Where can I buy 8mm or 5/16" dia by 1.1 meters or 43 1/4 inch Silver Steel??

[raynerd]

Hi Guys
I`m looking for a long pendulum rod to fix a synchronome clock I`ve just got. Infact, the clock is totally missing pendulum and fixings which does make things more flexible as I can make parts to suit but I`d prefer to make them as near as possible to the original design.

The pendulum rod should in an ideal world, be made of invar, 5/16" dia by 43 1/4" length.  I can`t find any 5/16" or 8mm invar of this length. The nearest I can find is 6mm but at £30, I just can`t justify the cost at present. I`m happy to have the clock working in concept and any inaccuracies I`ll just have to adjust every so often.

So basically, that leaves me using silver steel or even bright mild steel with the critical dimension being the length. The piece I purchase must be at least  1100mm. Anyone got a UK supplier of 8mm steel of this length at a reasonable price.... probably including postage if they are not North West based.

Any help appreciated!

Chris

[Jasonb]

 Just go into your local steel stockholder and you will be able to get BMS in 3.0m lengths for far less than the 1ft or 2ft lengths the ME trade suppliers charge. May even be able to get some PGMS.

2.0m lengths of silver steel are available but would be special order, J&L can order it in but do keep 1.0m long in stock

Personally I would go for somewhere you can collect from as then there is no risk of the postie bending it.

J

[dsquire]

Chris

Join 2 shorter pieces together. Either screw together or key and weld together then grind and polish the joint. This would work if you can't get full length pieces. 

Cheers 

Don

[DMIOM]

.......The pendulum rod should in an ideal world, be made of invar, 5/16" dia by 43 1/4" length.  I can`t find any 5/16" or 8mm invar of this length. The nearest I can find is 6mm but at £30, I just can`t justify the cost at present. I`m happy to have the clock working in concept and any inaccuracies I`ll just have to adjust every so often. ....

Chris,

just an idea - maybe you can turn this round! and maybe even include an adjuster.

Two possiblities come to mind, both involve using shorter lengths with a (decoratively turned) joint.

You could use a couple of shorter lengths of invar, or maybe make your suspension rod out of several lengths of different materials chosen for their various co-efficients of expansion so that whilst the rod will not have a homogeneous co-eff of thermal expansion, maybe you could come up with an assembly so that the net effect of the expansion of different materials 'in series' have a reduced co-eff?

Your joining piece could also include a penny-tray to allow balance weights to be added?

Dave