Deep pockets

[AirAce]

I would like comments on this: PCNC 1100 machine, .5" dia. 4" long carbide cutter. I want to cut a pocket 3" dia. 2" deep in annealed 4130.
Is this practicle or am I whistling Dixie?

I've been playing with this using 2024-T651. I get an aweful lot of chatter.

I would also like a recommended book on this subject.

[Paul_S]

2024 AL is not 4130 steel. RPMs too high for the length of cutter. Taking too much material will cause tool too much deflection and chatter. Depending on your cut you may have to reduce your RPM & feed to as little as 3% the material removal of a ,5 dia x 1 1/4 em, being that it is 4" long. .03 - (1.25/4)^3. Of course you want to use the highest material removal rate which the machine and tool will allow. Adjust up from the minimum to get your optimum feed. I would use a drill, rough and pre-finish and finish cut. The finish cut should be closer to normal of what you would use, but with reduced RPM.

[AirAce]

Thanks Paul

Yea, I know that it will have to be a lot different when I put 4130 in the machine. I am using the AL to develop my code.

Mainly what I wanted to know is, is it possible to do that if I get the feed and speed right.

I talked to the Tormach Cats and they said the machine can handle it.

[Paul_S]

Yes, it is possible to do. But for a 2 deep pocket I would use a 1/2 dia x 2 1/2 carbide not the 4 inch.

[Delw]

Thanks Paul

Yea, I know that it will have to be a lot different when I put 4130 in the machine. I am using the AL to develop my code.

Mainly what I wanted to know is, is it possible to do that if I get the feed and speed right.

I talked to the Tormach Cats and they said the machine can handle it.

4340 will cut fine alum wont with your endmill, I highly doubt your machine will handle either one, there is not enough rigidity, you would be better off using a good tool steel/cobalt endmill for this in the machine you have.
Carbide is too stiff and will bounce causing chatter, toolsteel/cobalt will flex a tad to get the machine on a load so no bouncing/chatter will occr.
with extra long endmills steels alot steels cut better with less chatter than alum.

Yes, it is possible to do. But for a 2 deep pocket I would use a 1/2 dia x 2 1/2 carbide not the 4 inch.

I believe he is saying the endmill is 4" long total length and not flute length. the 1/2endmills I have are total length of 4" I believe.

[AirAce]

Yes, the OAL of the tool is 4" only 2.5" of the tool sticks outside of the Tormach TTS. That way I can get a 2.2" pocket without interference with the tool holder.

I've got a Cincinatti Milacron Sabre 500 I bought used. It is in excellent mechanical condition. It was used in a school and never in a production mode. I am removing X, Y & Z motors and drivers upgrading to Automation Direct Sure/Servo AC servo system. And running it with a PC. But I'm finding that I don't have time to do all of this on my own. I'm finding that I can get the parts made by outside shops economically. Machining is not my primary function. It is incidental to my product. aeromatic.com. So, I may as well sell the Milacron and farm out the bigger jobs.

I appreciate all the feedback I'm getting from all of you.