cutting parallel slots into a hammond box using 5mm wood router bit

[numpty]

Has anybody tried this yet? (With care - using a drill stand, jig some kind of cooling fluid and goggles etc) if so, do you do it in one pass slowly or several?

[ampman50]

Looking at the safety aspect, if you are thinking of using a wood router I would say forget it. The spindle speed of a router is way to high for metal work, there would be a big chance for the bit to shatter.  If you know of someone with a vertical end mill (Bridgeport machine), which are made for metal working, it would be worth the money to pay them to have it done.

[R.G.]

Good advice. It is barely possible to do this, just like it is possible to cut 1/8" aluminum sheet in a woodcutting radial arm saw. But boy, is it ever ugly and dangerous. If you try this - and my advice is not to try it - you will need to rig up some fixtures which let you move the router exactly along the desired tool path repeatedly, and make cuts only perhaps 1/2 to 1mm deep per pass. You will also wear a face shield and shielding over any part of your body which you don't want pieces of sharp metal piercing (a) when the shavings are thrown out by the 20,000 rpm blace or (b) when the bit shatters and throws chunks of its hard, sharp self out at high speed.

Wood routers get their smooth cut by going really fast. That is a fundamental mistake on metals, where the tool cutting speed is something that experts argue about as a critical factor.

It is reasonably possible to do this in a drill press which turns at a lower speed than a 20,000 revolutions per minute router. However, the woodcutting bit is still too hard, too brittle, and the edges are not shaped properly to cut metal. They're not backed up enough and will shatter easily.

However, it is possible to buy 5mm metal cutting mill tools for not much money.  If you chuck a milling cutter into a drill press - a real one, not a drill held in one of those adapter rigs - you can make the cuts in several passes. You'll still want goggles for protection for your eyes, and the metal shavings will get everywhere, but the danger of shattering the bit is smaller if still not zero. The small passes are intended to keep the bit from digging in because the light-duty frame flexed and let the bit bite too much. The only difference between a drill press and a milling machine is that the drill press has looser, wobblier bearings holding the spinning shaft, and the drill press is as flexible as a noodle compared to the hundreds of pounds of cast iron and steel in the mill.

Oh - do NOT try to hand guide this. Create some kind of guiding setup so it can only move where you want it to, and add some kind of guiding handles so it absolutely cannot pull your hands into it or whip around and cut you when (not if!) the bit grabs in the work.

Remember - education is what you have left when the wounds heal and you have forgotten exactly how that scar got there. 

[alanlan]

If you've got the time and patience you could do a good job by hand.  But, you need time and patience

As an apprentice, we had to cut and file a pair of pliers out of two blocks of mild steel (which was subsequently case hardened).  It took a good week of hard toil but taught me a lesson that a pair of hands is a very good tool if you don't have access to machinery.

[numpty]

Hi
  Thinking about it further I tried an experiment just after posting the question, using a router bit in a drill press at its highest speed with a piece of 1/8" aluminium in a crude jig it only took a minute to set up, It didn't make much of an impression but i made a small groove, I'm sure you are right- that a proper (cnc) milling tool would work 

[numpty]

BTW i for to add this in the previous post http://www.tool-shop.co.uk/acatalog/Mulling_Bits.html#a683

[R.G.]

One thing I have done before when I had to, along the lines of Alan's note, is to mark very carefully the outline of the slot you want. Then you drill a hole at each end of the slot, again being very careful to use a drill just slightly smaller than the slot, and being careful to not let the drill wander outside the outline. Then carefully drill another pair of holes close to but not touching the first pair, and again inside the slot outline.

Drill holes until you get a run of holes which can have the spaces between them cut out by a diagonal cutter. Once you cut out the spaces, insert a hacksaw blade or perhaps a metal cutting jigsaw blade, and cut most of the metal out of the marked slot. Finish up by carefully filing exactly to the marking on the slot.

This process is slow, but it is much, much safer to do, and more certain of success. As well as probably cheaper.

If you're really interested in doing this kind of thing, look for "Zona saws" or "piercing saws" as they're called in the UK. They may also be known as "jeweler's saws".

[alanlan]

There is a blueish wash you can get, but I can't remember what it is called, which you paint on the surface and then using a scriber (preferably a tungsten carbide tipped variant) you mark the surface.  Gives better results than trying to mark with a pencil on top of masking tape or similar.  If you scribe the surface deep enough using successive strokes of the scriber, it helps to define a clean cut out.

Still, a machine will do it better and more precisely.

[frank_p]

Just don't do that, especially with carbide tools. I worked in that field: doing R&D on carbide tools for shapers.  A carbide blade leaving an industrial wood shaper can be as destructive as a arrow leaving a crossbow: That is enough cinetcial energy and cutting effectiveness to kill a dear.  Even with good protection you might get bad surprise.  Blades leaving the rotating tool could often pass trough a 1/2 to 3/4in plywood sheet in destructive failure tests. The sound of the carbide tool breaking or the brazings leaving off  in a traction machine is the same as a gun.    Even if I knew the blade would break I could not help but be scared each time and jump a bit being surprised. 

[Joe]

As a side note, a band saw works pretty good for cutting aluminum if the blade is lubricated pretty well. Much safer than trying to use table saws etc.

[sean k]

I've kinda thought about that myself in the past but always realised that the easy way is often the long way.. all the time taken to just jig everything up takes far long that cutting little holes with the drill then getting the tiny files out. If you've got a completely wrecked chisel, for wood, you could regrind the end to something alot steeper and given the material you wanna cut through you could chisel it out in about 15 mins after reshaping the chisel. Just don't overheat the chisel and keep water handyto cool it as you grind.

[R.G.]

As a side note, a band saw works pretty good for cutting aluminum if the blade is lubricated pretty well. Much safer than trying to use table saws etc.

Yep. I'd have suggested that except it's really a PITA to get the band through a slot in solid material and back out again.

Fine-toothed metal cutting blades do work in a woodcutting bandsaw, but it's best to rig some way to lower the blade's speed. This isn't so critical for aluminum, which metal workers view as a form of solidified silly putty, but it's really important for steels.

I finally gave up and bought a $250 metal cutting bandsaw which flips either vertical for delicate work or horizontal for metal-butchery.

[frank_p]

Oh - do NOT try to hand guide this. Create some kind of guiding setup so it can only move where you want it to, and add some kind of guiding handles so it absolutely cannot pull your hands into it or whip around and cut you when (not if!) the bit grabs in the work.

Remember - education is what you have left when the wounds heal and you have forgotten exactly how that scar got there. 

Yes this is very important when drilling into plates, sheet metal, shims, etc. Even if you have a pressdrill with a clamp.  Make sure everything is well tightened and place your hands lower than the plate.  If you use a drill bit the sheet of metal can climb on it like it would on a screw.  I opened my hand while holding the vise and the plate had been pulled out from it, and cutted my hand deeply once.  Silly enough I was working on a traumatology striker prototype...

Like Seen said, you can fabricate your own custom tools with old chisels, broken files (broken handles makes great punches) (used ones can be converted into knifes, chisels, etc.), metal saw blades can be bended, refined.  And before working on your boxes, get any scrap metal and practice your skills on that junk, you might find all sort of great experiences for future projects.  If you want to learn how to sharpen your own tool find someone who can teach some basic skills, it can save you a lot of time.  Sharpening stones makes wonders !

[ampman50]

The blue dye, also comes in red, is called Dykem. It's a layout fluid for machinists, I use it for lining up the tooling on screw machines. In the US it is available from MSC Industrial Supply.