You don't need (or even want, IMHO) a spring. Just screw down the press until you see a little bit of whey seeping. Keep your eye on it and adjust the tension to keep a little bit of whey seeping. The first 15 minutes you'll probably have to adjust if 1-2 times (if you even put any weight on it at all). The next 15 minutes, you might have to adjust it once. The next 30 minutes probably not at all. The next 30 minutes you definitely won't.
People press their cheeses waaaaay too hard generally. If you have to put 30 lbs of pressure on a 1-3 lb cheese, *you have done it wrong* (assuming it's not a cheddar, in which case there are scenarios where you're probably OK). Even commercial parmesan producers put less than 25 kg on a 25 kg cheese. You don't need much weight if you are hitting your drain pH correctly and not over pressing at the beginning.
Furthermore every single recipe that includes pressing weights is suspect, IMHO. Your pressing weight and my pressing weight will be dramatically different just due to circumstance. Especially if they give a pressing weight, but *not* a drain pH, it's like saying, "Here's a random cheese. Let's press with random weight!" Virtually every single video you see on the internet shows people massively over pressing their cheeses (often by 10x the amount of weight they should be putting on the cheese). Sometimes it works out OK. Frequently it does not.
The goal of pressing a cheese is to close the gaps in the cheese. That is all. 100%. Finished. Nothing else to do! As long as you don't over press the cheese it will completely drain itself of whey on its own. People think they have to press to get whey out of the cheese. That's just absolutely and completely wrong. Totally!
Was that emphatic enough? :-)
You need to keep the cheese structure open for the first 2 hours of draining so that the whey can get out. If you press it too hard, you will close the cheese and whey can not escape. However, you want to close it as soon as possible after that because the cheese knits the most easily the higher the pH. You want to *very* slowly close the gaps in the cheese over the first 2 hours with the goal of completely closing it exactly at 2 hours. It's better to err on the side of too slow rather than too fast.
One thing to keep in mind. Above a pH of 6.0, virtually all cheeses will close without any weight. By the time you get down to a pH of 5.3 you're starting to need multiples of the weight of the cheese, if the cheese is dry. If you are finding that you need a lot of weight it's essentially because you got into the mold too late. The pH is too low. You make have additionally over cooked or over stirred the cheese, leading to case hardening or just very dry curds. Pretty much it all boils down to making fairly large mistakes in the make. It's too acidic, you raised the temperature too high too fast, you fractured the curd and it dried out, you cooked too long, you stirred too aggressively.
Oddly, the amount of culture you added to your milk (and how you handled the make) is crucial because the more active culture you have, the faster the cheese will acidify. The faster it acidifies, the more difficult it will be to close the cheese. Measuring and tracking how the cheese is acidifying, getting the cheese into the mold at the correct pH, and maintaining the correct room temperature while pressing are crucial to pressing your cheese. Small variations in these parameters will have massive effects on the amount of weight you need.
This is one of the reasons I only use mother cultures when make cheese. Directly adding DVI cultures to small cheeses is an invitation to having absolutely no idea how quickly the curd is acidifying. I always do a flocculation test so that I can see how quickly the curd is forming. The faster it forms, the faster the milk is acidifying. I use that timing to inform me how much time I have to get the cheese into the mold. Then I cut, cook and stir the curds with the goal of hitting that target. You can also use a pH meter to track your progress, but it's not necessary once you get the hang of it.
I always recommend making a simple cheese like a caciotta several times to get to the point where you can make a good solid cheese with barely any (or even not having any) pressing. Once you have your skill at that level, you can make other cheeses much more easily.
