I am in the process of building two 1 inch furnace burners. I'm following the plans from Michael Porter's book. I'm at the stage where I need to cut the air slots out and was wondering if I could make 3 wider slots instead of the 6 that the plans call for. Any help would be greatly appreciated. I do have a rotary tool with all necessary attachments to cut out slots.

Yes you can, and that is what he recommends nowadays. Add together the total width of all six slots combined, and divide by three instead of six. divide the width of the six ribs by three to get the new widths of the ribs. But, wait; thats is just too simple. maybe you want to put some of the area gained this way to enlarging the air openings more? Ever hear of the KISS formula? Buy a hex bolt; you should already have the layout angle. Push the hex bolt in the burner tube, and make ink dots on every other hex point; now rotate the bolt to about where you think the air openings will be right. Mark every other point, that weren't used the first time. Draw lines down both sets of ink dots, and see if you like the result. No? Then use a little thinner on a rag to erase every other line, and move the bolt somewhere else, and start again. When you're satisfied with the results, complete the layout of the air openings. You should end up with a stronger burner (mechanically) and more powerful two.

So, why oh why didn't the danged author do this in the first place? He was being over cautious at the time

Him

Thank you for taking the time to answer my question. I am very excited about these burners and  wanted to make sure I build them correctly. I also want to thank you for your book and wealth of information posted on this site.

You're welcome.