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DO NOT DISMANTLE YOUR FOCUSER OR ANY GUARANTEE WILL BE VOID!
DO NOT BLAME ME FOR OUR OWN IDIOCY IF YOU COPY MY EXAMPLE!
Please ignore any marks or dust on the Feather Touch focuser you see here. These are entirely my own fault from frequent handling for taking measurements, etc. The focuser was absolutely flawless on arrival and superbly [double] packed to survive the worst disasters.
Please ignore any marks or dust on the Feather Touch focuser you see here. These are entirely my own fault from frequent handling for taking measurements, etc. The focuser was absolutely flawless on arrival and superbly [double] packed to survive the worst disasters.
Note that I have a very long lifetime's experience in a whole variety of mechanical work, clock making and restoring, cycle and vehicle mechanics, building and maintaining my own cars, motorcycles and cycles, machine workshop practice, making telescopes, optical instruments and mountings, machinery maintenance, scale modelling and building my own hi-fi turntables & pickup arms, etc.etc.
I'm not bragging. Merely pointing out that I have some experience at fixing things which were not broken. I was prepared to take the risk in dismantling the focuser even though Starlight Instruments, very sensibly, told me not to. I shan't show how I went about it in case it encourages the ham fisted. There may still be those who find interest in "exposed parts."
I'm not bragging. Merely pointing out that I have some experience at fixing things which were not broken. I was prepared to take the risk in dismantling the focuser even though Starlight Instruments, very sensibly, told me not to. I shan't show how I went about it in case it encourages the ham fisted. There may still be those who find interest in "exposed parts."
First I removed the pinion housing which allowed the focuser to break down to its major, constituent parts. This avoided using too much guesswork as to turning the base ring to fit the focuser.
I started by boring 1cm into the top of the base ring in the lathe. Then I opened it out to the correct diameter to just fit over the 3435 housing. More boring followed to achieve a perfect, sliding fit.
Then I could cut a bevel on the inner edge of the ring to lower the ring enough to engage the collar thread. After that I had to reverse the ring and turn a shoulder into the other side of the ring for the drawtube stop screw.I was aiming for a deep engagement of the collar on its thread while simultaneously, almost contacting the faces of the housing and the base ring. A close up of the telescope end of the focuser main housing with collar withdrawn as far as it will normally go. Note the bevel.
The focuser collar with the base ring newly fitted. The collar has a fine, embedded O-ring to achieve a subtly adjustable and non-damaging grip on the base ring. Which FT call an "adapter" since it usually adapts a focuser to a given OTA.
Still in the lathe, the collar and main housing are all fitted together before I dare to remove the base ring from the chuck. Which would lose perfect concentricity.
Another view of the main housing with collar and base ring fitted. Inside the housing, the small gap between the housing and base ring is almost closed.
The telescope side of the base ring showing the shoulder to clear the drawtube stop screw. I went on to deepen it further after taking the photograph. This side will fit into a counterbored housing in a 180mm diameter backplate.
The bored out base ring almost completed. I am smoothing and polishing the bored out surface where it rides on the housing. A nice fit is desirable to allow the entire focuser to be rotated smoothly once the collar is slightly loosened.
The stainless steel, helical pinion of the 3545 focuser. The brass component is the pinion brake.
The collar and housing with the complete pinion and knob assembly in the foreground.
Those who buy a Feather Touch focuser will usually be fitting it [or having it fitted for you by the dealer] to a commercial OTA. Starlight Instruments makes a whole range of adapters to fit their fine Feather Touch focusers to these telescopes. NO dismantling of the focuser is usually required.
I wanted to fit my focuser to a heavy backplate so chose to follow a different route. My thanks go to Starlight Instruments for their expert advice and to Teleskop-Express for supplying the superb focuser.
T-S also made me a custom base adapter ring to a very high standard within two weeks of accepting my order and rough drawing. I gave T-S no instructions to turn the inside of the custom ring because I had no idea what was required until I received the focuser. Having a lathe allowed me to modify the custom base ring myself to fit the FTF3545B-A to match my own needs.
I wanted to fit my focuser to a heavy backplate so chose to follow a different route. My thanks go to Starlight Instruments for their expert advice and to Teleskop-Express for supplying the superb focuser.
T-S also made me a custom base adapter ring to a very high standard within two weeks of accepting my order and rough drawing. I gave T-S no instructions to turn the inside of the custom ring because I had no idea what was required until I received the focuser. Having a lathe allowed me to modify the custom base ring myself to fit the FTF3545B-A to match my own needs.
Click on any image for an enlargement.
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