SonexBuilders.net

I was curious to know how some of you went about cutting the 3/16 aluminum sheets. These are obviously critical parts, I want to make sure I cut them without weakening the material. I am working on the tail support brackets.

I did pretty much all my aluminum cutting using a cheap 9" Ryobi band saw with a 3/8" metal cutting blade. The 3/16" plate does tend to dull the blade, so I try to put some BoeLube (or use whatever you have like candle wax) to help extend the life of the blade. 3/16" plate is tough to file down so try to get your cut fairly close (I shoot to be within around 1/32" of the line)

If the pattern I was cutting out was intricate, I sometimes took the time to draw up the part in CAD, printed it out, then spray glued it to the plate. If the layout was fairly straightforward, I just drew it directly on the aluminum w/ a sharpie.

To clean up the cut, I have a Harbor Freight 10" disk sander which I use to sand the part down to the line...any remaining cleanup I do with a file and/or sandpaper.

I was never able to get a straight cut in aluminum on my bandsaw (cheap one) so I used a hand held jig saw with a 14 tooth blade in it. Squirt a little WD40 on the blade to keep the aluminum from sticking and it worked like a charm. One key to it though was that I was using a decent jig saw. I tried a cheap $30 black and decker one and the thing vibrated so bad I couldn't see the part I was cutting. When I bought a $100 bosch saw the difference was night and day.

One thing to remember when cutting the aluminum is that you should never cut it right up to the line. Cut it a little bit big and then sand / file it down to size. This lets you take out all the saw cut marks and stress risers you create when cutting. The better you get with the saw the closer you can get to the line and the less sanding you will have to do. I found that 1" and a 4" belt sander were the two most used tools in the shop when building. A sanding drum in the drill press also worked wonders for smoothing out some of those radius cuts.

Keith
#554

Larger pieces can easily and accurately be cut on a table saw with a 60 minimum tooth carbide blade 80 is even better.
I would not attempt small parts unless you can securely clamp it to a cut off box otherwise a band saw is best.
If it feels like it will be risky don't use the table saw.Fingers come in groups of 5 and that opposing thumb only comes one to a set ;)

Thanks! I am going to give the bandsaw a try. I found the scotch brite wheel is amazing at helping smooth things out.

I used a bandsaw for all long cuts with a coarse blade 6TPI with plenty of bees wax, which worked great. :D I never tried candle wax but I certainly will when I run out of bees wax. ;)

For docking the angle into lengths I used an electric mitre saw. For this one I used as many teeth per inch as I could get. The more TPI the smoother the cut. When docking on a mitre saw, the best way to place the angle in the saw is corner up and edges down. Think upside down letter V. Band saw is also fine for docking it just needs a lot more work to smooth it out afterwards.

If you don't want to spend money on tools there is always a hacksaw. They work just fine. If you know how to use it wont take much more time than a bandsaw. It will just make the user sweat a lot more. A friend of mine built his sonex using only a hacksaw to rough cut all the angle pieces.

Enjoy the build

Steve 892

sonex 1614 wrote:Thanks! I am going to give the bandsaw a try. I found the scotch brite wheel is amazing at helping smooth things out.

Don't forget about the Vixen file, amazing tool to have

Some of the angles are long and you'll need to trim the whole length of one or both legs, the Vixen file is THE tool for the job here.

I actually just got that in the mail this weekend. It is amazing how good of a job it does! I am still playing with scrap metal before I make the "real" parts. Thanks again for the info!

Harbor Freight has a good band saw for less than $100.00 that works fine. Keep your blade guide close to your cutting mark and cut slowly. If the blade becomes dull it will turn to one side or the other and will difficult to cut a straight line. I bought a Vixen file from Aircraft Spruce, the file makes quick work on the 3/16 aluminum saw blade marks.
Jack (rotorhead)
plan 784 scratchbuilding

I didn't have a vixen file. I used a couple of body filler files I had on hand, to smooth out the bandsaw cuts, It worked great, I guess the same as the vixen files.

Now here is a link from the CX4 yahoo group this guy appears to use a wood plane for the same job. I've never tried it personally but I have a couple of wood planes and I'm sure I will try using them on aluminium in the future.

The homebuilt CNC machine is awesome I want one.

http://www.hainesengineering.com/rhaine ... er_cx4.htm

Steve 892