Aluminum: is bigger or smaller bit better?

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John_TX
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Aluminum: is bigger or smaller bit better?

Post by John_TX » Sun Apr 03, 2016 2:27 am

I need to machine some 3/4" dia holes in 0.070"-thick aluminum. I will use the fastest router speed setting and a very slow feed (I'm thinking 5 IPM?) and low DPP (I'm thinking 0.005"?).
But I have the choice of using 1/4, 1/8, or 5/64" endmills. (I'd prefer to use one of the first two, as the third is on 1/8" shank and I'd have to use my cheap adapter.)
I am still fuzzy on the concept of "chip load" but obviously the 1/4" bit will remove more material at a time. However that material will be spread out over larger area.
Is there a right or wrong choice for me to make here?
Thanks!

Gamble
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Re: Aluminum: is bigger or smaller bit better?

Post by Gamble » Sun Apr 03, 2016 3:14 am

It's only .070 thick. I wouldn't worry so much about it.
I have been using a 1/4" bit, 2 flute. 65ipm, .1 doc. And just spit out a piece that was 1/2" 6061 and at the fastest rpm the dewalt router will go which is about 33k
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AnonymousPerson
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Re: Aluminum: is bigger or smaller bit better?

Post by AnonymousPerson » Sun Apr 03, 2016 12:18 pm

John_TX wrote:But I have the choice of using 1/4, 1/8, or 5/64" endmills. (I'd prefer to use one of the first two, as the third is on 1/8" shank and I'd have to use my cheap adapter.)
Pick either of those then. As a first thought, are any of your 1/4" end mills the 2 flute variety? If so, pick that one first. :)

Next thought, do you have some scrap of the same metal you can practise on first? It's always a good idea with new materials, to try on a piece you're not wanting to keep. It lets you figure out reasonable settings, before needing to do it "for real".

Btw, the aluminium you're working with is very thin (sheet metal?), so it'll be difficult to go too wrong once you've established some reasonable settings. You'll be fine. :)
Last edited by AnonymousPerson on Mon Apr 04, 2016 12:22 am, edited 1 time in total.
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joethejammer
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Re: Aluminum: is bigger or smaller bit better?

Post by joethejammer » Sun Apr 03, 2016 11:05 pm

Generally speaking, larger bits are better for aluminum because they have less of an issue with getting clogged up with chips

John_TX
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Re: Aluminum: is bigger or smaller bit better?

Post by John_TX » Mon Apr 04, 2016 1:58 pm

Thanks all for the help!
I used my 1/4" 4-flute endmill at 1 ipm plunge, 20 ipm feed, and 0.01 depth per pass. All went well, and next time I may be more aggressive. I will probably go much deeper per pass next time, especially if I can ramp in Z.

Fablicator
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Re: Aluminum: is bigger or smaller bit better?

Post by Fablicator » Mon Apr 04, 2016 2:12 pm

John_TX wrote:I need to machine some 3/4" dia holes in 0.070"-thick aluminum. I will use the fastest router speed setting and a very slow feed (I'm thinking 5 IPM?) and low DPP (I'm thinking 0.005"?).
But I have the choice of using 1/4, 1/8, or 5/64" endmills. (I'd prefer to use one of the first two, as the third is on 1/8" shank and I'd have to use my cheap adapter.)
I am still fuzzy on the concept of "chip load" but obviously the 1/4" bit will remove more material at a time. However that material will be spread out over larger area.
Is there a right or wrong choice for me to make here?
Thanks!
What CAM are you using?

Bigger cutters are almost always better.
A 1/4" end mill and a good path will probably make that hole in a few seconds.

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