cal3d_converter: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/cal3d_converter - from package: libcal3d12

You may install the required package with command apt-get install {package}

Error in other languages:
cal3d_converter: bevel nie gevind nie
cal3d_converter: comandă negăsită
cal3d_converter: comando não encontrado
cal3d_converter: commande introuvable
cal3d_converter: command not found
cal3d_converter: käsku ei ole
cal3d_converter: không tìm thấy lệnh
cal3d_converter: komanda nerasta
cal3d_converter: Kommando nicht gefunden.
cal3d_converter: kommandot finns inte
cal3d_converter: komut yok
cal3d_converter: nie znaleziono polecenia
cal3d_converter: níor aimsíodh an t-ordú
cal3d_converter: no se encontró la orden
cal3d_converter: no s'ha trobat l'ordre
cal3d_converter: opdracht niet gevonden
cal3d_converter: parancs nem található
cal3d_converter: perintah tidak ditemukan
cal3d_converter: príkaz nenájdený
cal3d_converter: příkaz nenalezen
cal3d_converter: команда не найдена
cal3d_converter: командата не е открита
cal3d_converter: 命令找不到
cal3d_converter: コマンドが見つかりません