This is for my tower balcony 24/7 seeker. With heavy EPs it's asking for a significant OTA rebalancing often. The first solution was an OTA counterweight (3lb) sliding on H&L tension belts. This one is finally the ultimate solution for this classic small tube long refractor telescope:
Design details as follows.
On the image above
Note the screw-less bottom sliding lock at the bottom of the image, the mount bar protrusion to the the right side with slight deviation in the base shape curvature, and the fact that this is actually two rings clamp (step-down bands on the OTA side of clamps), not one, controlled with a single screw.
1. At the top, the red colored clamp hand screw is abstract. But its head base OD and the screw size follow the particular handle I have at hand.
2. That red screw dictates the size of the side bulge, which is distributing the compression force from the handle to the outside halve of the 64mm ID clamp by utilizing dynamic surface shapes. Also trying to minimize the bulge volume.
3. On the opposite end there is a standard hex nut counterbore (later plugged with the separate bolt end cap) visible in the top lip of the inside clamp halve on above img. The counterbore is completely hiding the nut. But guarantees 8mm of material thickness in front of it. The flat side of the hex nut counterbore wall is perpendicular to print layers.
4. The opposite end is implemented as a screw-less "fist lock". It's not free opening even with the screw fully removed as it's strength is relying on the OTA rigidity. To disengage the ring you need to slide the outer halve (screw handle side) up or down the OTA.
5. The inside halve outer surface designed to match the original compression forces distribution of the Celestron simple EQ mount OTA holder mechanism. The precise shape of the mount bar and small but important counter-bulge curvature is paramount for Celestron mechanism correct functionality.
6. On the image bellow the mounting bar profile is shown with contours of screw holes for 2x original Celestron mount M4 tension screws (need to be carefully removed from the OTA). The important dimension here is the hex well depth (coming-in from the OTA wall side) defining the thickness of the material under the screw to match or exceed the original length of the screws available for finger-nuts of the Celestron mount. It's also possible to replace screws with a longer size. Or even make the connection permanent.
Img 2. from layers surface side with hidden inner edges. |
7. Printed with layers perpendicular to the OTA OA (parallel to your screen on the Img 2).
8. Inner edges of virtual rings pair (inside the clamp) are beveled to prevent sharp edge on the OTA paint and reduce supports needed.
Log
- 3D-Print (PETG/H0.4/L0.2mm/W6/S5/I25%) - check, 6 hours.
- Process - check, minor.
- Mount - parts fit is good, but OTA clamping is a bit weak.
- Test - works, but the clamp diameter is a bit larger than anticipated. Not worth re-printing, so adding the OTA sleave (about 0.4mm thick C-shape in PU) to compensate instead.
- Decide print parameters improvement.
- -0.4mm inner diameter,
- Top gap +2 mm
- Hex counterbore +1.6 mm closer to the handle.
- Invert the "fist lock", so with #3 it makes more open shape.
- move bolt 2 mm up.
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