High-helix end mills vs normal ones

[addertooth]

For smaller desktop machines, I really like the Asymmetrical spiral flutes (each flute has a slightly different pitch angle). They create less vibration because the bites are irregular enough to avoid making the machine resonate.

 

[mikey]

I'm finding the comments here about high helix end mills requiring greater rigidity and speed to be quite interesting. I've used high helix end mills on my little Sherline mill for quite some time now and haven't found this to be the case. In point of fact, I find high helix end mills to work really well in aluminum on my little mill (and also my RF-31). I do not find they require greater feed force, nor do I see any indication of them pulling up on the work piece. They do seem to clear chips better and they cut accurately and finish very nicely on my little mill so what am I missing here?

 

[macardoso]

12K rpm is way outside the envelope of my manual mill which can do 2.2 K max. What I can't understand is with the cutting edges so sharp, why is it more effortful in biting metal compared with ordinary end mills when used on manual mills ?

I read this at the beginning and was confused. I use the aluminum specific endmills in my tiny G0704 for the exact reason that they cut easier and consume less HP for the same cut compared to other endmills. I'm wondering if something else was going on.

12Krpm is the "optimal" speed. Truth is that in my experience, running them at a much slower speed is also perfectly acceptable, but you can't cut quite as fast.

I'm finding the comments here about high helix end mills requiring greater rigidity and speed to be quite interesting. I've used high helix end mills on my little Sherline mill for quite some time now and haven't found this to be the case. In point of fact, I find high helix end mills to work really well in aluminum on my little mill (and also my RF-31). I do not find they require greater feed force, nor do I see any indication of them pulling up on the work piece. They do seem to clear chips better and they cut accurately and finish very nicely on my little mill so what am I missing here?

I'm in the same camp mikey. My comments about pulling out of the toolholder or chucking the workpiece really only applied to marginal work/toolholding arrangements. The radial forces on these endmills are actually less than standard endmills thanks to more force being transmitted axially. I use high helix endmills almost exclusively for all my aluminum projects.

 

[Dabbler]

@mikey Any of these end mills can cause excessive force.... or not It depends on your feed rate and depth of cut. There have been underlying assumptions in several of the explanations as to how to compare X vs Y. You seldom take shallow cuts using a skip tooth rougher, and usually take very deep passes with them, so one could also argue that those take even more HP to run them!

-- it is all in how you use them, and what your mill can dish out before wimping out.

 

[mikey]

All my high helix end mills are from Niagara Cutter or Brubaker. Wonder if the maker makes that much of a difference. I've been blissfully blundering along with these things for a long time and have come to prefer them in aluminum. Just never had problems with them even on a tiny mill at mortal speeds and feeds so I found it curious. Anyway, back to our regular programming.

 

[mksj]

Similar to Mikey, I have been using carbide high helix variable 3 flute endmills from Wadia, Niagara, Minicut, etc., they run very smoothly and give very smooth finish cuts in aluminum. The 2 flute I had too much vibration and the finish was not that good, 4 flute would load up. There is a lot of variations between brands, so I stick with brands I know works well. I have some generic 3 flute high helix endmills in metric, and they are unimpressive. If I recall I picked up 4 of the 1/2" Wadia endmills for around $125 on eBay, they each can last 1-2 years with light duty and usually I will chip a tooth by knocking it as opposed to wearing it out. With a light coolant spray system they work very well, I am usually running the 1/2" at around 3200-3500 RPM. If you want to remove a lot of material very quickly then use a rougher, I also use the Minicut powdered metal 3 flute 3/4" end mill, they have a wave high helix edge so you get high material removal rates with a nice finish. Roughers tend to have more flutes in the larger sizes but break up the chips in longish slivers.

Deep slotting with a 5/8" rougher, shouldering with a 7/8".

 

[Dabbler]

I'm still using some 1/2" colbalt HSS 4 flute end mills from 40 years ago. Resharpened lots of times - probably over 50. I'm sure I've removed a lot of 1075 and 4140 steel and a 'ton' of aluminum with those end mills. I cannot cut as fast as with a rougher, but my cutter costs are quite low...

yeah, I do have some carbide, but I still prefer old school HSS (!!)