A "Ceiling Jack" is a tool that will push up on something overhead fairly strongly. It could be used to hold up a porch roof while replacing a rotted post, support a tree limb to more properly tie it to the tree for support, or even hold a shower liner in place with a plywood spreader foot while expanding foam cures to adhere it to the wall. I have even used it to remove overhead demolition parts by simply pushing them off their nails. This design can honestly exert close to two thousand pounds of force, though I have probably only tried to do half of that. The weak point would be the crush/collapse strength of a piece of Unistrut on end. The cable and winch are rated at 2000#, and the snatch block for some multiple of tons.

Every once in awhile I will notice that someone has run their car over a corner stop sign, (or a RR sign, or a bus stop, or some sort of public notice like "No Parking,, or "Lane Ending", that is on an aluminum plate). Nowadays most of these are posted on a two inch square hollow steel pipe with a 7/16' hole every inch. If I see these lying on the ground, I salvage them. With the frequent holes they make fabulous gate posts, jig parts, and I have found they fit perfectly in the two inch receptacle of a tow hitch.

You will please notice that the common "Unistrut", (probably a copyrighted name), fits perfectly inside the two inch square tube.

Now I am gonna explain how to use these two items together, with a bit of other hardware, to make what I consider a truly useful tool, a "Ceiling Jack." I have also used it to push on a wall, do overhead demolition work by pushing parts off of their attachments, and just pushing a car a couple feet in a driveway.

If you make one, and come up with attachments or special ends, I would appreciate you adding them in the comments.

Step 1: Step One: FIND a BROKEN SIGN POST

After finding and salvaging a broken signpost, (and I have recently while on vacation in Hawaii discovered that this may be hard to do there, as they use an octagonal version), eyeball down the post to check for straightness. (Crooked won't pass the internal parts well.). Then cut off the damaged end, (where it got bent while being run over), file off the sharp bits, and set it aside.

Since I have never found waste Unistrut, as it is usable even in the most shortest of bits, I went to the big box HD and bought a ten foot piece. Not really very expensive. Plus,......hmmmm, well, it seems I need to make a list. Next Step is a shopping list.

Step 2: Step 2: SHOPPING LIST

Ten foot length of Unistrut.(HD)
Three Screw-type chain repair links (HD)
One "Snatch Block" type pulley. (HF)
One Boat Winch. (HF)
Couple cable connectors. I suggest these flat style, the "U" bolt style may be too large to fit inside the Unistrut. (HD)
Two or three bolts to hold winch. 3/8" x 1" with nuts and washers. (HD)
One two inch square post from a run over sign. (Found on side of road.)

Step 3: Step 3: CUTTING UNISTRUT

Since you already cut and dressed the end of the post, that is taken care of.

The Unistrut will likely be cut in half, depending on how long you want the final jack to be, and the operating range you expect to build into it. Figure you will want a couple feet of the Unistrut to remain in the post at the most full extension, that gives you three feet of range in the pushing motion If you put a five foot piece in six feet of post. You could cut it at six and four feet, or whatever you wanted, to offer various ranges of motion. I made two of these at the same time, and did two five foot sections of unistrut in two six foot posts.

Considering that formerly I had to balance a hydraulic car jack on a 4x4 or 6x6, which was cut to exactly the right length to allow the jack to fit into the equation of what was the distance from base to what was being pushed, and giving 4 or 5 inches of range of motion, the three feet of range is a great improvement. On average the salvaged portion of the sign post is about six or seven feet long, so the Unistrut, if allowed to fit inside the post, could be that long and offer more range. But normally a ceiling is at about eight feet, so two six foot models worked well for me. Mine have six feet of post, with half of the purchased Unistrut, five feet, inside each.

After cutting the Unistrut, file dress the cuts to remove sharp burrs.

The "U", groove/open side in the unistrut fits nicely around the bolts that hold the boat winch to the post, and the pulley, and the cable that goes to the bottom of the unistrut. Before installing the unistrut, drill a couple of the holes in the "back side" of the post larger, (I used a stepped bit from HF), so the heads of the bolts that pass through the post to hold the boat winch have room for a socket to hold them inside the post. Imagine the post standing on the floor, and the winch a comfortable four feet or so up on the post.

Cut a slot in the upper portion of the post so the snatch block pulley will fit into the slot, hung by two threaded chain links from the upper two holes. (If you cut the post properly, removing half of the first hole, the link will fit in the depression of the first hole.)

