Hey Harold -

Yup - that's just it - I've got the bearings as far forward (if you mean
toward the eyepiece) as I can get them. When I said "as far back" as I
could earlier I was referring to the tube itself. Although there is room
on the sliding brackets to move the bearings farther forward, I wouldn't
be able to point the scope at the zenith with them that way. So I use my
old scuba gear to get the thing balanced. I'm not crazy about it, but i
works OK. Although I have a 42-acre ranch to observe from, I do a lot of
public outreach and this rigid tube is a pain to haul around. I am
seriously considering pulling the mirror and using it to build a
truss-tube Dob. I guess I could always sell it and then buy a new mirror
and do the same thing. ;-)

Dave Grosvold
Diamond Bar G Ranch (3 mi south of Morrow, AR)

Harold wrote:
>
>
>
>
> --- In Discovery-Dob-Users@yahoogroups.com
> <mailto:Discovery-Dob-Users%40yahoogroups.com>, Dave Grosvold
> <dgrosvold@...> wrote:
> >
> > I don't know about the Split-Tubes, but my older Rigid-Tube 12.5" is
> > just the opposite. I can't move the bearings back far enough on the
> tube
> > to get mine to balance. I have it as far back as I can get it without
> > the bottom scraping the rocker box, and I've had to add a scuba weight
> > belt and approximately 15 lbs of lead shot to balance the tube with
> 14mmmy
> > favorite EP - a 12mm T4 Nagler. I have a Telrad w/dew shield and 2"
> > extension plus a Stellarvue F50 Finder on it. Surely it should be
> easier
> > to balance than that!
> >
> > The views in this scope are great, but balancing ti is a pain. And
> yes -
> > I use both finders a lot. I don't have DSCs, so I do a lot of
> starhopping.
> >
> > Dave Grosvold
> > Diamond Bar G Ranch (3 mi south of Morrow, AR)
>
> HEY DAVE:
>
> I recently sold my 12.5" Rigid-Tube PDHQ, and would like you to know
> that I also had a balance problem after adding a big 80mm StellarView
> RACI Finder and a Green Laser Pointer, and cured the nose-heavy
> problem by sliding my altitude bearing as far forward as it would go,
> and the balance was perfect, even with my heaviest one-pound Meade
> 4000 14mm UWA eyepiece!
>
> HAL
>
> > jacksoneu45@... wrote:
> > >
> > >
> > > I have the 16"f/4.5 Discovery splittube and 12.5" Discovery Dob.
> Sold my
> > > 17.5" f/5 Discovery split tube, bad move. I love the tube scopes
> as you
> > > can add just about anything piece of equipment to them. No weight
> > > problem at
> > > all.
> > >
> > >
> > > Eurvin
> > >
> > > [Non-text portions of this message have been removed]
> > >
> > >
> >
>
>

I have the 17.5 F5 Split tube PDHQ, and I love it! No balancing issues and I
added accessories to it. The split tube for the most part doesn't present me
with ill aligned optics. I did the wheel barrel modification, Argo Navis DSC,
ambient tempertaure sensor (connected to primary mirror), cooling fan, laser
pointer and I'm planning on adding a Moonlite focuser. I'm not a big fan of
their JMI focuser because I spoiled myself with Moonlite on my 10" telescope.
Big difference in my books!

I moved away from the desert area and now I'm having problems with dew, so I'm
looking at making my own dew zapper. I came along a website where a guy has
instructions on how to make your own. Here's the website for those interested.  
http://www.simcoeskies.com/dew/no_can_dew.html    Here's another website the
shows how to make the heat straps.  
http://www.dewbuster.com/heaters/heaters.html I'm making it for my eyepieces not
my telescope but probably would if I had a Mak Newtonian, refractor and etc. Oh,
I also found this website with high power laser at cheap prices!! Various powers
and the cheapest I've ever seen!! Some of these lasers have a added
Kaleidoscopic feature but it easily screws off. Here's that website.  
http://www.dinodirect.com/se/productname-laser.html  I bought Orion's Dovetail
attachment and laser holder and assembled it on my Discovery. This is such a
nice feature. It's the best way for two star alignment (with eyepiece reticle)
  or freehand as far as I'm concerned!

I just purchased an enclosed 6'x12' trailer, so now it's much easier to take the
scope out. I was using my 10" a lot more because it was easier to use but now
things are much better.

Clear skies,

Dell




________________________________
From: Harold <colt45hal@...>
To: Discovery-Dob-Users@yahoogroups.com
Sent: Mon, October 19, 2009 11:29:37 AM
Subject: [DDU] HOW  ABOUT  AN  INFORMAL  POLL,  DISCOVERY  OWNERS  ONLY:



How many of you own the Truss-Tube, the Split-Tube, or the original Rigid-Tube
Dob?  (All three of my past Discoverys were the Rigid-Tube PDHQ's...17. 5", 15",
and 12.5")

What aperture sizes do you own?

Thanks...
HAL







[Non-text portions of this message have been removed]

I purchased the 12.5" rigid tube new in 2004. I love it today as much as the
first time I set it up.

--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
> How many of you own the Truss-Tube, the Split-Tube, or the original Rigid-Tube
Dob?  (All three of my past Discoverys were the Rigid-Tube PDHQ's...17.5", 15",
and 12.5")
>
> What aperture sizes do you own?
>
> Thanks...
> HAL
>

I have the 12.5" F/5 truss Discovery. I've added a Feather touch focuser, Argo
Navis, dew guard system, fan, balance weights and a 12v 7 amp battery to run
everything. It lives on a scope buggy in my garage covered by the scope cover
that Discovery sells.
Two winters ago I sanded all the wood on the scope and refinished it in a dark
cherry finish. Even added little brass decorative corners on it (like a Rob
Teeter scope.) Very pleased with how it turned out.

