Cannot adjust Cap Screw length Less than 2"

I am building butterfly valves. Some valves require lengths that are to be exact per manufacturer. The cap screws come out on the Iso Bill Of Material.

I was going to adjust per the XTRA in the SBOL, or adjust FTHK in the BLTP.

I can make the Cap screw longer, but when I enter negative values, The Cap screw never adjusts to be less than 2"

Where can I enter data to make a cap screw adjust to the length that I require?

Thanks ... -jpl-

I am building butterfly valves. Some valves require lengths that are to be exact per manufacturer. The cap screws come out on the Iso Bill Of Material.

I was going to adjust per the XTRA in the SBOL, or adjust FTHK in the BLTP.

I can make the Cap screw longer, but when I enter negative values, The Cap screw never adjusts to be less than 2"

Where can I enter data to make a cap screw adjust to the length that I require?

Thanks ... -jpl-