Attic hoist / elevator design

[Molynoox]

Hi All,

I'm working on a design for an attic hoist / elevator that will be used for getting boxes etc up and down. We have installed a loft ladder already and it's good for walking up but not great for carrying stuff up.
I've done a bit of research and it doesn't seem like there are any kits on the market that I can just buy and install. So I'm having to design one.

Here are my thoughts so far:

Details:

• I can get an electric hoist for about £100, much cheaper than I expected, so Im using that as the drive
• I thought U channel and runners fixed to the wall for the lift to go up and down on
• The hoist cable will be routed through rollers so it pulls from both sides
• I have that weird raised platform because I need to have it coming through between two trusses that are not adjacent to the wall
• and also because I have added a strengthening gusset (the little triangle thing) on the elevator that needs some clearance under the truss joists.

I thought I could make it out of 50mm box section steel and then weld together. I don't have a welder but I have access to one.

Help needed

• general thoughts - am I mad, will it kill somebody etc
• what is that u channel stuff and what sort of stuff do I need and where can I get it?
• are there better designs than this that anybody can think of?

Pics of there actual mezzanine:

this is a later pic from last week, the tiles were only half on at this stage and the breather membrane was casting a blue light, but it shows a more complete picture.

thanks
Martin

 

[ChaiLatte]

• I thought U channel and runners fixed to the wall for the lift to go up and down on

The difficulty you will have is that the upper rollers will be pulling into the front of the channel and the lower rollers pushing into the back of the channel.

Something like industrial sliding door channel might do, but 50% of the rollers (the lower ones) in your application will be exerting force on the channel in the opposite direction to its conventional use. Maybe you could supplement the lower ones with external wheels that press on the face of the U-channel so that the rollers that run inside the channel only act as guides.

Example product:

https://www.bullerltd.co.uk/sliding...gear-industrial-and-stainless-sliding-tracks/

Something like a round tube with a shaped roller on the back of it at the top and a shaped roller on the front of it at the bottom might work better. It does mean you have to fix the tube from the side so the rollers do not clash with the fixings. Look at how the mast of an Alimak hoist works - the hoist cage cantilevers from the mast in the same way as your design.

 

[Molynoox]

Hmm, that's a good point about the forces.
You don't think the rollers will be happy pushing up against the back face of the U channel?

Never heard of alimak hoists but after looking I can see that's pretty similar set of design constraints. I want to keep the runners flush to wall so not sure I can steal too many ideas.

I wonder if you can get u channel with rollers on both sides (inside and out)

 

[Jacob]

Hook in ceiling/joist etc with block and tackle? Works for me.
A few slings and karabiners for holding stuff, as necessary.
Single pulley with climbing rope (easier to hold) for light stuff (e.g 8x4' 18mm ply), through to chain block for heavy stuff.
Did a combi machine about half a ton, and a piano.
They were one offs through a temporary hole but made a permanent hole for woodwork stuff which I closed off with floor board panel when not needed, hence taking up no space at all.
PS looking at your photos you would need the hole central under the ridge, to give you the height for the pulley and/or block

 

[Fergie 307]

Could you repurpose a car lift? I am thinking of the type with free standing pillars either side of the vehicle and arms that swing out under the jacking points. You can buy second hand ones quite cheaply

 

[Molynoox]

Hook in ceiling/joist etc with block and tackle? Works for me.
A few slings and karabiners for holding stuff, as necessary.
Single pulley with climbing rope (easier to hold) for light stuff (e.g 8x4' 18mm ply), through to chain block for heavy stuff.
Did a combi machine about half a ton, and a piano.
They were one offs through a temporary hole but made a permanent hole for woodwork stuff which I closed off with floor board panel when not needed, hence taking up no space at all.
PS looking at your photos you would need the hole central under the ridge, to give you the height for the pulley and/or block

Why does it need to be under ridge? From cad it looks like I have loads of clearance and could shift it closer to eaves... Or am I missing something?....

 

[Molynoox]

Could you repurpose a car lift? I am thinking of the type with free standing pillars either side of the vehicle and arms that swing out under the jacking points. You can buy second hand ones quite cheaply

I can't have legs as a car parks directly underneath it

 

[Jacob]

Why does it need to be under ridge? From cad it looks like I have loads of clearance and could shift it closer to eaves... Or am I missing something?....

I'm just guessing. But it depends on the height of things you might want to shift, plus length of hook, pulley, slings etc hanging down.

 

[ChaiLatte]

You don't think the rollers will be happy pushing up against the back face of the U channel?

I wonder if you can get u channel with rollers on both sides (inside and out)

I simply do not know. All I can say is that it is not the way a horizontal door track works, with all the weight pulling downwards. It is something you might have to buy a short length and experiment.

These are thoughts, not experiences: possibly the two rollers could cant in the channel and jam up. Possibly the depth of the roller assembly would mean it touches the outside of the channel when pushed towards its back. Possibly the rolling (fillet) radius of the channel section at the back is incompatible with the roller shape.

You could put two channels back to back (or side-by-side with the open facees opposed) with the upper runner in one and the lower runner in the other. That is more money, back to back makes the whole structure fatter and you have to reach around the side to connect the lower one to the hoist basket. Side-by-side opposed could work, with the wall fixing bracket in the middle between the two items.

If you could pull the basket from all four corners instead of just the two nearest the mast, that would make it go up less skewed. Even moving the two-rope pull point from near the mast to midwidth of the basket would improve things (consider making the pull point adjustable across the width, like an engine leveller - if the basket is loaded near the tip, move the pull point nearer the tip).

