A re-engineered mount to replace a C11 with a C14 Edge HD

[Barv]

I thought I would give a brief insight to some modifications I have recently carried out to a home built equatorial mount. Actually modifications is probably not the best way to describe this as 90 percent of the new mount will be replaced with new components. The old original mount was constructed by myself with some components being taken from a very old equatorial tripod supplied to me over 30 years ago by a guy called Henry Wildey, (a very well respected telescope maker of the time based in Finchley, London). I was very into astronomy as a teenager, (I had ground a 6" mirror from scratch before I was 16), and a year or two later Henry supplied me with a 10" refelecting telescope back in the 1980's. As many do, I left the hobby for many years and a couple of years ago my brother Richard got me back into it. I was always fascinated with optics and engineering which is basically what has steered my way to this point. The old mount shown here has been used to good effect but needed strengthening and improving to accept the new scope. The drive on the old mount was supplied by AWR in Kent and worked well with full GOTO capability with the help of his Intelligent Handset. There were problems with the mount however that I have not been happy about, and with my new found interest in planetary imaging and a serious condition of 'Aperture Fever' I decided to make some changes and am now very glad I did. 

I toyed with the idea of a Skywatcher EQ8 for some time or maybe a Mesu Mount, (but didn't want to spend nearly five grand), and as I already had the raw components in the drive etc I decided to modify what I already had. 

The old mount had inch and a quarter shafts but was running on phosphor  bushes on both the Dec and RA axis. This led to tight spots in the worm wheel etc which consequently affected the Goto's, as it was difficult to stop the stepper motors from stalling and setting up the worm properly. Please see pictures:

The Old Mount

 

I was determined to overcome these problems with the new mount. This has the same shafts (but are stainless steel) and it also has massive bearings on both axis. The only part of the original mount used in the new mount is the angled bottom piece, the Dec wheels, drive motors etc. (Although the drive is now being upgraded to a 28 volt system with different gear ratios to increase slew speeds and torque. The old old 6" worm on the RA axis has been replaced  with a 12" one and the whole structure has been re-designed and improved. The new mount is massive by comparison and immensely strong. That said I have had trouble with accuracies on the matching of the new worm and crown wheel, but have found a way of grinding them in situ and virtually eliminating backlash completely. I will do a seperate post of this on it's own as I am sure many ATM's out there would find this interesting and  could benefit greatly with this knowledge.

The New Mount:

The work is ongoing and the new mount needs stripping and protection etc. I would love to hear your comments or from anyone undertaking a similar project!

Regards

Harvey

[DIYASTRO]

Harvey,

That is going to be a really nice sturdy mount!

The only thing that I would be a little concerned about is the main RA shaft, it looks like a concentrated / considerable weight from RA gear which is the DEC assembly.
Some counterbalance may possibly be useful on the RA shaft which you may intend to extend.

On the whole from the pics you have posted of your excellent work, you are well on your way to owning a really awesome astro imaging system! Keep us updated as to your progress!

Boyd

[Barv]

Harvey,

That is going to be a really nice sturdy mount!

The only thing that I would be a little concerned about is the main RA shaft, it looks like a concentrated / considerable weight from RA gear which is the DEC assembly.

Some counterbalance may possibly be useful on the RA shaft which you may intend to extend.

On the whole from the pics you have posted of your excellent work, you are well on your way to owning a really awesome astro imaging system! Keep us updated as to your progress!

Boyd

Hi Boyd and thanks for your comments. 

To be honest, the photo's do the new mount an injustice as it is indeed massive. The pier is sitting in a cubic metre of concrete, is 200mm in diameter with an 8mm wall thickness. There is 300mm of distance between the 2 RA bearings with most of the other weight sitting above itI I am quite certain that the mount as is will more than be up to the task. The old mount managed a C11 with parallax rings, guide scope etc and with this load on it the weight will probably be not far short of the C14.

Many thanks for your input Boyd, it is very interesting. I will of course keep things updated as progress continues.

Kind regards Harvey

[JamesF]

Looks like a fascinating project to me.  Have you made it entirely yourself?

James

[Barv]

Looks like a fascinating project to me.  Have you made it entirely yourself?

James

Hi James.

I have made a lot of it. The Dec axis base plate I had made as it is 35mm thick and I dont have the facilities to deal with this. The Losmandy clamp is Altair Astro and the RA tube I also had made again because of the size. The drive is from AWR Components in Kent and I carried out all welding, design and assembly.

Kind regards

Harvey