Cutting/Drilling Aluminum

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Hello!  I am new and have a question.  I am starting a small equipment business and have some parts made and make some myself.One part is made of 3"x3" aluminum angle 3/16" thick and has a lot of 0.39" holes (about 35) spaced along its length.  It also has a square notch cut out of each end on one of the angle sides.  I have had this piece cut on a water jet, but it gets expensive, especially for short runs (about 50 to 100 pieces).  I was thinking of haveing a template cut on water jet or laser with holes for the collar of a plunging router to fit in.  Then building a jig to hold the aluminum angle and the template.  Then use the plunging router with a 3/8" drill bit to drill the holes, and maybe a bit to cut the notch in the ends.  I figure this would give me good repeatability (does not need to be super precise) and bring it back in house and be a low $ investment.  Will this work, or am I nuts?If it will work what are the best bits for cutting aluminum?Thanks,Garrett
Reply:Since your going to be drilling the holes why not get a drill press and make a jig for it.  Basically a flat piece of metal that has a spring loaded plunger in it that is the diameter of your holes.  Drill the first hole and slide the part down until the button plunger pops into it.  Drill the next hole... repeat as neccessary.  you slide the kig closer or further from the spindle center line to adjust spacing on the AL angle.Less fancy would be a piece of flat bar with a hole in it.  Drill first hole, slide angle down and drop a bolt,pin,etc into the hole.Less complicated jig, A Drill press that is better than a router at drilling holes as well as more uses around the shop.Steven
Reply:Thanks for the info on the drill press.  I do have a drill press, but there are two concerns I have one the piece of angle is 94" long, and second the holes are not evenly spaced along the piece.I guess I can put a setup with rollers out along the press to feed the piece across the press to take care of the length, but how do I set up the jig to space the holes varying distances relatively quickly?Thanks!
Reply:Give me an idea of the spacing and I might be able to come up with something.For now..  mabye a little hard to explain but I will try.   Have the template (A  piece of angle this time) attached to the press.  Lets say there are three different spacings.  You would have a piece of rod bent into a angle.  one end would attach to the template angle via a simple hinge.   The other end would swing down to align in the desired hole you want to index the next hole from.   Make one of these for each distance you want to index.  Flip down the one you are using the others are flipped up.Hopefully that is clear as mud..Steven
Reply:You might want to take a photo of a finished one and post.  Is there any regularity about the hole spacing...does the spacing repeat in any observable way? For example, are there 5 holes evenly spaced and then 6 holes evenly spaced but offset from the 5 by an inch and so on.  Stuff like that can make automation simpler.  If this kind of regularity exists, you can make a couple or few jigs and do sets of holes at each stage.  It adds steps, but reduces complexity.  That way you could take a stack of angle and do just one set of holes, then start over and do another set of holes and on an on until you are done.  Just something two think about over the second cup of coffee.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Another way to locate the holes for drilling on your drill press would be to make an aluminum template that clamps onto your work piece, with the holes drilled in it.Then use a transfer punch to mark the center of each hole.this is a simple punch- the outside diameter is the same as your hole, and the punch makes a mark at the center, for spotting your drill. You can buy a whole set of them in 1/64" increments.routing does work on aluminum-- you need to clamp your work VERY securely to a sturdy table, you need a big, high powered router, and you need to use 1/2" shank bits. Kickback occurs easily, and a router is a nasty tool to get cut by. Got a few stiches in my left index finger to prove it.But a drill is better than any router for making round holes.
Reply:Another approach is to make a jig the same size as the angle with drill bushings at all the hole locations.  A 0.390 hole would drill pretty fast, specially with a pneumatic drill.  Carr Lane or even McMaster would have a selection of drill bushings.  I used this approach on the aluminum frame rails of a Panoz AIV Roadster a few years back.  There were about 40 holes per frame rail - all 25/64ths (your same .390 dia).  The frame rails had a bend in the middle and were about 10 feet long, so setting them up in a drill press was too ackward.  I set up the drill fixture to be about 3' off the ground so you could get great leverage on the drill, and 1 guy could knock out the 40 holes in about 10 minutes or less.The one drawback to drill bushings is they do tend to wear on the drill bits more...  I almost forgot that after doing about 75 sets of frame rails I updated the jig.  This time I used cheap motor bearings from McMaster carr instead of drill bushings.  10mm id bearings are .393 dia and made a nice fit.  I used 2 per hole spaced about 2 inches apart to keep the bit stable.  The bearings spun with the bit and both the bearings and the bits held up longer.JasonLast edited by TubularFab; 02-24-2006 at 12:51 PM.
Reply:Here is a picture of what the end result is.  I like the idea of the template with drill bushings!  So you welded the motor bearings to the template?What is the most efficient way of cutting the end notches out too?Thanks, Attached Images
Reply:I actually made up some tubes that the bearings pressed into.  The end that welded to the fixture has the bearing pressed in about 1/2" below flush and has windows so the chips can exit.  You probably don't need the second bearing since you're only going through one thickness of plate.  I was drilling through a box section where the second wall was 2.75" from the first, and I couldn't tolerate the bit wandering off at an angle.Here is a picture of the bearing holder tube, and below the tube welded into place: Attached Images
Reply:lots of good ideas here. I would build an alum drill jig with drill bushings,set up an easy roller system to rest the work on,keep your tool sharp and cool,set down and start pullin' the handle. A UNI-PUNCH system on a small press would be cool too.
Reply:For notching and cutting consider a table saw or a chop saw with an aluminum cutting carbide blade.  With a table saw I have ripped legs off Tees and notched ends for window framing.  Any setup that you can do with wood you can do with aluminum.  I find that notching with router bits is a problem since the cutter tends to grab if both sides are cutting at the same time in a slot.  a saw blade notches faster and cleaner.
Reply:Thanks for all the help every one!  Just a couple of things.  Panozeng how long of a drill bit did you use to get through the jig and box frame it must have been pretty long?  Also Rodney, what exactly is a uni-punch system? I have heard the term before, but never really new if it was a general term, or a name brand.
Reply:I love that I have found this forum. You guys are great. So many ideas and different approaches to the same end. I can't tell you how many times I have sat and spent more time making a jig or fixture that took me days to make, only to actually spend minutes on the real project I was supposed to be working on!