Assuming that you have a plastered ceiling then the neatest way to do this involves lifting floorboard in the room above. This is my cunning plan so far, there are easier ways to do it but this should provide a safe and secure suspension point.
The advantage of using a cross member between two joists is that you can get a crossmember of appropriate width for drilling the hole for your eyebolt. You don’t want to drill a hole directly through a thin joist to accommodate your eyebolt and weaken the joist itself! With any luck this method will also not result in lots of holes drilled through your ceiling as you aim for a joist or crossmember blindly from below.
Lift floorboard above where you want the suspension point.
Drill a pilot hole, mid way between to joists, down to check you are in the right place in the room beow.
Drill a hole through a beam to use as a cross member. The cross member should be shorter than the joists to allow space for the top of the eyebolt and the nut(s).
Install a crossmember between the two joists over the pilot hole.
Drill through the pre-drilled hole in the crossmember and through the plaster into the room below.
Pass the eyebolt up through your shiny new hole.
Place a large washer or reinforcing plate over the end of the eyebolt to further spread the load.
Install at least one nut preferably 2 with one of them being a lock nut
Tighten each nut in turn while someone in the room below holds the eye in the orientation that you are hoping to achieve.
Before refitting the floorboards above consider adding an access hatch so you can check on the suspension point easily. You’re less likely to check if its hard to do!
Make sure it is a nice fat one that is stainless steel and forged. Read the Crash Restraint article linked above for why you need one of these and not a cheap one.
I want to build a lighting rig. In fact I want to build a couple of lighting rigs. I think I can canabalise a kids trampoline to do this. Before anyone whinges, I’ve got another trampoline from freecycle and the boy gets to choose his favorite before I hack apart the other!
The first rig I want to be a simple small bar over my desk as a place to rig a couple of lights for testing and to have them out and in use as oppose to boxed for most of the time. I should be able to do this from either the legs of the trampoline or the uprights that hold the netting that stops the boy bouncing off it.
The trampoline breaks down into 4 sections that gives me several modular options of making a small circular rig, an S shaped rig using all four pieces, 2 smaller S shaped rigs or 4 separate curved sections.
Normally the pieces just slot together and are held in place by the tension on the springs and the bit you bounce on, as I’m not going to have this, I’m going to drill through the bits that slot together so that I can drop a bolt in to hold them together.
Ideally I would weld a loop at the end of each section to attach a supporting chain. But as my welding is none existent I’m going to have to settle for bolting the sections together with eyebolts, having the supporting chain go around the bar and attach to itself AND the eyebolt with a quick link. This way the bar rests on the support chain and the load of the whole rig plus lights is not on the nut on the underside of the eyebolt. The eyebolt will prevent the chain slipping along the bar but should not be considered as load bearing.