Here's a truth: The cheaper the air tool (Harbor Fright and I-R mass marketed most notably) is the poorer it works. The way to make it cheap is to not worry about clearances, tolerances, seals and bearings, then use excess air bleed to cool the cheap bushings. The result is a tool that may spin like crazy at no load, but uses/wastes a ton of air volume, requiring a large volume compressor (the spec consumption is at no load) or constantly waiting for it to catch up and stalls instantly when under even a small load, so the tool is basically useless. A common complaint with the HF 4" angle grinders, both air and electric use a non industry standard undersized arbor disks basically limiting you to buying HF's low quality overpriced disks. (The H-P printer ink cartridge business model: give the unit away and greatly overcharge for the proprietary consumables.) A cheap air grinder is a waste of money IMHO! Always check the availability and prices of the consumables (and the customer reviews on an independent website, NOT on the seller's website, before making the purchase.
I have 2 Makita 4" electric angle grinders, one mounted with cutoff wheel and one with fiber sanding/grinding disk, still going strong after >15 years, well worth the money!
Note: always wear face shield and gloves with cutoff wheels!

 

AX, thanks for that detailed explanation. I was wondering how they could sell so cheap. For most of the work I do a lot of the cheap tools work because I don't use them that much or put too much load on them. Air tools are a little different story. Yeah, I won't use them much either, but if they bog down to be ineffective as soon as you put them under load they are not much use.

 

One thing that no one mentioned is a jig saw with metal cutting blades. Works very well on flat sheet metal.
Elmo

 

One thing that no one mentioned is a jig saw with metal cutting blades. Works very well on flat sheet metal.
Elmo

 

Being a sheet metal worker for 45 years and now retired I will say my wiss left and rights are the best cutters I have in my arsenal. Listed in order of use

4" milwaukie grinder w/6"x 1/16 cutting discs, only found at a industrial supply house
straight and 90 air die grinders w/carbide bits and polishing discs
air carbide cutter w/ 3" blades-- great for polishing t welds if needed
plasma cutter
wiss inlaid snips 14" handles
wiss snips the video shows them laying on the bench in the background
harbor freight disposable 4"grinders 7.99 apc
files
14 gauge electric double cuts