Aluminium cutting

**Kentobi** · 25-03-2015

some good advices here, thanks for posting

**Boyan Silyavski** · 17-04-2015

Dean, did you ever test the bits?

**AGTM** · 24-09-2014

Hi Bush Flyer

I am new here, but I went through the posts. Would you please tell me why you are using a single flute cutter for aluminium?
I have been working aluminium for years, but mostly with 3 flute cutters. You can plunge, slot and side milling with no problems.
Depends of the tool I am running the cutters around 8000 - 10000rpm.
For me is interesting why single flute, why not 2 or 3 flutes?

**JAZZCNC** · 24-09-2014

Originally Posted by AGTM

For me is interesting why single flute, why not 2 or 3 flutes?

Because of machine stiffness and feedrates at DIY level. With 3 flute you need much higher feed rates at lower DOC and most DIY machines can't cut at those feeds and are not strong enough or have powerful enough spindle to cut at correct DOC for 3 flute cutters.

I agree thou they are better than single flute and give nicer finish if you can use them.

**AGTM** · 25-09-2014

Hi JazzCNC,

Thanks for the fast reply. Now I understand the situation. OK, here is what I would do if I have to use a single flute cutter for aluminium:
My rule specially for aluminium is Fz=D/100 or for example if you have 6mm diameter cutter your feed rate will be Fz=0.06mm/rev. And if you have available 10000 rpm, your feed rate will be F=600mm/min. I would not go more than DOC=1D
and WOC=1D.
Always helical plunging if it is possible as F=1/2 for the plunging. The single flute should go straight plunge (drilling) with no problems. Finally, It really depends of the carbide grade of the cutter. It might not be suitable for high speeds. Recently, I did a custom order for 3 flute uncoated cutters for aluminium. I made 12mm cutter with 45deg spiral. The tool has 24mm working length and 80mm total length. The carbide material of this cutter is WC25, a grade for stainless steel processing. This cutter works since four weeks, it is still in use and it works with S=10000rpm and F=3800mm/min.
So, if the single flute cutter brakes on the recommended cutting conditions, I am sure we can fix this problem with custom made tool. The good part is that the price is the same as the standard one, but there is a requirement for min 5 cutters.
I have one of those 12mm cutters left. If you want I will send you to try it or to some friend of you.

**JAZZCNC** · 25-09-2014

Hi AGTM,

Problem most DIY users here wanting to cut Aluminium is spindle power or lack of it.! Most are using router based machines and spindles with high speeds but little torque with typical 2.2Kw.
So DOC=1xd on 6mm cutter with WOC=1xd is mostly impossible with the spindle torque they have available.! Then you have the stiffness of the machine. Again being router based most are flimsy in comparison to even the weakest milling machine so chatter and poor finish dictate using much lower feeds/DOC etc.

I may give your cutters a try but I mostly use smaller 4-8mm cutters. Again due to spindle power but also material saving when nesting parts.
I'm a big believer that when it comes to tooling cheaper cutters are uneconomical as they wear quickly and put more stress on the machine not to mention much poorer finish quality.

Also I feel most people use the wrong tool for the Job, like not using a ripper for roughing.? Often this is down to the fact they don't want to change tools so will use one tool to do the whole job. This again is False economy because with a cerated edge ripper you can cut far deeper and remove far more material in fraction of the time without wearing the tool away or stressing the machine/spindle.
Also they don't actually save time by not changing tools it actually costs them time and money because the smaller tool cutting at lower DOC takes much longer than any tool change. Plus the tool and machine are getting hammered because they are working much harder than they need to.
On top of this Finish quality is lowered because by the time they get to the end of the job the tool cutting edge is so worn finish is poor. They don't realise that by using rippers and then just doing a finish pass they actually save money because time is reduced and tools last much longer as they are cutting efficiently and they get a much better end result.!

That's my take on it. . .

**Bush Flyer** · 21-04-2014

Hi Jonathan, and jazzcnc.
Jonathan many thanks for the info I hope this will get me in the ball park, Jazzcnc that's a big difference in chip load, where can I find more information on line about chip loads and calculations, I know about GWizard But I would rather have one with no cost or a one off payment as I mainly will cut ply and balsa and some small parts in aluminium. Once I can get near the correct settings I would have no or very little use of Gwizard calculator and yes I have been plunging into the aluminium but a very slow rate.

**JAZZCNC** · 21-04-2014

Try this for a one off fee. http://www.mycncuk.com/forums/comput...html#post57489

Other than that then can't help as I tend to use rule of thumb and my ear or occasionally I'll use G-wizzard.
Google can be your friend sometimes.

To be honest your best approach is to setoff of slow and find your machines sweet spot and only way to do this is thru trial and error. Like I said doesn't mean my settings or anyone else's will work well for you or your machine so your best finding the limits of your own machine. Unfortunatly the price can be a few snapped cutters.

Best tip would be set your best guess for feedrate and spindle speeds then use feedrate over-ride to lower and setoff slow to judge how it's cutting. Between changing feedrate and spindle speeds it doesn't take long to find the machines sweet spot. Then start tweaking the DOC when you feel more confident and have a feel for the machine's/cutters limits.

**Washout** · 22-04-2014

For single flute cutters I'm using APT www.shop-apt.co.uk - they are more expensive than some of the ebay sellers, but I'm finding the quality and longevity much better - I wouldn't recommend it but I managed to cut my finger by clumsily taking the plastic cap off of an APT cutter and brushing the edge, whereas a batch of ebay cutters were no where near as sharp - I'm not sure that the correct way to test cutter sharpness however ;-)

**Bush Flyer** · 22-04-2014

I have just tried the HSMadvisor free calculator and like it, easy to use. The G-wizard calculator is too expensive for all that I would use it. Anyway where are you buying your single flute carbide bits from? I have been buying from aliexpress.com and am beginning to think I should buy some better quality bits. the bits I have been using were listed as suitable for cutting acrylic, organic board material, Metal, Copper, Aluminium, but I have my doubts now.