This is the biggest scope I can manage, so to increase aperture I bought an
Image Intensifier Eyepiece this past April. For me, this is the perfect setup.
Maureen

--- In Discovery-Dob-Users@yahoogroups.com, "Don D'Egidio" <djd521@...> wrote:
>
> I should have mentioned mine is an F/5.
>
> Don
>
> ----- Original Message -----
> From: "Don D'Egidio" <djd521@...>
> To: <Discovery-Dob-Users@yahoogroups.com>
> Sent: Monday, October 19, 2009 1:10 PM
> Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:
>
>
> >I have a 17.5" Truss.
> >
> > Don
> >
>

I forgot to add that I bought mine in 2004 - I think.
Maureen


--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
> How many of you own the Truss-Tube, the Split-Tube, or the original Rigid-Tube
Dob?  (All three of my past Discoverys were the Rigid-Tube PDHQ's...17.5", 15",
and 12.5")
>
> What aperture sizes do you own?
>
> Thanks...
> HAL
>

I own a 12.5" f/5 solid tube, which I'm contemplating splitting.

Ken....


--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
> How many of you own the Truss-Tube, the Split-Tube, or the original Rigid-Tube
Dob?  (All three of my past Discoverys were the Rigid-Tube PDHQ's...17.5", 15",
and 12.5")
>
> What aperture sizes do you own?
>
> Thanks...
> HAL
>

Hello folks,
 
I have noticed a few have some balance issues with their scope, which I also
have on my homebrew dob.  In the Kriege book on building a truss dob, they have
a neat trick.  They connect a heavy multilink chain on the back of the scope
with some links on the ground. As you point the scope upward, less links and
less weight is on the mirror box, as you move the scope towards the horizon,
more links come off the ground and weight is added by the chain.
 
I haven't tried this, but it seems like an idea some of you could use.  It's
nice to see some activity on the Discovery Dob email.
 
Jeff




[Non-text portions of this message have been removed]

--- In Discovery-Dob-Users@yahoogroups.com, "StargazerTony" <stargazertony@...>
wrote:
>
> I purchased the 12.5" rigid tube new in 2004. I love it today as much as the
first time I set it up.

HEY TONY!  Is that you?  Have you joined this Forum?  I hope you have...it's a
kick! (I just joined this month) Everybody owns Discovery scopes here!

HAL









> --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> >
> >
> > How many of you own the Truss-Tube, the Split-Tube, or the original
Rigid-Tube Dob?  (All three of my past Discoverys were the Rigid-Tube
PDHQ's...17.5", 15", and 12.5")
> >
> > What aperture sizes do you own?
> >
> > Thanks...
> > HAL
> >
>

--- In Discovery-Dob-Users@yahoogroups.com, Jeff Berman <k9yr@...> wrote:
>
> Hello folks,
>  
> I have noticed a few have some balance issues with their scope, which I also
have on my homebrew dob.  In the Kriege book on building a truss dob, they have
a neat trick.  They connect a heavy multilink chain on the back of the scope
with some links on the ground. As you point the scope upward, less links and
less weight is on the mirror box, as you move the scope towards the horizon,
more links come off the ground and weight is added by the chain.
>  
> I haven't tried this, but it seems like an idea some of you could use.  It's
nice to see some activity on the Discovery Dob email.
>  
> Jeff
>

HEY JEFF:

You may blame me for the current rash of postings!

HAL
>
>
>
> [Non-text portions of this message have been removed]
>

--- In Discovery-Dob-Users@yahoogroups.com, "kdadey2000" <kadey@...> wrote:
>
> I own a 12.5" f/5 solid tube, which I'm contemplating splitting.
>
> Ken....

HEY KEN:

Be careful and think out all your moves well before pulling the cord on that
chain saw!

HAL


>
> --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> >
> >
> > How many of you own the Truss-Tube, the Split-Tube, or the original
Rigid-Tube Dob?  (All three of my past Discoverys were the Rigid-Tube
PDHQ's...17.5", 15", and 12.5")
> >
> > What aperture sizes do you own?
> >
> > Thanks...
> > HAL
> >
>

I used a chain for a number of years but then switched to a sliding rail system
from scopestuff.com. I found, for me, that the type of system you use is
influenced by the weight of the various eyepieces you have. I am very satisfied
with my current eyepiece collection and have no intention of adding to it. (Note
to self - must not look through 21mm Ethos.)
Maureen

--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
>
> --- In Discovery-Dob-Users@yahoogroups.com, Jeff Berman <k9yr@> wrote:
> >
> > Hello folks,
> >  
> > I have noticed a few have some balance issues with their scope, which I also
have on my homebrew dob.  In the Kriege book on building a truss dob, they have
a neat trick.  They connect a heavy multilink chain on the back of the scope
with some links on the ground. As you point the scope upward, less links and
less weight is on the mirror box, as you move the scope towards the horizon,
more links come off the ground and weight is added by the chain.
> >  
> > I haven't tried this, but it seems like an idea some of you could use.  It's
nice to see some activity on the Discovery Dob email.
> >  
> > Jeff
> >
>
> HEY JEFF:
>
> You may blame me for the current rash of postings!
>
> HAL
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>

--- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@...>
wrote:
>
> I used a chain for a number of years but then switched to a sliding rail
system from scopestuff.com. I found, for me, that the type of system you use is
influenced by the weight of the various eyepieces you have. I am very satisfied
with my current eyepiece collection and have no intention of adding to it. (Note
to self - must not look through 21mm Ethos.)
> Maureen


HEY MAUREEN:

The TV Ethos is a fine ocular...I've looked through one!

