I have a table I'm building that is going to cut sheet metal. It doesnt work yet, but it will use a 100 watt CO2 laser. (Please resist the temptation to post that 100 watters dont cut sheet metal -- they do).

My question is about the platform/support that will hold the sheet metal.

The original top on my CNC table was a 1/2 thick plate of aluminum. I bolted down 24 disc shaped neodymium magnets on this plate with a 4-40 socket head bolts. The idea behind these things is that they'll supply some magnetic force on the sheet metal to hold the sheet in place. The main thing I like about the system is that it is very level. This is important because the "sweet spot" of the beam waist is rather small, and changes in the Z-height of the metal will could result in cases where the beam will not pierce the metal.

The set up as it is now works fine in that they hold the sheet metal quite nicely. The bolt head projects about 1/8th of an inch above the magnet but because its made of steel it transmits enough magnetic force up the post to adhere the sheet metal.

The question I got is if this system will work. One thing I'm wondering is if the beam hitting the aluminum plate will put off undersireable fumes. The other question I have is if there should be more distance between the part and the support underneath. The gap between the sheet metal and the aluminum is around 3/8ths of an inch. I think it'd also be better if I had a grate underneath the part. That would definitely make for better ventilation -- I could put a vacuum system below the part to pull off fumes. Comments are welcome.

This is the table:
http://nilno.com/laser_dir/mag_table_003.jpg

These are examples of the magnets:
http://nilno.com/laser_dir/mag_table_004.jpg

This is a part held on the table.
http://nilno.com/laser_dir/mag_table_005.jpg

owen