Reclaiming gunked up bits after cutting aluminum

[byoc]

I've been going through bits like crazy because they keep getting gunked up with aluminum. So I'm looking at a dozen $25 bits that aren't good anymore and I decide the trhow them in some feric chloride. In 5 minutes, all the aluminum is gone and the bits are like new.

[scottcox]

Keith,

Good tip. When cutting some aluminum a while back, I had the same problem with aluminum sticking to the bit. I talked to the Onsrud folks and they helped me figure out that I was moving too slow through the material, causing the bit to overheat. The aluminum chips/shavings would then re-weld to the bit.

I decreased my depth of cut and increased my feed speed and I could cut for an hour and the bit would be still be at room temperature with no rewelding.

Worked for me. Good luck.

[olecrafty]

Scott,

When cutting aluminum does a coated bit help with the chips sticking to the bit.

Kaiwa

[scottcox]

I haven't tried the coated bits. I've only used the solid carbide spirals from Onsrud. After I figured out the feeds/speeds, they've worked well for me.

[joewino]

Scott - what Onsrud bit are you using and what are the feed speeds...if you don't mind?

[aaasigncom]

hey keith if you having aluminum welding to the bit then something is wrong! .080 aluminum cuts in one pass just as easy as plexiglas. see earlier posts for cutting aluminum - your chipload / chip size should be sililar to plexiglas chips - large. if you add a universal mister ($45) and spray alcohol as a coolant / lubericant, all of your problems will go away. use a 2 sided o flute cutter - climb milling. you will be amazed how easy alum cuts with the proper setup. tony - indianapolis

[scottcox]

Hi Raymond.

I had best success with the onsrud 63-624 (1/4") climb milling at 1/16" depth and stepover at 2.5 ips and 16k? rpm (I think). Onsrud says to get max cut, use chip calculator and go deeper until you start breaking bits. (Of course they say that. Their bits are $$$)

I also tried a single flute 1/2" 63-631 and my 5HP Colombo started vibrating badly at 5K rpm. I didn't even cut with that one. They said the single flutes weren't balanced like the two-flute so probably the 5HP spindle couldn't handle it. They did accept a return for credit.

I've been staying with Onsrud when I can because they're willing to spend time on the phone with me coaching me through some pretty tough jobs. What they have given me as far as starting points on speed/feed has always worked. Just consider that they're used to dealing with the "big iron" guys, so with the shopbot, you'll likely have to decrease the depth of cut to compensate.

Here's a link showing some thicker stuff ....http://www.talkshopbot.com/forum/messages/312/14964.html .

I've had a couple of inqueries about cutting the thinner aluminum sheets and I know they can be cut in a single pass. If you have any success stories with the thin stuff, please share.

...And you definitely need to share some of that artistic talent! I was recently talking to someone about your signs and couldn't find you online. Do you have a website?

[byoc]

Hey Tony,

I am cutting die cast aluminum which is much softer and denser than the typical stuff people use for signs and such. And I'm running my machine as fast as it will go while still being able to maintain an acceptable amount of accuracy (18krpm/500ipm). I have tried other combinations that would produce the same chipload and they just don't work as well.

What I'm finding is that I don't really get much "welding", untill I hit that piece of material that isn't held down quite tight enough...and it makes a loud chattering noise. Then once the bit gets that first little bit of material stuck to it, it's all downhill from there.

So sometimes I'm able to cut 200 units without trouble...sometimes only 20. But it's not big deal now since I've got about a dozen bits in rotation and none of them seem to be showing any signs of wear.

I've been using onsrud 1/8" super O carbide bits. Most of the holes I'm cutting are too small for a 1/4", but I've recently started using a 1/4" for the few holes that are big enough. It's a pain having to change bits, but the results are much better so it's worth it. I've experimented with some 2 flute bits and the chipload is beautiful...it just spits out one big coiled chip. But the tooth on the 2 flutes that I've tried aren't aggressive enough. I guess I need to keep looking around.

I've only had my PRT alpha 96 in use for about 3 months, so I'm definitely still experimenting. I also just sold it and won't have my new PRS alpha 48 for another two months or so.

[byoc]

Link to the universal mister?

[aaasigncom]

LINK TO MISTER http://www.littlemachineshop.com/products/product_view.php?ProductID=2226&category= --- BUT THERE ARE MANY BRANDS AND TYPES AVAILABLE
8800

[byoc]

And if you use alchohol as a coolant, it just evaporates? Isn't that kinda dangerous? How messy is that Kool Mist 77 stuff...if you've tried it?

Maybe I should try a cool air attachment. I'm not having that much trouble with the welding when my material is properly secured. And I did notice a small increase in the bits' longevity when I added the dust skirt.

[aaasigncom]

ANYTHING YOU USE CAN GET ON YOUR SPOILBOARD / SOAK IN. NO, I HAVEN'T TRIED ANY COMMERCIAL PRODUCT. I USUALLY 20% WATER WITH A COUPLE OF DROPS OF DISH SOAP. LOOK AT MY DUST SHOE, IT HAS BOTH AIR AND MIST. ALSO NOTICE THE SIZE OF MY CHIPS / LARGE. THE ALCOHOL EVAPORATES BEFORE IT GETS INTO MY SPOILBOARD. ALUMINUM DOES NOT SPARK WHILE CUTTING. I LEARNED ALL I KNOW FROM THIS BOARD. SEARCH CUTTING ALUMINUM - TONS OF HELPFUL INFO.

[terryd]

Last time I milled aluminum I just painted the sheet with margerine about 1/8" thick and machined away. cut was good, bit survived and the spoil board smells like popcorn. At 99 cents a pound I couldn't go wrong.

[byoc]

I tried spraying a little WD40 on the bit once. It gunked up almost immediately.