=20 In a message dated 28/11/2008 23:42:02 GMT Standard Time, =20 gel@................. writes: I=E2=80=99m just getting started with my first vertical seismometer. I will= be using=20 an extension spring and supported at 90 degrees. Bearing concept is 2 sets=20 of tungsten carbide rods and a silicon carbide ball bearings. One of the=20 springs I have tested is a Century Spring No. 312. K factor is .28 pounds/i= nch and=20 resonant period is 1.25 seconds. The tungsten rods are as received and have= =20 not been polished yet. Undamped, I measured the damping constant to be 372=20 seconds. I used the equation of Y=3DA*e-t/T. How does the 372 seconds compa= re to=20 other vertical systems. =20 Hi Gary, =20 If you can extend the top spring position beyond the vertical support=20 and also lower it a bit, you will get a longer period. The aim is to have t= he=20 vertical above the hinge nearer the ''zero'' length of the spring. =20 If you put a C shaped plate on the end of the horizontal beam, you coul= d=20 use two short piano wire supports in tension. I have also used a pair of=20 razor blades extracted from single blade cheap plastic razors in compressio= n. I=20 stick them between Al cross strips with acrylic adhesive with a gap of ~0.1= ". =20 You should be able to improve on 1.25 seconds. Aim for a period of 1.5=20 to 2 seconds.=20 =20 Regards, =20 Chris ChapmanIn a message dated 28/11/2008 23:42:02 GMT Standard Time,=20 gel@................. writes:<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I=E2=80=99m just getting started with my first vertic= al=20 seismometer. I will be using an extension spring and supported at 90 degre= es.=20 Bearing concept is 2 sets of tungsten carbide rods and a silicon carbide b= all=20 bearings. One of the springs I have tested is a Century Spring No. 312. K=20 factor is .28 pounds/inch and resonant period is 1.25 seconds. The tungste= n=20 rods are as received and have not been polished yet. Undamped, I measured=20= the=20 damping constant to be 372 seconds. I used the equation of Y=3DA*e-t/T. Ho= w does=20 the 372 seconds compare to other vertical systems.=20
Hi Gary,If you can extend the top spring position beyon= d=20 the vertical support and also lower it a bit, you will get a longer per= iod.=20 The aim is to have the vertical above the hinge nearer the ''zero'' length o= f=20 the spring.If you put a C shaped plate on the end of the=20 horizontal beam, you could use two short piano wire supports in tension= .. I=20 have also used a pair of razor blades extracted from single blade cheap plas= tic=20 razors in compression. I stick them between Al cross strips with=20 acrylic adhesive with a gap of ~0.1".You should be able to improve on 1.25=20 seconds. Aim for a period of 1.5 to 2 seconds.Regards,Chris Chapman