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    Default Re: Cutting aluminum - Share feeds and speeds

    Quote Originally Posted by louieatienza View Post
    I think that came out pretty good for your first part! As to the edge finish, could be a number of things... maybe a tad too fast for your finish pass, slightly too slow spindle speed for finish pass, workpiece possibly could be more secure, looseness or flex somewhere, tool runout... biggest thing though in my opinion is tool stick out. The closer the collet is to the work without interfering is best. Use stub endmills whenever possible.
    Yeah, that's a 3" bit and I shoved it as far up as I could in the collet. Figured if I only had one bit, needed reach if I wanted to cut something bigger. But maybe that's worth
    revisiting.



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    Default Re: Cutting aluminum - Share feeds and speeds

    Quote Originally Posted by Kosh View Post
    OK, so last night and tonight I finally got around to making that bulkhead out of aluminum. I just received my pro linear motion upgrade from CNCRP, and I have to bust the machine down now and rebuild it. I figured this was a good time to get WD-40 all over the spoil board as I'll making a new one once I rebuild it.

    I basically followed Louie's guidelines and it cut very well. I actually stopped it after about 3 hours worrying the bit was getting hot, and was pretty much cold to the touch. Seemed to have a good chip load too. However, close ups of the cut quality at the end here, would be interested in feedback on whether they are smooth enough and how to fix if they aren't. The chamfer seems a little rough too... moving too fast? (445 mm/min).

    Overall, it came out well, esp for my first time in alum! No broken bits!

    Attachment 366526
    I think that cutter is far too long. Get a considerably shorter one and your results will improve dramatically.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Quote Originally Posted by Kosh View Post
    Yeah, that's a 3" bit and I shoved it as far up as I could in the collet. Figured if I only had one bit, needed reach if I wanted to cut something bigger. But maybe that's worth
    revisiting.
    That's the other thing... if you put the flute fade out into the collet ypu may experience some runout. The fade out should be at least 1/16" or so past the collet.

    The stiffness of the tool decreases exponentially the farther it sticks out.



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    Default Re: Cutting aluminum - Share feeds and speeds

    Quote Originally Posted by louieatienza View Post
    That's the other thing... if you put the flute fade out into the collet ypu may experience some runout. The fade out should be at least 1/16" or so past the collet.

    The stiffness of the tool decreases exponentially the farther it sticks out.
    No, I didn't put it in that far.



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    Default Re: Cutting aluminum - Share feeds and speeds

    Had another job come up for an aluminum part! Was a good opportunity to really dial in speeds and feeds for the first prototype.


    Stock was .5" thick 6061

    Single Flute .25" endmill
    Adaptive clearing toolpath from Fusion:

    .25 DOC .03" stepover, trochoidal milling

    70 IPM 15k RPM

    Results were very good! No pictures unfortunately as the part is not in production yet.



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    Quote Originally Posted by NIC 77 View Post
    I've never actually tried to mill aluminum with a 1/8" bit. Oh wait, I have. Yes, I broke the bit. Then I stuck with 1/4" minimum after that, although I have used 1/8" drill bits to peck drill holes with no problems.

    1/8" bits are easy to break. Especially if they're carbide.
    do you know where I can find 1/4 mdf



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    Lowes and Home Depot sell various size sheets of 1/4 MDF



    Quote Originally Posted by Manrhpg View Post
    do you know where I can find 1/4 mdf




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    Default Re: Cutting aluminum - Share feeds and speeds

    oops! photos that I uploaded didn't enlarge properly. reposted again. sorry.

    Attached Thumbnails Attached Thumbnails Cutting aluminum - Share feeds and speeds-img_3383-jpg   Cutting aluminum - Share feeds and speeds-120506-1-jpg   Cutting aluminum - Share feeds and speeds-120506-2-jpg   Cutting aluminum - Share feeds and speeds-120506-3-jpg  

    Cutting aluminum - Share feeds and speeds-120506-4-jpg  


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    Default Re: Cutting aluminum - Share feeds and speeds

    Quote Originally Posted by DonFrambach View Post
    congrats on the nice panel! Thought I'd share a way that I used to make the lettering stand out.
    Cutting aluminum - Share feeds and speeds-img_3383-jpg

    A few years ago, I made similar lettering on an aluminum panel for my DIY router
    Cutting aluminum - Share feeds and speeds-120506-1-jpg

    I painted the panel with flat black paint
    Cutting aluminum - Share feeds and speeds-120506-2-jpg

    I then sanded the panel with my random orbit sander to give it a fingerprint resistant "pseudo-brushed aluminum" look
    Cutting aluminum - Share feeds and speeds-120506-3-jpg

    It came out pretty well
    Cutting aluminum - Share feeds and speeds-120506-4-jpg
    Great idea Don, I may give that a try!



