Retired old fart working with wood
I have the Bosch 1617evs and it comes with 2 collets: 1/2” and 1/4”. They do not come apart. Trying to pry it apart has caused damage, and you may need a new one. I use my 1/4” collet every day and insert a 1/8” adapter in it. I only use the 1/2” every once in a while. This is probably the best router out there so it is worth purchasing a new 1;2” collet.