Shop made rise and fall mechanism

[NDRiley]

Evening All,

I'm trying to figure out how to make a mechanism which will raise and lower a 700mm long c.20mm dia rod or dowel. The rod/dowel will need to stay horizontal and will need to carry a load of c.90kg. My intial idea is as per the sketch attached. The plan would be to use a piece of threaded bar at each end of the rod/dowel, held vertically and turned using winding knobs attached to the top. The threaded bars would pass through a threaded hole near each end of the rod/dowel and as the knobs are turned the rod/dowel would move up and down. The rod/dowel will not be loaded while it is being moved - it will only need to carry the c.90kg once it reaches the desired position.

My question is how do I create the threaded hole at the ends of the rod/dowel. My preference is to use a wooden dowel as that's where my skills lie and I have the most kit. I would consider using a metal rod but that's more outside my comfort zone. Either way it will need to be round. The ideas I have come up with so far are:

1: Use a wooden dowel: Drill vertical holes through the dowel and put in a metal threaded insert. To make this strong enough I will need to go for a dowel sigificantly bigger than 20mm dia. That can be accommodated.
2: Use a metal bar (or tube): Drill a vertical hole then tap a thread. If I use M8 threaded bar, any idea how big a bar/tube I should be looking at to accommodate the required hole/tap?
3: Try to identify a pre-made fitting (maybe a KD fitting?) which has some means of attaching it to the end of wood dowel and a threaded hole perpdendicular to the long axis of the dowel. I'm not really sure what to search for on this and a general Google search of KD fittings etc has come up blank.

Would be grateful to hear anyone's thoughts on the above suggestions or, preferably, come better ideas!

Many thanks

 

[Jameshow]

Just a suggestion how about taking a scissor jack apart they are about 18" long iirc.

You would then have the threaded rod and the fittings required.

Cheers James

 

[bp122]

How much stroke are you looking at? If it is small stroke, you could look at a cam, it will be lot quicker than a helical adjuster like a screw.

 

[Lons]

Am I right in thinking that's 0.9 kg (900 grams) not 90 kg
Either wood or metal would do the job though you might need to use 25 mm dia dowel to accommodate the insert thickness. I have some and could measure the dia tomorrow if you need it. My preference would be a solid mild steel rod as tube would have to be thick wall anyway, it's easy enough to drill and tap.

As said it would take a while to wind it up and down with an 8 mm thread unless you use a cordless drill of course instead of hand wheel.

 

[NDRiley]

How much stroke are you looking at? If it is small stroke, you could look at a cam, it will be lot quicker than a helical adjuster like a screw.

 

[NDRiley]

How much stroke are you looking at? If it is small stroke, you could look at a cam, it will be lot quicker than a helical adjuster like a screw.

Thanks for the idea. Unfortunately Stroke needs to be c.200mm

 

[NDRiley]

Am I right in thinking that's 0.9 kg (900 grams) not 90 kg
Either wood or metal would do the job though you might need to use 25 mm dia dowel to accommodate the insert thickness. I have some and could measure the dia tomorrow if you need it. My preference would be a solid mild steel rod as tube would have to be thick wall anyway, it's easy enough to drill and tap.

As said it would take a while to wind it up and down with an 8 mm thread unless you use a cordless drill of course instead of hand wheel.

Thanks for your thoughts. No, it is 90kg! The cordless drill idea is also a great one - stroke needs to be c.200mm so that would avoid a lot of tedious winding.

 

[TheTiddles]

I’d buy a TV lift mechanism or take apart a desk mechanism as a first option.

Aidan

 

[TRITON]

Are you basing your idea on the UKJ router lift ?. 4 gears,one each corner and a chain to connect ?

I'd say might find such a lift, unless engineering is your thing, would be tricky to complete and a high degree of accuracy would be required, or you might find it tightens or seizes when trying to turn it.

+1 for a scissor-jack affair.

 

[TheUnicorn]

I have a jack that tilts a ride on mower, so very heavy duty, with a really heavy threaded rod as the basis for it, i remember at the time that someone commented that you couldn't buy the threaded rod alone for the cost of the whole jack, it might be good to take apart and use for its parts https://www.amazon.co.uk/ACHATPRATI...ords=ride+on+mower+jack&qid=1606475789&sr=8-3

 

[Tris]

Look out for caravan corner steadies on ebay, they're cheap, have a fast thread and are driven with a 19mm socket in a cordless drill. All the parts you need should be there, just a bit of ingenuity required to get the threaded insert into your dowel/rod

 

[mindthatwhatouch]

As others have stated, Scissor jack, the beauty also is with a left and right hand thread movement along the screw is quick.
I adapted one for lifting my cyclone off the bin, works well. I’ll try and get some pics if it helps.

 

[NDRiley]

Thanks everyone for some really helpful suggestions- much appreciated. I’m going to digest all that then get back to the drawing board.

 

[mindthatwhatouch]

As I was emptying my dust extractor, I thought I'd get a couple of snaps.
Should be fairly self explanatory.

 

[Terrytpot]

The op never actually specified exactly what he was trying to move but sounds a bit like a similar issue I could do with solving which in my case is not having rack and pinion table hight adjustment on my Meddings pillar drill although whilst it is substantial I don't think the table weighs in at 90kgs..