Solid carbide router bits can route holes in 1/16" aluminum?

[jonathanb3478]

I was wanting to make 4.75" diameter holes in a sheet of 1/16" aluminum. I was thinking I could use my 1/4" solid carbide up-cut (single flute) bit with my router and circle jig.

I think I remember seeing that carbide bits can be used in (at least) non-ferrous metals like aluminum. The mfg of the bit recommends 18,000 RPM for MDF, but I imagine I should reduce that a good bit for use in aluminum, right? I was thinking 10K-12K RPM

Anyone have any experience to offer?

[Kaneohe boy]

Routing aluminum

I would not it, if you've ever drilled into metal I'm sure you've seen the sharp little pieces that come off. Now imagine them flying off at high velocity as wood does from my router, not to mention the probable damage to your bit.

[jimluu]

I remember reading on the web that you can use carbide router bits on such thin aluminum. I tried to find the article but couldn't. If I remember correctly, the guy recommended a lower rpm, went real slow, and had a friend spray silicone lubricant at the point of contact as he goes along. I think that heat is the biggest issue.

[cjd]

Not sure about cutter speed, but be aware you'll have a lot of metal shavings flying about - not good for you (particularly eyes and lungs) and not good for your router should any get into the workings. Heat is the biggest issue - lubricant isn't really needed but heat control is. Taking it slow slow slow is necessary for heat reasons a well. Bit starts to gum up, stop, let it all cool down.

I wouldn't do it personally.

C

[ThomasW]

A few issues, 1/16" is so thin clamping the piece isn't going to be effective. Other than that it's not a whole lot different that going through high pressure plastic laminate.

I think you should bond it to a backing surface or if possible to the the actual surface where it's going to end up. Double sided tape may work but you risk bending the material as it's being machined or during separation from the backing.

If possible run a test piece to get the speed setting dialed in, then you shouldn't have too much trouble

Do this outdoors since the cuttings are hot and a standard dust collection system won't be too effective picking them up.

[Brian C.]

Carbide can certainly be used on aluminum, as well as most steels. However, aside from the heat issues mentioned earlier (which are actually exacerbated by lower feedrates), running a 1/4" carbide cutter on aluminum calls for spindle speeds in the neighborhood of 10,000-12,000rpm. I would not recommend anything other than a true end mill for cutting aluminum, and controlling the router will be one of the big issues. Aluminum is soft, and it will want to "grab" at the mill. Climb cutting is the only recommended method, to reduce galling of the cutter, which is going to be a major issue without any means of flooding the cutter with cutting fluid.

I'll back up what CJD said about aluminum chips and dusting being a big problem. Either gets in your router, say "bye-bye router". Aluminum dust is not something you want to inhale, as it's suspected to contribute to a host of health problems. As far as flying chips being dangerous, they're really no more of a threat than wood chips. The chips are so small and have so little mass, they don't turn into "projectiles of death". Now, a broken carbide cutter, on the other hand, can be a bit more of a problem...

BTW... I'm a machinist by trade. And I'm planning on incorporating a few aluminum pieces into my speaker cabinets, primarily for a rear access panel to the crossovers. 8)

Or, if CJD sees the need for a little closer nesting of drivers in that huge center channel we've been talking about, driver flanges can be milled... (hint, hint) :W

[cjd]

:lol:

I do my hole cutting with a jewelers saw when I can, or I look for alternatives. Hack it out and file to size is often a viable method. Very little machining experience.

Aluminum shavings in the eye are worse than wood chips in the eye, by the way. Well, any metal can be really nasty, but if they curl at all like Aluminum likes to do, it's really ugly if you need an extraction.

C

[jimluu]

:lol:

I do my hole cutting with a jewelers saw when I can, or I look for alternatives. Hack it out and file to size is often a viable method. Very little machining experience.

Aluminum shavings in the eye are worse than wood chips in the eye, by the way. Well, any metal can be really nasty, but if they curl at all like Aluminum likes to do, it's really ugly if you need an extraction.

C

any chip in the eye is bad. but hot aluminum is sterileand innert, wood is much more dangerous inside the eye.

[Brian C.]

Anybody doing ANYTHING with powertools and not using proper eye protection is NUTS. Wrap-around eye protection is MANDATORY.

Problem solved! :


My dad's been a machinist for nearly 40 years now, and the ONLY time he ever had to go have a chip extracted from his eye (about 30 years ago) was because he WASN'T wearing eye protection!

Oh, and keep your mouth closed when you're cutting/machining...

:

[cjd]

any chip in the eye is bad. but hot aluminum is sterileand innert, wood is much more dangerous inside the eye.

Sorry, wood doesn't tend to embed itself like metal does. Or cut quite as bad if it's just fine grit.

Neither is good, to be sure.

C

[Chris7]

If you've got a Dremel, you may want to consider using the Dremel circle jig to cut the hole, rather than your router. It's probably a more appropriate tool for this job.

