[Palmhoej]

Okay i have had this machine for 1½ year and i really love it. Sure there has been some small bumps on the road, but it is all forgotten as soon as i see aluminum chips flying.

https://www.youtube.com/watch?v=6W5K4rdEuN8

If i were to order the components that this little machine has produced in the last 1½ year i would have paid triple of the cost of this machine (of course this is not including working hours... if those were included i would call it a draw!).

Chip in (got it?) with your experience and produced components :-)

[handlewanker]

Hi, I have to wonder why you use such a long cutter.

It will not take much to break it with all that length acting as a leverage.
Ian.

[Palmhoej]

Hi Ian.

i use these carbide bits from china:
1pc 6mm Carbide CNC Router Bits Single Flute Tools 22mm New | eBay

I sometimes go through a 20mm aluminum plate, so thats why it is so long. I did order the shortest i could find (17mm cutting edge), but either they resonate bad or the batch i got was crap (probably the later). I did not investigate this further, since the 22mm cutting edge on the video works fine. I had one going for 8 hours on aluminum without any sign of wear. I broke it because i made a mistake. This is usually the way bits are dying on my machine, so its a good thing that they are cheap

What bits do you use for aluminum cutting? If someone could find some that have a 12mm cutting edge i would love to try those to see if i could up my DOC.

The specs were:
Diameter: 6mm
Cutting edge/tool length: 22mm
Feeds: 800 mm/s
DOC: 0.8mm (Depth of engagement)
Speed: 20k rev/min

Sincerely Kristoffer.

[G59]

What Ian is talking about is the total exposed length, or stick out. A 2.5" long end mill has a better chance at transferring chatter/vibrations throughout the spindle and gantry, and is more prone to breaking as the tendency to flex is greater. If you could find a shorter end mill (total length), you could also gain an increase in cutting speed, less wear on the machine and cutting edges of the tool. If you could shorten the exposed length by 1 inch, you more than double the rigidity.
Oh and BTW, a 1/4"(6.35mm), 2 flute endmill can be had cheaper and with many different cutting length, from ebay.

[slaith]

I bought some of these, they cut like butter through everything and are short.
5pc 6mm Carbide Endmill 2-Flute Flat Bottom TiAlN

These might work too?
6mm Carbide Endmill Aluminum Finishing-3F-0-5mm-rad
I read somewhere about a guy using therese with a machine similar to ours with 5mm DOC, don't know about the intake though.
I go those to but haven't gotten around to using it yet.
Got to finish my fogbuster first, something similar to yours is on my mind.

[Palmhoej]

@G59: you are right, but i knew that this was what Ian was talking about (I am studying mechanical engineering ) . But i could not find anything with 1 flute, that was shorter than 17mm on ebay, so that was basically why this was so long

@Slaith: I mainly do aluminum, have you tried the 2 flute in aluminum? My concern would be that i would have to lower my RPM for the correct speeds and feeds for 2 flute, resulting in going below the 1.5kw spindles torque range. But i might be wrong... what speeds and feeds have you been using?

[slaith]

I haven't milled any alu with any of the above, but from what I read it works well.
Gotta make a fogbuster first

I really don't know the torque range of the spindle, is there a chart to be found somwhere?

FsWizard online is really good for calculating

[Palmhoej]

admittedly it have been a while since i played around with FzWizard, since the speeds and feeds i use have worked quit well. But i think to remember that according to FzWizzard that 2 flute was not an option if the feeds were not allowed to be higher than 1000 mm/s and you would like to go above 14k rpm. But again this is theoretical, if someone have been using the 2 flute on extensive aluminum jobs on a 6040 cnc, i would believe them.

[riche543]

Hey palm great stuff , can I ask what setup you have for cooling your end mill while cutting .
Cheers
Riche

[Palmhoej]

Its alcohol. Its really effective cooling. The bit is icecold no matter how long you cut and the aluminum does not get more than handwarm (and that is if you are cheap on the alchol). Usual consumption is around ½ liter pr. hour. It evaporates, so no need to clean the CNC or your build.

Its comming out through a DIY Fog Buster (build plans here: buildlog.net ? View topic - CNC Conversions).

Two concerns: Vapours and fire hazzards.

I run my CNC under a exhuast fan, but sometimes i forget to turn it on. I really can't feel anything, but worst case is that i get a bit tipsy

The fire hazzards are more dangerous. If it were to catch fire i would imagine that i have myself a good blowtorch (alcohol and compressed air), but i suspect that the mixture is to thin to actually catch fire. Just don't have anything that could ignite it nearby...

[G59]

Hmmm. After spending a few minutes looking for a good "cheap" end mill, I have to admit your right about being left with very little, as selection.
But, I have had excellent luck with Kyocera. Super long lasting endmills, and sharp as hell. I have used a 1/16" endmill of theirs and they have outperformed Kennametal ones that were twice as expensive.
Either way here is what I meant by shorter end mill.
1 4" 2500 Carbide 2 Flute Endmill Stub Length Square End Kyocera | eBay

Good Luck.

[BW56]

I broke it because i made a mistake. This is usually the way bits are dying on my machine, so its a good thing that they are cheap .

That's called "sudden tool fatigue" in my shop.

[Palmhoej]

@G59: Have you done aluminum with these bits? My concern again being that they are 2 flute and the theory says 1 flute for d=6mm (1/4 inch) endmill for the speeds and feeds the 6040 machine like. But experience usually beats theory, so if you have had success and could share your feeds and speeds im all in

I might try the 3mm & 4 mm ones, since a small diameter equals higher speed or more flutes, so here they might be a good choice.

[G59]

No I think for a router, you should stick to single flute so you can maintain motor speed to sort of compensate for the low torque. If you went with the 2 flute, you would have to increase your current feed by 2. Which would now require double the HP. So, 1/4" , 18000 rpm, 0.2 hp at 76 inches per minute at 0.0625 depth of cut at 0.002" chip load (per tooth) with 1.5 inch of tool stick out. This is for HssCo 2 flute bit with coolant in 6061.
I haven't seen any stub, single flute end mills. For a single flute, reduce ipm to, 39 ipm. Sorry, but i don't know how to do metric calculations yet.
I was also thinking going smaller 3-4 mm with high RPM, but make sure you go with carbide now.

[Palmhoej]

No problem about the imperial... i did the calculations, so i also know the answers in metric. If you stumble upon some short single ones, then let me know

[G59]

Ok.

[Dean Elliott]

In an effort to consolidate all of the 6040 and 6040z threads please post here: http://www.cnczone.com/forums/open-s...ml#post1790768