PSN-L Email List Message
Subject: Re: Real time traces
From: Barry Lotz barry_lotz@.............
Date: Sun, 16 Aug 2009 04:18:19 -0700 (PDT)
Dave
I'm interested in finding out more and impressed also. I reduced the size o=
f the STM style vertical 12" but like your design. Didn't you try a hacksaw=
blade(s)=A0 before? I don't remember the thickness but would the taping bl=
ade material STM mentioned work? I'm not sure about my heat treating abilit=
ies (proper annealing etc). I have read Bretts excellent documentation in t=
he past.
Regards
Barry
--- On Sat, 8/15/09, Dave Nelson wrote:
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 =
Dave I'm interested in finding out more an=
d impressed also. I reduced the size of the STM style vertical 12" but like=
your design. Didn't you try a hacksaw blade(s) before? I don't remem=
ber the thickness but would the taping blade material STM mentioned work? I=
'm not sure about my heat treating abilities (proper annealing etc). I have=
read Bretts excellent documentation in the past. Regards Barry
--- On Sat, 8/15/09, Dave Nelson <davefnelson@.......> wrote:
From: Dave Nelson <davefnel=
son@.......> Subject: Re: Real time traces To: psn-l@..............
m Date: Saturday, August 15, 2009, 6:43 PM
=0A=0A =0A =0A=0A Hi M=
eredith. =0A <=
/div>=0A The spring is cut to width on =
my personal shear and =0Aheat treated in the home oven in the automatic cle=
aning mode. The heat =0Atreat significantly increases the yield stren=
gth. The temperature is just right =0Aas measured with a thermocouple. The =
width for the instrument pictured is 16 mm =0Aand thickness is 12 mils.&nbs=
p; (Sorry for the mixed units -- our European =0Afriends will think we can'=
t make up our minds ) =0A =0A  =
;I have a large quantity of the raw material =0Afor the springs -- enough f=
or any conceivable quantity of instruments. I am =0Aworking on the re=
peatability in the shearing process. Right now I can do =0A+- ~.15mm. =0A =0A <=
font size=3D"2" face=3D"Arial">As you suggest the period is a functio=
n of =0Athe spring length and adjusted at the clamp. It sometimes takes a f=
ew tries but =0Athe process is quite easy. The period and rough cente=
ring are done with =0Athe center capacitor plate PC board remov=
ed to allow for a motion =0Aover large angle for convenience. The final mas=
s centering is done by adjusting =0Athe moveable mass either by eye o=
r using the LED's on the electronics =0Aboard with the loop open. The integ=
rator is designed to hold center over a wide =0Atemperature range so reente=
ring is probably not necessary under all but the most =0Asevere climatic te=
mperature changes. We estimate +- 30C but that is not =0Afully confir=
med. =0A =0A =0A Actuator is homebrew based in a Neodymium magnet =
=0Apurchased on Ebay. The coil is wound on a modified PAC plumbing part&nbs=
p; (1 =0A1/4 Schedule 40 plug from Lowes). It takes a few minute=
s of lathe =0Awork to make it . The coil is 770 turns of # 32 for=
about 50 ohms and =0A15 N/A. I fabricate the magnet assembly also but it d=
oes take some minor =0AMIG tack welds. The materials are available&nb=
sp; from Online Metals. =0A =0A =0A There=
is another small mass at he coil attach point =0Aof ~ 10 grams. =
=0A =
=0A The overall size of the basic mecha=
nism exclusive =0Aof the case is 4.5 x 9.5 inches. I have a new (untried) d=
esign which will be 4.5 =0Ax 5 inches in a somewhat different configuratio=
n which may allow for =0Abuoyancy compensation. The new de=
sign is also easier to build or at least =0Athat is the goal. =
=0A =0A =0A Regards, Dave =0A =
=0A =0A =0A =0A ----- Original Messag=
e ----- =0A =0A =0A =0A Sent: Sunday, August 16, 2009 00:18 =0A =
Subject: Re: R=
eal time traces =0A
=0A Hi Dave, =0A =
=0A Thanks for the info. Was wondering about the ma=
in spring =0A width...its hard to judge from the photo; and where you got =
such =0A and the ~ cost? The photo spring looks to be a or=
iginal coil strip =0A or a good home shear. I understand (via the we=
b) its =0A magnetic; but apparently it works fine regardless of =
the boom end =0A coil/magnet actuator feedback influence. =0A =
=0A Midway atop your vertical mechanism there appear=
s to be a screw =0A adjustable mass balance or centering counterweigh=
t. =0A =0A I presume....that the main spring p=
eriod is adjusted via the back clamp =0A alone. =0A &nbs=
p; =0A The very small size of the vertical is rather s=
tartling for the =0A ~ giant ~ mechanisms we're used too seeing on PSN.=0A I can't really tell if their is more added mass to the boom vi=
a =0A the photo's besides the ~ frame, coil, capacitance plate.<=
/div>=0A =0A What did you use for the coil? H=
omebrew wound or otherwise a =0A commerical coil? =0A =0A What is the magnet, ring ceramic or neodymium? =0A =
=0A Take care, Meredith Lamb =0A =
=0A =0A On Fri, Aug 14, 2009 =
at 12:12 PM, Dave Nelson <davefnelson@.......> wrote: =0A =0A =0A Hi Meredith, =0A =0A The spring is 17-7 stainless condition C =0A heat=
treated to condition CH900. Thickness is 12 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 p=
ivot is not =0A necessary. =0A =0A =0A Dave =0A =
font> =0A <=
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