Hi folks. I have a hunk of lava that’s nicely pot shaped that needs some drainage and tie-down holes. Any suggestions on tools, drill bits, techniques etc? Is there much danger of cracking the whole thing?
The best material would be a diamond impregnated drill bit, they are available in numerous sizes. Use water and low speed. Let the bit do the work, meaning don’t push the bit very hard into the material.
Hope this helps 
Get a bit rated for stone. I’ve used Bosch bits from Lowes. Let the water flow over them and only use the lightest pressure. I’ve drilled through different stone types all with the same bit.
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If your drill has a hammer action on it, turn it OFF.
Drill slow, drill smooth, use water to cool the bit. Ceramic tile bits will also work, but masonry will do fine and tend to have a better selection of diameter.
How hard/soft is the slab?
There will always be a bit of a blow out as you punch through, so you may want to go from the outside, in.
Support the slab on the back of the hole with something you can drill into (timber), as this will reduce the chance of splitting the slab.
Don’t put holes in a line that follows a fault. Look for the most solid sections to drill through.
You can always use a 2 pack epoxy putty to glue on tie down wires.
A picture of the slab would really help.
Thanks for the suggestions. I used a series of carbide bits, going up in size to avoid damage. Worked great.
I did end up drilling from the inside out to make sure I was hitting the lowest points, no blowouts on the bottom.
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Thanks! Loving the lichen!
What are you planning on planting in it?
Thanks Andy. Hopefully the lichen does OK.
Here’s my lame attempt at superimposing the pot on the spruce that will go in it next spring, or the year after. The roots could probably use another year of development.
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And on that note, should I have the tree mostly styled before planting it on the rock? I’ve only done some basic structural work, it’s not quite in the refinement stage.
Interesting question. One school of thought says you should style first and then repot- that way you are less likely to damage roots when styling. The other school says that with spruce, where individual roots can relate directly to specific branches, you should repot first, then when the tree is happy, style.
Awsome… A little cold to wire now. Unless you are above 40F, then wire away…
Just my opinion… I would turn the pot 180, so the curve cradles the tree curve… movement to right.
I see what you mean. If I kept the orientation above I would plant it further to the left than the picture above, but I’ll play with the option you suggest. It’s put away for the winter, so it’ll have to wait for spring. I don’t want to undo my bonsai winter storage Tetris 
Yup…I just finished puting mine away last week.
Been a long year.
Bought about 100 lbs of akadama.
Looking forward to spring. Club meeting today was sparse…
Super pot and tree combo! Tetris…LOL
@Brad You never did say where you are… I could use one of those pots…
45 F here in day, 22 F at night. Pacific NW. Hoping spring will hold off till March…