Just reading about bues i and it’s tripping me up a bit. When would I use this instead of on i or wnes i for example?
Also there’s been a couple of times during the lessons when I’ve been thinking on i but nes i comes up as the answer. Can’t remember specific examples, sorry. Is there a clear, idiot proof, distinction between the two. Is wnes i a bit more of a specific action like I met someone?
Regarding “bues i”, you could get away quite happily with not using “bues i” at all!
But here is a thread on the form of the verb from the always useful and reliable Forum Wales, if you want to read it!
http://www.forumwales.com/fwforum/viewtopic.php?f=34&t=10292&p=76303&hilit=Buodd+Ieuan#p76303
Edit - and here:
http://www.forumwales.com/fwforum/viewtopic.php?f=34&t=10874&p=78729&hilit=Bues+I#p78729
Yes. 
I did run, I ran - nes i redeg / (rhedes i)
I was running - O’n i’n rhedeg.
There will be occasional times when they don’t quite coincide but they normally do.
There was a thread on here where Gareth King chipped in on bues i etc, not sure where that was, but quite recent. I was going to chip in, but maybe best to read the other link as well.
OK, can’t resist saying something. To me Bues i, since it’s from bod - to be, is more of I had been, which can be subtly different to I was and I did - but not sure how that distinquishes it from on i wedi bod, except it is a bit shorter and gets straight to the point.
That’s what was explained to me when I asked a while ago, and as a result that’s how I read it when I come across it in a book (which is fairly often) and it does seem to make sense.
My tuppence on o’n i : wnes i, there are lots of occasions where one or the other is “correct” and lots where you could “correctly” use either but rest assured that you will never be misunderstood. Just listen and it will definitely become more clear as time goes by.
diolch
Just thinking about this in English - the listener probably has no idea of the mood that we are trying to express. In English - I was going to the shops earlier, I went to the shops earlier, I did go to the shops earlier and I had been to the shops earlier are all different, but all correct with slight diferences implied in the way you say them, but whatever one you choose to use the listener is going to appreciate that some time earlier you were actually in a shop.
Unsure how much use this will be, but I found it helpful to think of bues i as something like “I did be”.
Wnes i gerdded (I did walk) - here, the -es ending (or the “did” in English) implies a completed action without focusing on its ongoingness. The event we’re talking about here happened at some point, and then that was it.
O’n i’n cerdded (I was walking) - here, the yn (or the “-ing” in English) implies an ongoing action. The event we’re talking about was underway at some point in the past, and it says nothing about whether it’s still ongoing now (I might still be walking, for all the listener knows).
Bues i’n cerdded (I “did be walking”, i.e. I did a session of “being walking”, but then that session finished) - this has both the -es (“did”) implying completion and the yn ("-ing") implying ongoingness, so we’re talking about an action that was ongoing at some point, but definitely isn’t any more. This why it’s often seen used for talking about having visited places - e.g. bues i yn yr Alban (“I spent some amount of time in Scotland (but am not currently there)”).
If that’s all a bit confusing: just remember that wnes i corresponds to “I did”, o’n i corresponds to “I was”, and bues i is sufficiently rare in everyday usage that you can definitely get away with ignoring it, at least until you have a solid instinctive understanding of wnes i vs. o’n i. 
I think I’ll go with the keep it in the back of my mind approach for now.
Just asked my brother in law (first language Welsh speaker), “how do you use Bues i?” - “I don’t”
Yep, that’s why it’s safe to not worry about It’s potentially useful to learn to understand it when you encounter it, but you’ll never really need to worry about being able to use it.
What are the ti, chi and ni versions of o’n i’n by the way?
They vary, but common are ®oeddet ti, ®oeddech chi and ®oedden ni, and their abbreviated equivalents o’t ti, o’ch chi and o’n ni. As I recall, the original version of the northern course back when I did it taught the former, and I believe the southern course taught the latter. (Corrections to this assertion welcomed. :))
I did the new levels and the Northern taught oeddet ti, oeddech chi ayyb
Just for the sake of info sharing, as you may come across this in written Welsh, the full version of “®o’n i’n” is roeddwn i’n
Yes, I knew about the longer versions but not the abbreviated ones. The book I learnt from is a few years old and has long versions but no abbreviations… so far as I’ve got into it.
I think a lot of us probably learned the longer forms of pretty much everything first off. I certainly did at school - it was the standard way of teaching Welsh in the 1980s and makes perfect logical sense. Trouble was that no-one mentioned at that time the link to shorter spoken forms, let alone that they even existsed or what they were. It’s hardly surprising that many at school were great at writing Welsh, but hopeless at speaking and listening. Hopefully that has now changed and kids doing Cymraeg as “yr ail iaith” will perhaps get a much fuller picture these days?. Maybe there was an assumption back then that people would naturally link Roeddwn i with ®on i - It seems like a natural link to make, but I certainly didn’t make that connection at that age and I was pretty used to hearing Welsh spoken.
Totally agree. I learnt Welsh in the first three years of secondary between 1978 and 1981.(i know, i dont lookold enough! Lol).
We only learnt the long forms and in three years i learnt only the forms of rydw i, roeddwn i, rydw i wedi, roeddwn i wedi and bydda i.
I learnt the negative and question forms of the above and various bits of vocabulary some of which i remember but most long gone.
In fourth months i have learnt more via SSIW and that includes a month off in August!
I didn’t realise some of the links fro some time either.
Sounds like we probably did the same course - I got an “O”-level in Welsh second language - so I guess you would have learned the numbers as pymtheg, un ar bymtheg etc, rather than un deg pump. Coming back to Welsh after thirty years, I felt like Rip van Winkle, I was blown away by the complete change to decimal, whch must have happened around about the time I left school.
I used to have a little book of Welsh idomatic expressions for writing essays. I really liked those and I would virtually construct my essays around them.
The only instictive shortening that I think I more or less figured out for myself was rwy’n, which is a obviously fine and a form that lots of people use, but not really where I live now or where my family came from. Thinking back it wasn’t that what we were being taught was wrong, its more the many little bits that we weren’t taught that would have made all the difference.