[kingpin]

Or, if CJD sees the need for a little closer nesting of drivers in that huge center channel we've been talking about, driver flanges can be milled... (hint, hint) :W

'Scuse me. What's this I hear about a huge centre channel."
opcorn: opcorn: opcorn: opcorn: opcorn:

Maybe I should finish my mains first.

Mike

[Martyn]

You could give this a try: Use your circle cutter to cut your 4.75" diameter hole in a piece of 3/4" MDF and then sandwich your aluminum sheet between this and a plain piece of MDF. Clamp them very tightly. Then use a template bit (with a top bearing) to plunge very gradually through the Al. You'll have to juggle the thickness of your MDF and the length of the cutter such that you start with the bearing on the MDF and the cutter clear of the Al. Remove only 10 thou or so with each pass. You'll need to stick the centre of the Al to the bottom piece of MDF to keep it in place when you break through. It might only work if the template cutter has carbide tips on the end to allow it to plunge.

Waiver: I've never tried this, but it might be worth a try. Go carefully and at your own risk!

[orbifold]

I've had to cut beaucoup Al with circular saws, and chop saws, some was 1/16", some 1/8" some complex extrusion, IIRC. I always had carbide tipped, 7" or 8" 24 tooth, or 10" about 40 tooth blades, the same ones used for decent wood cuts. You gotta think, the 10" saw is 3000-5000 rpm At 40 times the diameter and 1/4 cutting speed(I forgot the exact rpm.) They use 3HP plunge-cut routers in mobile home construction to cut access holes, probably whole window openings, in completed wall sectioms with some Al, some other material in the cut. The only thing is, the solid carbide up-cut spiral I have looks like a fairly acute edged rascal. aluminum may cause more wear than you'd like.
Don't think you'll need lubricant, and I'd try the speed you spoke of first. The main thing I would be watching is feed speed into the material. Honestly, go by feel, and for sure stay away from any "climb cutting" scenario with a hand held router, which I'm sure you're aware of since you're not a stranger to routing. The use of climb cutting Brian mentioned on a mill is different, I think. The work would very securely held, and very securly moved via screw feed. I only used a mill once, and managed to bork a nice end mill, as a matter of fact ops: Oh, yeah, that clamping; secure the stuff to a pool table or approved equal, if you can, before cutting. I still feel that a more obtuse-edged cutter would be better, one with less "hook" to stay away from the trouble with grabbing Brian mentioned. You could cut a hole in MDF to use as a pattern with the spiral and Casper Jig, and use that with maybe a panel pilot bit. It has very little hook, but you are going to want ear protection. The aluminum may produce more sound than the speaker it goes into!
Ditto wrap-around eye protection--an absolute.
You may also not want to chew gum or smoke stogies :B

[orbifold]

found a bit...

well, I'm looking for translam ideas, and just saw this bit. Made for our favorite periodic table citizen! Maybe a possible for you. Notice the up shear on the cutter. And, the prices are not bad! I'm getting a couple. If the idea proves non-stupid, you'll see it here :T

http://www.pricecutter.com/product.asp?pn=P11-1607&cn=243788&bhcd2=1168152124

[Jed]

Why not just use a jig saw? There are blades to cut metal for this tool. With a steady hand you should be fine.

[jonathanb3478]

Why not just use a jig saw? There are blades to cut metal for this tool. With a steady hand you should be fine.

I would have to buy one, first. The router, bit, and Jasper jig I have already.

I have my dust collection adapter on my router (but won't hook up the shop vac, this time around, due to hot bits perhaps not getting along well with the MDF dust in the bag already), and with an up-cut bit some material should be pulled up into the DC adapter above the workpiece. I have (and obviously will use) a pair of "over glasses" style wrap around goggles (wich is the style I need, as you can plainly see in the Paint Self-Portrait over to the left, there). Any flying shrapnel should not end up in my eyes.

Thanks for the advice, guys. I should be doing this later today. I am going to go for it at 10K RPM, as I first thought. As it turns out, however, my router does go down to 8K RPM, so does anyone think it would be better to drop down to 8K with my single flute up-cut bit?

Regardless, I do appreciate the heads up on potential issues from all you guys. This is what I have, and I don't want to drop any more for tools at the moment, so this is how I will get it done.

I will let you know how it goes. :T

...but, if you never hear from me again 8O

:B

[jonathanb3478]

well, I'm looking for translam ideas, and just saw this bit.

Well, I started with the idea of doing a translam enclosure for my speaker project, but after close cutting 28 on my scroll saw (from the early '90s), chewing through 3 blades to do so, and routing all of them to my master template's outside profile... I changed my mind.

This is because, by that point, I had a real good idea of what would be involved in finishing the ~100 more I needed, then close cutting them all on the inside so I could template-route the various final inside profiles I needed for different parts of the internal enclosure structure (sub-enclosure, bracing, etc).

