Re: Home-Built Beam Balance

From: Lee Dammann <ldamnann_at_new.rr.com>
Date: Mon, 11 Dec 2006 18:53:46 -0000

Bill
I like the looks of your "bearing" much better than mine. It will
keep the beam in place, whereas mine slides around if I get to
rough. May be time to build another one with everyones tips.
Would it be possible to post a pic of your whole scale?

Thanks
Lee

--- In Indoor_Construction_at_yahoogroups.com, "Bill Gowen"
<b.gowen_at_...> wrote:
>
> Lee
> Maybe you have a bearing for your beam balance that you like. I
put a picture of mine in the "Tools" folder. It works real well and
is simple. I don't depend on my scale too much for absolute weights
but I can see weight differences down to a milligram or so.
>
> ----- Original Message -----
> From: Lee Dammann
> To: Indoor_Construction_at_yahoogroups.com
> Sent: Saturday, December 09, 2006 9:53 PM
> Subject: [Indoor_Construction] Re: Home-Built Beam Balance
>
>
> Gary
> Your right about the rigid pans and the possible error. I just
went
> down and put a 120 mg EZB motor stick on the pan. When moved all
> the way in and all the way out on the pan, I can get a 10 mg
> difference in weight. (+5, -5)
> Hanging the balsa pan on 3 or 4 threads would be an easy fix.
Thanks
> for the heads up. Although in the back of my mind I knew there
> would be an error, so I have always set the piece in the middle.
>
> All your other ideas are great. Its part of the fun of a 2
dollar
> homemade scale. You could but into it as much as you'd like.
>
> I have fould that dampning is not necessary for what I'm doing.
If
> you keep the limit bars close, settle time is not bad. I would
like
> to have a centered pointer with scale so I wouldn't have to wait
for
> settle, just check that the ossilations are even on the scale.
> You may also be able to put a magnet under the T-pin. With the
> right strength and distance, it may be good enough. Something
more
> to play with.
>
> Thanks
> Lee
> --- In Indoor_Construction_at_yahoogroups.com, dgbj@ wrote:
> >
> > LD,
> >
> > This is very good. Thanks for sharing it with us. Having the
> pads glued to
> > the bar introduces a serious error. Because the pads are
rigidly
> attached
> > to the bar, placement of the object to be weighed will
influence
> the balance.
> > Placing the object close to the blade will show a lower weight
> than placing
> > it farther out. Try it. The pads must be suspended with a
> nonrigid
> > attachment from a point on the beam.
> >
> > There are some refinements to consider.
> >
> > Trim nut. Having a machine screw with a nut on it sticking out
> from the end
> > opposite the scale will allow fine trim of the balance by
moving
> the nut
> > along the screw..
> >
> > Vernier. A vernier is a small scale attached to the sliding
> weight that
> > allows reading one finer division of the scale. It has 10
> divisions, but is
> > 9/10 of the length of 10 scale divisions. If the index point
on
> the vernier is
> > between two of the divisions on the scale, the subdivision
> corresponds to the
> > value where the vernier marks most closely approximates the
> corresponding
> > mark on the scale.
> >
> > Damper. The oscillation of the beam can be slowed with a
> magnetic damper.
> > A damper consists of a thin aluminum plate attached to the end
of
> the beam
> > and a strong magnet near by. As the aluminum plate moves
through
> the magnetic
> > field an electric current is induced. The induced current
> opposes the
> > magnetic field and exerts a force on the aluminum that is
> opposite to the direction
> > of movement.
> >
> > Gary Hinze
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
Received on Mon Dec 11 2006 - 10:56:32 CET