Hi,

just tried this idea with neodymium magnet, 1 pen, 2 straws and a small 
mass at the end.  I get a period of 1.4 seconds and indeed it does go on 
for a while.

Silly question coming up - please be merciful(!) - how can I turn this 
into a long period teleseismic device (period of 10s of seconds)?

Thanks

Ian

ChrisAtUpw@....... wrote:

> In a message dated 09/11/2007, gmvoeth@........... writes:
>
>     DID you clean the ink off the tip
>     before doing this ?
>
> Hi Geoff,
>  
>     The BIC pens have tungsten carbide balls. If you cut off the 
> plastic ink holder, you can push out the 1 mm ball with a fine drill / 
> piano wire. You can then clean everything with methylated spirits and 
> reassemble it. The ball can be crimped or glued in position with two 
> part acrylic adhesive. 
>  
>     However, you can buy martensitic SS balls from www.smallparts.com 
>  They are ferromagnetic.
>  
>     Regards,
>  
>     Chris Chapman 


-- 





  
  


Hi,



just tried this idea with neodymium magnet, 1 pen, 2 straws and a small
mass at the end.  I get a period of 1.4 seconds and indeed it does go
on for a while.



Silly question coming up - please be merciful(!) - how can I turn this
into a long period teleseismic device (period of 10s of seconds)?



Thanks



Ian



ChrisAtUpw@....... wrote:


  
  
  
  

  
In a message dated 09/11/2007, gmvoeth@........... writes:
  
DID you clean the ink off the tip

before doing this ?

    
  
  
Hi Geoff,
  
 
  
    The BIC pens have tungsten carbide balls. If you cut off the
plastic ink holder, you can push out the 1 mm ball with a fine drill /
piano wire. You can then clean everything with methylated spirits and
reassemble it. The ball can be crimped or glued in position with two
part acrylic adhesive. 
  
 
  
    However, you can buy martensitic SS balls from www.smallparts.com They are
ferromagnetic.
  
 
  
    Regards,
  
 
  
    Chris Chapman 
   


--