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    Default Re: Cutting aluminum - Share feeds and speeds

    Congrats on the nice panel!! Though I'd share a way that I used to make the lettering stand out
    Cutting aluminum - Share feeds and speeds-img_3383-jpg

    A few years ago, I made similar lettering on an aluminum panel for my DIY router.
    Cutting aluminum - Share feeds and speeds-120506-1-1-jpg

    I painted the panel with flat black paint
    Cutting aluminum - Share feeds and speeds-120506-2-1-jpg

    I then sanded the panel with my random orbit sander to give it a fingerprint resistant "pseudo-brushed aluminum" look
    Cutting aluminum - Share feeds and speeds-120506-3-1-jpg

    It came out pretty well
    Cutting aluminum - Share feeds and speeds-120506-4-1-jpg



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    Question Re: Cutting aluminum - Share feeds and speeds

    Hi all, first post after perusing the forum for a few days.
    I'm trying to determine some "optimal" feeds and speeds for cutting 6061-T6 aluminum on a desktop CNC-type machine (ShopBot Desktop) and there seems to be some contradictory information on the internets.
    The few people in this thread that mentioned specifications (RPM, IPM, etc) including the OP and others used a relatively high rotation speed (~12 - 16k RPM). However other reference pages with tables, formulas, etc recommend much slower speeds (~4000 - 8000 RPM). A few such pages are listed below:
    https://daycounter.com/Calculators/G...lculator.phtml
    https://www.cnczone.com/vb/cnc-machi...uminum-206831/
    https://littlemachineshop.com/refere...tingspeeds.php

    What gives? Why is there such a wide discrepancy between the recommended speeds and personal experience? Am I misinterpreting the tables / formulas?
    Any feedback is appreciated. Thanks



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    Default Re: Cutting aluminum - Share feeds and speeds

    Feeds and speeds depend HIGHLY on the tool itself. What material the tool is made of, and coatings it may have, cutting edge geometry, and the number of flutes all play a major role.



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    Default Re: Cutting aluminum - Share feeds and speeds

    Quote Originally Posted by Wildkard View Post
    Feeds and speeds depend HIGHLY on the tool itself. What material the tool is made of, and coatings it may have, cutting edge geometry, and the number of flutes all play a major role.
    Thanks for the response. Love your name BTW. Always Sunny fan?

    Well yes, of course, I understand that. But that's not answering the question. Can you please tell me, specifically, why there's a difference between what these calculators recommend and what people are using in real life?
    I would like to know to educate myself so that I can choose the appropriate feeds and speeds when I make my part.

    For instance, for aluminum, using the formula:
    RPM = (12 * Surface_Speed) / (PI * Cutter_Diameter)
    with a 1/4" mill yields: 12*280/(pi*.25) = 4278 RPM.

    Now I realize that's just a guideline but why are people cutting at say 12,000 RPM instead of something closer to that number?
    Perhaps that formula assumes your bit has two teeth (it doesn't say that, but anyway). Well if you were using a singe flute mill, for instance, then you would want ~8400 RPM instead to maintain a similar chip clearance. We're still not anywhere near the 12 - 16K RPM that seems to be successful for other people.

    Anyway, can someone please just step me through the process of how you might choose an appropriate RPM for milling 6061 aluminum with a 1/4" bit?
    Thanks again.



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    Default Re: Cutting aluminum - Share feeds and speeds

    SFM is more of a range than a hard target, the 280 you have there from the daycounter site would be at the lower end of the range for uncoated HSS tooling. With the upper range being around 500sfm. Carbide could be anywhere from 800-1500 depending on coating. Aluminum tends to like sfm near the higher end, tends to stick to the cutter less.

    What cutters are you using exactly, would be able to help more.



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    Default Re: Cutting aluminum - Share feeds and speeds

    Quote Originally Posted by Wildkard View Post
    What cutters are you using exactly, would be able to help more.
    Sorry for the delay, haven't been over there for a few days.
    Looks like what I got for milling aluminum was as set of HSS 2 flute end mills from MSC:
    https://www.mscdirect.com/product/details/63324719

    I have other bits as well such as these and these but I believe the set above was ordered specifically for aluminum

    Last edited by pmillho; 05-03-2019 at 04:05 PM.


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Cutting aluminum - Share feeds and speeds

Cutting aluminum - Share feeds and speeds