Hi Dave I sent a note to Brett but maybe you are the one to ask. Now that my sensor= s are behaving I would like to experiment with a sensor similar to yours. W= here did you buy your spring stock? I checked the internet and only found l= arger quantities. Is there a way to calculate the sensor geometric control = points? ie spring attachments, center of mass & center of hinge? Regards =0ABarry =0Ahttp://www.seismicvault.com --- On Sat, 8/15/09, Dave Nelsonwrote: From: Dave Nelson Subject: Re: Real time traces To: psn-l@.............. Date: Saturday, August 15, 2009, 6:43 PM =0A=0A =0A =0A=0AHi Meredith.=0A=A0=0AThe spring is cut to width on my pers= onal shear and =0Aheat treated in the home oven in the automatic cleaning m= ode.=A0 The heat =0Atreat significantly increases the yield strength. The t= emperature is just right =0Aas measured with a thermocouple. The width for = the instrument pictured is 16 mm =0Aand thickness is 12 mils.=A0 (Sorry for= the mixed units -- our European =0Afriends will think we can't=A0 make up = our minds )=A0=0A=A0=0A=A0I have a large quantity of the raw material =0Afo= r the springs -- enough for any conceivable quantity of instruments. I am = =0Aworking on the =A0repeatability in the shearing process. Right now I can= do =0A+- ~.15mm.=0A=A0=0AAs you suggest the period is=A0 a function of =0A= the spring length and adjusted at the clamp. It sometimes takes a few tries= but =0Athe process is quite easy.=A0 The period and rough centering are do= ne with =0Athe=A0 center capacitor plate PC board =A0removed to allow for a= motion =0Aover large angle for convenience. The final mass centering is do= ne by adjusting =0Athe moveable mass =A0either by eye or using the LED's on= the electronics =0Aboard with the loop open. The integrator is designed to= hold center over a wide =0Atemperature range so reentering is probably not= necessary under all but the most =0Asevere climatic temperature changes. W= e estimate +- 30C=A0 but that is not =0Afully confirmed.=0A=A0=0A=A0=0AActu= ator is homebrew based in a Neodymium magnet =0Apurchased on Ebay. The coil= is wound on a modified PAC plumbing part=A0 (1 =0A1/4 Schedule 40 plug fro= m Lowes).=A0=A0It takes a few minutes of lathe =0Awork to make it=A0. The c= oil is 770 turns=A0of # 32 for about 50 ohms and =0A15 N/A. I fabricate the= magnet assembly also but it does take some minor=A0 =0AMIG tack welds. The= materials are available=A0=A0from Online Metals. =0A=0A=A0=0AThere is anot= her small mass at he coil attach point =0Aof=A0~ 10 grams.=A0 =0A=A0=0AThe = overall size of the basic mechanism exclusive =0Aof the case is 4.5 x 9.5 i= nches. I have a new (untried) design which will be 4.5 =0Ax 5 inches in a = somewhat different configuration which may=A0allow for=A0 =0Abuoyancy compe= nsation. =A0The new design is also easier to build or at least =0Athat is t= he goal. =0A=A0=0A=A0=0ARegards, Dave =0A=A0=0A=A0=0A=A0=0A=A0=0A----- Orig= inal Message ----- =0A=0A From: =0A meredith lamb =0A To: psn-l@webtroni= cs.com =0A Sent: Sunday, August 16, 2009 00:18=0A Subject: Re: Real time = traces=0A =20 =0A Hi Dave,=0A =A0=0A Thanks for the info.=A0 Was wondering about the m= ain spring =0A width...its hard to judge from the photo; and where you got= such=0A and the ~ cost?=A0 The photo spring looks to be a original coil s= trip =0A or a good home shear.=A0 I understand (via the web) its=0A magne= tic; but apparently it works fine regardless of the boom end =0A coil/magn= et actuator feedback influence.=A0=0A =A0=0A Midway atop your vertical me= chanism there appears to be a screw =0A adjustable mass balance or centeri= ng=A0counterweight.=0A =A0=0A I presume....that the main spring period is= adjusted via the back clamp =0A alone.=A0 =0A =A0=0A The very small siz= e=A0of the vertical is rather=A0startling for the =0A ~ giant ~ mechanisms= we're used too seeing on PSN.=0A I can't really tell if their is more add= ed mass to the boom via =0A the=A0photo's besides the ~ frame, coil,=A0cap= acitance plate.=0A =A0=0A What did you use for the coil?=A0 Homebrew woun= d or otherwise a =0A commerical coil?=0A =A0=0A What is the magnet, ring= ceramic or neodymium?=0A =A0=0A Take care, Meredith Lamb=0A =A0=0A =A0= =0A On Fri, Aug 14, 2009 at 12:12 PM, Dave Nelson wr= ote: =0A =0A =0A Hi Meredith,=0A =A0=0A The spring is 17-7=A0 stain= less condition C =0A heat treated to condition CH900. Thickness is 12 mi= ls. =A0The pivots are =0A 2 mil stainless single axis=A0.=A0 Pivot lengt= h is only about 12 mils. =0A They are held=A0 tension by the=A0C spring.= A two axis pivot is not =0A necessary.=0A =A0=0A =A0=0A Dave =
Hi Dave
I sent a note to Brett but maybe y= ou are the one to ask. Now that my sensors are behaving I would like to exp= eriment with a sensor similar to yours. Where did you buy your spring stock= ? I checked the internet and only found larger quantities. Is there a way t= o calculate the sensor geometric control points? ie spring attachments, cen= ter of mass & center of hinge?
