Instructables

Step 5: Put in the lag bolt and finish up adding the mortar mix.

Before putting in the lag bolt, mark off with a sharpie where 1.5" is from the pointy end so you know how far to push it down.

Put the lag bolt into the mortar mix. Because the lightbulb shape has some undercutting with the mold, the mortar mix wants to clump up in the middle of the bulb and not grip the sides. You can use the head of the lag bolt to tap down the pile in the middle of the bulb so it starts filling in all the gaps.

Keep adding mortar mix around the lag bolt to fill it up. Holding the lag bolt firmly to make sure it does not rattle, keep shaking the bulb and tapping the sides to fill in gaps and liquefy the mortar mix.

Take a coffee stirrer you "borrowed" from Starbucks and use that to tap down the mortar mix. You want to keep adding the mix, tamp and fill, tamp and fill. Finally the entire bulb is all done and you are tamping on the top. You want the mortar mix to be level with the top of the hole but not sticking out in a bulge.

When you are all done, put the lightbulb with the lag bolt pointing up in a spare plastic cup. The ones I used where also borrowed from Starbucks. Take a rag and clean up the metal threaded part of the lightbulb as well as you can - you don't want the mortar mix drying on it.

Set this to the side for at least 72 hours to let the mortar mix cure. I normally write the date it was made on the glass with a Sharpie so I can keep track.
 
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asteidl2 years ago
Haven't got solid plans for my afore-mentioned home-made tool idea, but I do have some ideas, revolving around http://www.amazon.com/0-04A-10000RPM-Vibrator-Vibration-Motor/dp/B005G0NQEG/ref=pd_sim_sbs_hi_2 and a big nail, a battery pack, and a few zip-ties.
asteidl2 years ago
A miniature concrete vibrator would be perfect for this project, I've seen enough concrete work in construction, I may try to make one, for this and similar projects. Concrete seems to be a great medium for functional art, being that it's cheap, strong, and durable, and can take a decent finish.
drakesword4 years ago
If you made the mix a bit thinner (add more water) you could shake the bulb for a bit and get most of the air out easily