Hi Roger If the bed is made from cast iron you could use 1.2mm dissimilar rods but the localised distortion and the normalising would mean the bed would need to be machined and trued I personally would go with the epoxy filler I have used this and if it is the same stuff you can tap it and machine it as though it was metal the only thin I would say against it is the need for the surfaces to be clinically clean. Hope this helps Steve --------------------------------- Yahoo! Messenger NEW - crystal clear PC to PC calling worldwide with voicemail MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.