Regards
=0ABarry
=0Ahtt= p://www.seismicvault.com
--- On Sat, 8/15/09, Dave Nelson = <davefnelson@.......> wrote:
= From: Dave Nelson <davefnelson@.......>
Subject: Re: Real time tra= ces
To: psn-l@..............
Date: Saturday, August 15, 2009, 6:43 PM==0A=0A =0A =0A=0AHi Meredith.=0A=0AThe spring is cut to width on my personal shear and =0Aheat treated in the= home oven in the automatic cleaning mode. The heat =0Atreat signific= antly increases the yield strength. The temperature is just right =0Aas mea= sured with a thermocouple. The width for the instrument pictured is 16 mm = =0Aand thickness is 12 mils. (Sorry for the mixed units -- our Europe= an =0Afriends will think we can't make up our minds ) =0A=0AI have a large quantity of the raw materia= l =0Afor the springs -- enough for any conceivable quantity of instruments.= I am =0Aworking on the repeatability in the shearing process. Right = now I can do =0A+- ~.15mm.=0A=0AAs you sugge= st the period is a function of =0Athe spring length and adjusted at t= he clamp. It sometimes takes a few tries but =0Athe process is quite easy.&= nbsp; The period and rough centering are done with =0Athe center capa= citor plate PC board removed to allow for a motion =0Aover large angl= e for convenience. The final mass centering is done by adjusting =0Athe mov= eable mass either by eye or using the LED's on the electronics =0Aboa= rd with the loop open. The integrator is designed to hold center over a wid= e =0Atemperature range so reentering is probably not necessary under all bu= t the most =0Asevere climatic temperature changes. We estimate +- 30C = but that is not =0Afully confirmed.=0A=0A= font>=0AActuator is homebr= ew based in a Neodymium magnet =0Apurchased on Ebay. The coil is wound on a= modified PAC plumbing part (1 =0A1/4 Schedule 40 plug from Lowes).&n= bsp; It takes a few minutes of lathe =0Awork to make it . The coi= l is 770 turns of # 32 for about 50 ohms and =0A15 N/A. I fabricate th= e magnet assembly also but it does take some minor =0AMIG tack welds.= The materials are available from Online Metals. =0A=0A=0AThere is another small mass at he coil attach poin= t =0Aof ~ 10 grams.=0A=0AThe o= verall size of the basic mechanism exclusive =0Aof the case is 4.5 x 9.5 in= ches. I have a new (untried) design which will be 4.5 =0Ax 5 inches in a s= omewhat different configuration which may allow for =0Abuoyancy = compensation. The new design is also easier to build or at least =0At= hat is the goal.=0A=0A= =0ARegards, Dave=0A==0A=0A==0A=0A----- Original Message -----=0A=0AFrom: =0A <= a rel=3D"nofollow" title=3D"paleoartifact@........." ymailto=3D"mailto:pale= oartifact@........." target=3D"_blank" href=3D"/mc/compose?to=3Dpaleoartifa= ct@.........">meredith lamb=0A =0A =Sent: Sunday, = August 16, 2009 00:18=0ASubject: Re: Real time traces=0A= =0AHi Dave,=0A=0AThanks for the info= .. Was wondering about the main spring =0A width...its hard to judge = from the photo; and where you got such=0Aand the ~ cost? = The photo spring looks to be a original coil strip =0A or a good home she= ar. I understand (via the web) its=0Amagnetic; but appar= ently it works fine regardless of the boom end =0A coil/magnet actuator fe= edback influence.=0A=0AMidway atop yo= ur vertical mechanism there appears to be a screw =0A adjustable mass bala= nce or centering counterweight.=0A=0AI= presume....that the main spring period is adjusted via the back clamp =0A = alone.=0A=0AThe very small size&nbs= p;of the vertical is rather startling for the =0A ~ giant ~ mechanism= s we're used too seeing on PSN.=0AI can't really tell if their= is more added mass to the boom via =0A the photo's besides the ~ fra= me, coil, capacitance plate.=0A=0AWhat= did you use for the coil? Homebrew wound or otherwise a =0A commeri= cal coil?=0A=0AWhat is the magnet, ring cer= amic or neodymium?=0A=0ATake care, Meredith= Lamb=0A=0A=0AOn Fri, Aug 14, 2009 at 12:12 PM, Dave Nelson <davefnelson@.......> wrote:
=0A=0A==0AHi Mered= ith,=0A<= /div>=0AThe spring is 17-7 s= tainless condition C =0A heat treated to condition CH900. Thickness is 1= 2 mils. The pivots are =0A 2 mil stainless single axis . = ; Pivot length is only about 12 mils. =0A They are held tension by= the C spring. A two axis pivot is not =0A necessary.= =0A=0A=0ADave=0A==0A=0A=0A[ Top ] [ Back ] [ Home Page ]