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Thread: Very rough surface finishing recently with c-beam build

  1. #13
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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by mactec54 View Post
    What kind of cutter would you use on a machining center to cut aluminum, the same as what he is using, it's all about the machine and coolant, it looks like his cutter is HSS which destroyed it's self in the first 10 seconds of cutting

    The Endmill is out of the collet to far, by what is showing in the photo, if he is using a trim router or similar the bearings and router are not designed to cut aluminum, so you can't expect it to be great, but should be better than this if setup right and the machine is rigid enough
    Agreed. Lubricant is a must.
    With the extension of the bit, it is possible to make a clean cut, but it has to be a slower feed rate and a lighter touch.
    HSS is not ideal here, eh?


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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by robwiacek View Post
    With the extension of the bit, it is possible to make a clean cut, but it has to be a slower feed rate and a lighter touch.
    Anything is possible if it is rigid enough, no feed rate or different cutters are going to change the one thing rigidity needed though, the shorter the endmill ( note Endmill not Bit ) is to the collet in this case the better chance the cut will be a little better, but don't expect any miracles, if the machine is not up to it

    Mactec54


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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by robwiacek View Post
    Agreed. Lubricant is a must.
    With the extension of the bit, it is possible to make a clean cut, but it has to be a slower feed rate and a lighter touch.
    HSS is not ideal here, eh?
    Tool extension and lack of rigidity aren't carbide friendly although carbides have become less brittle. Add into the mix a less than ideal spindle.
    On my X2 mini-mill I avoid carbides and get much better results than pictured here. Also my max rpm is half a router's min rpm.
    Since your router can't be dropped to mini-mill rpm I suggest lots of passes of small engagement and decent feed rate. Lube helps and compressed air if you've got it

    Edit/ I looked at a feed/speed calculator for HSS and you're kind of between a rock and a hard place with the available rpm.

    Anyone who says "It only goes together one way" has no imagination.


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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by robwiacek View Post
    That has a lot to do with it.
    But the consistency in the burr around the top of the cut shows it’s making an even pass with material being pulled out.


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    You simply do not use down cut bits in Aluminum. Trying to use such would lead to swarf jamming, mill breakage or other problems.



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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by user834342 View Post
    I had the same problem with a brand new tool so thought it wasn't really the tool.

    Here's an example:
    Very rough surface finishing recently with c-beam build-img_20180704_131813-jpg

    I also tried a really slow feed/plunge rate.
    Well it could be the end mill if you are buying the wrong type of end mill.

    Your picture is pretty terrible but the little bit of magnification allowed seems to indicate a lot of chip welding on the cutter. You will need to inspect a little closer to verify but if so you likely will need to lower RPM, address lubrication and feed rates. IF there is significant chip welding you might as well throw the cutter out. In any event the cut surface seems to indicate a lack of cutting and instead tearing which is another chip welding clue.

    Frankly I can't imagine a C-Beam based machine being rigid enough to cut aluminum with any quality but ignoring that, you can look at any rigidity related issues the machine may have and address them. In general though Aluminum requires the right feed rates, a cutter with good swarf removal functionality, lubrication (try WD40). I suspect that you are not achieving the right feed rates for the spindle you are using.

    Oh there is one other gotcha here, Aluminium varies vastly in the way it cuts baseed on the alloy, temper and other factors. if the bar you are milling today is different than the bar from a month ago you iwll see differences.



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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by wizard View Post
    You simply do not use down cut bits in Aluminum. Trying to use such would lead to swarf jamming, mill breakage or other problems.
    I did not know this.
    I work primarily in Corian, Wood, Brass
    Works in these materials as long as I use air and in some cases lubricant


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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by robwiacek View Post
    I did not know this.
    I work primarily in Corian, Wood, Brass
    Works in these materials as long as I use air and in some cases lubricant


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    I just looked at a Spiral O bit.
    Works beautifully in aluminum.
    Check out You Tube



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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by user834342 View Post
    I also tried a really slow feed/plunge rate.
    Imo that's doing yourself no favours. With high rpm of a router that tool has to be kept moving to concentrate the heat in the chips.
    When dropping the Z ramping into the cut helps to both maintain speed and clear chips.
    Also that rectangular cut is a tough job unless there's a really good way to evacuate chips. Re-cutting chips is the quickest way to get into trouble.


