Focus Motor Bracket

[centroid]

I am in the process of adding a Motor Focuser to my 115 Triplet APO, and am not happy with the mounting bracket being attached with just a single fixing screw.

Unfortunately, I far as I can ascertain there is only one way of securing the bracket, and that is to utilise the Focus Tube locking screw (see attached picture), with a back-nut to allow it to be tightened, without going far enough in, so as to lock the focus tube.

I will be using a flexible shaft coupler to connect the motor shaft, to the focuser shaft, so as not to place any undue stresses, due to any minor misalignment.

I could of course drill and tap another hole to create another fixing, but I really don't want to be drilling a hole in a brand new scope.

Have any of you guys come up with an ingenious method for attaching such a bracket?

Edited September 11, 2021 by centroid
typo

[banjaxed]

I have never seen a bracket fitted with only one screw before as they are meant to be fitted with two of the focuser plate cover screws. The Skywatcher usually comes with two brackets to enable it to be attached with two screws. Your scope looks like it has a different plate but without taking the focuser bracket off it is not possible to see.

[centroid]

The scope is an Altair Astro Starwave 115mm Triplet APO, and the focus motor, a Skywatcher unit.

As you can see from the attached picture, there is no suitable means for attaching a focus motor bracket, and I have utilised the M4 focus tube locking thumb-screw, albeit not an ideal solution.

There are several small grub screws, but I feel that these should left alone. I have had both Skywatcher, and William Optics refractors in the past, and there was always suitable screws that could be utilised.

One solution that I did see was to use a custom made bracket mounted on the finder scope bracket, with a rubber belt to the focuser knob, but I really don't want to go down this route, especially as the finder scope bracket is already carrying a finder scope.

Perhaps I'm expecting too much of the Chinese designers/manufacturers, but given that the majority of astro imaging users, are likely to use a motor focus, it would have taken very little intelligence to included a couple of pre threaded mounting holes. 🙄

I could of course drill and tap a couple of holes, but I really don't want to be drilling holes, in a brand new £1200 scope.

 

 

 

Edited September 12, 2021 by centroid

[banjaxed]

Yes it is obvious now that you have removed the bracket, there is no practical way to fit the focuser any other way. I have built a few of my own design motor focusers but they all use the focuser cover screws for attaching. I understand your reluctance to drill holes in a £1200 scope but it doesn’t look like you have much choice if you want a firmly fixed motor.

[CraigT82]

Didn't Altair astro confirm the skywatcher motor unit would fit this scope? Perhaps they know of an alternative way to get it on there? 

[centroid]

I did ask on the Altair users FB group, if this focus motor would be suitable for this scope, and was told yes it would be., by a nember of the Altair selected Admin Team, I believe it was.

It may well be that one or more of the M4 grub screw holes could be utilised, but I need to know if this would be acceptable, as I don't know what their purpose is. They are certainly not securing a cover plate.

I have now asked if any of the users have fitted a motor focus to this scope, and if so, how they did it. 

[CraigT82]

Ah ok hopefully you'll get some ideas from there. 

[centroid]

I have just looked back, and found that it wasn't the Altair user group where I asked the question, but I had e-mailed Altair directly, and the reply came from them. Hopefully, they will have the answer. They were very helpful when choosing a scope, and the two cameras I bought.  Had never dealt with them before, but found them very knowledgeable, and pleasant to deal with.

Edited September 12, 2021 by centroid

[Knighty2112]

I’d be interested in what they say as I was potentially thinking of fitting the same motorised focuser on my ED80 or ED101 that has the same focuser.

[centroid]

Watch this space Gus, and I'll let you know. I don't think it matters what motor focuser you use, it has to be attached, and as far as I can see, there is no way of attaching a bracket.  Other than utilising the focus tube locking screw, which is not ideal, as it only provides a single fixing point.

[centroid]

I see that Lakeside advertise a focus motor bracket for the Altair 115 APO, so I assume they know of a way to fit to this scope?

However, at £49 for a small metal 'L' bracket with holes in it, is just crazy 😮

The complete Skywatcher Motor Focus, with two brackets, albeit not made to fit the Altair 115, was just £51.

I will continue my research, and if I get to see picture of a 115 with a focus motor bracket on it, I will fabricate one, and it won't cost £49 😅

This reminds me of the five years I spent owning a Motor Cruiser, which I kept on the Broads.  Put the name "Marine" in front of anything, and 'whack' the price up. Stainless Steel screws were prime example, quadruple the price from the Chandlery, than from my local nuts & bolts shop.

Connect something as simple as a small 'L' bracket, with Astro, and the same applies apparently.

 

Edited September 13, 2021 by centroid

[centroid]

And here it is, £49!!

[centroid]

Ok, I have resolved the problem. The last M4 grub screw in the line of three and nearest where the knob is removed (see attached photo), is securing nothing, it shows as a vacant hole on the inside of the focus shaft housing, outside of the shaft bearing, and appears to serve no purpose. As such, I have modified the SW bracket, and can now affix it to the scope, using a stainless steel M4 machine screw at one end, and utilising the M4 focus tube locking screw, with a back-nut, at the other end. I purchased a flexible 6mm to 6mm shaft coupler, and the focus motor now works perfectly 🙂. The pleasing thing is, it did not require drilling any holes in the scope, which was an absolute 'no-no'. Just need to give the SW bracket a coat of Satin Black paint, after my mods. I must say that I have been very surprised at what I thought was a popular scope, and yet nobody on this group, or two others, appears to have one, and has fitted a motor focuser. If they have, then they are keeping it a closely guarded secret. 🤐

Edited September 14, 2021 by centroid
typo

[banjaxed]

Glad you found a satisfactory solution, the old saying “where there is a will there is a way comes to mind”

[centroid]

1 hour ago, banjaxed said:

Glad you found a satisfactory solution, the old saying “where there is a will there is a way comes to mind”

Indeed, and it didn't cost £49 😉