another way to look at resolution is how it relates to scale.
actual 1/4" is 12" in scale
1/8" is 6"
1/16" is 3"
1/32" is 1.5" in scale. anything smaller is too weak or looks like an undefined blob.
so the smallest diameter of a handrail that can be printed is 1/32' but at that size unless supported will be way too weak.
also if those bolts are less than 1/32" or 1.5" diameter you need to test how your printer prints this small a detail.