Ok i have somethign majorly wrong here...

[300sniper]

i've been using ma ford 3 flute aluminum cutting endmills and have had great luck with them in aluminum. with that deep slot, i think the op would really benefit from a three flute high helix carbide endmill, of what ever brand he chooses.

although i have great success with the ma ford ones, i may have to look at the maritool. i see they are about half the price of the the ma ford ones i am using now. the ones i am using now are pretty expensive for hobby use, especially when i do something stupid.

[pete from TN]

I think the Maritool cutters are 38 degree helix or something like that. Not crazy fast but they seem to work very well in aluminum. I spin them at around 6500-7000 RPM and adjust feedrate accordingly. I have a 1/2 incher that really digs for quick metal removal. I actually bought an aluminum rougher that does not seem to work as well as the maritool finishers. The other nice thing is they seem to get them to me with standard ground shipping very quickly. Mcmaster Carr is the only supplier I use who has consistently beat them but not by much. I know Frank Mari also posts over on PM and many of the pro's there seem to use his tooling as well. So far I have been very pleased with the many orders I have made with them. I am gonna try some of their coated mills for steel soon as I get a chance. Peace

Pete

[tikka308]

Re: using the full RPM available - just wanted to point out that I believe the max HP rating for the high-speed pulley on the PCNC 1100 is somewhere around 3,000 RPM's. So, while I agree that using all the RPM's you've got is the general go-to move for aluminum, remember that don't have max HP.

[philbur]

I think you may have that the wrong way round. Below the rated rpm for the motor you have constant torque so reduced HP. above that rpm you have constant HP so reduced torque.

Phil

Re: using the full RPM available - just wanted to point out that I believe the max HP rating for the high-speed pulley on the PCNC 1100 is somewhere around 3,000 RPM's. So, while I agree that using all the RPM's you've got is the general go-to move for aluminum, remember that don't have max HP.

[pete from TN]

The issue here is not HP it is surface finish with the endmill he is using. I do not own a Tormach but it had sure as hell have enough power to drive a 1/2 inch endmill in aluminum at full speed or it is not worth the iron to build it. It only has like 5500 rpm or so anyways right? He should be able to easily cut that part with a reasonable doc and speed with a 2 flute in aluminum. With a three flute I am optimistic the surface finish assuming all parameters are correct would increase the finish quality. Besides I want to see the pictures of this lower receiver when it is finished. Peace

Pete