The 'Gaunt' gets RA and Tangent Arm

[cjb (Chris)]

Hi Matt,

Loving hearing about your build! I made a GEM a few years ago and used the Sitec Servo Controller 2 system for the GoTo system. I found that in many cases the wiring configurations were not standard but used the same RJ45 plugs with different pinouts. Fortunately the wiring info provided by Sitec was very good if not somewhat confusing. Look forward to seeing your next update on the "Gaunt"

Chris

[Kunama]

Looking good Matt . One suggestion though, as the load has now increased substantially now might be a good time to remove the brass ''birdcage" bolts I had fitted to it and go with a stronger direct mounting of the head to the pier. Perhaps just with some of the brass washers between the pier and baseplate of the eq head to clear the casting inaccuracies on top of the pier.


For those who have not seen the start of the restoration/recommissioning of this mount here is a pic of it on arrival in Jindabyne some time ago from Lars's Emporium. My humble efforts breathing life into it followed by MattT's excellent work (which quite honestly, I would not have had the patience for)
have resulted in a beautiful project. Just fantastic work MattT.

http://i13.photobucket.com/albums/a2...on/Gaunt3a.jpg

http://i13.photobucket.com/albums/a2...on/Gaunt2a.jpg

[MattT]

Ahh yes the bird cage...the final frontier...Got plans for the demise of that too! Aluminium and Marine Ply discs built up with some form of azimuth adjustment which is still in the very vague stage
The bird cage however is still strong enough, might not work for AP but that's not my concern.
Speaking of Lars's Emporium the Polarex finder and the Orion f11 belonged to him at some stage too. I think I should name this the 'Lars Refractor'
Chris I looked a Sitech too but was put off with the price...and the fact I didn't want goto and was using a tangent arm for the Dec. Until Fahim gave me the G11 parts I was going to go with 12v DC motors and a train controller. Got as far as buying the controller in kit form. I'll have to save that for another build.

Matt

[MattT]

I have managed to install the RA motor. Yes it works....so happy! The only problem after a while was the motor stalling. In the cold lght of the day the problem has been traced back to the clutch plate moving a few mm as the gear turns, enough to rub on the M5 bolts on the 360 gear aluminium plates. The solution is to take a few mm all tound off the clutch plate or countersink the M5 bolts or both.
Dec next.
A few photos.
1 The black line around the clutch plate shows the tiny bit of movement...small but enough to foul the works.
2 Motor and Driver
3 From the front after 30mins of tracking Alex please note the black counterweights

Edit: The clutch plate moves less than a single mm. The guide pin holes is where the movement comes from, an easy fix.

[mental4astro (Alexander)]

Originally Posted by MattT

Alex please note the black counterweights

Yep, duly noted,

Such a lovely piece.

[traveller (Bo)]

It's looking better with each photo Matt, may have to visit you again soon
Bo

[MattT]

Had the 'Beast' out tracking for several hours after grinding off the edge of the pressure plate, to use it's correct name, and nothing getting caught up on anything else so problem solved

Bo, anytime you like. Just hope it's clear next time!

The Dec axis gets the treatment next which 'should' be a walk in the park.

Lucky last on the list is an Azimuth adjuster along the lines of the Losmandy G11 and using the same tangent block as the Declination.

Just wish cast iron wasn't so heavy...it's movable but only just. Thinking about attaching the EQ head to a wooden tripod I made a while back
Time for a
Matt

[MattT]

Spent the best part of 8 hours in my shed over the last week and have managed to get the Dec motor in and operational.
Part of the way in I looked at my EQ3 with dual motors and kept thinking a slip clutch would be a really good idea. The motors are good but a bit on the slow side and a quick swap to hand control via a slip clutch was born.
Doing this made the motors a bit slower with the gearing from the EQ3 but couldn't be helped, at least for now. The whole thing needs a clean up and a paint job still, at least it's finished and working
Only thing to do...Azimuth adjustment as mentioned in a previous thread.
A couple of photo's
Any ideas for a flexie control like scopes of old had, the long floppy cable?
The EQ3 is looking a bit sad minus a few bits
TBC....
Edit: When I say the motors are slower I mean they turn the Dec thread slower because of the gearing from the EQ3 parts, these are still the G11 motors.

[MattT]

Not a lot has been happening since the last post.
One of my brothers is an Engineer who designs gearboxes for mining machines. I asked him what would be a good lubricant for the RA and his reply was soap. Ordinary laundry soap….the old yellow bar stuff
So I tried it. Perfect According to him it doesn't retain dirt….obvious really. Tracking nicely last night even in windy Melbourne.

