"I'm looking for a 6in bench vise. I used to have a 6in craftsman, but sold it years ago and now regretting that. I'm looking to stay under $100. I have looked around and haven't heard anything go I d about harbor freight bench vise's."
I broke my home bench vise and because I needed one asap I rushed out and bought one at my local Harbor Freight. I returned it the same day. It was pretty bad. The rotational clamp would not hold due to a really poor casting. The entire vise had very rough edges good for ripping skin open.
On the way home I got an Irwin at local farm store and broke that vise within a year . Replaced under warranty, I traded the replacement still in the box for a bunch of pizza coupons.
Then I bought a vintage Craftsman 5.5" on craigslist that has worked out quite well.
I have a 6" Wilton as a backup for when I break the next vise at home or the shop. (yeah one broke there too but I didn't do it).
IMO, weight is a major factor on what makes a decent vise. Lightweight hollow castings are just too weak for any real use.