Re: OPW Adjustment Steps with Belleville Washer
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Seb, My thinking is: The Oldham coupler is best left in place, but not tightened down until the end of the assembly process. So...as you said: 1. Get the worm in its final position ? ? a. Tight within the left and right worm blocks. ? ? b. The worm blocks are lined up straight ? ? c. The worm is gently in full contact with the ring gear teeth. ? ?d. Both work blocks are tightened down. ? ?e. The worm can spin pretty easily? by your hand and not feel pinched 2. Put on the Oldham coupler metal part on the worm, and gently put on the white plastic center, but only lightly set the setscrews.? You will move the coupler later. 3. On a straight old type drive: ? ?a. Put on the other metal Oldham coupler part on gearbox drive shaft.? Again, don't tighten it much as you may have to move it in a later step. ? ?b.? Put the Oldham coupler firmly into each other, as you also line up the gearbox shaft with worm shaft.? I had to use a thin round file (aka "rat-tail" file) to slightly enlarge my gearbox mounting holes, to get the gearbox exactly in the best position. ? ? c. Rotate the worm if possible to see that the Oldham parts only rotate...you prefer the white plastic center to not slide, and you prefer no angle between the gearbox shaft and the worm shaft. ? ? d. Then bolt down the gearbox position. ? ? e. Then, you may want to loosen the Oldham parts:? slide them so that the white middle is exactly centered in the gap between the Gearbox shaft and the Worm shaft.? And make sure the white center is tight between the metal parts. Here is a photo of a DEC axis with original 2 piece worm blocks and precision brass worm. If you look carefully, you can see the far (right) bearing block has its bearing sticking a bit out (toward the worm), because the R4 Belleville washer under the bearing is pushing it that way from under the bearing. The bearing there was polished down in OD and lubed to slide in it's mounting cylinder sleeve. 4. On a newer tucked motor system: There is also an Oldham coupler hidden in this system too.? It is very hard to get to this.? The coupler in this system attached between the worm shaft and the inner transfer drive gear shaft.? Again, try to line the Oldham parts up.?? Best of luck, Michael On Wed, May 20, 2020, 12:14 PM Sebastian Kotulski <sebkotulski@...> wrote: I don't have a OPWB. Not yet. My plan is to remove the scope, ?counterweiht, counterweight bar and a worm cover. Than I will remove the motor and a gearbox. Then I will slightly rotate the ra axis and lightly press the worm against the worm gear while holding the worm blocks between fingers. I will lock the worm block srews and try to rotate the worm with my fingers and also check if it moves between the worm blocks. If there is any movement between worm block or excesive backlash between wom gear and worm I will repeat the proces. I dont exactly know what I should do next. Should I mount the coupler to the worm shaft or gearbox shaft? |
Michael Herman