[queenidog]

Hi,
I built a CNC using plans from Solsylva. It works very well thankyou. I started cutting patterns into wood with my trim router spindle until I started frying the bits. I'm not a carpenter and only used routers sporadically in my life, so I know little about feed rates, wood types, etc. I know which bits are best material (carbide) to buy but not how to USE.

I can cut Styrofoam really well!!

My intention is to mill sheet aluminum to make parts for my car and stereo system but I'm afraid to start until I get the feedrate/bit type sorted out. Is there someone who can shed light on this? Is there search words I should look for in particular to find it on this forum? I'd also like to use a laser or plasma cutter with my CNC, so if I can be directed to an area where I can get info that would be great.

Bottom line:

-What types of bits do I use for aluminum (sheet to say 3/16" thick)
-how many flutes (I've read from 0 to 4. How can you have 0 flutes?)
-bit diameter (I have a Dremel, 1/8" collet, and the trim router, 1/4" collet)
-how fast do I feed? (I found out I was cutting my wood too SLOW).
-Cooling required? Alumicut? or something else? Liquid? compressed air cooling?
-spindle speed. My trim router has one speed, about 20,000 rpm. should I consider variable speed?

THanks guys.

[Jason3]

Hi,

With either of your spindles you'll need a light DOC (depth of cut) and brisk feed rate. As to number of flutes, the more flutes, the higher the feedrate so you want 1 or 2 most likely.

For a 1/4" cutter in aluminium recommended chip load is usually around .0015" - .004" per flute. For your machine I'd try to stay nearer the .0015" feed per flute. So, 20,000 rpm x .0015" x 2 flute say = 60 IPM. If you can't go that fast, then try a single flute cutter @ 30 IPM. If that's still too fast for your machine, then you will need a variable speed spindle, or something slower anyway.

The dremels usually have the bearings mounted in plastic, so the trim router is a likely a better choice for aluminium cutting. For either, you will need a very light depth of cut, like .01" Coolant usually helps reduce cutting pressure which should help with your machine, but I don't know what others are using - I tend to avoid it, but only because I get good results without it.

Try carbide tools, NOT TiN coated, TIALN is good, a very sharp uncoated carbide can go well too.

Have a look at this video I made - it might give you some idea of feed, DOC etc. It was running 100 IPM, about 30,000 rpm and .01 DOC. Uncoated 1/4" 2 flute carbide cutter:

[ame="http://www.youtube.com/watch?v=mcUqS9t0Yyw"]YouTube - CNC milling 6061 aluminium[/ame]

Hope this is some help!

Regards,

Jason

[queenidog]

thanks for the info. This is exactly what I needed to know. You're right about the cooling, if I can avoid liquids (since my base is currently wood), this would be very advantageous. I don't have to modify my system.
I'll check out your video.

Do you have tool brands and part nos I could check out?

[Jason3]

Sure, I was using this one in the video: http://www.use-enco.com/CGI/INPDFF?P...5502&PMCTLG=01

It's Enco part no. SC323-5504 - nice and sharp. Haven't worn one out yet! I have snapped one though... There's a similar ball nose one too, they are just as good.

Edit: Oops, sorry - the link goes to the catalog page. It's the 1/4" dia. 1/4" shank, 1/2" flutes x 2" overall, 2 flute one, in the right hand side column...