However, I still enjoy the 82 deg. FOV in my Naglers, and would buy another one
rather than an Ethos. (I have four premium oculars in my EP case, but only use
two at star parties, and sometimes only my 20mm Nagler all night!)

Nice Skies...
HAL

12" Meade LX200ACF
TV & Meade 4000 UWA Oculars
Coronado Solar Scope
Ordering Discovery 15" or 16" Split-Tube or Truss Dob
(Expect to pick it up sometime around the 2012 Presidential Election)












> --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> >
> >
> >
> > --- In Discovery-Dob-Users@yahoogroups.com, Jeff Berman <k9yr@> wrote:
> > >
> > > Hello folks,
> > >  
> > > I have noticed a few have some balance issues with their scope, which I
also have on my homebrew dob.  In the Kriege book on building a truss dob, they
have a neat trick.  They connect a heavy multilink chain on the back of the
scope with some links on the ground. As you point the scope upward, less links
and less weight is on the mirror box, as you move the scope towards the horizon,
more links come off the ground and weight is added by the chain.
> > >  
> > > I haven't tried this, but it seems like an idea some of you could use. 
It's nice to see some activity on the Discovery Dob email.
> > >  
> > > Jeff
> > >
> >
> > HEY JEFF:
> >
> > You may blame me for the current rash of postings!
> >
> > HAL
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
>

Thanks for the tip, Jeff  -

I'm going to have to experiment with that. I have that book. It just
didn't connect for some reason.

Dave Grosvold
Diamond Bar G Ranch (3 mi south of Morrow, AR)

Jeff Berman wrote:
>
>
> Hello folks,
> �
> I have noticed a few have some balance issues with their scope, which
> I also have on my homebrew dob.� In the Kriege book on building a
> truss dob, they have a neat trick.� They connect a heavy multilink
> chain on the back of the scope with some links on the ground. As you
> point the scope upward, less links and less weight is on the mirror
> box, as you move the scope towards the horizon, more links come off
> the ground and weight is added by the chain.
> �
> I haven't tried this, but it seems like an idea some of you could
> use.� It's nice to see some activity on the Discovery Dob email.
> �
> Jeff
>
>

Hi Hal,

I have the 8mm & 13mm Ethos so I am a fan but right now the cost/benefit ratio
is an important factor. I just don't think I will use it enough to justify the
cost. Of course all bets are off on this because Paul Dellechiaie (who designed
the Ethos) is a member of our club and he just is constantly offering "free"
views through the thing - so i just have to avoid him.
Maureen

--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
>
> --- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@>
wrote:
> >
> > I used a chain for a number of years but then switched to a sliding rail
system from scopestuff.com. I found, for me, that the type of system you use is
influenced by the weight of the various eyepieces you have. I am very satisfied
with my current eyepiece collection and have no intention of adding to it. (Note
to self - must not look through 21mm Ethos.)
> > Maureen
>
>
> HEY MAUREEN:
>
> The TV Ethos is a fine ocular...I've looked through one!
>
> However, I still enjoy the 82 deg. FOV in my Naglers, and would buy another
one rather than an Ethos. (I have four premium oculars in my EP case, but only
use two at star parties, and sometimes only my 20mm Nagler all night!)
>
> Nice Skies...
> HAL
>
> 12" Meade LX200ACF
> TV & Meade 4000 UWA Oculars
> Coronado Solar Scope
> Ordering Discovery 15" or 16" Split-Tube or Truss Dob
> (Expect to pick it up sometime around the 2012 Presidential Election)
>
>
>
>
>
>
>
>
>
>
>
>
> > --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> > >
> > >
> > >
> > > --- In Discovery-Dob-Users@yahoogroups.com, Jeff Berman <k9yr@> wrote:
> > > >
> > > > Hello folks,
> > > >  
> > > > I have noticed a few have some balance issues with their scope, which I
also have on my homebrew dob.  In the Kriege book on building a truss dob, they
have a neat trick.  They connect a heavy multilink chain on the back of the
scope with some links on the ground. As you point the scope upward, less links
and less weight is on the mirror box, as you move the scope towards the horizon,
more links come off the ground and weight is added by the chain.
> > > >  
> > > > I haven't tried this, but it seems like an idea some of you could use. 
It's nice to see some activity on the Discovery Dob email.
> > > >  
> > > > Jeff
> > > >
> > >
> > > HEY JEFF:
> > >
> > > You may blame me for the current rash of postings!
> > >
> > > HAL
> > > >
> > > >
> > > >
> > > > [Non-text portions of this message have been removed]
> > > >
> > >
> >
>

Hello all,

Re the poll: a 12.5" Truss-tube.  Easy up, easy down, solid performer.  Only
complaint at all would be the (not entirely minor) collimation slop/slippage I
get when moving toward zenith.  Have been unsuccessful in solving...

Bought it new couple and a half years ago.

Marc
   ----- Original Message -----
   From: Dave Grosvold
   To: Discovery-Dob-Users@yahoogroups.com
   Sent: Monday, October 19, 2009 12:40 PM
   Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:


     Hello -

   For yor poll, I have an original Rigid-Tube 12.5" PDHQ. I bought it used
   from another astronomer here in NW Arkansas.

   Dave Grosvold
   Diamond Bar G Ranch (3 mi south of Morrow, AR.)

