I too use Alibre. But I find its dxf handling to be abysmal. Always has been. DXF is the worst standard in the world, and various cad programs handle the files variously
Id try the DXF's in other programs, there are quite a few on the web. When you find one that loads it, see if you can save it to another format that alibre might like better. I use vectric for near everythin
g so I never have much of a problem, I use alibre rarely now for that exact reason, it isnt very friendly with formats other than its own. I wish I could do something about it to make it more solid for various cad programs, but in the end they vary so much that its a never reachable target. GM's output is verified on many programs though, both in 2d and 3d so Im pretty confident they are fine.
There are issues in 3d with some types of gears such as bevels where the shaft holes are not closed, but I have fixed up some of those as well for the next
version. I will probably re-release in early september as I start a new developme
nt season, but I have been adding things in the off season so that we can start with more capabilit
es. Perhaps by then Ill be able to better the dxf's for more programs as well , though I cannot promise that one.