I'm building a spine tester as per an article I read in an old Trad. Bowhunter mag,and am having trouble getting the scale correct.Any help out there?

Give us a few more details.  What type are you making?

If you have an assortment of shafts that are a known spine you can use them to make your scale with.  Do a google search, there is some articles on making spine testers and they have scales you can print off.  Hope this helps.