   Harold wrote:
   >
   >
   >
   > How many of you own the Truss-Tube, the Split-Tube, or the original
   > Rigid-Tube Dob? (All three of my past Discoverys were the Rigid-Tube
   > PDHQ's...17.5", 15", and 12.5")
   >
   > What aperture sizes do you own?
   >
   > Thanks...
   > HAL
   >
   >




[Non-text portions of this message have been removed]

--- In Discovery-Dob-Users@yahoogroups.com, "saegaema" <saegaema@...> wrote:
>
> Hello all,
>
> Re the poll: a 12.5" Truss-tube.  Easy up, easy down, solid performer.  Only
complaint at all would be the (not entirely minor) collimation slop/slippage I
get when moving toward zenith.  Have been unsuccessful in solving...
>
> Bought it new couple and a half years ago.
>
> Marc


HEY MARC:

I had the same problem with my 20" Obsession when I owned it back in 2000.  It
would slip collimation 2 or 3 times a night when I went from near horizon to
zenith and back.

I sold it and went right into a solid Discovery 15" PDHQ, which held collimation
like a rock!

A lot of the Obsession's problem was due to the "sling-mounted" primary mirror,
I think.

HAL














----- Original Message -----
>   From: Dave Grosvold
>   To: Discovery-Dob-Users@yahoogroups.com
>   Sent: Monday, October 19, 2009 12:40 PM
>   Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:
>
>
>     Hello -
>
>   For yor poll, I have an original Rigid-Tube 12.5" PDHQ. I bought it used
>   from another astronomer here in NW Arkansas.
>
>   Dave Grosvold
>   Diamond Bar G Ranch (3 mi south of Morrow, AR.)
>
>   Harold wrote:
>   >
>   >
>   >
>   > How many of you own the Truss-Tube, the Split-Tube, or the original
>   > Rigid-Tube Dob? (All three of my past Discoverys were the Rigid-Tube
>   > PDHQ's...17.5", 15", and 12.5")
>   >
>   > What aperture sizes do you own?
>   >
>   > Thanks...
>   > HAL
>   >
>   >
>
>
>
>
> [Non-text portions of this message have been removed]
>

It's disappointing to hear you, too, experienced collimation going out of whack
and only found resolution by turning to a solid tube assembly.  I was hoping for
a fix ;-(

I own solid 6" and 8" dobs, but the 12.5 is the one I use most, for obvious
reasons.  I've socked down everything as tight as possible (though not the
clamps holding the mirror, of course, as to pinch the optics), but still get the
slop.  I also have skies with so much ambient light you can read legalese print
without the aid of a flashlight when under the six stars I can see, so having a
scope I can transport to dark skies without having to buy a trailer is a plus.

Thanks for responding, however, and clear and ambient, light-free, dark skies to
all.

Marc

   ----- Original Message -----
   From: Harold
   To: Discovery-Dob-Users@yahoogroups.com
   Sent: Friday, October 23, 2009 11:41 AM
   Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:




   --- In Discovery-Dob-Users@yahoogroups.com, "saegaema" <saegaema@...> wrote:
   >
   > Hello all,
   >
   > Re the poll: a 12.5" Truss-tube. Easy up, easy down, solid performer. Only
complaint at all would be the (not entirely minor) collimation slop/slippage I
get when moving toward zenith. Have been unsuccessful in solving...
   >
   > Bought it new couple and a half years ago.
   >
   > Marc


   HEY MARC:

   I had the same problem with my 20" Obsession when I owned it back in 2000. It
would slip collimation 2 or 3 times a night when I went from near horizon to
zenith and back.

   I sold it and went right into a solid Discovery 15" PDHQ, which held
collimation like a rock!

   A lot of the Obsession's problem was due to the "sling-mounted" primary
mirror, I think.

   HAL

   ----- Original Message -----
   > From: Dave Grosvold
   > To: Discovery-Dob-Users@yahoogroups.com
   > Sent: Monday, October 19, 2009 12:40 PM
   > Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:
   >
   >
   > Hello -
   >
   > For yor poll, I have an original Rigid-Tube 12.5" PDHQ. I bought it used
   > from another astronomer here in NW Arkansas.
   >
   > Dave Grosvold
   > Diamond Bar G Ranch (3 mi south of Morrow, AR.)
   >
   > Harold wrote:
   > >
   > >
   > >
   > > How many of you own the Truss-Tube, the Split-Tube, or the original
   > > Rigid-Tube Dob? (All three of my past Discoverys were the Rigid-Tube
   > > PDHQ's...17.5", 15", and 12.5")
   > >
   > > What aperture sizes do you own?
   > >
   > > Thanks...
   > > HAL
   > >
   > >
   >
   >
   >
   >
   > [Non-text portions of this message have been removed]
   >





[Non-text portions of this message have been removed]

About 4-5 years ago Don Penske(?) (Starman1 on CN) suggested replacing the small
washers under the screws that hold the spider with fender washers. I tried it
and am happy to report that my 12.5" truss hold collimation very well.
Maureen

Hi Marc,



One big problem I have had with my Discovery 17.5" truss DOB is the constant
need for re-collimation several times during an observing night. The first
thing I discovered was that the mirror cell didn't support the mirror all
that well. The mirror actually fell forward out of the cell on 3 different
occasions. That was kind of scary so I built a new 18 point mirror cell
based on the design used by David Kriege and Richard Berry. The second thing
I discovered was that the nylon spacer used in the secondary mirror mounting
bolt was split. I replaced this with a thicker version and this eliminated
the secondary mirror problems. The third thing I discovered was that the
pole attachment to the secondary cage would slip during use and cause the
secondary cage to shift thus causing the collimation to change. I designed
and built an offset bracket system for the pole attachment to the secondary
cage to replace the original bracket system. These three modifications
stabilized the collimation to the point that during an observing night I can
detect almost no change after moving the scope around the sky through the
course of the evening. Many times after transporting the scope to a site I
can set it up and find that the collimation is very close, only minor tweaks
are needed.



