Be sure you properly maintain your pin punches, especially if you are using them with polymer parts.
With hard use, the end of a pin punch can flatten and a sharp lip can develop around the edges. That's not good even for use in metal parts, but it's especially bad if you're using the punch with polymer parts.
The lip increases the diameter of the punch and that, plus the fact that the lip tends to be sharp, means it can easily ream out the holes in the part to a larger diameter, creating a loose fit when the pins are reinstalled.
It's a good idea to occasionally check the ends of your pin punches. If the ends start to flatten and develop a lip, carefully remove the lip with a file, a whetstone or even a piece of sandpaper.
I go a step further with punches I use on polymer parts. They get a slight chamfer on the end. Not much, just enough to insure that the edges of the end of the punch are slightly rounded. That insures that even if I get a little sloppy or careless with the punch, it's unlikely that I'll shave the soft polymer material from the inside of the hole.
With hard use, the end of a pin punch can flatten and a sharp lip can develop around the edges. That's not good even for use in metal parts, but it's especially bad if you're using the punch with polymer parts.
The lip increases the diameter of the punch and that, plus the fact that the lip tends to be sharp, means it can easily ream out the holes in the part to a larger diameter, creating a loose fit when the pins are reinstalled.
It's a good idea to occasionally check the ends of your pin punches. If the ends start to flatten and develop a lip, carefully remove the lip with a file, a whetstone or even a piece of sandpaper.
I go a step further with punches I use on polymer parts. They get a slight chamfer on the end. Not much, just enough to insure that the edges of the end of the punch are slightly rounded. That insures that even if I get a little sloppy or careless with the punch, it's unlikely that I'll shave the soft polymer material from the inside of the hole.