Hi Tom and all
It sounds like you have done very well. I have enjoyed looking at your
photos. Haven't come across Correx before. Its got me thinking on the
next one. Because I.m very limited to simple house hold tools such as
kitchen scissors and glue, I'm restricted to cardboard at present. I
have some cardboard that has a wax coating which may help with the
dampness. Coat of paint may help some more. Cardboard does crease when
trying to get it into shape. I find a rolling pin helps to prevent this.
Interested to here how you are progressing
David
tk7859 wrote:
> --- In Secomb's <> wrote:
>
> > I have used the site that you mentioned and found it very
> > useful,especially the spreadsheet which one change to get the desired
> > size and focal length. I have tried using cardboard but found
> achieving
> > a reasonable shape challenging. How did you go getting the shape using
> > plastic and are at the stage of testing it yet?
>
>
> Hi David and the Group
>
> I also considered using cardboard but decided against it because of
> perceived durability/damp problems. I thought I would try Correx.
> This is just like the corrugated cardboard that packing cartons are
> made of i.e. two sheets of plastic separated by a corrugated piece of
> plastic. It is available in various thicknesses - I used quarter inch
> (6mm).
>
> After feeding the spreadsheet with my design parameters I very
> carefully copied the resulting dimentions of one panel onto 6mm
> plywood. This I very accurately cut out and shaped using a coping saw
> followed by a bench mounted disc sander. This template was then used
> to markout the 12 panels used in the construction. Because the Correx
> material was 6mm thick I found the inside joints mated relatively
> accurately but those on the outside had quite big gaps.
>
> I used hot melt glue to join the outsides of the panels. This worked
> well as it easily filled the gaps and also ran into the corrugations.
> A very strong seal was therefore achieved but a lot of hot glue was
> needed. The gaps on the inside face were very minor - in many places
> no gap at all in others no nore than 1mm. Initially I thought I
> would cover these with electricians tape but ended up using wet
> fingers to massage Araldite epoxy glue into the gaps. This has
> resulted in a good finish for the reflecting surface without resorting
> to tape - probably added to overall strength as well.
>
> The last two days have been spent making the handle, the mic
> positioning assembly and the mic holder (due consideration being given
> to isolating these item from the dish). These have been designed as
> they were being built - very seat of the pants and quite a few changes
> being required enroute. However they seem acceptable.
>
> I will use the same stereo pair capsules made up for the Jecklin disc.
>
> At 7pm this evening I could not restrain myself. I added the
> capsules, guessed where the focal point might be and went out into the
> back garden for a first test.
>
> It works. How well I don't know as this is the first time I've ever
> used/heard a parabolic. It is certainly directional. Pointing it to
> the open door to the kitchen I could hear the England versus Rest of
> the World Soccar game on TV. Pointing away from the house - no soccer
> game but plenty of birds in a somewhat confusing situation (I could
> hear plenty, some very strong, but I could not see any). Clearly a
> learning curve is about to be climbed.
>
> The "Parabolic Reflector" album at
>
> m("btinternet.com/my_photos","//uk.pg.photos.yahoo.com/ph/g0sbw");">http:
>
> has had six new photos added which reflect (sorry about the pun) the
> current state of affairs.
>
> Clearly the mic lead needs to be taken care of - when it hits the edge
> of the reflector there is a mighty knock, I wondered what was going
> on. A wind shield is required and I need to spend some time finding
> the true focal point and its shape. A member of the Group kindly
> emailed me a good tip on how to do this but it needs the Sun which
> seems to have gone walkabout these past 10 days.
>
> A good coat of khaki paint would be a finishing touch.
>
> Cheers
>
> Tom Robinson
>
>
>
>
>
>
> "Microphones are not ears,
> Loudspeakers are not birds,
> A listening room is not nature."
> Klas Strandberg
>
>
>
> SPONSORED LINKS
> Science kits
> <http://groups.yahoo.com/gads?t=3Dms&k=3DScience+kits&w1=3DScience+kits&w=
2=3DScience+education&w3=3DScience+kit+for+kid&w4=3DNatural+sound&w5=3DMy+f=
irst+science+kit&w6=3DSound&c=3D6&s=3D122&.sig=3DLz9nlutNQy4QT0lkCYssxg>
> Science education
> <http://groups.yahoo.com/gads?t=3Dms&k=3DScience+education&w1=3DScience+k=
its&w2=3DScience+education&w3=3DScience+kit+for+kid&w4=3DNatural+sound&w5=
=3DMy+first+science+kit&w6=3DSound&c=3D6&s=3D122&.sig=3DzxdoipO7RHo6Ovyfekb=
5NA>
> Science kit for kid
> <http://groups.yahoo.com/gads?t=3Dms&k=3DScience+kit+for+kid&w1=3DScience=
+kits&w2=3DScience+education&w3=3DScience+kit+for+kid&w4=3DNatural+sound&w5=
=3DMy+first+science+kit&w6=3DSound&c=3D6&s=3D122&.sig=3DJdnZrWeIBv-vL8kM6Zy=
jqA>
>
> Natural sound
> <http://groups.yahoo.com/gads?t=3Dms&k=3DNatural+sound&w1=3DScience+kits&=
w2=3DScience+education&w3=3DScience+kit+for+kid&w4=3DNatural+sound&w5=3DMy+=
first+science+kit&w6=3DSound&c=3D6&s=3D122&.sig=3DQX11IJRDIZK15-qRl5t-Fw>
> My first science kit
> <http://groups.yahoo.com/gads?t=3Dms&k=3DMy+first+science+kit&w1=3DScienc=
e+kits&w2=3DScience+education&w3=3DScience+kit+for+kid&w4=3DNatural+sound&w=
5=3DMy+first+science+kit&w6=3DSound&c=3D6&s=3D122&.sig=3DrKjlPw9iHIZMsTKrVR=
XSNw>
> Sound
> <http://groups.yahoo.com/gads?t=3Dms&k=3DSound&w1=3DScience+kits&w2=3DSci=
ence+education&w3=3DScience+kit+for+kid&w4=3DNatural+sound&w5=3DMy+first+sc=
ience+kit&w6=3DSound&c=3D6&s=3D122&.sig=3DunzpqxF2mHIXi0JiJrzopQ>
>
>
>
> YAHOO! GROUPS LINKS
>
> * Visit your group "naturerecordists
> <http://groups.yahoo.com/group/naturerecordists>" on the web.
>
> * To unsubscribe from this group, send an email to:
>
> <=3DUnsu=
bscribe>
>
> * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
> Service <http://docs.yahoo.com/info/terms/>.
>
>
>
>------------------------------------------------------------------------
>
>No virus found in this incoming message.
>Checked by AVG Free Edition.
>Version: 7.1.394 / Virus Database: 268.7.2/349 - Release Date: 26/05/06
>
>
----------
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.394 / Virus Database: 268.7.2/349 - Release Date: 26/05/06
|