The first chain link will also fit through the slot in the Unistrut.. Cable passes up from winch through snatch block, then down through the Unistrut open slot to the bottom of the unistrut. (I used a chisel that has rounded tip for denting metal to dent in one of the "spaces" between the holes in the flat side of the Unistrut, that way the cable doesn't bind against the inside of the post as it is sliding up or down,) Loop the cable out at the top of the dent, then back in the next hole at the bottom of the dent.

Then end of cable is u-bolted or connected to itself inside the Unistrut. My piece of post is about six feet tall, the Unistrut is half of a ten foot piece, five feet long. This gives me about three feet of range to jack something from six feet to nine feet, and somewhere around a ton of capacity. A bit more range could be added with wood blocks. The pieces could be cut differently for special applications.

I stick a 3/8" bolt in a cross hole in the top of the post , then crank the Unistrut up tight against the bolt, to hold the Unistrut in during transportation.

I have used it to push up a ceiling, a full small water heater on it, push a wall sideways to hold it in place during construction, and to hold a shower wall in place while the foam adhesive cured inside the wall.

Step 4: Step 4: PREPARATION OF UNISTRUT

The "U", groove/open side in the unistrut fits nicely around the bolts that hold the boat winch to the post, and the pulley, and the cable that goes to the bottom of the unistrut.

Before installing the unistrut, drill a couple of the holes in the "back side" of the post larger, (I ussed a stepped bit from HF), so the heads of the bolts that pass through the post to hold the boat winch have room for a socket to hold them. Imagine the post standing on the floor, and the winch a comfortable four feet or so up on the post. Cut a slot in the upper portion of the post so the snatch block pulley will fit into the slot, hung by two threaded chain links from the upper two holes.

The first chain link will also fit through the slot in the unistrut.. Cable passes up from winch through snatch block, then down through the unistrut open slot to the bottom of the unistrut. (I used a chisel that has rounded tip for denting metal to dent in one of the "spaces" between the holes in the flat side of the unistrut. that way the cable doesn't bind against the inside of the post as it is passing out, down, then back in the next hole at the bottom of the unistrut in the post. Then end of cable is u-bolted or connected to the cable in a small loop with one of the new flat cable connectors inside the unistrut. My piece of post is about six feet tall, the unistrut is half of a ten foot piece, five feet long. This gives me about three feet of range to jack something from six feet to nine feet, and somewhere around a ton of capacity. A bit more range could be added with wood blocks. The pieces could be cut longer for special applications. But the post is salvage, the unistrut from HD, the one ton winch is about twenty bucks in HF, the cable comes with it. The snatch block pully runs about seven bucks and is rated at a couple thousand pounds. The bolts, and chain connector links add probably less than ten bucks to the cost, or you may have them laying around. I stick a 3/8" bolt in a cross hole in the top of the post , then crank the unistrut up tight, to hold the unistrut in during transportation. I have used it to push up a ceiling, (With a full small water heater on it), push a wall sideways to hold it in place during installation, and to hold a shower in place while the foam cured.

Step 5: Step 5: DRILLING POST

Using a TiN coated stepped tapered drill bit, I make two or three holes for bolts head's to pass through. The opening of the Unistrut will be at the bolts. Space the holes so the boat winch holes fit them. The bolts pass through the post, the boat winch, and then get nutted into position.

Step 6: Step 6: CUTTING POST

Depending on your snatch block, two or three threaded chain repair links attach it into place. Then cut a hole in the post that the snatch block will fit through on edge. I did this with a Dremmel and cut-off wheels.

Step 7: Step 8: ASSEMBLY

If you already attached the boat winch, and the pulley, Now the cable attaches to the bottom of the Unistrut by looping around the dented section between the holes, then the end of the cable gets attached to the cable itself.

Push the other end of the cable up through the bottom of the post and out through the snatch block pulley, then carefully insert the Unistrut up through the post, keeping slack of the cable pulled up to prevent kinking.

Allow several feet of extra cable to the winch to wrap around the winding pulley. This allows the friction of the cable on the pulley to help hold it on. then bolt the end of the cable to the pulley as it shows in instructions.

Keeping some tension on the cable, (but never allow cable to slide through your hand!), wind up the winch till the Unistrut starts out of the post.

Now go push something up. Or sideways.