Jack

Edmonds, WA

   _____

From: Discovery-Dob-Users@yahoogroups.com
[mailto:Discovery-Dob-Users@yahoogroups.com] On Behalf Of saegaema
Sent: Friday, October 23, 2009 8:52 AM
To: Discovery-Dob-Users@yahoogroups.com
Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:





It's disappointing to hear you, too, experienced collimation going out of
whack and only found resolution by turning to a solid tube assembly. I was
hoping for a fix ;-(

I own solid 6" and 8" dobs, but the 12.5 is the one I use most, for obvious
reasons. I've socked down everything as tight as possible (though not the
clamps holding the mirror, of course, as to pinch the optics), but still get
the slop. I also have skies with so much ambient light you can read legalese
print without the aid of a flashlight when under the six stars I can see, so
having a scope I can transport to dark skies without having to buy a trailer
is a plus.

Thanks for responding, however, and clear and ambient, light-free, dark
skies to all.

Marc

----- Original Message -----
From: Harold
To: Discovery-Dob- <mailto:Discovery-Dob-Users%40yahoogroups.com>
Users@yahoogroups.com
Sent: Friday, October 23, 2009 11:41 AM
Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:

--- In Discovery-Dob- <mailto:Discovery-Dob-Users%40yahoogroups.com>
Users@yahoogroups.com, "saegaema" <saegaema@...> wrote:
>
> Hello all,
>
> Re the poll: a 12.5" Truss-tube. Easy up, easy down, solid performer. Only
complaint at all would be the (not entirely minor) collimation slop/slippage
I get when moving toward zenith. Have been unsuccessful in solving...
>
> Bought it new couple and a half years ago.
>
> Marc

HEY MARC:

I had the same problem with my 20" Obsession when I owned it back in 2000.
It would slip collimation 2 or 3 times a night when I went from near horizon
to zenith and back.

I sold it and went right into a solid Discovery 15" PDHQ, which held
collimation like a rock!

A lot of the Obsession's problem was due to the "sling-mounted" primary
mirror, I think.

HAL

----- Original Message -----
> From: Dave Grosvold
> To: Discovery-Dob- <mailto:Discovery-Dob-Users%40yahoogroups.com>
Users@yahoogroups.com
> Sent: Monday, October 19, 2009 12:40 PM
> Subject: Re: [DDU] HOW ABOUT AN INFORMAL POLL, DISCOVERY OWNERS ONLY:
>
>
> Hello -
>
> For yor poll, I have an original Rigid-Tube 12.5" PDHQ. I bought it used
> from another astronomer here in NW Arkansas.
>
> Dave Grosvold
> Diamond Bar G Ranch (3 mi south of Morrow, AR.)
>
> Harold wrote:
> >
> >
> >
> > How many of you own the Truss-Tube, the Split-Tube, or the original
> > Rigid-Tube Dob? (All three of my past Discoverys were the Rigid-Tube
> > PDHQ's...17.5", 15", and 12.5")
> >
> > What aperture sizes do you own?
> >
> > Thanks...
> > HAL
> >
> >
>
>
>
>
> [Non-text portions of this message have been removed]
>

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

Thanks to all who responded with suggestions for correcting collimation slop.  I
will give a few of the recommendations a try.  I'd done a search some time ago
in archives and found the recommendation (I believe you're correct, Maureen,
from Don Penske) suggesting fender washer replacement, which I tried. 
Unfortunately, it didn't solve the problem.

I'm dedicated to fixing this issue, however.  I love the fall and winter targets
and want to give the 12.5 a lot of time under the stars/nebulae, galaxies, PNs,
etc.

Marc



----- Original Message -----
   From: skiestogaze
   To: Discovery-Dob-Users@yahoogroups.com
   Sent: Friday, October 23, 2009 5:52 PM
   Subject: [DDU] Collimation Slop


     About 4-5 years ago Don Penske(?) (Starman1 on CN) suggested replacing the
small washers under the screws that hold the spider with fender washers. I tried
it and am happy to report that my 12.5" truss hold collimation very well.
   Maureen





[Non-text portions of this message have been removed]

--- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@...>
wrote:
>
> About 4-5 years ago Don Penske(?) (Starman1 on CN) suggested replacing the
small washers under the screws that hold the spider with fender washers. I tried
it and am happy to report that my 12.5" truss hold collimation very well.
> Maureen
>


Yes, Maureen...the fender washers allow you to place more tension on the spider
vanes by allowing that tension to be distributed over the wider area presented
by the bigger washers.

HAL

I used fender washers too, when I first got the scope (15" TD), but finally
built a new upper cage assembly, shaving off two pounds and greatly increasing
rigidity.  This allowed removal of several pounds of counterweights from the
mirror box.  (You mean Don Pensack?)

--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
>
> --- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@>
wrote:
> >
> > About 4-5 years ago Don Penske(?) (Starman1 on CN) suggested replacing the
small washers under the screws that hold the spider with fender washers. I tried
it and am happy to report that my 12.5" truss hold collimation very well.
> > Maureen
> >
>
>
> Yes, Maureen...the fender washers allow you to place more tension on the
spider vanes by allowing that tension to be distributed over the wider area
presented by the bigger washers.
>
> HAL
>

Marc,

Don is extremely knowledgeable and helpful. He also own a 12.5" Discovery truss
scope.
I haven't seen him post on here in a very long time but you could reach him by
posting on Cloudy Nights or sending him a PM through that site. I'd be surprised
if he couldn't help you.
Maureen

