a) Regular weight should be 90pt
b) Regular should be 4th in a row
c) Bold should be 7th in a row
d) And there should be 9 instances:
1.Thin
2. ExtraLight
3. Light
4. Regular
5. Medium
6. SemiBold
7. Bold
8. ExtraBold
9. Black
I have Light Master (10pt) and Bold Master (220 pt). When I just use Family Stem Weights Calculator or Insert Instances script I end up with Regular that has 53pt, which is too light.
Logically speaking, the only way to make specific value appear at specific position would be to manipulate the start or end value. Otherwise you can calculate twice, using target Regular value as the end and start value, but it doesn’t create smooth transition. My advice is to not be afraid to modify the interpolation value that the script gave you.
If you are forced to go from 10 to 220 in 9 steps and the 4th step has to be 90, then just use Equal Steps.
It’s not a sin. Many DSType families are equal step progressions, and they work perfectly well.
Or, as Tosche said, you can also modify the Thin and Black values.
Even if your Thin master is 10, your Thin instance can be 20 or 30.
And if you Black master is 220, your Black instance can be extrapolated to 230, 240 or 250, and then reinserted as a new Black master, replacing the original one.