We have had 2 scales (not counting the hanging scale for newborns). The first one was old style with weights that you put on the balance arm. We had to calibrate it with a 50 lb. sack of feed when we used it. Not super accurate, but close enough for market hogs and lambs. The one I have now I bought used as well, but it is digital, battery operated and mounts on a walk-through scale box. I liked the old scale, but I LOVE this one. Another thing it is good for is weighing animals to know how much meds to give them.
Once you build your walk-through scale box you can just set up a runway and start weighing.
My taxes are supposedly frozen for senior citizen. But if I build new structures, it will be taxed. But being as my house is a manufactured house, it depreciates and taxes go down. Plus Ag exemption and homestead.
Here is the what the Washington State AG handout on raising hogs says on weight gain:
"An average of 1.6 to 1.8 pounds per day should be expected for a healthy, growthy pig on a growing and finishing ration. Pigs generally will gain approximately 1.5-1.7 pounds a day during the grower phase, up to about 110 pounds of body weight, and then daily gain should increase to approximately 1.8-2.2 pounds per day as the pig increases in size during the finishing phase.
. . . It is important to remember pigs often grow slower during the hot summer months."
This pretty much is what we learned in 4-H about our hogs and why it was important to weigh them. They can gain too much or too little before Fair weigh in date depending on how they are fed so weekly weighing is necessary.
We used this weight gain average to figure out how much our hogs would weigh by weigh in (using days to Fair). If our hogs were too heavy about a month or 6 weeks before Fair we started cutting their feed with oats. Oats put on nice hard flesh but cut the rate of gain. You wanted to put them back on full feed abut 3 weeks before Fair so they would look "fresh". Holding back a hog too close to show date is apparent in the appearance of the hog and judges can tell they have been held back. If you need to hold them back, you must do it midway through the growing process. Then you can push them the last month or so.
If the hogs were 2 years old when you bought them, they must be some sort of miniature hogs. Standard time to slaughter (for 4-H Fairs and youth auctions) is 6 months. You can grow them older and butcher younger, but at 2 years you might only be wanting to eat sausage off them.