A few questions as never heard of cross threading before or never done it 

The question is that if you can do it up by hand the bolt all the way to till the end of the internal thread female end in the engine and then can tighten it up its fine with a spanner until it stops 

If a bolt had a slight resistant, then on the next turn it was easy to turn and then all the turns all the way up to the end was easy then is it okay or if the same situation occurred again on the same bolt and still went easy on the turns afterwards is it okay until the end.

Is cross threading where your stripping the bolts at a angle as misaligned and also where the male bolt the tip of it is touching the side of the wall on  the female thread and it hard to turn as the tip of the male thread is trying to go though the metal hope that makes sense in order to maintain that angle . Which will cause pressure and could cause it to snap as it will bend the bolt and also bend the threads causing stress and allot of force from whoever turning it . Hope this makes sense.

Cross threading is when the threads don't match each other and the bolt (or nut) will be impossible to turn by hand.   If you use a spanner to force it you will eventually strip the thread.

matt1234 i agree with how you describe cross threading. a typical example of when this might occur is a sparkplug in a recess because it is hard to see if the sparkplug is in dead straight alignment with the hole. you have it in at a slight angle and start doing it up with the socket and ratchet and then realise all is not well. you then undo and try to get it straight. but now the threads are already damaged/bent and it wants to go in misaligned again as you have bent the threads that way. it is then hard to get it to go in correctly. the more you do it up at the wrong angle the more you knacker up the thread and it might get very tight and snap or it might just strip the threads off so it goes round and round and won't tighten.

My GS550 motorcycle. 4 cylinder. the spark plus are angled in a recess in the finned (air cooled) head. many years ago one got cross threaded. I just could not get it straight and in the end did it up tight (it was tight all the way) but cross threaded at a slight angle. Used it for years like that. Then bike was not used for 19 years. last year decided to get it going. had trouble getting it to run right. Decided to take the spark plugs out. Forgot one was cross threaded. When i tried to undo it, it snapped off level with the top of the threaded part. As you might imagine I was slightly annoyed.

If you turn a nut/bolt anti-clockwise before driving it home it can help avoid cross-threading by making the threads line themselves up. You should be able to feel the 'click' and the end of the threads fall away from each other and seat themselves. Try it on a loose nut and bolt and you'll soon get the feel for it.

Spark plugs, as touched on, are common culprits and particularly notable given the difficulty with which a repair may need to be made. In addition to the anticlockwise-before-clockwise trick a short piece of hose can also be used to start driving them home. The very low torque available with such a 'tool' means that if you have cross-threaded them you will not be able to cause any damage.

I don't disagree with anyone here.

If you did/do ever strip a thread however, don't ever have a 'cardiac' like many folk do!

You indeed have a problem on your hands but it isn't the end of the world;

(female) Threads are reparable with inserts (start by searching for heli-coil for example).

I've cut thousands of threads and repaired many.

In many circumstances (i.e. aluminium) the threads are strengthened/improved by steel inserts.

I've installed thousands.

A stripped thread IS repairable and very cheap but hugely undesirable.

Generally speaking, there's two ways of stripping a thread;

1) Angular;  If you can turn the bolt/nut by hand with hardly any leverage you have got the bolt/nut at the right angle. If you can't, you probably haven't, so don't ever force it!

2) Force;  Never, EVER over tighten a bolt/nut (spend some time finding the specified torque but as a general rule, never exceed 90 degrees after the grip).  If so, you're likely to partially or completely strip it!

H.