how can I "lengthen" an M4 bolt?

[gjgm]

Not sure if I can explain this adequately !
I have a bolt that seems to have a hidden, inaccesible locking nut or something so that I cant remove it. However, the bolt itself isnt long enough to clear the fixing. So, as far as I can think, I either need some sort of threaded M4 "tubing", to extend the bolt and then use a bolt form the other side too, or something similar to what is used for holding kitchen units together where the second "bolt" is actually a tube with a screw head.
Any ideas where to get something like this?

 

[pampas]

What equipment are you working on? Knowing that I expect others may have the correct method, thus saving you more hair pulling.

 

[dt4134]

Daft question: but why can't you just replace it with a longer bolt?

I'm sure you must've thought of that, so I've missed something from your explanation.

 

[bendyone]

What about the sort of fitting that hold kitchen cabinets together Basically a threaded tube with a screwdriver slot on the head.

 

[NicM]

Not that clear on what you are doing but from your description of the fixing I think it is refered to as a 'sex bolt'.....yeah seriously....so if you do a search you may find one long enough.

 

[hutchy]

try maplin,they might have motherboard mounting tubes that are tapped right through.have fun

 

[gjgm]

ah.. it is boaty!
Its a bit like two stainless steel tubes.. the bolt goes through the first tube,is locked inside the second tube, and so cant be removed, but not long enough to clear this second tube, and so get a nut onto it to secure the two tubes together. Unless it snapped off at some point, and did originally clear the second fitting.
So, I cant get the too-short bolt out, and I cant get a nut onto it, as the bolt hasnt cleared the second fitting.
I ll look up sex bolts meantime !

 

[lw395]

Threaded hex spacers are available via the electronics trade, try rswww.com, rapid electronics, cpc etc. They are usually nickel plated brass though, so may not be a good idea around other metals.
Try googling 'stud connector'
The fittings sometimes used to hold adjacent bookcases together- a screwhead on each side one of which is an internally threaded tube- are sometimes called interscrews and have been known to exist in stainless. Occassionally used for yacht windows?

 

[santeana]

Can you not cut the bolt, or grind the head off, and poke it out?

 

[gjgm]

Thanks all.
I probably should look at how this actually works on another example of the boat !

 

[MoodySabre]

You mean a spacer like this. Ring Farnell and ask them if they have stainless.

There are some here

 

[gjgm]

You mean a spacer like this. Ring Farnell and ask them if they have stainless.

There are some here

Yep, thats the sort of thing !
What alot of knowledge is on here....