Cutting aluminum with an end-mill bit

[camfambmw5]

I am trying to shape some aluminum stock in preparation for making my first router cnc. I have a router table with a fence, the problem = when I start feeding the aluminum, the end mill creeps out of the chuck. I have tightened the crap out of the router chuck, but the end mill still creeps out. Has anyone bumped into this problem? If so, what gives???

John

[lsfoils]

Hi John,

I assume you are using a hand held router?
I have had this problem in the past using a 1/2" end mill. Found out the collet chuck was worn out on my router... it was pretty old at that time. But, I found that by using a carbide tipped router bit I could get away with using the old collet chuck. I found that I couldn't take a very big cut (I was edging some 1/4" material and could only shave off about .010", full depth, at a time). I later learned from someone I respect that the helix on end mills makes it difficult to hold them in a standard collet chuck. Don't know if this is true but he seemed pretty sure.

Anyway, make sure to use the right lubricant, no matter what. It'll save your bits and ease your cutting. Once upon a time I was a fitter in a place that made aluminum horse trailers. We used a Craftsman 3 hp and trimmed all our sheeting to the extrusions they were welded to. Even used a 1/2" round-over! We always used A-9 or Alumicut. Night and day differance in cutting compared to using fluids normally used to cut steel. (WD-40 )

Hope this helps, be safe and good luck.

-Doug

[CDignition]

the Endmill will tend to pull itself out of the collet, especially light duty collets like are on a router...CNC machine tools use havvy duty collets that have much more clamping ability...but they stiill can pull out...so most of the time it is a good idea to use a set screw tool holder or a collet wit han indexing lug...I do realize this may not be possible on a CNC router tho..

[castguy2003]

Within the limitations of bearings, clamping power, etc, try this trick. Make sure your collet and the collet seat area is clean,(use acetone) Go to an industrial supply house and get a small bottle of Dykem Blue Layout Dye. Coat the cutter shank and let it dry (Just a few minutes) then insert far enough so the entire collet has shank in it. Tighten the crap out of it and take LIGHT cuts.

Mike

[balsaman]

I am guessing your collet is worn. My endmills don't pull out. I have a new router.

[Laff Riot]

I do not cut a lot of aluminum, maybe 2 or 3 blanks a month for letters, .080 to .25 thick max. Just to be clear I am not an expert and I know 75% of this group can advise you on bits moreso than I can.

We had the same problem with the endmills working thier way out of the collet.

Fortunately we had a local rep for Fastenal who came in to look at the router and returned with a 2 flute end mill specifically designed for cutting aluminum.

Night and day performance. I can cut at almost the same feed rate as hard wood now.

If you have a local rep for bits its worth the time to have them come by and recommend bits for each cutting application. We now have specialty bits for wood, aluminum and acrylic that outperform the standard 4 flute endmills.

I'm sure some of the others in the group can point you at some great online resources for saving money on bits - but again I recommend the onsite tour so your rep can get his hands on the machine and materials.

gl.

[camfambmw5]

Maybe it is the router...I have a brand new end mill, 2 flute, it’s a streaker TICN coated from Imco, came highly recommended. I am going to try cleaning the collet and end mill with Toluene..maybee that will clear up. The problem.

thanks


John

[strat]

while on the subject balsa you told me you were running your router at full speed when you cut you alum what are we talking on rpm i am using a craftsman rotozip copy but turning either 20000 or 30000 with the flip of a switch would it be a better thing to pick up one of the router speed controls from grizzly and slow it down ? thanks much guys this forum has been great on the answers to my ?'s
really helps us newbies out

[routalot]

I have known instances when routing wood or other materials when the cutter creeps out of the collet.It has usually been because the cutter was too deep in the collet before the collet nut was tightened.Could I suggest that when you install your cutter, you retract it a shade before tightening the collet nut as this will leave a gap for the cutter to move into as the final tightening takes place.

[balsaman]

Wide open on my router was 30,000 rpm. I am not sure thta's the best rpm to cut aluminum but I needed all the power I could get to keep the thing from bogging down too much. I was using a small 7A plunge router. If it still was bogging (heavy sparks at the commutator), I slowed the feedrate down, then prayed.

Eric