Saving file does not save size?

Hi,
I have a gear that comes in as a DXF file.  If I look at the grid everything is fine in terms of the size of the gear.  If I then save the drawing and attempt to open it with MeshCam, there is no size information and it appears extremely small.
Can someone point me in the right direction?
Thanks

I think it is a defect in the header of the dxf file. Try to save the file again to a new dxf file. Herefore you can use Teigha converter, This program is also useful to convert dwg to dxf, so I use it a lot. If this does not work you have to realise that dxf is a textfile and you can edit this with every editer ( leafpad or gedit) . On the Autodesk site you can find a pdf file that explains a lot of dxf files: http://images.autodesk.com/adsk/files/autocad_2012_pdf_dxf-reference_enu.pdf.
Hope this is useful

A lot of succes