Jump to content
  • Join the online East Midlands astronomy club today!

    With active forums, two dark sites and a knowledgeable membership, East Midlands Stargazers has something for everyone.

Need a gearbox.


Doc

Recommended Posts

I need a gearbox for my Skywatcher 300P Auto dob. It is the altitude one if that makes any difference, I doubt if it does. As far as I know the motor works fine, it's just the gearbox is slipping.


 


Martyn popped round and we stripped it all down and you can turn the spur gear while operating the controller so there is no resistance at all hence slipping. 


 


Anyway where would I get one. Had a look at scopestuff and OVL with no luck.


Link to comment
Share on other sites

PM'd you Mick.


If all else fails send it down to me I might be able to fix it for you. The gearbox that is not the dob  :rofl:


Edited by Graham
Link to comment
Share on other sites

Mick have you tried tightening the clutch.


If your not sure how to do this give me a bell and I will talk you through it.


Edited by Graham
Link to comment
Share on other sites

Right then to prove a point.


 


I removed the gearbox and motor and you can turn the spur gear (Brass gear on end of shaft) with your hand


 


NnkQND.jpg


 


I then removed the azimuth gearbox and motor and this one you cannot turn at all.


 


I then swapped them around so the azimuth became the altitude and it works perfectly, no slip at all.


 


Of course now the azimuth (damaged ex altitude gearbox) doesn't drive the scope in azimuth


 


So it's definitely the gearbox internals that are allowing slip in the shaft.


Link to comment
Share on other sites

Nice one Mick.


Certainly the proof needed.


Send the gear box down to me if you want and I will see if I can repair it.


I have managed to repair these in the past.


Not on this particular model but very similar arrangement.


Link to comment
Share on other sites

Right all sorted Mick.


 


Your problem was the penultimate compound gear.


 


The smaller gear is pressed into the larger gear.


 


Micks%20gearbox%201.jpg


 


At some point the dob must have jammed or over time the rocking back and forth has worn the fit between the two gears allowing the small gear to turn inside the large one thus the reason for the lack of drive.


 


Micks%20gearbox%202.jpg


 


 


Solution.


 


Quick swim for the gears in the Acid bath to remove the grease.


 


Place on a heat block and apply gentle heat with a blow torch and solder the two gears back together.


 


This is the finished result.


 


Micks%20gearbox%203.jpg


 


Clean up the excess solder.


Rebuild the Gearbox and its as good as new.  :party:


( Well hopefully better than new. )


  • Like 2
Link to comment
Share on other sites

Well done Graham, hopefully another satisfied customer!! :) :)


Link to comment
Share on other sites

Thank you so much Graham amazing what you can do with a blow torch  :lol:


 


Cheers  :thumbsup:


Link to comment
Share on other sites

Awesome repair Graham. Nothing much you can't achieve with fire and a hammer.  :thumbsup:


Link to comment
Share on other sites

Just an update.


 


Have fitted the gearbox this morning and I have drive in all directions.


 


Lovely job Graham.


 


Thanks  :D


Link to comment
Share on other sites

Thanks for posting Mick - now I have to find time to look at mine, I bet it's the same problem.


Link to comment
Share on other sites

Just an update.

 

Have fitted the gearbox this morning and I have drive in all directions.

 

Lovely job Graham.

 

Thanks  :D

 

Your more than welcome Mick.  :2thumbsup:  :2thumbsup:  :2thumbsup:

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.