Where to put the blower hole

[GoldyCon]

First year coming up and I have been building a 275g oil tank to use as my arch with steam pans. I was thinking I need to add a blower but instead of buying one I would like to use my leaf blower for the first year. My plan was to have a hole under the grate in the firebox that will connect to something like a dryer flexible duct. I'll put some mesh on the hole so large embers don't fall in but is there any reason not to have the hole directly under the firebox? The fire will be supported with angle iron so I suspect most of the ash will stay in that.

[psparr]

If you go that route, I would suggest diffusing it somehow. Straight up would only hit the fire in that spot, and leave the rest of your firebox without the most effect of the air.
I use a leaf blower. It works well, but you'll also need a way to restrict the flow from the blower itself. Way too much air for auf. My lazy butt just placed a towel over most of the intake grate of the blower.

[GoldyCon]

I'll probably put a box over the leaf blower with some vents in it so I can somewhat control the flow. Do you have any recommendations for an air diffuser?

[psparr]

I don't know. Maybe just a v shaped piece of steel over the hole?

[maple flats]

My under fire air goes in from the rear into a 4" stove pipe, capped on the end, and then I have 3 sets of 5/16" holes, 1 top center, and 1 each facing each outer edge of the grate. The holes are about 2" apart in each row. That has worked well for my set up.
If you do decide to go straight up under the fire, use a section of metal duct and elbow it or just an elbow to keep hot coals out of the blower.