Finding or making 15 foot long acme threaded rods ...

[arvidj]

I would like to find two 3/4 or 1 inch acme threaded rods that are 15 feet long.

I have looked on McMaster and other places and the longest I can find [insert 'reasonably priced' disclaimer here] is 12 feet.

Options seem to be :

Try some of the industrial suppliers and see how much they would cost. I am assuming sticker shock will be in order and have therefore not bothered with that yet.

Figure out a way to splice two reasonably available pieces together ... i.e. a 9 foot and a 6 foot or a 12 foot and a 3 foot or 5 3 foot pieces or ??? Suggestions on how to make a reasonable splice would be appreciated.

Get a 15 foot long rod and then figure out a way to cut the threads on a 14 x 40 lathe.

And in case you are wondering, it would be for an elevator to the second floor of my new shop. I thought about cables but then have the 'what if the cable breaks' scenario. Two threaded rods would address the need for a brake, etc. and provide a very compact form of motive power.

Thanks for you suggestions,
Arvid

 

[markba633csi]

Check with Roton, they may have stock that long. Have you considered roller chain with a worm drive motor? More than strong enough, and safe.
Mark
ps you could cut a long thread on a lathe, thread in sections using rests, tricky but possible. Do some reading about Otis elevator company and their safety systems.

 

[arvidj]

Check with Roton, they may have stock that long. Have you considered roller chain with a worm drive motor? More than strong enough, and safe.
Mark
ps you could cut a long thread on a lathe, thread in sections using rests, tricky but possible. Do some reading about Otis elevator company and their safety systems.

According to the Roton site they most they have is 144 inches or 12 feet.

Thanks for the idea of the roller chain. I will have to think about how I would route that and make it work. Thoughts and ideas gladly accepted.

I'd thought about how to do it with the lathe however my vision of the supports for the overhanging ends ... both at the head end and at the tailstock end ... have a definite Rube Goldberg look to them.

Arvid

 

[mikey]

Give Roton a call. They can probably do a custom order for you.

 

[Groundhog]

There are a lots of ways to insure safety when using wire rope for lifting, usually requiring a second wire rope or a pipe. Either one with a rapid descending apparatus attached.
Go look at a car hoist at your local mechanics shop for ideas or google OSHA approved descender rigs.

Edited - do not use any of these methods to move people!!

 

[Wreck™Wreck]

I built an elevator for a customer about 10 years ago, one 1/4" wire rope in each corner all four were pulled by one 72" long ball screw and nut driven by a gearmotor with a brake. Pulling the ropes from the middle doubles the travel so the lead screw only needs to be 1/2 the desired lift distance.

In the past I did a good deal of work for elevator service companies, no traction elevator that carries people has only one rope and many have as many as 6, each of which has a working load above the capacity of the car with max passengers and counter weight itself. In order for the car to crash all 6 would have to fail at the same time.

As a side note elevator mechanics have some of the most amusing on the job customer stories of any trade, a guy told me that he once went on a n emergency service call at 3:00 AM on a Saturday, 3 drunks stuck between floors for 2 hours before he gets there, one of them staggered into the control and hit the E-Stop. Of course none knew what the big red button was for or how it worked, He yells up the hoist way "try pulling on the big red button" and boom, fixed.

 

[markba633csi]

LOL boy you have to be pretty clueless (and drunk) not to figure that one out
Mark

 

[Ulma Doctor]

i believe that anything that carries people is supposed to have a 10:1 safety factor.
simply put, if the payload is 1000lbs, the structure and components should have 10,000lb failure rating

 

[dave_r_1]

For joining two pieces together, you could make a several-inch long nut to align the thread of both rods (nut is half on one piece and half on the other), then clamp both rods down, then wind the nut off to one side and weld the pieces together. Then single point the welded area so the nut can go over it. I would use the 12'+3', you won't need a huge lathe to do it (the 12' section you need to rig up a support out past the thru-hole).

 

[arvidj]

For joining two pieces together, you could make a several-inch long nut to align the thread of both rods (nut is half on one piece and half on the other), then clamp both rods down, then wind the nut off to one side and weld the pieces together. Then single point the welded area so the nut can go over it. I would use the 12'+3', you won't need a huge lathe to do it (the 12' section you need to rig up a support out past the thru-hole).

Interesting. I had considered joining two pieces together but had not figured out how to ensure the alignment was correct. Thanks for at least one solution to that part of the challenge!!