Question:
How do I work around borer with keys on a keychain? Can I select one that I don't need for now if leaving house now with the key? I don't need it now so how do I select it from the keychain. thank you
Answer:
Hello,
I’m having a hard time understanding the circumstances of your question. If there is an eruv, you may carry the whole ring of keys, which would be tiltul min hatzad, letzorech daver hamuter. Unless you have the remote control of a car attached to the ring[1], then the whole ring is a bosis, and it cannot be moved, and removing the key won’t be possible.
If you are referring to Yom Tov, and you want to separate the key you want because you don’t need to carry the other keys. Since you are taking the good from the bad, you may do it even if it is for later that day, (see M:B 510-7).
But let’s say that you do have a case where borer would be an issue. If it is the key to your house, then you will be using it to lock the door now, and it isn’t for later. If you need the key let's say to open the aron kodesh of the shul, then open it right when you get to the shul, separate the key right before leaving to shul. Walking to the shul would be considered part of the preparations to be able to use the key, and would also be considered for now (according to some poskim). But let’s say you are not going straight to shul, but you will stop off in a different shul to learn for an hour before going to daven. You can think of a use for the key before you take it off[2], such as to scratch your head or back with it now, then it is still considered as taken for an immediate use.
Best wishes
Sources:
[1] לוח מוקצה ערך צרור מפתחות הערה 853.
[2] ע' פסקי תשובות ס' טי"ש אות ז' שהעריך בזה שכדי שדבר יהיה נחשב למיד א"צ שההשתמשות יהיה השימוש הרגיל של הדבר. וכן שמעתי מכמה פוסקים שאפילו לגרד את הראש במפתח יחשב כמו שלקחו עבור עכשיו, אע"פ שהוא יכול לגרד ראשו אם כמה דברים אחרים, עדיין הוא לקח החפץ הזה עבור שימוש של עכשיו.
