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The lowest speed setting on the Dewalt DWP611 router. I'm new at this so I could be way off but I will say I was really nervous after reading online that Aluminum is hard to cut but now I've had good cuts all day and this is my first day of cutting. I've varied feed rate from 15ipm to 45 ipm.

 

These are the what I'm using to cut: LMT Onsrud 63-610 Solid Carbide Upcut Spiral O Flute Cutting Tool, Inch, Uncoated (Bright) Finish, 22 Degree Helix, 1 Flute, 2.0000" Overall Length, 0.1250" Cutting Diameter, 0.2500" Shank Diameter: Spiral Router Bits: Amazon.com: Industrial & Scientific

5052 Aluminum. .080 and .190 thickness

 

I'm cutting .03 per step down into the material. Started at .01 and .02 and worked my testing up.

 

Looking at my pieces. 15 ipm and .01 the edge cut was smooth like glass. The others have a slight rough edge.

 

2540 steps per inch set in Mach3
800 steps per revolution set on the motor driver

 

Today I was doing some more cutting and got good results with a feed rate of 45 ipm and .01 depth of cut.

I can push it more but I'm not sure how that effects machine and tool life so I'm thinking I will stick with the .01 depth of cut even though cut times are longer.

I haven't used any cutting oil yet. I have air blowing the chips out and that seems to work well. I'm a little concerned introducing oil will cause the chips to stick.

 

I've cut hours worth over the last few days and the only bit I've broken was from the work piece moving because of incorrect tab settings.

On .190 thick 5052 I'm starting to get some "chattering" of the cutter so tomorrow I'm going to adjust some settings. I don't know if it's my feed rates too high or if it's because the cutter is 1/8" diameter and going too deep.

I'm also wondering how much cutting you get before the end mill gets dull. I doubt I'm there yet but maybe the new sharp edge is worn a little and that is the change I've seen.

 

I figured out where my chatter came from. At some point I had slightly turned up my RPM on the router.

I'm getting what I consider nice cuts with the following:

- Dewalt Router RPM turned all the way down the most it can go
- 30 IPM feed rate
- .01 depth of cut
- 1 flute 1/8 end mill (Onsurd 63-610)

I could push it faster and deeper but I'm not sure what that does to tool wear and machine stress over time. I let the CNC run and go do something else so I'm not overly concerned with getting the fastest speed at this point.

 

I use this to blow the chips away: Amazon.com: Mist Coolant Lubrication Spray System For 8mm Air Pipe CNC Lathe Milling Drill: Home Improvement

1/4" quick disconnect from the air hose screwed right into it. Hooked it up to my air compressor so it constantly is blowing chips away.

 

I haven't tried the misting part but the air spray works fine. You can unscrew that 8mm connector and it has 1/4" threads that fit a standard air hose connector.

 

I made a modification to my CNC to make it more rigid. My problem was on parts 1 end of the part would be higher than the other causing the end mill to dig in hard on the outside cut.

My first attempt to fix this I just put in a 1/4 end mill and had it mill my spoiler board level. This helped a bit but wasn't a full fix. I think the flex in the MDF platform was the issue.

So I ordered a large aluminum plate 3/8" thick to replace the MDF platform then mounted the mdf spoiler board on top of the aluminum. Again I milled the MDF down to a flat level.

This has greatly improved how level my material is from one side to the other and has fixed my issue. It also has the added benefit of giving me an extra 5/8" Z travel.

 

Reasons I've broken end mills while cutting aluminum:

• Unlevel material causing too deep of cut on 1 end
• Too small tabs on the work piece and it came loose
• Aluminum plate not screwed down to the spoiler board tight enough and vibration caused the end mill to catch the wall of the groove it cut
• Making a hole I didn't have the tool path correct to remove all material. There was a small sliver in the middle of the hole that came loose when the cutter got deep in the hole. This caused binding and snapped the end mill.

These might be obvious to others but maybe someone can learn from my pain.

 

I might have to try that. I'm currently having an issue that seems to only happen when cutting on the far front. When doing .190" thick aluminum with a 1/8" bit cutting around the outside of a part I start to get more than normal vibration and chatter. I've broke 1 bit because it hit the side of the cut from the vibration and I've had to stop the machine a couple more times because it sounded bad like it was about to break the bit.

 

To further fine tune things and try to reduce chatter I finally downloaded a feeds and speeds calculater here: CNCCookbook: Be a Better CNC'er

I was running at 30ipm with the Dewalt RPM at the minimum. The calculator suggested 37 ipm at the max RPM (27000). I've now tried this on a couple parts and it seems to have reduced the chatter some more.

This seems to be a 1 step at a time learning process to get everything dialed in. I will keep posting here to help others and help myself remember.