Attacking "the fair-weather friends" of the post-McCrone agreement, Mr Smith said that all the teaching unions had signed up to the changes and could not now distance themselves from aspects they did not like.
Last month, the SSTA opened up a major union fissure by breaking the silence on the job-sizing outcome and condemning the pro-primary bias of the EIS.
Mr Smith replied in his set-piece address: "That charge might have stood up were the job-sizing toolkit being applied to a common base. But it is not.
In primary, some 425,000 pupils are educated in 2,300 schools, with around 3,800 promoted postholders - one post per 110 pupils. In secondary, some 318,000 pupils are educated in 390 schools, with around 12,000 promoted postholders - one post per 27 pupils.
"Any half-fair, half-objective job-sizing scheme would have to impact differently on the sectors, given the very different scale of management provision made hitherto in the respective sectors. This is not about devaluing what anyone does. This is not a case of robbing Peter to pay Paul."
In a further broadside, he emphasised that job-sizing was never intended to be "a covert fifth pay rise exclusively for senior promoted staff". It was brought in to create a fairer method of determining salary which reflects the size of the job.
Mr Smith later described the working group on job-sizing as "one of the most harmonious" and accused the SSTA of "inconsistency inside and out".
He also castigated critics of the chartered teacher programme who he said had forgotten that the alternative was - as it is south of the border - performance-related pay, where pupil test passes help to determine whether teachers are allowed to cross the pay threshold. There was also a cap on how many staff could benefit, unlike the chartered teacher programme.
Some 5,878 teachers - about one in four of the 22,000 eligible at the top of the scale - have registered with the General Teaching Council for Scotland for the programme's first year.
Mr Smith called it "a very encouraging start".