--- In Discovery-Dob-Users@yahoogroups.com, "saegaema" <saegaema@...> wrote:
>
> Thanks to all who responded with suggestions for correcting collimation slop. 
I will give a few of the recommendations a try.  I'd done a search some time ago
in archives and found the recommendation (I believe you're correct, Maureen,
from Don Penske) suggesting fender washer replacement, which I tried. 
Unfortunately, it didn't solve the problem.
>
> I'm dedicated to fixing this issue, however.  I love the fall and winter
targets and want to give the 12.5 a lot of time under the stars/nebulae,
galaxies, PNs, etc.
>
> Marc
>
>
>
> ----- Original Message -----
>   From: skiestogaze
>   To: Discovery-Dob-Users@yahoogroups.com
>   Sent: Friday, October 23, 2009 5:52 PM
>   Subject: [DDU] Collimation Slop
>
>
>     About 4-5 years ago Don Penske(?) (Starman1 on CN) suggested replacing the
small washers under the screws that hold the spider with fender washers. I tried
it and am happy to report that my 12.5" truss hold collimation very well.
>   Maureen
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

HELLO!

I visited Discovery's manufacturing facility today to see if the three 15"
Split-Tube components Bill provided for me would fit in my compact Toyota wagon,
just for a fit-check.

THEY FIT!

Then Bill took my wife and I on a complete tour of his plant, and we visited the
Incoming Warehouse, where the 500-pound 48"x60" Schott blanks are stored from
their trip from the Schott Glassworks in Germany.

Then we went to the Cutting Room, where the large blanks are sawn into squares
of various sizes for the round mirror blanks.

Then we saw the various-sized diamond-toothed "Cookie Cutters" that generated
the round blanks.

From there, the blanks were flat-surfaced on both sides, then they went to the
Annealing Ovens.  From the Ovens, which were programmed to allow cooling at a
prescribed rate, they went to the Rough Grinding Machines, where a spherical
curve with the correct saggita for the desired focal length was generated.

Then the mirrors are shipped out to a Local Optician, where they are figured to
the desired parboloidal focal ratio, then shipped back to Bill for Aluminizing
and Overcoating, both operations done in the same Vacuum Chamber.

Bill's aluminizing chambers can handle mirrors of up to 24", which is the
largest size tlescope in his catalog.  From there we toured his Machine Shop,
his Tube-Cutting Shop, his Woodworking Shop, and his Packaging Department.

Then came the big surprise:

I asked Bill if a 16" mirror would fit in the tubes made for the 15" telescopes
in his Catalog.  He said they would, and offered to make me a 16" f/4.5
Split-Tube Dob, to which I heartily agreed!

This special order (at extra cost, of course), is not even listed in his retail
catalog of Dobsonian Telecopes!

So there you have it...I made a deposit on an unlisted 16" f/4.5 Discovery Dob,
which Bill said would be ready in no longer than 90 days, and if he overruns,
I'll get a 10 percent discount off the price.

This will be my fourth 16" f/4.5 Dob, and also my 4th Discovery Telescope!
(Previous dobs: 17.5", 15", and 12.5")

HAL.

Congratulations Hal! Thanks for the interesting report on Bill's operation.
Hopefully, he'll be able to turn things around and get Phil Harrington to "take
back" his negative comment in the next edition of "Star Ware."
Maureen

--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
> HELLO!
>
> I visited Discovery's manufacturing facility today to see if the three 15"
Split-Tube components Bill provided for me would fit in my compact Toyota wagon,
just for a fit-check.
>
> THEY FIT!
>
> Then Bill took my wife and I on a complete tour of his plant, and we visited
the Incoming Warehouse, where the 500-pound 48"x60" Schott blanks are stored
from their trip from the Schott Glassworks in Germany.
>
> Then we went to the Cutting Room, where the large blanks are sawn into squares
of various sizes for the round mirror blanks.
>
> Then we saw the various-sized diamond-toothed "Cookie Cutters" that generated
the round blanks.
>
> From there, the blanks were flat-surfaced on both sides, then they went to the
Annealing Ovens.  From the Ovens, which were programmed to allow cooling at a
prescribed rate, they went to the Rough Grinding Machines, where a spherical
curve with the correct saggita for the desired focal length was generated.
>
> Then the mirrors are shipped out to a Local Optician, where they are figured
to the desired parboloidal focal ratio, then shipped back to Bill for
Aluminizing and Overcoating, both operations done in the same Vacuum Chamber.
>
> Bill's aluminizing chambers can handle mirrors of up to 24", which is the
largest size tlescope in his catalog.  From there we toured his Machine Shop,
his Tube-Cutting Shop, his Woodworking Shop, and his Packaging Department.
>
> Then came the big surprise:
>
> I asked Bill if a 16" mirror would fit in the tubes made for the 15"
telescopes in his Catalog.  He said they would, and offered to make me a 16"
f/4.5 Split-Tube Dob, to which I heartily agreed!
>
> This special order (at extra cost, of course), is not even listed in his
retail catalog of Dobsonian Telecopes!
>
> So there you have it...I made a deposit on an unlisted 16" f/4.5 Discovery
Dob, which Bill said would be ready in no longer than 90 days, and if he
overruns, I'll get a 10 percent discount off the price.
>
> This will be my fourth 16" f/4.5 Dob, and also my 4th Discovery Telescope!
(Previous dobs: 17.5", 15", and 12.5")
>
> HAL.
>

--- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@...>
wrote:
>
> Congratulations Hal! Thanks for the interesting report on Bill's operation.
Hopefully, he'll be able to turn things around and get Phil Harrington to "take
back" his negative comment in the next edition of "Star Ware."
> Maureen


HEY MAUREEN:

I know nothlng of which you're speaking.

