Ridgid contractor saw. Virtually all contractor saws use either gravity or a spring. As height changes, the spring takes up the slack, but it is a very short spring so the tension changes quite a bit. Gravity is probably a bit more consistent.
My tools are not professional production level. No money, no room, no excuse. For sure, as I have suggested to as many first time anything buyers, bigger and heavier is better. This is why I am killing myself deciding between a Harvey, Powermatic, and PCS 3 HP cabinet saw as an upgrade. I decided against the Bailey and Grizzly as they are dovetail trunnions. My reasoning is they are assisted by a gas spring which only last a few years and I have no idea if they are generic. I am slightly scared on the PCS as it has so many unique parts like the very short secondary belt that again, will it be available 20 years hence?
DP is the ubiquitous Delta 17 from years passed. I made the mistake of thinking it was a quality machine but even 20 years ago, seems the Taiwan factories started shipping junk. I would have bought the Palmgren but for the T-slot table. Never had one and my go to clamps and jigs are all for through slots.
Joiner (reasonably smooth) is again, the ubiquitous Emerson/Craftsman/Ridgid/ you name it 6 1/8 inch. I am happy with it. ( see below)
BS is my new Harvey C-14. Smooth as can be. Love it. Drive belt is a very short multi-rib. Big massive iron wheels.
Planer is my modified Delta lunchbox. It will probably be replaced with the Delta 735 like everyone else, even if they lie like a dog on the power requirements.
Did some testing on my DP. Running @ 450, played with the tension. It is very clear when the minimum tension comes in. I don't have a force gauge, but my "moderate" uncalibrated thumb says it is about 1/2 inch on the rear belt. Just a tad loser than I might typically have set. Tighter did not change the vibrations. I have not tested at higher RPM. I rarely go above 1200. I would like to go slower, but the smallest motor sheave is way below belt spec and does not have enough wrap, so I get slippage when spinning a big circle cutter that slow. The chart says I should be running 3000 for small bits in almost everything, but all that does is burn its way through. When I am cutting metal, I expect to produce curls or chips, not dust.
If I want smoother drill, I have to buy one. Tolerances in the sheaves are just not that good. I found the motor mount to be way off skew but with some tweaking, it is now in a parallel plane. Good enough for woodworking. If I get more serious in metal fab, then I guess a Smithy would be needed.
Belts should be just tight enough to not be flopping. I have been reading as much as I can find from belt manufactures. One thing you maybe can do with 2 belts is if the sheave is "standard" go to a single bonded belt. Basically the same two belts but joined. Much stiffer laterally.
So, I have two choices for my joiner. I can either put on a link belt, or put the motor on a hinge with an eccentric on a lever to release the tension between uses. I only use it every few months, so the likelihood of the belt to take a set is greater. The motor is quite a way from the cutter. I think a big block and a shorter belt would be even smoother.
Observation: Y-tubes showing vibration and fixes only show the the machines idling, not cutting. Different blades/cutter heads, etc. may set up different harmonics. This is why I was thinking about a damper to lower the Q.
Back to installing my new DC ductwork. Last pieces came last night.