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i am working with pre-molded stems and iv found that they whistle a little when i take a heavier draw on it. iv tried smoothing the slot out and opened up the hole from 7/64 to 1/8 but to no avail. any suggestions.

Molded stems don't draw well as-is. Think of them more as a "stem in the raw" that has already had most of the excess material removed, but that's it. Removing the remainder is critical to getting them looking good and performing well.

You are on the right track, but it sounds like there's still a significant constriction deep in the slot where it meets the cylindrical part of the airway. Getting that area right takes a fair amount of experience and several specialized tools. How you proceed depends on what you have available to work with.

i'v got a set of needle files. what other tools or advice would you offer to help me open up the airway

You need to make a slot saw. It's really the best tool for the job. I make mine using jigsaw blades that I grind down. I grind down the non-business end to fit into a needle file handle. I don't have any photos but maybe I'll snap a shot next week or maybe one of the other experienced guys on here can post a photo of theirs. I would also open up the airway with at least a 9/64" tapered drill bit. 5/32" is another common airway diameter.

Kurt made a fantastic video explaining this process a while back. It's somewhere on the forum if you have a look around.

That's the one! Factory molded stems won't take the place of good handcut stems any time soon, but if you spend a little time on them, you can make them 100% better.

Let me know if there are any questions on how (or even why) I do it like that.

--K

i use premold stems for now because i dont own a lathe i have to shape each one completely by hand. I made a slot saw out of a hacksaw blade so it wasn't as wide and fit it in a exacto knife handle and it worked like a charm i opened and smoothed out the airway and no more whistle problem at all. thanks for the info guys

I have a Savinelli that used to whistle, until I opend it up to 5/32. It also improved the smoke dramatically. Sometimes that's all it takes.