HAL



> --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> >
> >
> > HELLO!
> >
> > I visited Discovery's manufacturing facility today to see if the three 15"
Split-Tube components Bill provided for me would fit in my compact Toyota wagon,
just for a fit-check.
> >
> > THEY FIT!
> >
> > Then Bill took my wife and I on a complete tour of his plant, and we visited
the Incoming Warehouse, where the 500-pound 48"x60" Schott blanks are stored
from their trip from the Schott Glassworks in Germany.
> >
> > Then we went to the Cutting Room, where the large blanks are sawn into
squares of various sizes for the round mirror blanks.
> >
> > Then we saw the various-sized diamond-toothed "Cookie Cutters" that
generated the round blanks.
> >
> > From there, the blanks were flat-surfaced on both sides, then they went to
the Annealing Ovens.  From the Ovens, which were programmed to allow cooling at
a prescribed rate, they went to the Rough Grinding Machines, where a spherical
curve with the correct saggita for the desired focal length was generated.
> >
> > Then the mirrors are shipped out to a Local Optician, where they are figured
to the desired parboloidal focal ratio, then shipped back to Bill for
Aluminizing and Overcoating, both operations done in the same Vacuum Chamber.
> >
> > Bill's aluminizing chambers can handle mirrors of up to 24", which is the
largest size tlescope in his catalog.  From there we toured his Machine Shop,
his Tube-Cutting Shop, his Woodworking Shop, and his Packaging Department.
> >
> > Then came the big surprise:
> >
> > I asked Bill if a 16" mirror would fit in the tubes made for the 15"
telescopes in his Catalog.  He said they would, and offered to make me a 16"
f/4.5 Split-Tube Dob, to which I heartily agreed!
> >
> > This special order (at extra cost, of course), is not even listed in his
retail catalog of Dobsonian Telecopes!
> >
> > So there you have it...I made a deposit on an unlisted 16" f/4.5 Discovery
Dob, which Bill said would be ready in no longer than 90 days, and if he
overruns, I'll get a 10 percent discount off the price.
> >
> > This will be my fourth 16" f/4.5 Dob, and also my 4th Discovery Telescope!
(Previous dobs: 17.5", 15", and 12.5")
> >
> > HAL.
> >
>

Hal,

Phil Harrington, in the last edition of "Star Ware" said that he couldn't
recommend Discovery scopes, not because of their quality, but because of the
problems with delivery times and poor communication with customers.
Maureen

--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
>
>
>
> --- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@>
wrote:
> >
> > Congratulations Hal! Thanks for the interesting report on Bill's operation.
Hopefully, he'll be able to turn things around and get Phil Harrington to "take
back" his negative comment in the next edition of "Star Ware."
> > Maureen
>
>
> HEY MAUREEN:
>
> I know nothlng of which you're speaking.
>
> HAL
>
>
>
> > --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> > >
> > >
> > > HELLO!
> > >
> > > I visited Discovery's manufacturing facility today to see if the three 15"
Split-Tube components Bill provided for me would fit in my compact Toyota wagon,
just for a fit-check.
> > >
> > > THEY FIT!
> > >
> > > Then Bill took my wife and I on a complete tour of his plant, and we
visited the Incoming Warehouse, where the 500-pound 48"x60" Schott blanks are
stored from their trip from the Schott Glassworks in Germany.
> > >
> > > Then we went to the Cutting Room, where the large blanks are sawn into
squares of various sizes for the round mirror blanks.
> > >
> > > Then we saw the various-sized diamond-toothed "Cookie Cutters" that
generated the round blanks.
> > >
> > > From there, the blanks were flat-surfaced on both sides, then they went to
the Annealing Ovens.  From the Ovens, which were programmed to allow cooling at
a prescribed rate, they went to the Rough Grinding Machines, where a spherical
curve with the correct saggita for the desired focal length was generated.
> > >
> > > Then the mirrors are shipped out to a Local Optician, where they are
figured to the desired parboloidal focal ratio, then shipped back to Bill for
Aluminizing and Overcoating, both operations done in the same Vacuum Chamber.
> > >
> > > Bill's aluminizing chambers can handle mirrors of up to 24", which is the
largest size tlescope in his catalog.  From there we toured his Machine Shop,
his Tube-Cutting Shop, his Woodworking Shop, and his Packaging Department.
> > >
> > > Then came the big surprise:
> > >
> > > I asked Bill if a 16" mirror would fit in the tubes made for the 15"
telescopes in his Catalog.  He said they would, and offered to make me a 16"
f/4.5 Split-Tube Dob, to which I heartily agreed!
> > >
> > > This special order (at extra cost, of course), is not even listed in his
retail catalog of Dobsonian Telecopes!
> > >
> > > So there you have it...I made a deposit on an unlisted 16" f/4.5 Discovery
Dob, which Bill said would be ready in no longer than 90 days, and if he
overruns, I'll get a 10 percent discount off the price.
> > >
> > > This will be my fourth 16" f/4.5 Dob, and also my 4th Discovery Telescope!
(Previous dobs: 17.5", 15", and 12.5")
> > >
> > > HAL.
> > >
> >
>

--- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@...>
wrote:
>
> Hal,
>
> Phil Harrington, in the last edition of "Star Ware" said that he couldn't
recommend Discovery scopes, not because of their quality, but because of the
problems with delivery times and poor communication with customers.
> Maureen


Thanks, Mo  (If I may...)

It's true that delivery times have always been the bugaboo with Discovery, but
they can never be faulted on Quality!

When I ordered my second Discovery, a 15" rigid-tube PDHQ, I called Bill on a
Friday, and since he happened to have one in stock, I drove down the next day
and picked it up!

Probably the shortest "wait" on record!

