View Full Version : Jib Crane
07-06-2009, 08:38 AM
I needed a small jib crane to move the rotary table, vice, chucks, and projects on and off my mill table and lathe. Heaviest item would be less than 200lbs. The pole is 1 ½ x 10 feet pipe tied to the floor with a ½ inch pin 1 inch in the concrete. The collar at the top is tied to the ceiling joists. The center is braced off the mill. The jib is 1 ½ x 5 foot unistrut. I made two winches. The one on top of the jib raises and lowers the jib. The cable goes from the winch through a pulley center top of the jib then to a pulley at the ceiling collar and back to the end of the jib. The one on the bottom raises and lowers the load. The load winch is moved in and out on the bottom of the jib with a 3/8ths all thread rod. The jib and upper pulley also pivots on the pole.
07-06-2009, 08:40 AM
The winches use 3/32 cable. 12 feet for the load winch and 25 feet for the jib winch. The drums and integral gears were made from 4140 H T. The pulleys and swivel load hook were made from the same material. It takes about 5 - 6lbs pressure on the end of the 6 inch handles to raise the load.
07-06-2009, 09:17 AM
Nice job there Bob!
Not many things are as satisfying as outsmarting Mother Gravity :D
07-06-2009, 01:43 PM
That’s pretty slick Bob, nice work. Do you have a handle on its capacity? I have a piece left over from a water plant project which looks to be the same as your jib. And this has given me an idea.
07-06-2009, 03:18 PM
That is a good looking jib there. I am also curious about the available load. Have you run any numbers or did you do a load twice what you plan to pick up just to see that all is good? Not hammering on you but curious none the less.
And its blue! Didn't you have any green paint? :)
07-06-2009, 03:59 PM
My heavy load would be less than 200lbs. The weak point if I did my calculations right is the pinon gears on the jib crane. More than 1,000lbs before failure. By using the pulleys to spread and even the load on the jib I feel safe at rating it at 200lbs. The pole and jib show no bending at 200 lbs, but I would make them larger for any heavier load.The load winch has heavier gears and starts to fail at 1800 lbs, but the 3/32 cable is only rated at 1200 lbs break strain. That means safe load single line is no more than 240lbs. Both my winches are using double line. Off winch around pulley and back. The winch drums were sized for 3/32 cable and if you used a larger cable you would need to make the drums larger, which would make the winches become larger also.
07-06-2009, 05:45 PM
07-06-2009, 06:11 PM
Unistrut is pretty strong stuff. I used the regular 1-5/8" variety with a bit of stiffening (backer bar clamped to it) to raise an 860# I beam into position for my bridge crane. I simply didn't want to cut up some of my square stock for a single use gin pole.
If anyone's about to build a mono rail or gantry crane, I have a 500# trolley I'd sell for $50 shipped. It's got cast frame plates and ball bearing guide rollers. I'll take pics if anyone's interested.
07-06-2009, 06:36 PM
Jim send me some info.
07-06-2009, 09:58 PM
This is page out of my old strut book. P1000 is the standard 1 5/8ths strut. My jib is supported every 30 inches which according to the chart gives me a safe loading of 625lbs.
07-06-2009, 10:29 PM
Unistrut has online info. www.unistrut.com/
07-06-2009, 10:38 PM
Nice job,anything to save the back helps.
Liked how you attached the top to the ceiling,I did the same thing with a heavier jib crane.It's hard to shove the roof off of a building;)
07-06-2009, 10:43 PM
Thanks Bob. I have been kicking the idea around myself but I would like to boom in my chucks for the lathe. The collet chuck is not bad but the scroll is a bit heavy. And if I position it correctly I could reach the Van Norman as well as the lathe.
07-06-2009, 11:02 PM
I made mine to reach the mill or lathe. The 3/8x16 rod that moves the load winch is slow even with the electric ratchet wrench, but it does give fine adjustment. The jib winch will move the jib from floor to ceiling. The brace off the mill is important as it greatly resists pole buckling. If you can't get a near center support you may need to go to 2 inch depending on load.
07-07-2009, 07:41 PM
Could you show how you made the wheels etc for the trolley inside the unistrut.
07-07-2009, 11:21 PM
These are very similar to the unistrut trolleys. The ones I got for my side sliding doors use a solid axle riveted to the wheels with delrin bearings captured in the frame/carrier.
Btw Bob has spoken for the trolley I mentioned.
07-07-2009, 11:39 PM
No wheels I used a flat plate that rides inside the strut. On top of the plate is the threaded part for the 3/8 all thread. A spacer goes from the plate to the winch frame all are welded together. The winch frames are weldments. I at one time had certifications for structural, and a few others.
I would have to disassemble to get pictures, but would probably be the easiest for people to understand. Hind sight should have taken pictures as I built things.
07-09-2009, 12:33 AM
The load winch hanger slides inside the 1 5/8 strut moved by a 3/8 threaded rod. Total travel is 50 inches. It is normally turned using a electric ratchet wrench from ether end. It moves easily under load.
07-09-2009, 12:37 AM
The gears were cut with a 20 diametrical pitch cutter. The winch flanges are .5 thick giving a total width of the gears of 1 inch. The drum is 2.187 inches total width. Max diameter is 3.15 and there are 61 teeth on the flanges. The bearing for the drum is 1 inch diameter and .020 wider than the drum. It is held in the frame with a 3/8ths bolt. This allows you to tighten the bolt without binding the drum. The pinions are 1 inch diameter with 18 teeth. The pinion shaft bearings serve two purposes #1 is for larger bearings. #2 is to allow a larger hole to be bored in the frames so that you can get the pinion shaft and gears in place. The stop dog has teeth that engage the pinion and swings against the flange gear.
Stop dog detent
Brown part on left is stop dog
Adjustable spring tension plate that keeps the cable smooth on the drum
Your Old Dog
07-09-2009, 10:42 AM
Damn neat looking project. Thanks for taking the time to post all the pics.