Today I was rekeying a house for some people who just moved in. It looked like the sellers slapped some shiny new doorknobs on a few of the doors to dress them up. I was surprised when I took one apart to rekey it to see that the entire lock cylinder seemed to be made out of plastic. Somebody could break into this house by melting the knob with a Bic lighter!
This is obviously not ideal. Aside from the obvious issue already highlighted the plastic lock cylinder will get worn out pretty quickly through regular use because a metal key is much harder than plastic. Some locks at the hardware store aren’t much better. A newer Schlage F series knob is not only made out of pot metal but also has what’s known as a floating cap. It’s a little clip that is attached to the top of the cylinder. They often pop off easily and the cylinder will wear out quicker than an all brass cylinder.
Kwikset locks also feature pot metal cylinders. In fact all residential locks tend to have pot metal lock cylinders at the lowest price point. Emtek and Baldwin hardware will have brass cylinders but also cost twice as much.
Once you get commercial grade hardware, you get solid brass lock cylinders. They won’t wear out quickly. A key can be inserted 400,000 times before the lock is wearing out. A residential lock cylinder might only last roughly 200,000 times in ideal conditions. In real world conditions they will last a few years with high use before wearing out or breaking.
That’s the difference between a $40 knob and a $60 knob. Not only that but once the cylinder wears out it can easily be replaced. Residential locks usually aren’t worth replacing the cylinder.
Additionally, grade 2 and grade 1 knobs feel more solid. Grade 3 knobs from the hardware store have a cheap loose feel. You might say that they invite people to try breaking in.