I might do a translam, elliptical version in the future, but that will be in a future where I posses a DIY CNC Router to do (most of) the work for me. That might be a while. Thomas called it in the thread the first link was pulled from :T

[jonathanb3478]

'Scuse me. What's this I hear about a huge centre channel.

Down, boy!

[ThomasW]

so does anyone think it would be better to drop down to 8K with my single flute up-cut bit?

If you're talking about a solid carbide spiral cut up twist (standard bit recommended for the Jasper) that's what should be used.

[jonathanb3478]

If you're talking about a solid carbide spiral cut up twist (standard bit recommended for the Jasper) that's what should be used.

Thanks Thomas. I thought a single flute could want a higher RPM.

Anyone want to second 8K RPM?

[ThomasW]

You'll just have to experiment with the speeds until you find the right one.

BTW I was serious when I said this piece of metal needs to be firmly attached to a subpanel of somesort. Clamps aren't a good idea. It could also be sandwiched between two pieces of wood. Use scrap 3/4" on the bottom, the alu then a piece of 1/4" something on the top. That will keep everything secure.

[Brian C.]

Thanks Thomas. I thought a single flute could want a higher RPM.

Anyone want to second 8K RPM?

Diameter of the cutter dictates spindle speed.

# of flutes dictates feed rate.

It doesn't matter if it has one flute or six... if you increase the speed at which the cutting edge moves through the material, you will see a host of problems. More heat, faster dulling of the cutting edge, galling (cutting metals), and poor surface finishes and/or blowouts.

I use either two or three-flute end mills (in .062 to 1/4") for cutting aluminum and steels. More flutes can be run at higher feedrates and produce finer surface finishes, are less "grabby" in softer materials, but also are prone to "loading up" and galling at too high feed rates.

Of course, this is all done on CNC's where I have total control over speeds and feeds, and very rigid workholding. Trying to do this with a router, hanging on to it by hand, is an iffy proposition. Once it grabs, you're in for a ride!

[jonathanb3478]

BTW I was serious when I said this piece of metal needs to be firmly attached to a subpanel of somesort.

Hmm... Well, this is the face of a panel of an aluminum structure that weighs close to 10lbs. I was going to oreint the whole thing so the surface I want the circles in was facing up, then clamp the whole thing to the 100+ pound table in my work area with a few c-clamps braced against part of the structure.

That seems fine to me, but I haven't done this before.

[jonathanb3478]

Diameter of the cutter dictates spindle speed.

# of flutes dictates feed rate.

Ahh... Thanks! Makes sense, at least now that you point it out. :T

[JRT]

I was wanting to make 4.75" diameter holes in a sheet of 1/16" aluminum.

Consider using a 4.75" hole saw like these, for use in drill:
Milwaukee 49-56-4750 6tpi bimetal blade ($25.28 on Amazon)
Milwaukee 49-56-0236 4/6tpi bimetal blade ($30.68 on Amazon)
Milwaukee 49-56-7010 arbor w/ .375" shank ($5.43 on Amazon)

Use a center punch to locate the holes.

Clamp the thin aluminum sheet to some backer board sheet stock such as MDF for support.

Use some cutting wax or cutting oil.

[jonathanb3478]

So, I gave it a shot.

Now, I think Thomas is right, the panel should probably be sandwiched between wood layers. At least, I hope that would overcome th e issue I had. With just the router on the aluminum panel, the up-cutting action raised the edge of the cut into ~1/8" tall (and rather sharp) ridges around the outside of the cut. They then interfere with the travel of the plastic Jasper jig.

I only made a 1" long cut on the first circle before I realized what was happening, but I didn't bring all my tools with me, so I didn't have the ability to try sandwiching the cut.

I'll have to try again, later.

[technimac]

It could also be sandwiched between two pieces of wood. Use scrap 3/4" on the bottom, the alu then a piece of 1/4" something on the top. That will keep everything secure.

:agree:

I absolutely agree with Thomas' approach. The sandwich gives the aluminum nowhere to go...and that's just how you want it! It'll also force the bit to remove all the machined aluminum, square to the cut, rather than having some of it roll over the edge.

These guys make burs specifically designed for cutting aluminum. Haven't used them though. http://www.helongco.com/nfburs/nfall.html

Cheers, Bruce

[jonathanb3478]

:agree:

I absolutely agree with Thomas' approach. The sandwich gives the aluminum nowhere to go...and that's just how you want it! It'll also force the bit to remove all the machined aluminum, square to the cut, rather than having some of it roll over the edge.

Well, then hopefully my second try works out, once I get around to it.

[roccovw]

If your cutting aluminum in a sandwich you should use a straight double flute carbide tipped router bit. A spiral or up and down spiral is used only to prevent chipping on the surfaces especially for laminates or paper finishes, also the double flute doesn't dig as deep and keeps vibrations down giving a cleaner cut.