There’s not a huge difference in changing to 12/42 as described.

You’ll notice two things if there’s an issue:

1. The string will break. That’ll be pretty obvious lol
2. Intonation might change

I’d be surprised if the intonation changes much

If the string breaks it’s likely because the slots in the nut or bridge need a tiny file to fit the slightly heavier string

This happened when I tried a wound 20 instead of a wound 18. Tiny rub of a file and it was fine

Interesting that you say the setup is perfect but you want to change it already. You have arrived.

Well I mean that the action and intonation are spot on.

I'm just teasing. Banjos naturally lend themselves to tinkering. I'm curious, though, about why you want to go to larger strings.

Enda makes a good point; the small change you want to make is not likely to affect the set up. I wouldn't be too worried about breaking the first string. A .012 string is not going to be that tight with the scale length of a seventeen-fret banjo.
Rub a pencil in the notches on the bridge and nut. You're not planning to make any huge changes in gauge so it's not likely you would have to enlarge the notches.
Go ahead and try the new string gauges. You may find they work better for you. If not, no harm done. The only way you can find what works best for you is to experiment.

I would say call upon your guitar playing experience. When you played guitar did you like light, medium or heavy strings? It's whatever you like best. If the IT-250 is a short scale with a 20 or 21 inch scale then you may want heavier strings just to get the tension right. If it's more like a 22 or 23 inch scale then it's probably OK as is. Also, rather than using a pre-packaged formula, you might want to use a string gauge calculator and assemble a custom set. D'addario for example sells loop end singles, so you can pretty much customize the gauge for each string that way, perhaps going heavier with the low strings. If you like phosphor bronze, you could also try a set of octave mandolin strings. Those tend to be heavier.

For the way I play, I think the 10 in the gold tone set is out of place, and doesn't feel right to me. For IT I'm on the deering set now (12/18w/28w/38w) and like it on several banjos. It's mostly a feel thing, and really only obvious on that E string. If the GT set was 12/20/30/40 I think I would prefer that on my 12" pot.

As far as being new and tweaking goes, strings are probably not the first thing to start changing, unless you can't stand the feel in your left hand. Myself, I'd do picks (and right hand technique) -> head tension -> tailpiece -> strings -> bridge -> head type. There are many more things you can play with, but those first three are the largest contributors to sound and feel.

I see you're from Baltimore. The Baltimore Irish Tenor Banjo Summit is Sept 25-27 this year. You should come join us. I'll be there doing minor repairs and setups again. Here is a link to last year's event.
baltimoreirishmusicschool.org/banjosummit

I don't know why that banjo has a 10, that is way too light. I would use a 12. The 42 will be fine and will give you a little more pop. The only thing to look for there is if it sits properly in the slots at the nut and bridge. You can use the piece of string you cut off to "file" the slot to make sure of a good fit.

The website for the Irish Tenor Banjo Summit is not allowing registration. Is the other information about the weekend and the instructors up to date?

Thanks.

quote:

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Originally posted by malarz

The website for the Irish Tenor Banjo Summit is not allowing registration. Is the other information about the weekend and the instructors up to date?

Thanks.

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The venue will update the website around a month ahead of time. It's a bit frustrating for the organizer, but it is what it is. It is an amazing event. It will be heavily promoted on Facebook. I will try to post something here when the website is live. I will post to my Trad Banjo Facebook page if you would want to follow there.

Thank you for that information.

It will be great to meet you in person, so please let me know if you will be there.

Will do.