Water filter won't thread onto kitchen faucet

[onceaduck]

I've got a puzzle I'm hoping someone can solve.

I replaced a kitchen faucet with one with the same (standard) size male thread on the spout. The aerators for each faucet will easily thread onto the other faucet, so I know they're the same size (55/64" - 27).

The problem is that the water filters that I had, at different times, used on the old faucet--and which still thread on easily--won't thread onto the new faucet. It's a little difficult getting them started and they will only go on about 1/3 turn before they bind and stop, kind of like they were cross-threading. I'm careful not to try to push past that point in case that's what's happening, but I'm also careful to start them properly, so they shouldn't cross-thread.

The filter I want to use is a Culligan FM-25 (the old one is a Multi-Pure). I see that someone else had a problem with the same filter not fitting onto a faucet (https://www.plumbingforums.com/threads/faucet-water-filter-doesnt-fit.8800/), but it appeared his filter was a different size than the faucet. That's not the case here.

Any thoughts on how I might get this filter to screw on all the way would be greatly appreciated!

 

[TomFOhio]

I just replaced a kitchen faucet that had a water filter attached to it. Had to take the aerator out of the
new faucet and put the threaded adaptor that went from the aerator thread to the filter thread. You can
probably buy one at your hardware store.

 

[onceaduck]

Thanks, TomFOhio -

In my case, there was no adapter for the filters on the old faucet, because the filters had the same size threading as the aerator. This is the case with the new faucet as well. The filters, which each have a built-in aerator, replace the stock faucet aerator and should just screw on in its place. The problem is that the filters only screw on part way on the new faucet, even though the old and the new faucet have the same size thread, which I know because the aerators that came with each are interchangeable. So there should be no need for an adapter.