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



## arvidj (Dec 18, 2017)

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


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## markba633csi (Dec 18, 2017)

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.


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## arvidj (Dec 18, 2017)

markba633csi said:


> 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


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## mikey (Dec 18, 2017)

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


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## Groundhog (Dec 18, 2017)

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!!


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## Wreck™Wreck (Dec 18, 2017)

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.


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## markba633csi (Dec 18, 2017)

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


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## Ulma Doctor (Dec 18, 2017)

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


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## dave_r_1 (Dec 18, 2017)

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).


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## arvidj (Dec 18, 2017)

dave_r_1 said:


> 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!!


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## Wreck™Wreck (Dec 18, 2017)

markba633csi said:


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


A majority of people spend their lives working in industries that have no E-Stop devices because they are not needed in most offices. 

As beneficial as it may be sales people have none either, this is an egregious oversight.


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## Wreck™Wreck (Dec 18, 2017)

Also a 180" X 1" diameter acme lead screw would develop a good deal of twist at the far end when rotated under load, a ball screw would be a far better choice for such an application, nearly zero friction.


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## f350ca (Dec 18, 2017)

Another thing to consider is the shaft whipping. It can be calculated, Im guessing 15 feet of 3/4 or 1 inch shaft would have a pretty low speed.

Greg


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## Eddyde (Dec 18, 2017)

Many small elevator systems use a hydraulic cylinder and cables, the cylinder can be a fraction the travel required using the cables around pulleys to multiply the travel and achieve the desired lift. There are several safety devices that can be employed ratchet paws or centrifugally actuated brakes. Steel cable is very strong and very safe if used correctly.


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## Scruffy (Dec 18, 2017)

I’d go with wrecks line of thought. Sounds like he’s been around this.
Thanks ron


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## savarin (Dec 18, 2017)

What about a water powered lift.
We have heaps of these in Oz, no pits, no huge headroom and very safe for one story.


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## Eddyde (Dec 19, 2017)

Like this?


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## savarin (Dec 19, 2017)

too complex, this is the sort of ting I was thinking of
http://www.aussielifts.com.au/installation/faq/


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## Z2V (Dec 19, 2017)

Arvidj 
This elevator is just for moving material only,  correct?


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## MozamPete (Dec 19, 2017)

I've always liked the 'Alimak' type hoists for a simple design - some guide rails and a vertical rack gear as long as you need attached to the wall, with a motor and a pinion gear attached to the platform and a trailing cable.  Normally I think the pinion gear is driven by a worm wheel gear motor so it wont roll back or fall if the power is lost - you actually need to drive the motor in reverse to bring it down so it is intrinsically safe.

Something like this but on a domestic scale.


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## JimDawson (Dec 19, 2017)

Portable Hydraulic Elevator


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## arvidj (Dec 19, 2017)

Wreck™Wreck said:


> Also a 180" X 1" diameter acme lead screw would develop a good deal of twist at the far end when rotated under load, a ball screw would be a far better choice for such an application, nearly zero friction.



Thanks for the thought but a quick look at the costs associated with a pair of 15 foot long ball screws puts it far outside my budget. Four digit numbers for just one screw in the cases where I could find anything long enough to work while a 12 foot long acme from McMaster is only about $63.

This company ... Ram Manufacturing ... seems to have been successful using acme screws in their commercial lift applications, to the point where they actually provide some justification for their choice of acme over ball screws.


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## arvidj (Dec 19, 2017)

Z2V said:


> Arvidj
> This elevator is just for moving material only,  correct?



This is similar to a question from my wife .

The only answer I can provide without taking this thread down the safety nazi rabbit hole [which is where similar threads have gone and is not relevant to the specific question presented] is 'Yes, materials only'.


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## Wreck™Wreck (Dec 19, 2017)

arvidj said:


> Thanks for the thought but a quick look at the costs associated with a pair of 15 foot long ball screws puts it far outside my budget. Four digit numbers for just one screw in the cases where I could find anything long enough to work while a 12 foot long acme from McMaster is only about $63.
> 
> This company ... Ram Manufacturing ... seems to have been successful using acme screws in their commercial lift applications, to the point where they actually provide some justification for their choice of acme over ball screws.


I just read the document from Ram Manufacturing, the idea there is CHEAPER then everyone else.
Yes ballscrews will back drive and require a brake. Most all commercial traction elevators also require one or more brakes, also a governor in the event that it overspeeds either up or down.
Old elevator controls are truly fascinating to watch in operation, simple relay logic top to bottom.


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## Z2V (Dec 19, 2017)

Wreck™Wreck said:


> Yes ballscrews will back drive and require a brake. Most all commercial traction elevators also require one or more brakes, also a governor in the event that it overspeeds either up or down.
> Old elevator controls are truly fascinating to watch in operation, simple relay logic top to bottom.



Ahh, something I can relate to. You could often times troubleshoot the old relay controls just by listening to the sequence of the relays picking and dropping. I miss the old relay logic stuff.


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## rock_breaker (Dec 20, 2017)

Off the wall I would look at a 2 drum winch system with an equilizer bar between the ends. If one cable broke the bar could be mounted so that stops for either end would hold the elevator. Obviously all components must be sized according to OSHA, MSHA or local safety standards.  
Have a good day
Ray


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## KBeitz (Sep 16, 2018)

You could use cables and a hydraulic cylinder dashpot.


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## rwm (Sep 16, 2018)

I'm thinking "lock." Yes, like on a canal. You put the material in a boat and then flood the shaft until the boat reaches...oh...nevermind.


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## GL (Sep 16, 2018)

You might consider looking at a car lift type arrangement. You haven't said what the load would be, but my 4 post will raise 9000lbs about 6'.  Runs with a long cylinder and cables.  The cable break is covered with lock lugs welded into guide channels every 6-8 inches.  You probably need less lift capability and more lift height, but that can be gotten by changing some geometry with pulleys.  Another approach might be to use an electric winch, and the car lift channel with lugs arrangement, as a substitute for a long hydraulic cylinder.


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## epanzella (Sep 16, 2018)

A simple way to make the long leadscrew you want is to build it in 3 foot sections. You can make it as long as you want and never have to deal with a section more than 6 feet long. Of course, if six feet is too much to handle you can use any length sections and deal with nothing longer than twice the length you choose. They can be joined by the the same method used in the captured nut puzzle only on a larger scale. The method used is to attach 2 sections together via internal threads and THEN thread the OD so the threads line up. Take the joint apart, add the next section and repeat as many times as you need for total length. When it's all done , reassemble with red locktite. In the picture below, the joint between the sections is exposed but undetectable and the nut traverses it smooth as glass.


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## higgite (Sep 17, 2018)

Where were you guys when he needed you last December?


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## epanzella (Sep 17, 2018)

Geez, didn't realize this started so long ago. I was responding to some replies from YESTERDAY!


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## mikey (Sep 17, 2018)

Happens a lot. Somebody joins the forum and wants to share, even when threads are very old. It will blow over eventually.


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