Going to need more info please.
How did you do a screw thread before?
FC0.17 does threads much better now, but there are some changes in the process.
Very quick explanation:
You need to make a helix in Part WB then in Part Design WB make a shape binder from the helix, then attach datum plane to shape binder, add thread profile sketch to datum plane then do additive or subtarctive pipe as required. There is a forum thread with more detailed instruction somewhere. Perhaps someone else knows where it is?
You can do a split washer that way too, in answer to your other thread.