[uscra112]

I'm starting a new thread to talk about specific tools, techniques, and things you need to know about using structural extrusions, since I've used many tons of the stuff over the last 8 or 9 years building everything from guard fences to tool racks to full-blown automatic systems for loading cast iron V-8 cylinder blocks onto the machines my company makes.

There are MANY suppliers of this stuff. Bosch, Parker IPS, AMC Quik Connect, Item Products, MK (German), fall out of my memory without even looking at my catalog pile.

80-20 is one of the better ones for us to use, since they will sell on-line and have a very complete catalog of accessories.

As I remember, 80-20 once (and maybe still) will offer to "kit" your design, i.e. doing all the cutting-to-length and machining.

If this is so, pay them to do it.

It is essential that the cuts on the ends be very flat and very square to make structures that line up right. If I had to cut it myself, I would use a "chop saw" with a carbide-tip blade, and make a series of trial cuts until I had the saw adjusted just right. Since I own a milling machine, I use that when I'm playing with the stuff at home. A milling machine is also the only tool to do the drilling and counterboring that is necessary for using the butt-connector parts that are common with this material.

Hence I recommend again that, if 80-20 will do the machining work for you, use that service. Unless you own or can access the right machine tools. It is not really possible to do the machining work well enough with hand tools.

(If you design so you can use corner-brackets for right-angle joining, you have a chance to avoid the machining problem. Put on your thinking cap!)

40mm x 40mm tube is not stiff enough for our router frames where the tube would be more than about 24" unsupported length. The 40x80 is MUCH stiffer, but of course more expensive.

The anodized surface will work fine a guideway when the mating slide is faced with teflon or nylon, as in the 80-20 "flange" linear bearings. But if you ever cut composites, like MDF, fibreglass, or carbon fibre, or even plywood, the swarf will score the aluminum very quickly. Room for careful design of way covers here!

Most of these companies one or more designs which add a steel element to the aluminum, to make a long-lived guideway. I don't see that in my old 80-20 catalog, but check it out - they may have added some since.

All for now - I'm supposed to be working !

Phil