Replies

1. 
   pzaxtl | Aug 29, 2008 03:00am | #1

   Any straight bit will work if you drill starter holes in each end.

2. 
   JMartinsky | Aug 29, 2008 05:45am | #2

   Dear low,
   I'm all for the unconventional, but I would like to offer a few words of caution:

   1) Aluminum shards flying at high speed at, shall we say... groin level... yikes.

   2) Aluminum dust, in addition to being flammable/explosive can't be too good for the lungs.

   3) Aluminum dust or shard in the eyes will probably ruin your day.

   Best,

   John

3. 
   ring | Aug 29, 2008 06:15am | #3

   You can rout it fairly easily with a straight carbide bit. The aluminum chips that fly out can be quite hot. Wear long sleeves and safety glasses.

   David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   jimmar | Aug 30, 2008 03:34am | #12

   I'd wear a face shield, myself.

4. 
   thumbnailed | Aug 29, 2008 06:19am | #4

   I've slotted aluminum and done other milling operations to it, and one thing to be very aware of is aluminum wants to grab onto bits and cutters. Be sure everything is clamped more firmly than you would in a comperable wood operation, take lighter cuts, and use the heaviest router and other tools you have to provide mass to best resist the grab. And as the guy before me mentioned, aluminum chips hurt, and are often hot . This doesn't mean you shouldn't try it, just take extra care, protect your eyes, and cover exposed skin.

5. 
   Rich14 | Aug 29, 2008 01:32pm | #5

   I used a 1/2" double flute carbide straight cutter, 1/2" shank, to clean the edge of about 20 lineal feet of 1/2" thick aluminum alloy after cutting the line with hacksaw blades in a hand jigsaw.

   It worked well and left a beautifully smooth edge.

   Take VERY light bites. Aluminum is a soft metal but it is much, much harder than any wood. As mentioned above, it can suddenly grab the bit. That happened to me and the bit completely shattered. VERY scary, but the pieces did not hit me, so the anxiety subsided soon enough.

   I was truing the edge of a slab 2' x 3' which was heavy enough (150 lb) that I didn't need to clamp it down. But I worked against a fence clamped to the slab. Don't try to work free-hand, you'll lose control of the bit.

   There is no airborne dust. Aluminum is too heavy. But there is a LOT of debris! I don't recall the dust and shards being hot at all.

   Rich

6. 
   RickL | Aug 29, 2008 02:51pm | #6

   As a Metalsmith I  machine a lot of non-ferrous, including aluminum, copper, brass, zinc, etc with standard woodworking machines. A negative hook saw blade does a nice jib of grooving and cutting the metal. It can be grabby with a router bit. Small passes work best and it's easier to open the cut up with the negative hook blade. These blades are designed to cut non-ferrous and are the recommended blade for radial arm saws in general so you may have one already.

   A face shield is better as the chips are fairly warm and not really hot in the sense of catching fire like cutting steel with an abrasive blade.  The warm chips on your face could make you flinch so a face shield is better. I typically cover the intake of the router with a piece of cloth as the chips can conduct electricity. Straight carbide bits will work as well as spiral bits.

   Overhead routers were a common way to rout aluminum in the aircraft industry so it's an accepted practice but does take some care and practice to get used to the technique.

7. 
   ETG | Aug 29, 2008 03:55pm | #7

   In the late 70's, routers were used to mill "dogbone tensile test" specimens in low carbon sheet steels.  A large Stanley router - don't remember the HP - with carbide tipped straight bits did a decent job.  Long sleeve shirt, face shield, gloves all necessary to operate it.  But it never won over the testing folks.

   There are a lot of thing you can route, including stone countertops and most metals.  Speeds and feeds are critical as well as cutting edge angle.  Be careful!

1. 
   lowangle | Aug 29, 2008 07:20pm | #8

   Thanks to all for your advice. I'll proceed with caution.

1. 
   dkellernc | Aug 30, 2008 05:48pm | #13

   We did this at a company's machine shop where I worked early in my career, usually to round over the edge of an aluminum production machine table.  The "standard" way to machine aluminum in the metal working industry is with a milling machine and a carbide end or side mill.  These bits are very similar to woodworking carbide router bits.

   One observation not mentioned in the thread is that if you have a variable-speed router, run it at the lowest speed available.  That will help in keeping the heat down.  The second most important observation is the one already mentioned - take bites out of the aluminum measured in thousandths of an inch (say 10-25 thousandths per pass), not the normal 1/16ths of an inch used in woodworking.

8. 
   notatexan | Aug 29, 2008 07:25pm | #9

   Use as short a bit as possible to reduce chatter.  Have as rigid a set-up as possible.  Cuts like butter.

   Before the wide use of 5 axis CNC machines complex aircraft structural parts were cut out of aluminum plate using routers and templates. I think some of those routers were 8 HP.  Those guys were built like Popeye.

   Jim

1. 
   RickL | Aug 29, 2008 07:34pm | #10

   Actually they were 10 hp Onsrud routers

1. 
   notatexan | Aug 29, 2008 08:04pm | #11

   You'r right, I'm sure.  That was back in 1975 when I watched them do it while I was also watching the same part being machined on a 5 axis NC machine. 

   They did the complex swarf cuts using two templates on each side of the part, a router cutter with a bearing on each end, a handle on one end, a big air motor on the other, and they made the cuts like using a drawknife.  They could cut up to 6 in thick aluminum plate.  Imagine your 6 in jointer cutting head attached to a 5 HP air motor and you pulling with both hands while following two templates.  The chips were like 6 inch needles and the Popeyes were in full leathers.

   Anyway, cutting AL with a WW router, piece of cake.   

   Jim