Technically the best method I've used for ABS-ABS is pretty much neat MEK. You can get it from plumbing stores in 250-500ml tins but NOT always MEK cleaner. Otherwise I know Tamiya have an ABS solvent and I think EMA or Slaters / etc do a modellers bottle also, but don't get it confused with the polystyrene solvent, which won't necessarilly work with ABS.
...Any other method is a mechanical bond and not a solvent weld, so doomed to fail at some point. Whether you go for the modellers bottles I suggested or the bigger solvent tins is your choice. I personally find MEK brilliant to work with in terms of performance, but absolutely horrible for my health in any quantities.
Rich