Advisability of routing aluminum?

[Bruce Darrow]

I have just ordered a Shark Guard. Lee was great to work with as regards to the necessary modification of my after market throat plate, and is even going to modify the dimensions of his splitter trio to make it all happen. Large kudos here.

In order to accommodate the Shark Guard, I need to cut a 1/4" (approximate) x 2 3/8" slot through the rear of my Wood Dynamics throat plate. The material in the cut location is 1/4" aluminum. Any relevant inserts will then need to be similarly modified, but I expect that to be easy, as they are either wood or wood product.

My first thought was the band saw, but was dissuaded (for now, at least) after talking with a fellow at BC saw about it. I figured a metal cutting blade would be handy to have around for various potential uses in the future, but according to the fellow I spoke with, once a blade is used to cut aluminum, it is useless for steel, and vice-versa. We didn't discuss brass or other metals. On top of that, the price for the recommended blade was in the $50 range, before shipping. Too much for this guy for a one shot deal.

Before I go looking for a machine shop to make the cut for me, I thought I'd sound out the Creek as to the feasibility of making the cut on the router table with a carbide bit raised in small increments.

What is the common wisdom here? Am I out of my mind? It wouldn't be the first time for me to plead to temporary insanity.......

[John Aperahama]

Would suggest a solid carbide bit. Have done this but it needs to be very small increments. Only reservation is swarf getting into router windings I have not lost a router this way but it is a concern. Very slow...... heat is the killer here.

[Bruce Page]

First, a standard generic wood cutting bandsaw blade will cut through ¼” aluminum like it was butter. I have cut up to 1½” thick aluminum plate on my old 14” Delta using a $10 blade from Home Depot. It is messy though. If you have a least favorite blade I’d use it.
Second, a router will also cut and carbide would be my first choice although high speed will also cut it. Use a fence or jig for your cut – don’t free hand it.
Personally, I’d go with the bandsaw option.

[Harvey Pascoe]

Routing aluminum is dangerous but it can be done. You need to understand something about the nature of machining metal, such as the workpiece must be VERY securely held w/o the possibility of unexpected movement. I would not attempt to do this on a small workpiece, a larger plate okay. I've cut slots in small aluminum stock on the table saw just fine after making a jig to hold the metal securely. Even then, I had a nasty accident once because it slipped - jig too small. I agree with Bruce, band saw no problem but I don't think that will produce the best results.

If you're talking about a standard table saw throat plate and you are making cut perpendicular to the length, what I would do is simply cross cut the slot on table saw with the miter gauge. No problem at all and you can do it with just about any kind of blade, even steel. For a very smooth cut I use a steel plywood blade .Do it in at least 2 depth of cut increments. Take the first cut and see how it goes and adjust accordingly. Just make sure you can hold the plate very securely.

[John Lanciani]

If it were me, I'd drill a 1/4" hole where the slot ends and make the cut with a (good) hacksaw with a new 18 tpi blade. Use machine oil for lube. I'd be done long before you're finished cleaning up the mess from routing. If you've just got the urge for power you could also use a jigsaw. Either way will reduce the mess and the pucker factor to almost zero.

[mike holden]

The very first time I used a router was to trim aluminum plate 3/4 inch thick. This was at work, was given a router with a carbide faced bit, 1/4 inch shank (!), a tyvek jumpsuit and pointed towards the job. Did all right, firm hold on the router and away you go. This was back in the 70's and it was hardened aluminum: 6061 T6.

You should not have any problems cutting aluminum with carbide bits.

Mike

[Myk Rian]

Keep an eye on the bit. Aluminum tends to clog them.

[Chris Fournier]

Certainly can and has been done but it is no fun. I'd go with John's suggestion and clean it up with a file. If you're careful it will look very tidy.

[John McClanahan]

Squirt some WD-40 where you are going to cut. It will help keep the bit from clogging. Make very very light passes.

John

[pat warner]

An inside cut, no priors? Then don't rout it.
Outside cut, (http://patwarner.com/images/tswebb4759.jpg) fine fixturing? Not a problem but priors still required.
Inside routing (plastic, aluminum & wood (http://patwarner.com/images/mort_jig3.jpg)), something I do, requires a lot of technique sensitive maneuvers, perfect fixturing, perfect bottom cutting bits, all solid carbide, especially for such a skinny cut (such as yours).

[Bruce Darrow]

Thanks all for the replies.

I'm persuaded that although it is possible, routing is not the way to go. I will probably hacksaw it, when the time comes (I'll wait until the Shark is in hand, so I can determine just how narrow a slot I can get away with), and will consider pulling out the blade my bandsaw came with and going at it with that.

Swarf and clean up figure large in my decision.

[David Kumm]

Good decision, Bruce. Even on my vertical mill with the cutter running at 2000rpm it is easy to kind of melt the aluminum onto the bit. It is a real pain to get it back off. You would have to slow the router way down. I would use a jig saw with a good blade. Dave

[Lee Schierer]

Yes you might be able to make this modification with woodworking tools and I would probably do it if I had no other options. However I do know some competent machinists.

My advice is to find a small local machine shop and ask them to do the work for you. Many aren't terribly busy and will be more than willing to help you out. Price out the cost of a replacement before you make the cut yourself. Then decide if a pro is better suited and likely to cost less to do the modification. Even at $60 per hour shop rate this is a 10 minute job on a mill so it might cost you $10 or a lunch for the boss/owner.

[Peter Quinn]

I'm thinking a jig saw with a decent metal cutting blade would be my prefered option. Easy to cut, easy to clean up, relatively quick, cheap blade cost, and relatively safe. If you have access to a Bridgeport or a good drill press that would be my first option , with an end mill. But otherwise the jig saw is my weapon.

[Bill Huber]

I am with Peter, a jig saw with a good blade will do a great job. Drill the hole at the end of the slot and then with the jig saw cut up both sides to make the slot, clean it up with a file and you are done in about 10,im.

[Jay Jeffery]

Squirt some WD-40 where you are going to cut. It will help keep the bit from clogging. Make very very light passes.

John

This is good advice. The main issue with cutting aluminum is that it clogs cutting tools. WD-40 works as well as any specialty cutting fluid I've used, it's cheap, ad it's versatile.

[Floyd Mah]

It's actually a very easy task. I just accidentally cut my sliding table fence with the table saw and didn't realize until it was too late that I was cutting aluminum. So, you could consider using the table saw and going slowly if you have a carbide tipped blade to sacrifice (probably won't hurt the blade).

Otherwise, there are several other approaches, many already mentioned: Hacksaw, jigsaw. You could waste most of the aluminum with drills and then file the resulting notch with a file. Just clamp some wood on either side or just a wood clamp and use that to guide the file. If you have any apprehension about using power tools, just use hand tools and the drill press. Aluminum files easily and you'll be pleased with the results. Some advocate putting chalk on the file to keep it from clogging with the aluminum.

Another consideration is to rough in the cut with the handtools and then do the finish cut with the table saw. If you are trimming very little with the table saw, you can run it past the blade without any risk of damage. A sanding disk mounted in the table saw can also be used in the same way for the final trim.

[Brian Tymchak]

I've seen advertisements for scroll saw blades for cutting metal, so if you have a scroll saw that might be an option.