Apologies to all but first time user of CAD software. Using lines and arcs I have created a number of drawings for MDF parts to be cut on a CNC Router. Although the files originally looked Ok I have been told that many of the points where lines join other lines or arcs, that the lines don't actually join. If I zoom right in I can see this. I have tried converting multiple selected lines and arcs to a Polyline but this doesn't join the points.

Is there any way I can select multiple lines etc. and join them automatically ?

Thanks in anticipation