Dob collimation/focus tube slop problem solved.

Like many, I have been bothered by play between the walls of the
focuser tube and a variety of collimation instruments
(cheshire/lasermate deluxe, etc). The level of resultant imprecision
undermined the level of collimation accuracy I sought.
I tried a variety of remedies, including little strips of scotch tape,
flocking paper, etc. to remove this play.
This morning I tried a new tape that worked well: black electricians
tape.
What made the difference is that this tape is elastic, and maintains
it's shape once stretched.
I cut three full-width strips, to be placed parallel to the focus tube
axis and at the three cardinal points relatively to the focus tube set
screw (orion xt8, old style, 1.25" focuser). I then stretched each
piece after gently positioning inside the tube, and then pressed the
loose ends onto an outer aspect of the tube, to ensure that the strip
stayed in place. I was able to then get a variety of eyepieces and my
laser collimator into the tube, but it was a tight fit. I then
sprayed a tiny bit of silicone spray on my pinky and lightly brushed
each tape strip, and let dry. That did it. Now, eyepieces and
collimator slide into the tube with precision, and recollimation was a
pleasure, since the laser stayed put.
Hope my discovery aids your efforts in improved collimation accuracy.
bob hertel

"Robert Hertel" wrote in message
om...
Like many, I have been bothered by play between the walls of the
focuser tube and a variety of collimation instruments
(cheshire/lasermate deluxe, etc). The level of resultant imprecision
undermined the level of collimation accuracy I sought.
I tried a variety of remedies, including little strips of scotch tape,
flocking paper, etc. to remove this play.
This morning I tried a new tape that worked well: black electricians
tape.
What made the difference is that this tape is elastic, and maintains
it's shape once stretched.
I cut three full-width strips, to be placed parallel to the focus tube
axis and at the three cardinal points relatively to the focus tube set
screw (orion xt8, old style, 1.25" focuser). I then stretched each
piece after gently positioning inside the tube, and then pressed the
loose ends onto an outer aspect of the tube, to ensure that the strip
stayed in place. I was able to then get a variety of eyepieces and my
laser collimator into the tube, but it was a tight fit. I then
sprayed a tiny bit of silicone spray on my pinky and lightly brushed
each tape strip, and let dry. That did it. Now, eyepieces and
collimator slide into the tube with precision, and recollimation was a
pleasure, since the laser stayed put.
Hope my discovery aids your efforts in improved collimation accuracy.
bob hertel

Excellent solution. Thanks for sharing it.

Cheers,
Larry G.

woodcraft.com has a thin adhesive teflon strip, works well in a Synta focuser.
Type "slick strips" in search box.
DL Smallen

I just now went to that site and it froze my computer. Perhaps it got wood chips
in my cpu?
Bill Meyers

D Smallen wrote:

woodcraft.com has a thin adhesive teflon strip, works well in a Synta focuser.
Type "slick strips" in search box.
DL Smallen