Still trying to the enthusiasm up to pull all this apart and paint it black.
Tried Brass paint…not bad...but not good enough.

At least I have worked out an Azimuth adjuster, which I will start on soon.

[MattT]

To make life easier and also to be able to use other scopes, such as my 10" OOUK Newt, I have added an ADM saddle for Losmandy style dovetails.

[Kunama]

Much has changed in the life of this mount:

[MattT]

Ohh yes, much has changed. Matti cleaned her up beautifuly and I think I've dragged her into the 1950's....
Here is an alternative set up...I prefer the refractor.
The ADM saddle is great. Ordered it from Andrews midday Wednesday and was at my doorstep Thursday afternoon...service
The eyepiece is a long way up on the 10" OOUK f4.8 Reflector.

[sharpiel]

Looks beautiful with that refractor set up...wow!

[MattT]

Thanks Les.

Finally have got around to a proper bracket to hold the Celestron Driver Box, nothing special but still took hours to cut drill and tap.

This was also the day to replace the ugly screws with recessed socket head m5's...Countersink Tuesday I call it. Now I have easy access to the two m6 grub screws that via a compression band taken from a GSO 35mm extension tube, lock to the tangent arm to the Dec housing. My clamp doesn't have enough holding power, close but not enough. It does have to hold a fair bit of weight.

Fianlly thanks to Trevor Hand, a 4" extension on the counterweight shaft. The ADM saddle added too much extra weight for the weights I had and the solution is a short extension and nice bit of work it is too

Painting is slowly being sorted out in my mind...what is going to be black, whats not etc.

I had thought that polishing the aluminium would be really nice....can't quite decide yet. Alex did a nice job on the aluminum long sliding weight bar on the top of the scope...looks like SS.

Still in the future is changing some aluminium parts for brass...mostly all the RA in fact. I will practice engraving the aluminum 8" circles before doing the brass. An azimuth adjuster is on the drawing board as I type. Something like the tangent arm...more to come on that soon.

Some more pics. Recessed bolts and driver bracket with ext shaft in the background.

[MattT]

CAD drawing of azimuth control. That is... Complete Analouge Drawing
Should work exactly the same as the Tangent arm on the Dec does.
Made up of 6mm and 12mm Aluminium plates bolted and JB Welded together.

[Julian]

Really nice scope, and the mount is coming along well also.

[icee_stars (Carl)]

Wonderful rig....refractors look fabulous, brass w/black super nice!

[MattT]

Hopefully this is the last of the tangent and RA saga. To make life simple in the dark 2 mods. On the RA replace the m6 bolts with wing nut thumb screws...no tools try finding a black allen key in the dirt in the dark, not that much fun.
The Dec needed to be locked in place better, not so easy with the long frac on top. My solution was to add a couple of bolts, m6 once again, held in place with a brass bracket. Easy to find in the dark. The bolts push on brass plugs that in turn push on a brass compression ring I nicked from a GSO extension tube. Once I paint the whole Dec black the brass will stand out nicely even though I know I should not mix Brass and Aluminium. There will be 6 coats of paint and 3 coats of clear varnish in betwween metal contact, soooo....

The last and not so pretty part, a brake on the Dec shaft. I didn't want to drill holes in the Dec plate so came up with the not so attractive clamp...it works, paint it black and you'd never know it was there, though I'll do something artistic with it later.

All I want now is some cloudy, but dry, weather so I can pull the whole thing apart and paint it.

The final bit...azimuth adjuster, which I have cut out of aluminium but can't face the hours of filing drilling tapping etc just yet...stay tuned!

[MattT]

Tangent arm has been pulled to bits and is now in my paint 'shop' with 2 coats of etch primer followed by 2 coats of gloss black and another 1 or 2 to go...just hope I can get it all back together again. Then it's the RA's turn.

[MattT]

So Gaunt fans this is the RA and Dec axis's done...with the exception of blacking out some bolts.

I have done the brass 8" circles, screwed them together with brass machine bolts and ground off the excess and polished up leaving some scratches etc to give it a slightly battered state.

In a week or so Argo Navis arrives Took the mount to Gary's while I was in Sydney and I'll have to make up some brackets to fit the encoders and then that's it...apart from the Az adjuster.

Hope you enjoyed this retro build.