We recently have designed some parts that make using a MakerBot large spool even easier on a Replicator 2.
When using a large spool some people have the occasional issue with the spool catching on protruding pieces on the back of the printer. To help with this we have made a simple spacer that will fit over the standard spool holder and provide some extra clearance between the spool and anything that may catch on it as it prints.
A second issue that is more apparent after installing the spacer is the filament taking a sharp turn into the guide tubes. This should be corrected in order to reduce the force required to pull the filament through the extruder. For this we have designed a tube holder/spacer that simply slides into the previous tube holders and creates a less sharp bend for the filament to feed along. This has the added benefit of easily securing your old or mangled tubes that don’t clip into your tube holders as well anymore.
A final issue we sometimes see with any spools and 3D printing is the printer pulling extra filament than needed through the momentum created on the spool. We have created a simple bolt-on addition to the tube spacer which is a spool tensioner. It will simply apply friction to the edge of the spool to reduce the excess amount of filament unwound.
Be sure to check out our design here: http://www.thingiverse.com/thing:744453