You can definitely mess up the threads. The NaOh will attack of course the thiniest metal or at least that is of course where it is most evident.
I have done this myself. There is a learning curve. Unfortunelty I fly by the seat of my pants so I have gone through some messes.
One of the best controled way is to use a product called greased lightning. It may not be available to you in your country.?
Being it is a already mixed solution it works great to slowly removed the old anodizing on a part. It takes about 1 to 2 hours for a good job.
I also use pure lye. I get it at the hardware store as drain opener. This can be very dangerous to you and the parts.
I put 1 to 2 teaspoons in 2 quarts of water and depending on the part being stripped it takes 5 to 10 minutes at most.
Once again this can easily damage the part that is why I suggest the other method.
Now you could dilute the mixture more.
What I do is, wearing gloves of course, constantly agitate the part and scrub it with a tooth brush. This way you help it along and you can monitor the progression of the stripping.
Once again the lye burns. If level of mixture is to high the solution can reach in the 300 degree range. I was warned of this by someone else.
This made me curious so I put a table spoon in about a 1/2 cup of water in a plastic container and it steamed and the fumes were strong.
The bottom of the platic container melted quickly. I don't recommended doing this but I am a little nuts.
In all these things you always need to remember to protect the hands, protect the face, lots of ventilation and never lye near the acid your going to use for anodizing.
Bottom line safety, safety, safety!
I hope I helped.
If you have more questions I will try to answer all questions.
Have a great day!
Ed