Help with aluminum speeds and feeds

Hello, I’m rather new to the cnc game and need a bit of help. I need to cut out a semi complex sign out of 5052 aluminum. I know it’s not the best, but it’s all I can get. I got 1/16th inch altin bits, and I have no clue what I should set my speeds feeds and cut depth to. Do I go shallow and fast? Deep and slow? Something different? Any help is greatly appreciated! Thanks in advanced!!!

Just to make it more clear, the bit is a 1/16th inch altin coated 3 flute bit.

Can you get a different material?

machinability only fair (poor)[70] Cuts usually look gummy on scrap/drops, easily welded.[71]

c.f., https://wiki.shapeoko.com/index.php/Materials#5052

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I cant as it needs to be 0.09 inches, and i cant get it in my area. I already have the 5052 as well. I am willing to do anything to make it look okay (ill spend 10 hours with it if I have to).

So I think a good place to start would be to find something from a larger vendor that has ballpark figures for what you have. Pulling up from Harvey tools:
http://www.harveytool.com/cms/SpeedsFeeds_228.aspx
http://www.harveytool.com/cms/SpeedsFeedsSignatureSeries_225.aspx
http://harveytool.com/secure/Content/Documents/SF_823000.pdf

That table has a bunch of information on it. Including recommendations for 5xxx alloy aluminium
Also Winston has a pretty good video on a few different topics including wrong alloy:

More for a general awareness, than me saying dont machine that alloy. Just pointing it out.

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Thank you. I understand that 5052 isnt the greatest, its just 6061 isnt available near me. I know im going to sound stupid, but could you help explain how to read that graph and convert it into something I can put into carbide create. Im still new to this whole thing and dont understand it all yet. Thank you!

No problem! I think this video/live stream would do a better job explaining.

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Hi @Caseyman,

Using the “wrong” kind of alloy AND a tiny endmill AND a 3-flute is basically a worst case scenario :slight_smile:

But I guess that’s not what you want to hear. In addition to the videos above, if you have some time ahead of you and want to understand how to derive those feeds and speeds, here’s my take on it.

If you’re going to do this, experiment will be key and you need to be ready for failure (i.e. gumming up or breaking a tool). I would probably use this starting point and go from there:

  • 18000RPM, 27ipm (to get a chipload of 0.0005", which is more or less the minimum under which you would rub, but at the same time is not high enough that a 1/16" endmill could not handle it. The runout should be minimized, so ideally you should use a high precision collet, but if you don’t have one of those then there is not much you can do about it.)
  • depth per pass: I would go really shallow to begin with, especially since I assume you will be doing profile cuts, which again is a worst case scenario. Say, 0.006". It will take 15 passes to cut through your 0.09", but you would be on the safe side to minimize tool deflection and risks of breaking your bit.
  • a spray of WD40 can’t hurt (or ideally a strong blast of air, if you can do that)

In any case, with a tiny 3-flute in potentially-gummy material, I’d go with fast and (very) shallow, rather than deep and slow

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Thank you!!! I know this is a worst case. I do have precision collets. Its going to be run on my xxl. Thus far ive only done 1 metal sign before. I am extremely new so thank you! If you dont mind, could you share how you calculated the chipload rpm and such. Thank you so much!!! Could you also suggest a tool which would be better for the job? It needs to be 1/16th inch. Ill be lubricating the aluminum and Ill use my air compressor. Thank you again!!!

FINALSIGNDONE.c2d (1.5 MB)
Heres my file. I know I absolutely abused the tabs feature but I really need this to come out. Right now with those settings (disregard the 2nd toolpath I couldnt delete it) its saying it will take around 11 hours to complete. Is there a way to make this go faster while still leaving the surface finish okay and with a not huge risk of breaking the bit? If not I will most definitely wait the 11 hours. Thank you for your help!!!

This was such a major help! Im still confused a little bit, but this did a great job of explaining things. Thank you!!!

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Oh my, you were not joking when you said you abused the tabs, this has got to be a new record :slight_smile:

You picked a vector that is very tricky to cut, do you have any opportunity to change it for a simpler one or is that a mandated one ?

As you probably saw, the resulting cut will look significantly different than the original vector, even with a small 1/16" endmill (just double-checking that this is indeed the look you are after?)

Tabs are normally intended to be cut off, but do I understand you want to keep them and that’s why you made them the same height as the stock ?

Anyway, to answer your question, the only way to tell if you could go faster/deeper would be to do test cuts, if you have some scraps of that 0.09" 5051. Starting from those “conservative settings” I mentionned or the ones from CC for “regular” aluminium:

), and then increasing depth per pass and testing again. You need to have a few bits to spare though, because while searching for the limit, you will find it…and potentially mess up the endmill.

Given how many hurdles you have for this project, your first step should definitely be to do some test cuts anyway.

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You are correct about the tabs. I would have done this in Inkscape instead of just putting tabs Willy nilly, but I couldn’t get Inkscape to work. I bought a sheet of 5051 so I have some scraps. Thank you for the advice on the testing. I got 4 bits so I’m fine if I break one or two. As for the logo, it needs to be extremely similar to the original. I wanted to be able to use a 1/8 inch endmill, but I don’t know how I could. Any suggestions are welcome and thank you so much!!!

You’ll be fine with 5052, I run it all the time. Use wd40 for sure and a Richard style dripper works well for this kind of work. The hardest thing about sheet is the work holding, superglue/tape is nice and easy.

Julien’s recommendations will work great and its good practice to start a few passes above the material in case there is bowing.

Have you thought about using a V bit to engrave the small details that can’t be cut out?

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I can’t get a V bit in the time that I have right now. How would I do that in carbide create if I were to? As for workholding, I have the Shapeoko 3 XXl T track and clamp system so it shouldnt be a problem. And I will definitely use wd40! Thank you so much!!!

Also can you give me your normal feeds and speeds for 1/8 inch and 1/4 inch bits? (and 1/16th if you have it) Thank you!

What region do you live in? Maybe we can help find a place to buy less troublesome alloys?

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I’m in Florida, but 6061 prices near me are absolutely ridiculous because the two suppliers don’t carry its. I’m in central Florida to be more exact. The Orlando metal supplier doesn’t carry anything past bar stock and the one in Ocala doesn’t sell anything under 1/2 inch.

I live just north of Seattle, WA., and there are so many things I can buy cheap due to being so close to ports, but for some reason, it is cheaper for me to order my 6061 aluminum from Midwest Steel and Aluminum, and pay shipping than it is to order from either of the two metal suppliers in my local area.

I am doing just random things with aluminum since I started cutting it just a week or two ago, so I have been buying 12" x 24" pieces to keep shipping down, and because right now I don’t need anything bigger than that.