OK, Computer squared away, now. (whew!)
This is the reference material I use most often:
http://www.wbka.com/wp-content/uploads/2013/06/The-Many-Uses-Of-A-Snelgrove-Board-by-Wally-Shaw.pdf It goes far beyond the Barnsley Beekeepers document
Anyway, I want to answer the OP's question about what to do when you find charged queen cells on inspection and want to forestall a swarm.
First of all, you have to know whether they already have swarmed. If not, then you're in time, but maybe just barely so time may of the essence. Don't put this off until a more-convenient time.
In a "regular" Snelgrove usage, it's a one step-process in which you leave the queen downstairs and (in a general way) put the doings for the bees to make themselves a new queen upstairs and then leave them alone to get on with it. Which in my experience they usually do quite well. It's not terribly critical as far as which,, and how many frames go where sense, beyond the basics of "queen
down" and "frame(s) with eggs or or very young larvae
up", along with sufficient bees and food and pollen resources in each part to carry on. And if you screw up the divvying up of the age-classes of the bees, the little doors allow to you easily move foraging and oriented bees between the sections to get it all sorted out.
But when you are faced with a colony that has already decided to swarm (or else they wouldn't have charged queen cells in place), the Snelgrove board is used for different purpose. And that is to significantly interfere with their plans.
The hive won't swarm unless they have things in the hive arranged so that the colony left behind has a good chance of surviving (swarming is a form of whole-colony reproduction, albeit a non-sexual one.) And a prime swarm, by definition, means the existing queen leaves taking with her a good whack of the colony's younger bees.
So the imminent-swarm usage of a Snelgrove board has to separate the queen from the resources she needs to carry out the swarm. It's an attempt to severely alter the distribution (between the two sections) of young and old bees, and thoroughly interrupt the sequence of maturing brood.
You need to read the instructions in the document linked above, Part III is what you want if you already have queen cells.
But in brief, the bottom box is stocked with empty drawn combs (with some stores as a back up), not with foundation, and two specially-chosen frames (with their attendant nurse bees) that have the proper-aged resources to make a new queen, i.e. eggs and very young larvae. And this is most important thing: Make sure the queen is not on either of these two frames. No need to find her among all the bees the whole hive, just make sure she is not on these two frame. I just look these two frames over very, very carefully, particularly if I have not seen - and temporarily isolated the queen in a nuc box.
(As a practical matter, if the weather is quite warm and well-settled, you could shake all the bees gently off of these two frames and install them above a queen excluder. Leave them for an hour or so and they will become covered with nurse bees, and not the queen. I almost never do this however, because of the risk the colony might truly be on the verge of swarming and that even an hour might make the difference between keeping them at home, or losing them. I do swarm checks with Snelgrove board stacked on my work cart, and if I find that I have failed to head off a swarm and they've made queen cells, I immediately deploy the SB.)
Anyway, the bottom part has the two queenless, but well-supplied with eggs and young larvae frames; lots of empty drawn combs, and all the
oriented bees which will be returning through their familiar entrance points. This part should also be well supplied with supers as the bees will have little else to do, and there is often a good flow on during swarm periods.
Meanwhile, upstairs there are all the other brood frames, both capped and open, all thoroughly examined and relieved of any queen cells you can find; herself, the queen (though you needn't try to go to the trouble of finding her at this point); several empty drawn brood frames; and a liberal supply of nectar, honey and pollen frames since it will shortly become forager-free as those bees will go downstairs. Depending on the weather, and the number of brood frames I sometimes even have a two deep boxes, at the outset.
What's going on here is this: the bottom section, finding themselves queenless will make emergency cells, The foragers and the younger oriented bees from both sections will usually end up here by the end of the day. If there is flow they may do very well gathering it.
In the upper section there is the queen, but she will be without the huge number of younger number of bees she needs to go swarming off with. There are far fewer young oriented bees in the upper section (if they are oriented they've flown out and returned downstairs) and the remaining bees are all needed to tend the brood frames. The queen finding herself suddenly in possession of a lots of empty drawn comb real estate gets back in the egg-laying business, again.
At this point, you may think you needn't do anything more, just like when making a simple division, but you are wrong in this special instance. If you simply left things alone the queen and her colony may simply build back up to the critical mass needed for swarming. And then you'd have a late swarm, which is even more of a problem than a May/June swarm. So there are two more things you need to do: first, bleed off some of the original bunch of nurse bees that were transferred upstairs, using the paired doors. You do this about day 4 or 5.
And then, and this is the most
the most time-critical and important part: you've got to move the queen back downstairs again. You do this on day 7 through 8 (preferred time period) and not later than day 10 after the Snelgrove was deployed. Of course, this means you have to find her, but she will be easier to see in the by-then much-smaller colony and not so runny like she probably was just before a swarm. So you take the frame you find her on, plus one other frame of mixed-age brood (the characteristics of the second frame aren't terribly critical, so don't stress) and stick them temporarily in a nuc box.
Then you lift off the box(es) above the Snelgrove board, and the Snelgrove board itself. Find the two frames of brood that you put down below at the start and move them to the top box. If you have too many queen cells, I would reduce them to a smaller number. (It you have notched the frame a la OTS splitting you may have dozens of cells, which is why I generally don't notch in this instance. With notching, you can get a huge number of cells because the section is so overstocked with bees, like a cell-builder might be. At this time of year it's usually easy to find a frame with eggs and young larvae, so)
After moving the two frames to the upper box, take the queen and her frames out of the nuc and place them in the lower box in the middle. Install the Snelgrove board, again and plunk the upper section's box(es) back down on it.
Now, finally after more than a week, the swarm emergency is over and you're done! The queen, back in her old lair on the bottom should should settle down and get busy laying in all of that empty drawn brood comb. For a several weeks the colony will not have either the sequential
capped brood resources, nor the requisite number of younger bees to make a swarm successful, so it will most likely just decide to give it a pass for the year. Upstairs, the bees with the capped queen cells which were moved up on the frames from below should carry on to select and a get a likely candidate out and mated.
This is jut the Cliff's Notes version of what Wally Shaw recommends, so please read what he wrote (Part 3 is the section dealing with interrupting an imminent swarm, you want the Snelgrove II - Modified version, which is what I am basing my abbreviated description here on.) I keep a laminated copy of the whole document on my bee cart during swarm season so I can refer to it without having to back to the house and hunt it up on the computer. I found Shaw far easier to wrap my head around than Snelgrove's own writings.
If you have still have questions, fire away. This is not hard to do, but it also is pretty demanding to get each detail - and the timing - exactly right. Since you are fighting the innate biology of the bees, this is not the right place for doing it in a half-hearted way. Do it right, or don't attempt it, for it will most likely not be successful and you will lose you one-and-only shot at keeping the bees.
Nancy