Connecting rods of different diameters/threads

[Deadeye]

I want to connect an M8 threaded rod with a 6mm unthreaded rod.

To-date I've ended up either
1. grinding off the thread to make an approx 6mm core and then using a 6mm sleeve. Recently elaborated this by drilling and tapping the sleeve for a grub screw rather than glueing
or
2. glueing the 6mm into a threaded 8mm connector

Both suffer from poor concentricity, but I can't find a female/female connector liek the standard hex connectors but with different bores.

Other, more elegant ideas?

 

[AndyT]

How many do you need? Just the one, or is this the start of a production run? Not hard to make, on a lathe or drill press. Any preference for overall shape - cylindrical, square section, hexagonal?

 

[Deadeye]

Hi Andy

Just two in the first instance.
I don't have a metal lathe and my metal working is rudimentary at best, but I could try on the drill press I guess. Got to learn somewhere/time!

 

[SteveF]

can you not just cut a thread on the 6mm and use
https://www.ebay.co.uk/itm/M6-M8-M10-M1 ... 1107093087

Steve

 

[powertools]

The only thing I can think of is to buy some 6mm connecting nuts and drill 8mm hole half way through and tap an 8 mm thread in that half.

 

[sunnybob]

Buy a piece of 14 mm hexagonal bar.
Drill the 6 mm pilot hole all the way down it. turn it over and drill the 8 mm pilot hole as far down as you need.
tap both ends to suit. easy peasy.
If it needs to come apart again use blue loctite. If its there forever, use red loctite

 

[gmgmgm]

The male adapters are findable on ebay, but the female ones are harder.

This shows some female/male ones "m6 m8 adapter female": https://www.ebay.co.uk/sch/i.html?_odkw ... e&_sacat=0 could you use those with some m8 or m6 sleeves?

These are M6 male to M8 male: https://www.ebay.co.uk/itm/Thread-Adapt ... :rk:7f:0

and these are M6 female to M8 male: https://www.ebay.co.uk/itm/M8-Female-to ... :rk:3f:1

 

[tomatwark]

These are female ones

https://www.ebay.co.uk/itm/M6-M8-M10-M1 ... 1107093087

 

[Deadeye]

Thanks everyone! This place is brilliant for beginners like me. Thanks again