[tracksntreadslou]

Thank you very much Madda ..I have never used carbide bits as most were too pricey ..Now that I am finding better connections and getting better at this cnc thing I am going to start using them..Jezz some of them are half the price as the HSS

Originally Posted by Madda

I've been using on my cnc these: http://www.shop-apt.co.uk/carbide-end-mills.html I only cut aluminium and their uncoated carbide bits are quite nice.
ctctools.biz endmills are cheap and also do the job.

Thanks GG..Been shopping around on ebay and some much better buys there for sure ..Definatley going to try the tranny oil as well..Have you heard of this new coolant thats mixed with air ..supposed to be very userfreindly..no oders
Anyway thanks for everyones input

Originally Posted by grumpygrady

lol I use harbor freight or ebay endmills and just go slow and they are all still sharp but I don't use any smaller than 3/8ths right now with 1/2 the largest and finish the corners with a rattail file or a dremal bit lol spell check may or may not be right lol

2 flute for aluminum and 4 for brass or steel in a cummins mini mill but I don't use it as much as you fellows do I am sure , as for cutting oil I use transmission fluid and it work ok anyway no mills are getting gummed up
hope that this helps a little

Thanks Pugs ..Now there is some great adivice ..I and going to dig a few of the older bits out and clean them up.....a few times i just used a small exacto knife and chipped them off ..doesnt last long as there seems to be a filum of aluminum thats left behind the more stuff sticks to .thanks for your good tips

Originally Posted by pugs

The gummy aluminum is probably Chinese stuff if it is marked as 6061-T6. It is just softer and sticks to tools, leaves bad finish. I specify US made aluminum when I order material after several bad experiences with the cheap stuff.

In alum I don't like 4 flute endmill, stick with 3 or 2 as that gives you more chip clearance for the aggressive cuts you can take. High helix mills designed for aluminum work really well. Lately I've been using OSG blizzard brand 3 flute, have used alot of CGS 2000 series 2 flute in the past. They aren't the cheapest but they seem to run longer and faster for me which means cheaper per part.

For taps I only use form taps in alum, so much nicer.

If you plug up a mill with aluminum, or lolipop it as I call it, get yourself some Lye drain cleaner (Red Devil) and a small container. put the endmill in some water into the container and sprinkle some lye in. It will start getting hot and bubbling while it eats away at the aluminum. really bad plugs may not completely dissolve away but usually good enough to be able to pop it off carefully. Do in well ventilated area as the vapors coming off are hydrogen. It will turn the endmill black but it leaves the edges sharp yet. Usually let it sit till it stops bubbling which can be 15 mins or more depending on how much lye you put in.

Thanks Nathan ..Taking a while but i think im getting the hang of it..Alot of times I can start the program ..Some will be fairly long a few hours ...spray a good dose of WD 40 and walk away ..I can come back every 10-15 minutes sweep away the chips and lube it up again ..Other times I have to be there to sweepout chips every pass and really babysit..I can tell with the softer aluminum will form a small lip on the top cutting edge so usually will slow the feed speed and that will usually help ..You can tell sometimes when a chip will get sttuck to the toolbit as the sound will change ..another good shot of lube .I am running my spindle speed at the second highest speed of around 6400 rpm..the highest speed available is 10800 rpm .. now that im bit more confident after stalling the motor a few times and breaking a few bits i may experiment with that faster spindle speed ....from what i have read the faster the better with aluminum ..wish I had a spindle motor with more balls
I guessing I speed up the spindle I will have less torque

Originally Posted by Espeefan

Lou, I agree that you can better feel what the cutter is doing with an all manual mill. I honestly don't know much about calculating the feeds, speeds, and depth of cut. I just do what feels, sounds, and looks right. I am sure it's much more difficult to figure out all of that with a CNC machine.

I wonder if the quality of your aluminum is to blame. The stuff that gums up much faster and seems to act less forgiving is probably a cheaper grade. I've only ever purchased T-6061, and I'm sure it helps to develop a feel for one grade and type of material.

I've had really good results using Rigid Nuclear thread cutting oil on aluminum. I'll run a bead of oil ahead of the end mill, from a squeeze bottle, every two or three passes. I also do my best to remove the chips so that they don't get dragged back into the end mill on a second pass. Harder to do with a CNC mill, unless you can have a constant supply of pressurized air to blow the chips away. For my small operation, I've been using a blast of air from the compressed 'duster' air cans. Alternatively, I could use a portable air tank, with a blow off nozzle, filled from the compressor in the garage, which would probably be cheaper in the long run. Anything is better then nothing though. I should buy a small airbrush compressor someday.