I have a project that involves milling a shape out of rather thick aluminum, but I don't have ready access to large shop machinery. I looked around at what was available for a decent price, and came across the Rotozip spiral saw made by Bosch. The concept is sound, in fact my employer has a CNC router that works in much the same way, just with about 40times the horsepower and much better bits. The website shows it just blowing through wood like it isn't even there, so I figured it should be able to handle nice soft aluminum as well.
The tool overall seems to be well made, the base flexes a bit more than I'd like but what I was doing wasn't ultra-precise work. The selection of bits is pretty limited as well, just two sizes of wood cutting, one odd looking metal cutting one and a few drywall specific bits. The Rotozip was $70, and the bits two for $10, so I figure for the price it wasn't much of a gamble. Well, first I tried it on the MDF scrap from making the pattern, and it chewed right through that, although it was hard to control. The bit wanted to pull due to the rotation, so a straight line is very hard freehand. The bits are a reverse spiral, blowing the chips downward, which is a nice feature when you're trying to follow a line.
I sprayed the bit with some WD-40, and tried the aluminum. It made a neat little divot in the edge, and that was it. The bit couldn't be retracted far enough to make a partial cut, and flexed like crazy when trying to push it through the full material. I swapped out the 1/8" bit for a 5/32, with marginally better results. In the end, I returned it. It just did not live up to the hype. I instead got a $30 jigsaw, finished the cutout in about two hours, and am fairly happy with the results.
If you're working with engineered or softwoods, then this might work for you, but much more and it'll leave you disappointed.

 

Jared,
Most of those Rotozip bits are self piloting.
They don't cut at the tip.
You use it to run around an electrical box or recessed can.
So you can't run them partially through material.

I have used my Rotozip with regular 1/4" solid carbide upspiral router bits on wood and laminates.
(they offer other collets)
Feed rates need to be slow.
The little router has speed but little torque.

Definitely underpowered for trying to cut aluminum.
Is this plate for one of your conversion projects?

 

Yeah, I'd love to find someone to CNC these but I can't justify the $250+ per piece they want. That doesn't even include material.

 

Do you need the tiny bit because you have to follow some small inside radius?
A larger router with a larger diameter bit will have more inertia and the cutting edge speed goes up in relation to rpms.
This will work better if you can rough out the blank and are not trying to remove all that material in the cut path.

Routing aluminum is a mess.
Hot chips everywhere and lots of noise.

I guess the first thing to ask is whether you have a clean CAD file.
When I was making repetitive pieces with complex curves it was well worth my while to have the local CNC shop cut pieces.

I paid for the coding and owned those files.

If the part is essentially two dimensional it would be a lot faster and cheaper to do it with a water jet or laser.
If there are counterbores it might be economical to do those yourself after the blank is finished.

 

Building a bit on ArdWrknTrk's advice there are many, many smaller shops setting up CNC machines these days. In fact there's a whole sub-culture (no offense) of CNC DIY's who are very much into one-off parts, could probably create the CAD file and part for cheap.

 

I just looked at Jared's other thread.
5/8" 6063 T6 aluminum is asking WAY more than this tool was designed for.

 

I knew it was a long shot to make it work, but it would have worked if I could have done it in multiple passes. Not being able to retract the bit far enough is a major loss of points. The bit I was using was a plunge cut bit, so no piloting. The only bits I saw that were piloted were for drywall.
This thing would not have had the power to run a 1/4" router bit. I do plan on getting a real router, Milwaukee makes a very nice 1.5hp one that will do the job quite well. The original plan was to make a steel pattern, plasma cut the blanks, drill, tap, then bolt to the steel pattern and run it through a router setup with a top roller bit. I'd have to run the router above the piece so it wasn't getting filled with chips, so basically I'd rotate the pattern and cutout through a slot against the bit, but a slight redesign left a recessed area that wouldn't work with that setup so I'll just have to move the router around.
There are a lot of little shops around here, but they all are "too busy" for some little project like this, or are insanely expensive. I have a cad file for this, but it won't open. I do have a PDF, but now I've worked the design up from that to use the lower bellhousing bolt holes on the M5R2, and another bolt on the Mercedes, so it doesn't do me a whole lot of good.

 

I have an ancient Bosch 1611EVS that I bought exclusively for fabricating solid surface counter tops.
I think it is rated at 3 1/4Hp.
This router has cut MILES of Corian.
I still wouldn't ask it to cut 5/8" aluminum.

An old industrial overarm pin router can follow a pattern without needing to cut all the way through.
This was how we did things before CNC, but it is dangerous to freehand something like that through a powerful machine.

Whatever you end up doing use plenty of lubricant.

 

Oh yes, lubrication is absolutely crucial in aluminum, especially in the lower grade stuff. Run it dry and it just turns into a gummy bit snapping mess.

 

I don't think a rotozip is the tool for cutting thick aluminum. I use a 3.25 hp router for my heavy cutting & it would not be my choice for metal. I have it in a table & use it to make cabinet doors & molding.I would not use it freehand. Its just too powerful.

 

The old Bosch is Electronic Variable Speed.
Which means 'soft start' and I can dial it down for running large diameter bits.
Automatically ramping up the speed means it doesn't want to jump out of your hands when you pull the trigger.

I would never run it freehand for something like panel raising or coping rails, but certainly do for profiling the edge of a 100#+ counter clamped to my workbench.

I don't really think it is fair to expect a tool intended for cutting drywall or trimming a single sheet of Formica to be effective in use on a aluminum plate.