Mandolin doesn't stay in tune

I bought a used Breedlove mandolin online recently and had it taken to the luthier to get it set up and fix the nut since it was causing a ringing on the open strings. He fixed the ringing but when I fret the notes they waver on the tuner and go sharp and flat. the intonation will seem in tune at the twelfth fret but I check it a minute later and it's off again. I'm hoping maybe it's a bad batch of strings and maybe a new set will fix it. I'm not sure what else it could be, bad tuners? Any suggestions or insight would be appreciated. Cheers

Sometimes when working on instruments we lower the tension and retune several times which wears the strings out prematurely. I would try a new set of strings and see what happens, it that doesn't solve your tuning problems take it back and ask your repair person.

How recently were the current strings put on by the luthier? They may just need to settle in, although you probably thought of that already.

When I install new strings I very lightly stretch them a few times until they wont stretch out of tune any more, do this very lightly, you will have to do it a few times.....A lot of tuners show the notes going sharp and flat when the string is plucked because the string is being stretched and has to settle down, that is why I just use a tuner to get them close and then tune by ear so that a chord sounds correct, some tuner companies suggest that you pluck the string with just your finger and do it very lightly, some of us have a heavy hand and tend to forget to ease up when tuning...

Let it settle down for a day or so you should be OK...

Willie

Thanks for the replies, the strings have been on for over a month. Full story: i recently moved and took the mandolin to the nearby shop i instrument for a setup along with some dadarrio flatwounds I never tried before. They told me it wouldn't be done until Friday, Saturday rolls around i call they now say Tuesday. I dont hear from them Tuesday I call Wednesday they say Friday. I call Friday they say Tuesday. every time I call one person tells me it will be done this day but everytime I call They say it's the guitar techs day off. at this point I'm fed up so I go in and grab it. I open up the case and someone strung up five of the eight strings but still hadn't done anything about the ringing open string. So frustrated and slightly bewildered at what the heck they were doing this whole time I took it to a luthier slightly further down the road. He had it set up two hours later and fixed the ringing.
The mandolin doesn't necessarily sound out of tune but when I play it against the tuner the notes waver and I start driving myself crazy wondering if it's me, the mandolin or the tuner. The D strings too will stall right before getting in tune and then make a stretching winding sound and then go sharp.
So I think I'll try and change the strings, hate to throw away expensive flatwounds but they might be the culprit

It sounds like the strings are binding up in the slots. I would try lubricating your string slots with graphite. Just loosen a pair of strings at a time and pull them out of the slots and draw in the slots with a sharp pencil until they look gray - both nut and bridge. Then put the strings back in the slots and tune them up and move to the next set.

It is also possible that your string slots are cut too narrowly for the string gauges you have on there now. Did the person who ultimately repaired the ringing string make a new nut for you? I'd try lubricating the nut and bridge slots if that doesn't do it, I would take it back to the person who fixed it and ask them to check the slot width to make sure they are correct.

I'd take it back to the luthier further down the road and explain your problem. Tuning can often be a problem when a mandolin has been fiddled around with. It's worth stretching the strings, tuning it up, palying it hard for a few minutes, retuning it and leaving it to settle for a day or so before worrying that there's something wrong with it. It's difficult to diagnose a problem from afar and not all mandolins react in the same way - don't change things just before you have some serious playing to do.

What kind of tuner are you using? Is the battery fresh?

I agree with al, the strings you have on are not what the nut is filed for. Tell you repair guy what strings you want to use and have him file the nut to match. The ping and going sharp is a dead giveaway for binding in the nut.

Nut binding sounds right to me.
As far as the tuner goes, play the mandolin,not the tuner. If it sounds right to you, and/or other players, don't fret about it.

You probably know this, but 'just in case'. When you're using your tuner, are you gently plucking the string somewhere near the middle of the string and waiting a second or two to let the 'pluck' settle down?

We recently had a whole thread about the problems with getting reliable results with electronic tuners depending on how hard you pluck and where on the string you pluck. So your problem might not really be a problem at all.:)

If a new mandolin is set up to take light gauge strings and then you change to mediums or heavies then the strings sometime bind in the bridge and/or nut slots...I bought a device that welders use to clean the tips of their welding torches and there are about 20 different size small files and a person can select the one that is the same size at the string slot he wants to work on...They cost about 4 bucks at Home Depot or Lowes a great investment...Just make sure if you use one that you tilt the file away from the fret board so that the string rests on the front of the slot for both strings in that pair...Not rocket science but go slow...

Willie