Unistrut channel might work as they do trolleys that go in it, but from my recollection, the SWL of the trolleys is quite low.

https://directchannel.uk.com/product-category/strutchannel/strut-channel/back-to-back-strut/

https://www.unistrut.co.uk/search?keyword=trolley

 

[Fergie 307]

I can't have legs as a car parks directly underneath it

I was thinking along the lines of just using one pillar, oriented so the leg is parallel to the wall. How much weight do you want it to lift?

 

[Jacob]

I'm just guessing. But it depends on the height of things you might want to shift, plus length of hook, pulley, slings etc hanging down.

and there are power hoists of course, which hang off a hook. Simple installation and a double trap door?

 

[Fergie 307]

Bearing in mind if you are going to use a hoist then you are just talking about guides, you could just use two lengths of say 30mm tube, and cupped wheels on your platform. Look at something like a roller coaster, this is how the cars are held on. You could just use short pieces of tube that fit over the smaller long tubes, but if your lift isn't even they will jam. Cupped rollers that hug the tube, ideally both above and below the platform, won't.

 

[Fergie 307]

In fact the cheapest thing to use would be scaffold tubes, and suitably sized cupped rollers, one in front of the tube and one behind. One set a the bottom of your platform and another above it then it will run up and down to your hearts content. You could probably find fixed wheels from a castor supplier that would have enough meat on them to machine the cup, or they may even supply cupped ones off the shelf.

 

[Jacob]

Bearing in mind if you are going to use a hoist then you are just talking about guides, you could just use two lengths of say 30mm tube, and cupped wheels on your platform. Look at something like a roller coaster, this is how the cars are held on. You could just use short pieces of tube that fit over the smaller long tubes, but if your lift isn't even they will jam. Cupped rollers that hug the tube, ideally both above and below the platform, won't.

May not need any guides with a hoist, depending on size of load and the opening.

 

[ChaiLatte]

In fact the cheapest thing to use would be scaffold tubes...

Scaffold ladder beams might be a good variation on that theme. The rollers run on the stile and the rungs can be used to attach fixings to the wall.

The roller coaster analogy is a good one because it both pushes onto its rails and tries to pull itself off its rails just as this hoist will do.

Draw an isolated tube in plan view and see how the parts would need to be arranged around it. The wall attachment would need to be at 1500; the lower roller at 1800; the upper roller at 0000, with its bracket covering the whole 1800-0000 (left side) of the tube.

 

[BucksDad]

Please keep us posted with pictures and a video of operation when it's done!

 

[Richard_C]

This looks hugely over complicated. If you need a hoist, which may only serve to encourage you to store far too much "stuff", a simple electric hoist above a suitable hole with the rope or cable steadied by human hand as it rises should be enough. Worked well enough for centuries for unloading carts and riverboats. It's not going to be windy, and gravity plays it's part in keeping the load below the hoist. Maybe the reason there is no off the shelf solution is that there is no need for one.

 

[Jacob]

This looks hugely over complicated. If you need a hoist, which may only serve to encourage you to store far too much "stuff", a simple electric hoist above a suitable hole with the rope or cable steadied by human hand as it rises should be enough. Worked well enough for centuries for unloading carts and riverboats. It's not going to be windy, and gravity plays it's part in keeping the load below the hoist. Maybe the reason there is no off the shelf solution is that there is no need for one.

Or even a hand powered pulley, block and tackle etc.
Both - as I said I lifted a half ton combi machine with mine. Too slow for light loads so I'd hang a single pulley on the hook instead. Attach a guide rope to keep things from rotating, if necessary.

 

[Molynoox]

I simply do not know. All I can say is that it is not the way a horizontal door track works, with all the weight pulling downwards. It is something you might have to buy a short length and experiment.

These are thoughts, not experiences: possibly the two rollers could cant in the channel and jam up. Possibly the depth of the roller assembly would mean it touches the outside of the channel when pushed towards its back. Possibly the rolling (fillet) radius of the channel section at the back is incompatible with the roller shape.

You could put two channels back to back (or side-by-side with the open facees opposed) with the upper runner in one and the lower runner in the other. That is more money, back to back makes the whole structure fatter and you have to reach around the side to connect the lower one to the hoist basket. Side-by-side opposed could work, with the wall fixing bracket in the middle between the two items.

If you could pull the basket from all four corners instead of just the two nearest the mast, that would make it go up less skewed. Even moving the two-rope pull point from near the mast to midwidth of the basket would improve things (consider making the pull point adjustable across the width, like an engine leveller - if the basket is loaded near the tip, move the pull point nearer the tip).

Unistrut channel might work as they do trolleys that go in it, but from my recollection, the SWL of the trolleys is quite low.

https://directchannel.uk.com/product-category/strutchannel/strut-channel/back-to-back-strut/

https://www.unistrut.co.uk/search?keyword=trolley

yeah I understand your point
I have found some metal rollers that work in unichannel that are rated up to 250kg, the rollers have a flat surface so I see no reason why they would have an issue running on the back edge
I also saw on website that somebody asked of you can fit a bolt head in channel and apparently not - so it must be quite snug in there, presumably so it can run on back of channel....
thats good for the design / function I want, but then I also need to think about how I will fix the channel to the wall now if I can't put a bolt in there.

perhaps a bolt top and bottom only would be enough?...

https://www.u-buy.co.uk/product/1CU...fulZJeTHWrOkQRzw7makxhh_7tgOM6j6Oqc_N69Iz_pCE

 

[Molynoox]

I was thinking along the lines of just using one pillar, oriented so the leg is parallel to the wall. How much weight do you want it to lift?

I see
only needs to take 100kg, but I will design for 250kg for future proofing