If you want to measure the relative amount of air your fan is moving you can attach an axial fan to the output (or input) and attach a voltmeter to the power wires. The fan will act as a generator, and the faster it spins the higher voltage it will produce. Be careful not to let the voltage get too high, even if the voltmeter isn't connected. If it spins too fast it can break because it's not perfectly balanced. You can attach it to different fans to see which moves more air, or attach it to your fan with and without the duct attached, but I don't know of any reliable way to get a real CFM measurement from it.
Hey, I am happy with my Lasko blower (best $75 I ever spent) Getting some good smelling flowers lately and needed to make a quick carbon scrubber with zero mechanical skills. Cut out a milk carton to fit the square exit. And set inside it a scarf full of carbon. It seems to slow the flow some but that's to be expected. Even on low this monster blower is my best ally against heat and stale air. Thanks to the fellow who did all this well described help to get the thing done right..one day I will get around to that. For now I love my Lasko blower.
OP...Thanks for the writeup! I got this fan at Harbor freight for $40...another $20 for the fittings and were pumping some air now damn it!
An update for 2014. The new fan model is u12100. I removed the intake covering on the side, something like five screws and left it off totally. Keeping it on meant the ace hardware piece the op used would not sit flush and would be difficult to glue on. I decided to remove. With a small amount of effort you could modify the cover to fit inside the ace hardware piece or whatever you use. I did not end up using the ace hardware. I found a 6in cover at Home Depot and by accident the same at lowes. Likely the one mentioned earlier in this thread. I found it a better fitting piece. The identical ace hardware piece was also at lowes for anyone wanting to use that. Removing the cover on the lasko fan and keeping it off meant a small issue. The screws are used to keep the fan body attached to the side covering. Removing meant the fan body was not really attached to much. Likely it would have been ok especially if the fan sits and does not move much. I decided though to be safe and fasten it. After some thought, I decided to epoxy the fan body to the side covering. A tube of slow curing epoxy from Home Depot was my choice. I roughed up with 60 grit sandpaper then turned the entire fan on its side (with the side I was gluing facing up) putting some sockets under to keep it steady. If this step is omitted the fan will tip when being glued. With the fan on its side, I slathered on the epoxy. The epoxy is rated for plastics and comes in a two part tube. Simply push each side,of the plunger onto something, I used a piece of paper, then mix with something, I used a small nail. A toothpick is what I usually use when mixing but had none. Do your best to get equal amounts from each tube. Mix well and apply to the fan body. Once slathered put the fan side cover on. A note here. Make sure the fan exhaust is pointing the angle you want. Once this is glued, it will not move. I pointed mine up some. You now have epoxy on and the side cover in place and exhaust pointed well. Put some weight on it. I used a full paint can, some wrenches, small books, anything to weight down and mate the two pieces. This is where you don't want the fan to tip and why I put sockets under. Once dried, I waited overnight, time to glue on the six inch piece. Before doing that, the bottom needs to be cut out, or at least I did. If you feel real lazy or don't have anything to cut with it may be ok to leave on. I'm not sure. If you cut correctly here I think the modified fan cover would fit great. I may leave a small lip on opposite sides where the cover could sit easily if I had to do over. After cutting the bottom time to epoxy. This is slightly tricky as it' does not want to sit totally flat. Not sure it was my piece or the fan. A note here . I used the epoxy again but think it was a bad choice. I think 3m 5200 or 4200 or 4000 would work better. (Check the uv rating if your fan will sit under lights) Epoxy was ok but there were gaps where it would not sit totally flush. The 3m products are in tube form and can be caulked. This means any gaps would be filled if you use the caulk gun right. After epoxying time to ad weight again. Full paint can and my entire tool box on top worked very well. Next day I had some sealant I went around the 6 in piece to seal so air would not go through. The bond was fairly good, though not excellent. If I pulled extremely hard or dropped it just right the piece may pop off. Doubtful, but slightly possible. That is the way I did mine and so far so good. Been a few weeks now and works without issue. Thanks op and everyone. Hope someone finds this update useful. Also if anyone sees any glaring issues with this method, let me know. Not seeing a way to post pics here. Will update when I got it figured.
This one is from lowes and is 8 in on the bottom (glue side) and 6 in on the top (ducting side). 6 and 6 I got from Home Depot and is black. Identical though. See the bottom grate? That is what I hacked off. Could be kept on I would think.
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Tough to say IMO whether or not its worth it over the blower styles already done. Axial just dont perform as well if you add a filter to them.