Thread: Aluminium cutting
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.
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.
Last edited by JAZZCNC; 21-04-2014 at 10:51 PM.
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.
At the risk of a bit of shameless self-promotion here's my channel link on Youtube - https://www.youtube.com/user/CCWashout/videos
The 5th Video is probably the best one with the two 5mm deep pockets being cut - the noisiest thing in the room was the compressor, but I have made some horrendous noises previously when F&S have been wrong, misting not running properly etc. Oh the description for that vid is slightly wrong as the previous vid was an 8mm Carbide Single Flute and the 5th vid uses a 6mm End Mill @16439rpm, 2mm DoC, 539mm/min.
I'll back Jazz up and recommend ramping for single flute cutters - I've broken the tips off of a number of them by plunging and I tend to find if you have to plunge try and set that in your CAM software at ~30% of your normal feed rate.
One of the things I found frustrating is the CAM software I am using, as Vectric's Cut3D and 2D does not always consistently apply ramping and in the case of Cut3D doesn't give you a ramping option at all. I am mostly using Deskproto now which does apply ramping, but only if there's enough room on the first move, but at least I can force it to plunge if there isn't at 30% feed.
I'm still learning myself and will post more vids as I progress and if you want to see something really cool look at Jazz's video of his machine using iMachining trochoidal toolpaths - that stuff is amazing (one day I'll be able to afford that :-) ).
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 ;-)
The Following User Says Thank You to Washout For This Useful Post:
I liked your videos, Thumbs Up. The 5th video is perfect, That's how I want to be cutting aluminium. I don't think I will use your method for testing how sharp the end mill is, It's a bit messy. Can you tell me the plunge rate you have on the 5th video, and I take it as your using the full rate as you ramp down? and you only use the 30% if you were plunging a hole with an end mill instead of a drill bit.
Just wondering why you didn't climb mill the 5mm pockets in the vid. Don't take this as a criticism as I bow down to your ability to self build such a nice looking machine. You would find yourself with a longer tool life though if you did all of the 5mm in one pass and cut the pocket using 30% step over. You could increase the feedrate then due to the chip thining so you would have a nice increase in material removal rate. I understand that you are not looking to lash off 1000 pieces so time probably isn't a bit deal but it would be better to let the whole tool wear a fraction than the bottom 2mm wear while the top section does no work.
Regarding speeds and feeds calculators I have a nice .xls file which I got from my tooling supplier. When I read the figures that came out first, I said no way, surely the tool can't handle it but they do. It gives you a range of speeds for carbide and hss tools, which is useful, as if you want to apply it to different brands of tools you can put in the lowest settings and still be in the ball park for things like stainless. Then you can speed up if the conditions allow. If anyone wants a copy just pm me and I'll send it on. One important point though is that I have a rigid NC bridgeport and home made machines wouldn't be expected to have the same rigidity so carbide tooling may not be suitable at high feed rates if vibration is an issue.
Regarding tool paths I'n keen to see how m_c gets on with generating trocoidal paths with cambam. If the software can do that for under £100 it sounds like a great deal. I use trocoidal all the time and cringe when I have to put a tool into a corner when the rads limit my options.
At that point I needed the parts off of the machine without mishap, as they had to go on the race car as one of the first bits of assembly, as they sit between the monocoque and the front sub-frame (replacing bonded ali and silly putty....I mean rubber OEM parts ;-) ). I also had limited amounts of 40mm 6082, so I needed safety and the machine was not long up and running at that stage. Conventional was quieter and I figured less stressful than climb, but I do use both these days and I hear you on the wear at the tip, but I have managed to tune my F&S's, using GWizard's help, to the point where (touching wood) I'm getting much better tool usage than I used to.
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