Nice Skies...
HAL









> --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> >
> >
> >
> >
> >
> > --- In Discovery-Dob-Users@yahoogroups.com, "skiestogaze" <skiestogaze@>
wrote:
> > >
> > > Congratulations Hal! Thanks for the interesting report on Bill's
operation. Hopefully, he'll be able to turn things around and get Phil
Harrington to "take back" his negative comment in the next edition of "Star
Ware."
> > > Maureen
> >
> >
> > HEY MAUREEN:
> >
> > I know nothlng of which you're speaking.
> >
> > HAL
> >
> >
> >
> > > --- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@> wrote:
> > > >
> > > >
> > > > HELLO!
> > > >
> > > > I visited Discovery's manufacturing facility today to see if the three
15" Split-Tube components Bill provided for me would fit in my compact Toyota
wagon, just for a fit-check.
> > > >
> > > > THEY FIT!
> > > >
> > > > Then Bill took my wife and I on a complete tour of his plant, and we
visited the Incoming Warehouse, where the 500-pound 48"x60" Schott blanks are
stored from their trip from the Schott Glassworks in Germany.
> > > >
> > > > Then we went to the Cutting Room, where the large blanks are sawn into
squares of various sizes for the round mirror blanks.
> > > >
> > > > Then we saw the various-sized diamond-toothed "Cookie Cutters" that
generated the round blanks.
> > > >
> > > > From there, the blanks were flat-surfaced on both sides, then they went
to the Annealing Ovens.  From the Ovens, which were programmed to allow cooling
at a prescribed rate, they went to the Rough Grinding Machines, where a
spherical curve with the correct saggita for the desired focal length was
generated.
> > > >
> > > > Then the mirrors are shipped out to a Local Optician, where they are
figured to the desired parboloidal focal ratio, then shipped back to Bill for
Aluminizing and Overcoating, both operations done in the same Vacuum Chamber.
> > > >
> > > > Bill's aluminizing chambers can handle mirrors of up to 24", which is
the largest size tlescope in his catalog.  From there we toured his Machine
Shop, his Tube-Cutting Shop, his Woodworking Shop, and his Packaging Department.
> > > >
> > > > Then came the big surprise:
> > > >
> > > > I asked Bill if a 16" mirror would fit in the tubes made for the 15"
telescopes in his Catalog.  He said they would, and offered to make me a 16"
f/4.5 Split-Tube Dob, to which I heartily agreed!
> > > >
> > > > This special order (at extra cost, of course), is not even listed in his
retail catalog of Dobsonian Telecopes!
> > > >
> > > > So there you have it...I made a deposit on an unlisted 16" f/4.5
Discovery Dob, which Bill said would be ready in no longer than 90 days, and if
he overruns, I'll get a 10 percent discount off the price.
> > > >
> > > > This will be my fourth 16" f/4.5 Dob, and also my 4th Discovery
Telescope! (Previous dobs: 17.5", 15", and 12.5")
> > > >
> > > > HAL.
> > > >
> > >
> >
>

Bill told (wrote) me many times about his operations and plans.
However, there was no improvements in lead times, they were generated by the
pyrex shortage.
Those long lead times went on and on for several years.

I wish I could visit his shop one day. Looks like he have plenty of glass now.
Very nice report Hal. And congrats with your order!
I hope I will be able to order a 22 incher...

johan


--- In Discovery-Dob-Users@yahoogroups.com, "Harold" <colt45hal@...> wrote:
>
>
> HELLO!
>
> I visited Discovery's manufacturing facility today to see if the three 15"
Split-Tube components Bill provided for me would fit in my compact Toyota wagon,
just for a fit-check.
>
> THEY FIT!
>
> Then Bill took my wife and I on a complete tour of his plant, and we visited
the Incoming Warehouse, where the 500-pound 48"x60" Schott blanks are stored
from their trip from the Schott Glassworks in Germany.
>
> Then we went to the Cutting Room, where the large blanks are sawn into squares
of various sizes for the round mirror blanks.
>
> Then we saw the various-sized diamond-toothed "Cookie Cutters" that generated
the round blanks.
>
> From there, the blanks were flat-surfaced on both sides, then they went to the
Annealing Ovens.  From the Ovens, which were programmed to allow cooling at a
prescribed rate, they went to the Rough Grinding Machines, where a spherical
curve with the correct saggita for the desired focal length was generated.
>
> Then the mirrors are shipped out to a Local Optician, where they are figured
to the desired parboloidal focal ratio, then shipped back to Bill for
Aluminizing and Overcoating, both operations done in the same Vacuum Chamber.
>
> Bill's aluminizing chambers can handle mirrors of up to 24", which is the
largest size tlescope in his catalog.  From there we toured his Machine Shop,
his Tube-Cutting Shop, his Woodworking Shop, and his Packaging Department.
>
> Then came the big surprise:
>
> I asked Bill if a 16" mirror would fit in the tubes made for the 15"
telescopes in his Catalog.  He said they would, and offered to make me a 16"
f/4.5 Split-Tube Dob, to which I heartily agreed!
>
> This special order (at extra cost, of course), is not even listed in his
retail catalog of Dobsonian Telecopes!
>
> So there you have it...I made a deposit on an unlisted 16" f/4.5 Discovery
Dob, which Bill said would be ready in no longer than 90 days, and if he
overruns, I'll get a 10 percent discount off the price.
>
> This will be my fourth 16" f/4.5 Dob, and also my 4th Discovery Telescope!
(Previous dobs: 17.5", 15", and 12.5")
>
> HAL.
>

Just put a "wanted" ad at Astromart looking for an 8" F/7. Obviously, a
Discovery would be my first choice. If you know anyone willing to part with one,
let me know.

Mike