I recently ordered and received the Gap Bed Insert for Rikon's 70-3040 lathe. To briefly review, the insert provides a full 54.5 inches of upper lathe bed when the machine is fully extended. This means you have lots of room to position your tool rest, tailstock and/or coring system in my case. Overall I really like the insert and plan on using it the vast majority of time I turn. The biggest benefit is now simply sliding the tailstock out of the way when I don't need it. When I do, I simply slide it back. I found it cumbersome to remove and then re-install the tailstock before. There's minor assembly of the insert required but it's pretty much plug and play. I do have some difficulty sliding the tailstock over the break between the exisiting upper bed and insert. I believe this is mainly due to my lack of making fine adjustments to the insert (the instructions detail this) and rust/shavings buildup on my upper bed which I should be more diligent in removing. If I want to remove the insert it's simply a few screws loosened and me lifting it out of the way. For approximately $200 at the moment, the insert is well worth it. I'm a relatively new turner with 15 months of experience but am on my third lathe. I haven't been compensated by Rikon or anyone else for my comments.
