be easier on the machine and bits.

yep.
drilling removes material much faster, easier, and with less stress on your machine and setup than plunge- or side-milling w/ an EM.
the Ray-Vin method is your friend (although to avoid a "cratered" FCG pocket floor, stop well before 1.250" & 0.630" when drilling, despite what the drawing says)

[PanchoVilla]

Hmm, My drill press is a small benchtop and would suck for drilling these holes. Maybe just write a CNC routine that drills the holes for you and use a drill bit instead of end mill in the mill itself? Then you just go through and rough out your lowers with the drill and then switch to end mill to finish them.