A question for the ACME threadists

[8ob]

I will possibly need to design/build a gantry which in part will have to accurately raise/ lower a vertical section, I was thinking along the lines of two vertical ACME threads with a chain/sprocket between them to keep them timed. Questions are, how do you size these threads for load? Are there good/bad or nuts to avoid that go with these things? lastly is there any longevity in these? The weight of the gantry will probably top 150kg.

Bob

 

[mtt.tr]

Simple answer, this will likely cause upset is pay an engineer.

 

[Woody.v8]

I will possibly need to design/build a gantry which in part will have to accurately raise/ lower a vertical section, I was thinking along the lines of two vertical ACME threads with a chain/sprocket between them to keep them timed. Questions are, how do you size these threads for load? Are there good/bad or nuts to avoid that go with these things? lastly is there any longevity in these? The weight of the gantry will probably top 150kg.

Bob

How far dose it need to raise? You need a old screw type car lift to scavenge.

 

[fizzy]

Land Rover Defender screw jacks perhaps? Rated at 1.5 tonnes each.

 

[Munkul]

Acme Lead Screws & Nuts - Engineering Data | Roton Products Inc.

Engineering data for our acme lead screws & lead screw nuts. Roton Products is a manufacturer of high quality Acme Lead Screws, Lead Screw Nuts, and more.

www.roton.com

Looking at this chart, you'll want a 3/8" diameter screw as a minimum, with a bronze nut. Ideally bigger, a 1/2" screw would be my choice for something that gets used a lot.

EDIT: That's single screws, you could more or less half the load (if it's balanced equally) and go for 2 1/4" screws, but I think I'd stick to 4x safety factor or better, and go with 3/8". That's 320kg capacity each with a bronze nut.

If it has to be properly tested and examined etc, you'll want different safety factors, but if that were the case you wouldn't be asking us, you'd be asking a qualified design engineer

 

[Milkybars]

How much action is it going to see ? I have substantial lead screw that may do the job, obvs you'd have to make the nuts !

 

[Agroshield]

Another factor to consider in addition to the simple one of load is how long are the screws and how fast will they rotate. You may have to oversize to get somthing that does not whip about when spinning or buckle under the load.

 

[Brad93]

Our old kettona hydroform had huge acme threads to raise and lower the top tool in a similar manner to how you describe.
Might be worth looking for used machines that could be robbed

 

[pint]

linear actuator as a drop in solution ?

 

[fizzy]

Our old kettona hydroform had huge acme threads to raise and lower the top tool in a similar manner to how you describe.
Might be worth looking for used machines that could be robbed

My manual Keetona has the same.

 

[nickk]

Farm type screw stands,sort you find on trailers,elevators etc,though only about 500 mm,they’re 40 ish diameter and acme.

 

[500e]

Leycock Coronation lift had 4 with bronze nuts think it was 5Ft 6Inches lift from memory they were 1 or 1/4 inch dia
Parts still available

Garage Equipment Direct - Flowtech

garageequipmentdirect.co.uk

 

[8ob]

Leycock Coronation lift had 4 with bronze nuts think it was 5Ft 6Inches lift from memory they were 1 or 1/4 inch dia

Garage Equipment Direct - Flowtech

garageequipmentdirect.co.uk

5` would be ideal and I would need four of them, may be a tad overkill but worth keeping in mind. I will do a simple Bob type sketch of what I am trying to do. Whatever I use needs to have proper control because there could be upward forces imposed on the gantry, the lifting and lowering needs hold station.

Bob

 

[500e]

The way the Coronation works there is no upward restraint if you look at the link the collets would lift out of post if something got between ramp and floor, we used one for steam cleaning.
Don't think it would be difficult To do what you want though.
May be screw lift

Werther 2 Post Lift Based H Frame Ramp 3000kg | eBay

Lift was removed in working condition. We will not unsafely load an unsuitable vehicle. Spares or Repair.

www.ebay.co.uk

Or

Consul 3000kg 2 Post Ramp Baseless Screw Lift | eBay

Find many great new & used options and get the best deals for Consul 3000kg 2 Post Ramp Baseless Screw Lift at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[Sergei Slovenija]

Special ready-made units are sold for such mechanisms. angular gears, synchronization, various types of threads and the like. Various load capacities, lengths and sizes. I saw Turkish, Chinese and European manufacturers. Link at home on the computer b If relevant, let me know, I'll find it in my bookmarks.

 

[Johnnybravo]

I’ve got a solid 38mm hardened ballscrew ,bearings and nuts that would be ideal for that. I wouldn’t mess around with trying to snychronise two or more acme threads. One ball screw to drive it,two or more pins and bushes for it to run along . You would need a braked motor though ,or counterweights otherwise it will drop when the power is off, or some sort of self locking mechanism/ rachet like they use on two poster lifts to stop it dropping far.

 

[8ob]

Simple answer, this will likely cause upset is pay an engineer.

I spend my life re engineering stuff the "experts" design.

Bob

 

[Hitch]

The more side load you can eliminate the better, so a couple of rail and linear bearings could help keep the load even which is optimum obviously.

How much travel it needs will have an impact too...
Most manufacturers have charts for oadings, compression loads, tension loads etc...

Butchering up a 4 post car lift for a few 1¼" screw seems a bit overkill for 150kg.

How much pressure does a clamp with a little ½" acme thread exert... ?

 

[Sergei Slovenija]

Here are the names of companies that make units of any size, self-braking gearboxes, and so on. Big constructor.

As I understand it, direct links are not welcome?
I did not save other companies. UNIMEC S.p.A.

They even make polymer gear housings, which can have value of their own.

 

[mtt.tr]

I spend my life re engineering stuff the "experts" design.

Bob

Like wise, and will take on anything for myself.

For others I'll design and get an engineer to spec it.