Many thanks for the replies. I can answer now that the wireless is working again!
Wow talk about constructive - so much food for thought.
1. John ... Hello. The 60:1 is not really critical as minor adjustment in the motor speed can be made. The reason it is chosen is because the final shaft after this reduction needs to turn about 0.5 revolution in 12 hours and to make the numbers look nice eg 60 RPM in and 1/60 RPM out look "nice" and the "clocks" that drive the motors are easily arrived at. That 59.35397Seconds crops up if one wants to keep time using the stare (sidereal time) instead the normal solar time. Making your clock run in synchronism with the stars (instead of the sun) would be awful - ones body rythm would "go to hell in a hand basket" .
And how are you doing? Prettey good.
2. Prime numbers were chosen to try and minimise the periodic errors at this stage the next stage is to attempt a worm wheel - I have a strange feeling that this will take alot of practice on my part to get it right.
3. mklotz ... greetings.
Yes my mistake in not quoting the number of teeth in the worm wheel and yes it is 90 teeth .
Each turn of the hand wheel advances the table by 4 degrees.
So 29/48 turn of the hand wheel advances the plate by
(29/48) x 4 degrees = 2.41667 degrees
31/48 turn advances the plate by
(31/48) x 4 = 2.58333 degrees
Now for 149 teeth the spacing between adjacent teeth is
360/149 degrees = 2.41611 degrees
Error in the first case is 0.00056 degrees ie. ( 2.41667 - 2.41611)
Error in arc seconds = 3600 x 0.00056 = 2.0"
Error in the second case is 0.16723 degrees ie. (2.58333 - 2.41611)
Error in the second case is = 3600 x 0.16723 = 607"
After 149 steps using a dividing plate the blank would have advanced 360.0833 degrees leaving the last tooth out by 0.083 degrees now if the gear is a 1mm module the pcd is 47.43mm so the last tooth will be out by 0.07 mm or in imperial measure 0.003 inches. I could even up the error between the two gaps to 0.035mm (0.0015 inches). This is the best that I can do at home.
Will this make a huge difference? I don't know and any advice and guidance will be received with thanks.
4. Ken ... thank you for the response.
Worm gears - these are more specialised and more difficult for me to make until I get a lathe in about 6 weeks time. What little I know about gears does not include the complexities of using hobs to cut gears. I do know that some amateur astronomers/machinists use them to make the large worm wheels required and this will catch up with me sooner or later.
Differential gearing for indexing? ... Way to go! But I do not have that capability. Perhaps I may invest in one but good ones are expensive and one has to juggle getting these things and spending on the stuff that I really want to do, like build a model engine.
Inertial loads ? These can cause big problems if not handled correctly. One could get a lot of practice cutting worm gears if we chose to ter the motors to go from forwart to reverse without stopping first -- very expensive exercise!! ;D
Tel ... Hi.
At first light these Worm gears look simple but, in my books, are more complex than a simple spur gear.
Of course any ideas as to how to cut the wheel and the worm itself will be most welcome. From what I understand the wheel gear has trapezoidal teeth and the worm itself has a "type of" involute profile - how does one one cuts this ? ... Don't know.
Both worm and wheel should not have an involute profile as meshing will be a problem also backlash will have to be addressed.
All advice is welcome.
Hi Ya Paul,
Yes the gear box is flexible. Modern electronics compensates for a lot of shortcommings. But I find its best to do a good job at the outset, it is somewhat like taking a photograph if the camera is setup right in the first place there should be no need to photoshop the hell out of it. Please, please no arguments.
Whew!
Hello John,
Guess what in about 6 weeks time I will be getting a lathe so I will have a brilliant tool to use.
BTW I am still trying to decide on the size. You see I have "absolutely coveted" an engine Kit called the Economy but it has a 10.5 inch fly wheel. Now here's the problem. The most suitable lathe for me is a 10" lathe but it looks as if it is a triffle too small. The next one up is 12" and not a great more expensive but a lot more capable. I'm agonising over that one.
My Kind regards to all,
Jerry