What's a double head screw called? + How do I fit one?

[OM2]

I want a double head screw as shown in the middle further below
What are these called? When I search on eBay, I don't find anyone selling these under 'double head screw'

How do I fit these?
I want to stack 3 tables - these are shown below the screw image - the tables are just from Ikea

Thanks

Screw:

Table:

 

[Burnerman]

The middle one is called a curtain pole joining screw....pilot holes are drilled in the ends of each pole, and by hand, the two poles are turned together.
John

 

[Trazor]

http://www.godfrey-diy.co.uk/miscellaneous-nuts-and-bolts/cat779.html

 

[Trazor]

But if you wish to stack and join those tables together,you will need to drill, dowel, and glue together, the screws will not work.

 

[EFLImpudence]

When I search on eBay, I don't find anyone selling these under 'double head screw'

Probably because they don't have any heads.

Double ended ???

 

[longdogs]

But if you wish to stack and join those tables together,you will need to drill, dowel, and glue together, the screws will not work.

Agreed. At a push you would only be able to fit one screw by turning the table round. Dowels a much better idea.

 

[longdogs]

When I search on eBay, I don't find anyone selling these under 'double head screw'

Probably because they don't have any heads.

Double ended ???

 

[ban-all-sheds]

Don't know about the legs, but Lack shelves are hollow, so so might the top of that table be.

You may not be able to fix them together as you plan.