[Vaffel]

Thanks for the link mcphil - I've signed up for a trial.

Thanks roninB4 for quite some insight!

So I should not worry so much about feed and spindle speed then, but rather keeping chips away. This is somewhat a problem atm as I dont have compressed air (another thing that I need cash for...). Now I just spray chips away with my coolant.

Is there a downside of having too little feed (or too fast spindle) other than the longer milling time? I believe I've read somewhere that if the feed is too slow, the tool will gnaw on the stock instead of actually cutting. Is this correct?

So if I understand correctly; the packing of flutes can come of two factors: 1: too much chips not being properly evacuated; and/or: 2: too hot, which melts the aluminium to the cutter.


Thanks again for very insightful answers It's much appreciated!!

[roninB4]

Thanks for the link mcphil - I've signed up for a trial.

Thanks roninB4 for quite some insight!

So I should not worry so much about feed and spindle speed then, but rather keeping chips away. This is somewhat a problem atm as I dont have compressed air (another thing that I need cash for...). Now I just spray chips away with my coolant.

Is there a downside of having too little feed (or too fast spindle) other than the longer milling time? I believe I've read somewhere that if the feed is too slow, the tool will gnaw on the stock instead of actually cutting. Is this correct?

So if I understand correctly; the packing of flutes can come of two factors: 1: too much chips not being properly evacuated; and/or: 2: too hot, which melts the aluminium to the cutter.


Thanks again for very insightful answers It's much appreciated!!

Speed and feeds are important but you can arrive at a starting point by using the calculators for this and making small adjustments per the application. The speeds and feeds should be calculated before you ever turn on the machine.

Geoff brings up a few good points that I left out, the number of flutes a cutter has can make a difference. If you're not taking a lot of material out then the number of flutes isn't a concern, I've used 4 flute cutters when finish milling pocket walls. But if you're having trouble with loading up the cutters then you really should be using a 2 or 3 flute (2 is better) cutter. You should also look at the depth of the flute if these are re-ground cutters. You want to have as much space for the chips as possible when removing large amounts of material. Geoff also brings up the high helix type of cutters, they are better than straight flute or standard helix (only for aluminum). Since you haven't mentioned what type of cutter or the material the cutting edge is made of some details may be overlooked. If there's too little feed you can "work harden" some materials but not aluminum. Unless you're way out of the ball park I wouldn't worry about too much heat either. When I used the term "welded" I probably should have used the term "bonded" when I wrote about the material sticking to the cutting edge. This is a bigger problem with carbide than HSS as prying off the aluminum from a carbide cutter as there's a chance you could chip the edge of the carbide, less likely with HSS. This is just my opinion but I see no advantage to using carbide on aluminum. If you do use too much feed or too low an RPM and the cutter gets packed up you could snap the cutter off. Look up what your speed/feed should be, adjust your settings, and try to use either a spitter/mister to clear out chips, using an appropriate fluid. If you want to see what difference it makes just set your spray bottle to stream (instead of fine spray) and continuously soak during the duration of the cut. If it works better then you know you're on the right path. Post up what you do, others may be having similar trouble.

[Vaffel]

Thanks both of you

Well, I only have one high helix end mill (4mm). Or at least I believe it's a high helix. It looks more like a screw than the others, like its much more twisted.

However, I haven't tried this one yet (but I will next time).

I've mainly been using carbide 2 flutes in aluminium. These are bought off ebay from asia, and are probably not of very high quality.

Yes, I'm using the spray bottle on stream, not on mist! However, I havent tried soaking the stock yet

I'll probably try some more later today, so I'll get back to it!

[roninB4]

By soaking I should say that you use a constant stream of cutting fluid to help wash the chips off/out of the cut path.

Sorry for any confusion, my English isn't so very good sometimes. A 2 flute (3 is ok too) is more important than it being high helix (that has more "twist"). You can also use a small brush to help drag chips out of the cut path but I'd be very very careful with that. I've used this to help but you can easily get the brush caught in the cutter. Not a good thing.

[Ed from NY]

Well, I only have one high helix end mill (4mm).

I do not know if that is representative of the endmills you generally use, but many people think "small machine -> small endmill". Not so. A machine with a small 1hp motor should be able to handle a 12 mm endmill no problem. The larger endmills are much more forgiving. And because of the much higher SFM they enable a "small and slow" machine to get much closer to good cutting conditions

Sorry if you already know this

EDIT: oh just saw that you are using a router as opposed to a mill. Nevermind what I said