Pick your suicide workers carefully. Make sure they don't have any magma safe materials in their possesion. Give them copper picks and lock them in the work area.
1. Dig a channel over the unrevealed SMR. This will reveal the layer underneath with an unusable upward ramp and create a magma flow floor tile where the channel designation was.
2. Collapse a regular constructed floor into the shaft to flatten the shaft to the bottom. This moves the magma flow tile down one level where the unusuable ramp was. Use a magma NON-safe stone or wood for this step.
3. Pour some magma into the shaft.
Just enough to fill the very bottom, you don't want more than one layer of magma in the shaft. If you do, you'll have to do more work to get rid of the obsidian. It turns out that creating obsidian in the upper part of the tube doesn't matter, just remember to dump the obsidian stones before you remove the stairs. The magma is used to melt/destroy all items present.
Don't proceed with step 4 until all items have melted and dispersed. The only thing on the tile when you loo(k) should be Magma flow and Magma 7/7. Any magma globs will suspend constructions for the next step.
4. Use a pond designation to pour a single bucket of water to remove the magma at the bottom. Since it is on a magma flow tile, it doesn't create obsidian.
5. The shaft should be clear of all items, build a constructed staircase down, one layer at a time. At the bottom, build a Upstair. Then remove the staircase from top to bottom. The dwarfs will stand under the construction being removed, So remove the bottom upstair last. This is essential so the whole process is repeatable. When the upstair construction is removed, the magma flow tile will be converted into a normal stone floor. This is a suicide mission.
6. Go to Step 1st for the next layer down.
note) It has been discussed that flooding the shaft with water and allowing the miner to swim out may be possible, but I have not verified this theory yet.
Tour 1
http://www.youtube.com/watch?v=nfSifBzgwIETour 2
http://www.youtube.com/watch?v=fSxv6TewdpABreach
http://www.youtube.com/watch?v=IwcZSvbMrowHow to mine Slade:
Video Part 1
http://www.youtube.com/watch?v=urM19dQrsJ4Video Part 2
http://www.youtube.com/watch?v=Hcalni8h8AkThis is very cumbersome method, but it works and yields as much slade as you could want, limited by how much floor space you decide to floor over. Otherwise, its limited to less then a 1/4 of the total floor area of the underworld caverns. I haven't tested it this works on the hills, but I don't see why it wouldn't.
Step 1. Find an Eerie pit next to your quarry. You will need to find a perfect spot. Two things need to line up. You need an Eerie pit edge. You need to find an accessible Magma flow tile directly above it. You'll need enough room to collapse a floor onto it to make it fall through and land in the Eerie Pit. This is just 2 3x3 rooms, one on top of the other, with a way in from the side.
Step 2. Prepare the drop site. Construct a floor over the Eerie pit tile. The Magma Flow tile needs to land on it.
Step 3. Prepare the drop shaft. Unlike the long difficult method of breaching SMR, once you are in the underworld, you can construct scaffolding up to the unrevealed ceiling and dig staircases from bottom to top through Semi Molten Rock with no problems. Stop short of breaking through and destroying the magma flow tile(if thats possible, I haven't tried) Channel out the stairs from top to bottom to leave an open shaft with nothing in it. Remove all scaffolding in the way between the Magma flow tile on top and the constructed floor over the Eerie pit tile.
Step 4. Prepare a Cave-in above the Magma flow tile. I build a support directly on the Magma Flow tile and put a floor on top of it, then make sure its disconnected from all 4 sides. Link the support pillar to a lever.
Step 5. Prepare the Mining Area. This is the most important step. You need to build constructed floors over the slade cavern floor over the entire area you plan to mine slade from. Floor over the entire area before you continue. It may not be possible to convert anymore unrevealed tiles after you begin. Use High value materials to pave the floors with, they will be duplicated and can be mined out for profit.
Step 6. Pull the lever to trigger the cave-in. the Magma Flow tile will fall down and crash through the constructed floor above the Eerie pit. This will punch an 'open space' hole in the Eerie pit tiles.
Step 7. Get a miner in there. Do whatever you can to get a miner to drop into that open space. I have him stand on a constructed staircase and remove it while standing on top. He will fall one Z-level and be stuck below.
Step 8. Use the Stuck miner to build a constructed floor on an adjacent Eerie pit tile. This gives him a place to stand.
Step 9. Make him build an upstair on the Magma flow tile then remove it. the Magma Flow tile will be gone now
Step 10. Make him channel straight down from where that Magma Flow was. Go as deep as you want, the bottom Z level of the map should be very close. Start to mine out a room.
Step 11. Mine or build upstairs every other tile. Extend those upstairs to the underworld floor above. The upper Z-level, just under the floor will not be changed into natural stone. It will remain Slade and can be mined from below.
Update:
As Tomsod suggested. You can use raw adamantine to pave the slade cavern floors. this will duplicate it and you will have multiple layers of fresh raw adamantine to dig up.
Obsolete Info:
I broke the game:
Original Post:
I've been reading up on how SMR works and have been experimenting. I think I figured out how to dig straight down through indefinite layers of semi molten rock. I haven't figured out how to optimize the process yet, its very experimental, but right now I have 3 layers dug out. Still haven't busted into hell yet.
I am also writing this thread to organize my thoughts and figure this thing out.
This what I am trying:
First, dig a channel in your stone floor with unrevealed SMR beneath it.
Create a controlled cave-in with natural stone wall to fall in the gap.
Sacrafice a peasant to mine out a staircase, designate an upstairs at the bottom, then make him channel out the upstairs at the bottom to get into the next layer of SMR. the miner is stuck now. Drop another natural wall on him and continue from the last step.
I have been using a magma and water reservoir to cast new obsidian walls to drop. I also had some mistakes. Like, don't send a mason down to build an up stair at the bottom then try to remove it, the mason will be stuck. But this can be used to remove a magma flow tile that is eating your cave-ins, so it might be nessesary. If that is the case, I may need to sacrafice 2 peasants per layer of SMR.
I haven't tested enough to know for sure if that step is required.