When using only screws, they will always rack. But to counteract this you chanfer the vice to compensate so when you apply pressure it twist flat. It may sound odd, but it definately works, Every bit of wood i've put in is held firm, vertical and the tops of both vices are firmly against the piece. Its a tried and tested way.
The challenge was to build a cheap bench. The screws came from the from Axmister York versions as linked earlier in thread. It does exactly what i need it to do. i did look at the Veritas and metal versions which address racking, but i thought these were too expensive for what i wanted. I'm just a weekend DIY'er.
Its currently only cost me £40 (oh ya and nearly the top of my finger, 15years of woodwork in my shed and never had a single accident, the odd scrape and scratch. i just wanted a shotcut, and ended up cutting a lovely 'V' joint into my index finger on the router table, before any of you say it. "i'm a #4@ing *****" yes i know, lesson learnt).
Whats the saying. "Router in haste and repent in leisure" or something like that anyway.
Will be making a dowel making jig the weekend to make the dogs. I will then try it without drawers and make my mind up later if i want to add them to it.