    My router has 16mm unsupported round rail on the Z axis, so it's not a very rigid machine compared to a lot of the machines on this site.
    For roughing the pocket in this picture: 2 degree ramp down at 20"/min, 0.05 stepdowns with 0.010" radial cut, all radial cuts @ 76"/min.
    On the finish cut I went a little nuts and tried 0.015" radial cut at full 0.400" depth @ 76"/min, that didn't go too well Rerunning that tool path 2X cleaned things up a bit.

    This was the first time trying metal on my router and if there's a next time I'll try more stepdown and less radial engagement.
    The one thing I would be reluctant to try is much slower feed as this was a 1/4" upcut carbide turning near 1000 sfm, about as slow as my router can spin. When the cutting was done the tool and work remained cool or at least not warm.
    Very rough surface finishing recently with c-beam build-pocket-test-jpg.
    btw, I was cutting 6061, some alloys are much 'gummier' causing much misery.
    Also there's a sticky regarding cutters at the top of this forum and the first 2 pages are a good read.

    Some posters frequently cut aluminium on routers so maybe one of them will chip in. I'll stick to a milling machine.

    Anyone who says "It only goes together one way" has no imagination.


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    Default Re: Very rough surface finishing recently with c-beam build

    Feed too slow, too many flutes, RPM too high, DOC too big. Recipe for disaster.

    This looks like my first attempts with alu.

    What is the rpm, feed and DOC you are running?



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    Default Re: Very rough surface finishing recently with c-beam build

    Wow, thanks for all the replies!

    Here I'll attach some more pics. It's just the standard OpenBuilds C-Beam Machine but I added extra brackets to help with rigidity.

    I tried lower feed rate but it didn't really help.

    Attached Thumbnails Attached Thumbnails Very rough surface finishing recently with c-beam build-20181231_135234-jpg   Very rough surface finishing recently with c-beam build-20181231_135247-jpg   Very rough surface finishing recently with c-beam build-20181231_135258-jpg   Very rough surface finishing recently with c-beam build-20181231_135314-jpg  

    Very rough surface finishing recently with c-beam build-20181231_135331-jpg   Very rough surface finishing recently with c-beam build-20181231_135343-jpg  


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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by mactec54 View Post
    plus not using some type of coolant
    I don't really space for a coolant system, it's a just a small DIY setup. Perhaps I'll try some WD40?

    Quote Originally Posted by robwiacek View Post
    Yeah but it looks like you should choose a down spiral bit
    What does that mean? Is the end mill the wrong type?

    Quote Originally Posted by mactec54 View Post
    The Endmill is out of the collet to far, by what is showing in the photo,
    OK I'll try and insert it further. Thanks.

    Quote Originally Posted by robwiacek View Post
    HSS is not ideal here, eh?
    You mean for cutting aluminium?



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    Default Re: Very rough surface finishing recently with c-beam build

    Quote Originally Posted by wizard View Post
    Oh there is one other gotcha here, Aluminium varies vastly in the way it cuts baseed on the alloy, temper and other factors. if the bar you are milling today is different than the bar from a month ago you iwll see differences.
    OK, I see, that's annoying!

    - - - Updated - - -

    Quote Originally Posted by wizard View Post
    You simply do not use down cut bits in Aluminum. Trying to use such would lead to swarf jamming, mill breakage or other problems.
    Is this bit "down cut"?

    Attached Thumbnails Attached Thumbnails Very rough surface finishing recently with c-beam build-20181231_140530-jpg   Very rough surface finishing recently with c-beam build-20181231_140615-jpg  


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