TEC 110FL FOCUSER
The APO110FL dimensions asked for a focuser that would fit OTA in
good proportion and be large enough to avoid vignetting for wide
field imaging. The FT 3545 that we used on all our larger scopes
was too large.
The focuser has been designed and made in our shop - it is
entirely a TEC focuser. While similar in appearance to
other focusers on the market, it has a few special
features that were required for today's imaging:
- It is all metal 2" collet type holder; being all
metal it does not change holding force under
colder temperatures and would not be
damaged from sun heat exposure either.
- Holding capacity (axial load) of TEC
collet itself is over 5 times the telescope
weight - thanks to special design of the collet.
Compared to traditional thumb screw holders the
collet type holder keeps item's axis strictly
concentric to focuser axis by definition.
- Focuser draw tube is held in the focuser housing all the way
around that also makes the axis of draw tube strictly concentric
to the optical axis of telescope. Holding draw tube in such a
way makes the focuser more robust, focuser has virtually no
play under radial load, 7lb weight shifts fully extended draw
tube for less than 20mk.
- The F5.6 ratio required finer focusing compared to our
typical F7 telescopes since permitted defocusing is two times
less. The planetary mechanism ratio is 1:10 and one turn of the
fine focusing knob moves focuser tube 1.8mm.
- The TEC focuser is "dry" - no oiling is required on the focuser
draw tube - this will keep focuser draw tube free from dirt.
Focuser parts
1.
Focuser locking collar
2.
Tension adjustment knob
3.
Focuser housing
4.
Focuser draw tube
5.
Draw tube end cap
6.
End cap locking screws (3X)
7.
Collet locking nut
8.
Collet sleeve
9.
Coarse focusing knobs
10.
Fine focusing knob
11.
Right knob set screw
12.
Pinion shaft housing
13. Pinion shaft housing threaded holes (4X)
14.
Pinion housing plastic screw
15.
Pinion housing screws (3X).
5
1
2
3
9
10
9
9
11
12
13
13
14
15
4
5
6
7
8
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