Long spiral like Yankee?

[GrahamRounce]

Hi all.
Is there a name for a long spiral driven "thread", like that on a Yankee screwdriver?
And any idea where they might be available, along with the associated "nut"/pusher? Preferably not cannibalising a Yankee!

For my purpose it won't need to go backwards, so a single channel not a criss-cross one will be fine.

Thanks again again,

 

[ChaiLatte]

Have a look at ballscrews. They are used all over the place from CNC machine tools to hospital beds. Every size you can think of and every pitch from very coarse, Yankee-like to reasonably fine.

 

[GrahamRounce]

Ok I will, thanks. Not the name I would have thought of myself.

 

[GrahamRounce]

Have a look at ballscrews. They are used all over the place from CNC machine tools to hospital beds. Every size you can think of and every pitch from very coarse, Yankee-like to reasonably fine.

From what I can see, these are all for making the nut move by turning the rod. I want the opposite. A looooong helical thread in the rod, so that the nut, when pushed, turns the rod. As in a Yankee?

 

[ChaiLatte]

From what I can see, these are all for making the nut move by turning the rod. I want the opposite. A looooong helical thread in the rod, so that the nut, when pushed, turns the rod. As in a Yankee?

See if you can find some videos of them. A ballscrew is very low friction. If you hold one vertically by the rod, the nut will drop (and rotate under its own weight). If you hold the nut, with the end of the rod off the ground, the rod will drop (and rotate under its own weight). So yes, you can push on the nut and the rod will translate and rotate.

The above works on even a relatively fine pitch one (low helix angle). On a coarse pitch one (high helix angle like a Yankee), the effect is magnified.

A lot of the engineering challenges in CNC machines that use them is designing in things like brakes to stop them doing this (the effect is called back driving).

They will work even better than a Yankee because of the lower friction - more of your push is converted onto rotation and not lost as heat/wear/noise etc.

 

[GrahamRounce]

Thank-you! But to get a goodly amount of the force on the nut/pusher translated into rotation of the (¼") rod, I'd like the helical groove to be about 1 turn per inch, or less.
(Is there a name for such a grooved rod, and its nut/pusher?)

 

[brocher]

Link to a ballscrew website might be helpful? Ball Screw | THK Official Web Site | [ U.K. ]

 

[Sachakins]

Have you considered making a nut to suit a old or cheap long sds bit, you see them on offer a lot in aldi n Lidl.
This is a lon g slow helix, and being sds masonry drills, there's no cutting edge on the flutes.

Amtech E0692 3 Piece 600mm (24") SDS Drill bit Set https://amzn.eu/d/8H9mNgc

 

[GrahamRounce]

@Sachakins - thats a good idea! It might just work, even tho the "thread" tpi looks about double that of a Yankee shaft (which is what I have in my mind's eye).

I thought it would be a standard thing, which I only needed the name of! Silly.

@brocher - I'm looking for something with a thread of 1tpi or less...

 

[Sachakins]

Try this Trend SNAP/QCYL Snappy Quick Chuck Yankee Shank Large 5027654529508 | eBay

£9.99

 

[AES]

I have no idea where you get them, sorry, but I was taught that they're called an Archimedes Thread (or Screw), and the "nut" is an Archimedes Nut.

HTH

HTH

 

[ChaiLatte]

What you are looking for is quite a specialised application. There are not so many products using them: Yankee screwdrivers and Archimedian drills are the only common ones. Another one is cable/rope spooling machinery - the screw guides the rope back and forth onto the drum so it winds on evenly (and these ones self-reverse).

Maybe an all-encompassing search term would be 'high helix screw'.

You would need to investigate the SDS drill bit idea: as the bits have two flutes, it will be a two-start thread. In drill bit terminology, 'slow spiral' means a fine 'thread', the opposite of what you want.

What sort of accuracy do you need? Decorative gates use twisted square steel. If you only need small diameter, you could buy some square rod and twist it yourself: the pitch of the spiral would depend on the length you started with, so if you need (roughly) one turn per inch, start with a piece 2" long and rotate the end 720 degrees. It will, of course, reduce in length as you twist is, so the thread will be coarser than calculated but you will need less prototypes than Edison before you suss it out.