I am looking for an inner thread M4 and M6 may be 20cm in the size I can add to my objects, as I will not design these every time I design a hole with these threads. Any advice where I can download this.
You only need to do it once. Here’s one good example from Dave: https://www.finewoodworking.com/2014/04/27/screw-threads-in-sketchup
you can create one pitch of the thread as a solid component and array copy it as often as needed for the desired length.
Cotty, you don’t have one by hand for M4 and M6? So you can share?
Sorry, I love modeling them so I create them fresh every time I need one as an exercise (and this isn’t too often, otherwise I would probably have one).
Maybe you can search in the 3D Warehouse? (Haven’t tried it)
They aren’t difficult to make on your own and you can make sure you have ones that are usable. As @Cotty indicated, you can manage with a single turn as a component and array it.
If you do find threads in the 3D Warehouse, make sure they are internal threads and not external threads that have just been turned inside out.
FWIW, here’s a quickie example internal thread. I have modeled it with the back faces out (green is my default back face color) so it can be stuck into a part later. As a component it would be saved for future use.
You might also want to chamfer the threaded holes to make the lead into the threads easier. Cones can be used for that.