Need Help!- Tool Bit & Spindle Choice for Router

[brw0513]

My CNC router assembly is progressing. I don't have all the hardware yet - just making purchases as funds permit. Enjoying the process too

I will be cutting model helicopter sideframes out of two types of material - 1.6mm thick aluminium and up to 2.0mm thick fibreglass sheet (G10 material). The sideframes include slotted holes that are 2.0mm in "diameter". There is lots of 3.0mm holes, 3.2mm internal radii as well as pocketing. Each sideframe will will fit on an A3 size piece of material, so my machine is at the smaller end of the scale. I won't be making huge quantities of frames, and production speed is not a consideration for me.

My budget is not huge, so a Chinese spindle and VFD is probably the way to go.

Question #1:

Am I right in thinking I need to identify the correct type of end mill first before I can pick an appropriate spindle?

Not sure if I need HSS or carbide tool or what no. of flutes would be required.

I presume a particular end mill will have a sweet spot i.e. cutting speed RPM and feed rate mm/min. So, Question #2:

For a given end mill, is there a "correct" ratio of RPM to mm/min that will result in efficient cutting of my chosen materials?

Question #3:

For my application, is there a benefit in choosing a water cooled spindle over an air cooled version?

Question #4:

Would a 0.8kW spindle suit my purpose?

Good advice appreciated.

[louieatienza]

1- If you're getting a spindle/VFD combo, you should be able to find the right spindle speed for whatever bit you use. I prefer 2-flute caoted carbide endmills for most aluminum work, and 3-flute when I need a fine finish, though 2-flute works well. Although HSS may be sharper initially, carbide stays sharper longer. You have to take lubrication or coolant into consideration when making your machine. You can machine aluminum dry, but you'll wear your bits out faster. I have 1/16" single flute bits also that work well.

2- Go to the toolmaker's website, and you'll find the information you need to calculate what speeds and feeds you need to run their bits. You may have to adjust down depending on your machine's ridgidity (depth of cut).

3- I presume water cooled is quieter, but you have to run hoses and a water pump and tank, maybe even a radiator. A lot of guys here use them with no problems however.

4- I use a 2-1/4HP router, which is about twice what you're looking at. I cut a lot of 1/4" aluminum, and it seems to do the job well. I started out using a 1HP router, and the difference is like night and day. I also use a SuperPID, and it gives me more "ooomph" at lower rpms. Your feedrate will be dictated by your spindle speed, and your depth of cut will be dictated by your machine ridgidity as well as your spindle's power. Basically, the faster the feedrate your machine can handle, the better the cut surfaces will be.

[ssutton]

Not an attempt to hijack your thread but....

"I have 1/16" single flute bits also that work well"

louieatienza can you give the details of this bit....who makes it....sales it?

Thanks,
Scott