Getting extremely bad cuts on 6061.
1/4" 2F ball @ 31ipm, a conservative .004" DoC, and even more conservative 1ipm plunge. DWP611 at dial 1 (~16k RPM). About 2" out of the collet.
This is the result. As soon as it plunges the cut chatters to worrying amounts of vibration. Continues all the way down so it’s not the surface being anodized. Tried Easel’s recommended 5ipm @ .003" DoC which chatters just as much and takes a long time.
Not sure what’s wrong. Very confident that it’s 6061, not sure of temper though. Am I just wrong about the alloy?
Did you check the play in the Z axis vwheels?
My recommendation would also be double checking Z. My first go round with aluminum was not pretty due to my bed not being level. After surfacing and tramming my machine I cut confidently at 40ipm .008 doc with .25 triple flute end mill. Somewhere around half that for .125 end mill. As stated, go though your Vwheels and make sure they are all snug to eliminate play (might be the source of chatter). Might be a good idea to give the belts a snug and do a quick calibration just for piece of mind. My X axis was off by almost a mil. If none of that works I would be looking real close at the bit. Last but not least make sure you are milling conventional. You can do a final pass in climb if need be.
Is a ball nose bit the right tool for such a job?
(my only experience is with flat bits, 1/8" and smaller)
In general a rigid machine is a requirement when cutting metals, so make sure yours is as firm as possible.
I agree with Phil.
That cut looks much deeper than .004". .004" is about the thickness of a piece of printer paper so it should be barely kissing the surface each pass and certainly wouldn’t be the width of the bit after one pass with a ballnose endmill. I would confirm your doc setting and z movement calibration.
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Something is definitely off on your setting. Like Phil said that is definitely not .004"
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First, thanks all for replying.
@JohnWhite That sounds good. I’ll probably try a calibration again, I maybe didn’t calibrate it right after replacing the ACME rod. Is there a way to tell Easel to generate a conventional path?
@PhilJohnson really sorry but I forgot to mention those pictures was after a couple of passes. Easel recommends .003" but I explicitly decided .004" to test.
@HaldorLonningdal Yeah I truthfully don’t have many bits larger than 1/16" bits, the 1/4" ball is my only “large” one, which I was testing to be used for a 3D roughing path.
Thanks again all, will update when I try recalibrating again. I have the habit of going back to the vwheels and re-tuning them after each time I turn on the x-carve, but I haven’t touched the belts in a while.
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for alu I always use lubricant. Makes a huge difference. Especially when dialing in settings.
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Yeah WD40 will do just fine. The bad part is you need to stay with the carve all the time to keep it soaked
Personally I have had better success with an air pump. I have tried wd40/alcohol/cutting oil, but all of these allow (or in fact encourage) chips to hang around.
I bought an air pump for a pond, and have it hooked up to a flexible coolant pipe. It has seriously changed my results and confidence when cutting aluminium.
It clears any and all chips, and since using it I have had no problems with aluminium, including cutting some 7mm dia holes in 20mm alu and 5.1mm in 15mm.
My machine was a bit beefed up from stock, but my £30 air pump has been a brilliant addition
I also have an air pump, with a mister recently added which I add denatured alcohol into the airstream with.
Leaves no mess since it evaporate unlike WD40 which leave oil residue behind 
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that is a valid problem. Thing is, if I don’t use oil, I may potentially get the rubbing the OP is experiencing as well. Depends on which endmill I use and which alloy I cut.
Yeah that cut looks way deeper than .004". I was running a job this weekend on a stock x-carve 1000mm with a 1/8" 2flute flat @ 0.01" depth, 45ipm. It still chattered, but the edge was good enough I could make another pass, full depth, with ~0.003" stepover and it cleaned it up nicely.
This is not a catch-all solution. I find it much more important to clear the chips out than to keep lube on the bit/work. Having a dust shoe is actually pretty useful in this regard, it usually pulls the chips right out of the slot. The problem with using WD40/lube is that unless you are also clearing the chips out of there, you’ll recut the aluminum. Recutting means chatter, chatter means chipping your tools, chipping your tools means horrible cut quality.
Aluminum cutting priorities (in order) are:
- get the chips out of your cut (dust shoe, air blast, mister, etc)
- clamp as securely as possible to reduce excess vibration
- lubrication/cooling
^^ assumes your machine is tuned, and you have correct cut settings, etc etc
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These are great, I have two of them on my custom built CNC.
Fair warning, they will use a lot of coolant if you decide to actually hook that part of it up. Even if the valve is just barely open.
But yeah auto pulse timer sounds like it’d solve that issue
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Agree, I have mostly been cutting 2mm plate lately. That kind of work does not need chip clearance as much as deep slotting does.
I use a different, cheap mister off ebay, which work quite well in that regard Consumption is approx 3fl.oz/hr which equal a light mist, but sufficient for my setup when running a 3mm (~1/8") flat end mill in 6061/6082 alu.
Wish I had the setup to get into liquids and stuff.
Anyways thanks guys, I checked the calibration on all axes which was fine. Re-tuned the z-axis vwheels to get things snug and secure. I got the same result on a cut again.
I tried a cut on some soft maple which worked beautifully actually, so even though I’m sure I was cutting 6061 I’m gonna try a thinner plate from a different seller, hopefully one with a known for sure temper.
Do you have a flat end mill to try?
I do, but all of them are no larger than 1/16", and I’ve only so many so I’m saving them from stress for now.
I shouldn’t be having this problem since I’ve done very thin 6061 sheets along with some 360 brass sheets with little/no issue, so now I’m seriously doubting this plate.
