Help with 8 inch Dob

I have a 8 inch dob from Hardin Optical, I am trying to remove the primary
mirror to center mark it. I have removed the 6 screws around the tube but
the mirror assembly does don't want to move. I am afraid to use to much
force. Do I need to remove or loosen the thumbscrews or the other smaller
screws to remove it?

Thanks!

Put the 6 screws back. They are for collimation. See
http://gilstrap.home.texas.net/collimat/NoTools.html for good instructions on
how to recollimate it now that you have messed it up.
Read the manual on how to remove the mirror cell, or call Hardin for
instructions. The screws or bolts which hold the cell are probably on the
outside bottom of the tube assembly. Be VERY CAREFUL when loosening these, you
do not want the mirror and cell to fall out of the tube or to slide down and
hit the secondary mirror - this would probably mess up both mirrors at least,
and at worst break the spider.
Mark one of the screws and its position on the tube before you remove any, so
you can get the cell back in the same place after marking the center. This
might help reduce the effort of the recollimation after doing all this.
It probably would have been better to just read the collimation URL INSTEAD of
trying to mark the center of the mirror....
Best of luck -

Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

Put the 6 screws back. They are for collimation. See
http://gilstrap.home.texas.net/collimat/NoTools.html for good instructions on
how to recollimate it now that you have messed it up.
Read the manual on how to remove the mirror cell, or call Hardin for
instructions. The screws or bolts which hold the cell are probably on the
outside bottom of the tube assembly. Be VERY CAREFUL when loosening these, you
do not want the mirror and cell to fall out of the tube or to slide down and
hit the secondary mirror - this would probably mess up both mirrors at least,
and at worst break the spider.
Mark one of the screws and its position on the tube before you remove any, so
you can get the cell back in the same place after marking the center. This
might help reduce the effort of the recollimation after doing all this.
It probably would have been better to just read the collimation URL INSTEAD of
trying to mark the center of the mirror....
Best of luck -

Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

I wouldn't make such a big deal out of this (e.g. "messed it up"). All dob
owners need to get comfortable with taking their scopes apart and
collimating, so this is just part of the learning process. Of course, one
needs to be careful when working on any scope.

I don't know this particular scope, but it should be pretty clear which
screws hold the mirror cell in the tube versus which screws are for
collimation. I would call Hardin if it isn't.

Dennis

"Bill Foley" wrote in message
...
Put the 6 screws back. They are for collimation. See
http://gilstrap.home.texas.net/collimat/NoTools.html for good instructions
on
how to recollimate it now that you have messed it up.
Read the manual on how to remove the mirror cell, or call Hardin for
instructions. The screws or bolts which hold the cell are probably on the
outside bottom of the tube assembly. Be VERY CAREFUL when loosening
these, you
do not want the mirror and cell to fall out of the tube or to slide down
and
hit the secondary mirror - this would probably mess up both mirrors at
least,
and at worst break the spider.
Mark one of the screws and its position on the tube before you remove any,
so
you can get the cell back in the same place after marking the center.
This
might help reduce the effort of the recollimation after doing all this.
It probably would have been better to just read the collimation URL
INSTEAD of
trying to mark the center of the mirror....
Best of luck -

Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

I wouldn't make such a big deal out of this (e.g. "messed it up"). All dob
owners need to get comfortable with taking their scopes apart and
collimating, so this is just part of the learning process. Of course, one
needs to be careful when working on any scope.

I don't know this particular scope, but it should be pretty clear which
screws hold the mirror cell in the tube versus which screws are for
collimation. I would call Hardin if it isn't.

Dennis

"Bill Foley" wrote in message
...
Put the 6 screws back. They are for collimation. See
http://gilstrap.home.texas.net/collimat/NoTools.html for good instructions
on
how to recollimate it now that you have messed it up.
Read the manual on how to remove the mirror cell, or call Hardin for
instructions. The screws or bolts which hold the cell are probably on the
outside bottom of the tube assembly. Be VERY CAREFUL when loosening
these, you
do not want the mirror and cell to fall out of the tube or to slide down
and
hit the secondary mirror - this would probably mess up both mirrors at
least,
and at worst break the spider.
Mark one of the screws and its position on the tube before you remove any,
so
you can get the cell back in the same place after marking the center.
This
might help reduce the effort of the recollimation after doing all this.
It probably would have been better to just read the collimation URL
INSTEAD of
trying to mark the center of the mirror....
Best of luck -

Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

On Sat, 23 Aug 2003 19:14:09 GMT, "sacstream"
wrote:

I have a 8 inch dob from Hardin Optical, I am trying to remove the primary
mirror to center mark it. I have removed the 6 screws around the tube but
the mirror assembly does don't want to move. I am afraid to use to much
force. Do I need to remove or loosen the thumbscrews or the other smaller
screws to remove it?

Thanks!


No you dont need or want to be touching the screws on the very bottom
of the scope, they are for adjusting the mirror.

The correct ones are the six screws around the outside of the main
tube which hold the mirror cell in place. Have the tube laying down on
the carpet when you undo these.

On my 10 inch scope, the cell comes out very easily and perhaps with
yours the best way might to snag the edge of the mirror cell with the
corner of a piece of wood, and gently tap as you work your way around
the tube.

*NOTE: the mirror cell has an indent which will match up with the seam
of the tube.

On Sat, 23 Aug 2003 19:14:09 GMT, "sacstream"
wrote:

I have a 8 inch dob from Hardin Optical, I am trying to remove the primary
mirror to center mark it. I have removed the 6 screws around the tube but
the mirror assembly does don't want to move. I am afraid to use to much
force. Do I need to remove or loosen the thumbscrews or the other smaller
screws to remove it?

Thanks!


No you dont need or want to be touching the screws on the very bottom
of the scope, they are for adjusting the mirror.

The correct ones are the six screws around the outside of the main
tube which hold the mirror cell in place. Have the tube laying down on
the carpet when you undo these.

On my 10 inch scope, the cell comes out very easily and perhaps with
yours the best way might to snag the edge of the mirror cell with the
corner of a piece of wood, and gently tap as you work your way around
the tube.

*NOTE: the mirror cell has an indent which will match up with the seam
of the tube.