Standard X3 requires 1/2" Endmill for AL?

[caleb105]

So....now a few more questions!

At least initially, my X3 will be limited to 2000rpm. From what I have read, Aluminum should have a surface cutting speed of 250-350 fpm.

If I aim for the low end of this (250fpm), then @ a maximum 2000rpm, aren't I limited to 1/2" or larger end mills?

I know that some people have gotten their X3's running at 6000rpm, which would let me go as small as about 5/32" end mill and still maintain 250fpm Surface Cutting Speed.

Thanks!

-Caleb105-

[HimyKabibble]

Originally Posted by caleb105 So....now a few more questions! At least initially, my X3 will be limited to 2000rpm. From what I have read, Aluminum should have a surface cutting speed of 250-350 fpm. If I aim for the low end of this (250fpm), then @ a maximum 2000rpm, aren't I limited to 1/2" or larger end mills? I know that some people have gotten their X3's running at 6000rpm, which would let me go as small as about 5/32" end mill and still maintain 250fpm Surface Cutting Speed. Thanks! -Caleb105-

Actually, for HSS cutting aluminum 400-600 SFPM is more typical, but you can't get there with only 2K RPM, so your feed rates with small cutters will be quite slow. Anything you can do to increase spindle speed will increase productivity.

Regards,
Ray L.

[caleb105]

So am I correct that I should be using at least a 1/2" end mill?

What do people use to machine their ballnut/motor/bearing mounts when they first get their mills?

Thanks!

-Caleb105-

[HimyKabibble]

Originally Posted by caleb105 So am I correct that I should be using at least a 1/2" end mill? What do people use to machine their ballnut/motor/bearing mounts when they first get their mills? Thanks! -Caleb105-

Well, even a 1/2" endmill wants to be going faster - I usually use about 3200 RPM in aluminum. But your spindle power and rigidity become bigger and bigger factors the larger the tool you use. Most people do the bulk of their work with 1/4-3/8" tools on X2s and X3s. You just need to scale the feedrate down by the RPM you *can* achieve. The most important thing is to maintain an adequate chipload, or tool life will suffer.

Bearing pockets, etc. can be cut using a rotary table or boring head. They can also be done on a lathe.

Regards,
Ray L.

[caleb105]

Originally Posted by HimyKabibble Well, even a 1/2" endmill wants to be going faster - I usually use about 3200 RPM in aluminum. But your spindle power and rigidity become bigger and bigger factors the larger the tool you use. Most people do the bulk of their work with 1/4-3/8" tools on X2s and X3s. You just need to scale the feedrate down by the RPM you *can* achieve. The most important thing is to maintain an adequate chipload, or tool life will suffer. Bearing pockets, etc. can be cut using a rotary table or boring head. They can also be done on a lathe. Regards, Ray L.

I know that I SHOULD be running at MORE than 2000rpm, but I CAN'T!

Also, the feedrate won't have anything to do with the surface cutting rate.

So....are you trying to tell me that people use a 1/4" endmill and are milling their aluminum with 130fpm surface cutting speed?

-Caleb105-

[escott76]

Originally Posted by caleb105 I know that I SHOULD be running at MORE than 2000rpm, but I CAN'T! Also, the feedrate won't have anything to do with the surface cutting rate. So....are you trying to tell me that people use a 1/4" endmill and are milling their aluminum with 130fpm surface cutting speed? -Caleb105-

Keeping the chipload in the correct area is important. You slow down the feed rate to "keep up" with the lower spindle. You are focusing on the SFPM only. Since you can't get the recommended one you adjust feed down so as to keep chipload consistent.

[caleb105]

Originally Posted by escott76 Keeping the chipload in the correct area is important. You slow down the feed rate to "keep up" with the lower spindle. You are focusing on the SFPM only. Since you can't get the recommended one you adjust feed down so as to keep chipload consistent.

Sigh....

I know that both the SFPM and IPM are both dependent on RPM. However, they are not directly related to each other.

What I am asking is....How are people dealing with lower SFPM? Are they just milling AL at 130fpm and praying that it doesn't gum up their endmills?

[HimyKabibble]

Originally Posted by caleb105 Sigh.... I know that both the SFPM and IPM are both dependent on RPM. However, they are not directly related to each other. What I am asking is....How are people dealing with lower SFPM? Are they just milling AL at 130fpm and praying that it doesn't gum up their endmills?

"Are they just milling AL at 130fpm and praying that it doesn't gum up their endmills?" - It's either that, or figure out how to increase spindle RPM. Ain't no other options.

Regards,
Ray L.

[caleb105]

And does that low of a SFPM have a negative effect on surface finish?

[HimyKabibble]

Originally Posted by caleb105 And does that low of a SFPM have a negative effect on surface finish?

Nope. Just makes your job take a lot longer.

Regards,
Ray L.

[Torsten]

Originally Posted by caleb105 I know that I SHOULD be running at MORE than 2000rpm, but I CAN'T! Also, the feedrate won't have anything to do with the surface cutting rate. So....are you trying to tell me that people use a 1/4" endmill and are milling their aluminum with 130fpm surface cutting speed? -Caleb105-

The SFPM is the cutting speed recommended by the manufacturer of the Endmill in an industrial manufacturing environment.
Meaning that this speed will be a good balance between Toollife and Metal removal rate.
In a hobbyshop where cost of Endmills may be rated a little higher and manhours a little lower it can make perfect sense to derate the SFPM.
The longest Toollife may be well below of the manufacturers recommended SFPM.

[project5k]

I'm regularly using 1/32" endmills on my x3, and while it does take for ever to run a complete job, it does work, and i dont have any gumming issues... good flood coolant is my thinking as to why i have been getting away with it...