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Old 15-10-2014, 11:34 AM
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The 'Gaunt' gets RA and Tangent Arm

Over the past few months I have been researching, designing and building a working RA with 360 tooth gear and worm and a tangent arm for Dec control on this old but goodie mount.
Earlier this year I bought this mount from Matt aka Kunama....thanks Matt
Nothing wrong with it at all but my DIY nature got into full swing and the process began.
RA first. Matt gave me a box of goodies that included an Astronomics 360 tooth bronze gear and worm. After much trawling around I settled on a slip clutch as the way I wanted to go. There was nothing left of the setting circles either so that was another thing I wanted to restore as much as I could. In another thread on JB Weld for Brass I found out that brass and aluminium do not go well together...in fact the two should not be mixed up together, thanks to everyone that responded to that thread. I had already cut brass circles and elements of the slip clutch from brass and decided that it's all brass or all aluminium. I went all aluminium for now as I had all the metal I needed and brass is expensive...but one day I will re build this in brass.
Time for some photos of the RA as it now is. I should point out that all this is easy to remove, should I ever sell this, and someone want to restore it to how it was when first built.
Photos left to right.
The mount before starting, the 360 tooth gear and worm, slip clutch and spring tension worm and gear and a side view before removing the brass parts.

There are a few more small parts to add mostly to the worm assembly to keep it in place when under load.
I want to add some simple form of stepper motor and control to this.Any ideas from anyone? I know zero about electronics. The scope is really well balanced so it doesn't move when pointed any where in the sky so I'm thinking that possibly a stepper motor for an EQ5 might be strong enough, with correct gearing?
As there is a slip clutch, moving the scope in RA manually while the drive is engaged is easy so I don't need fast slewing...though dropping GOTO on this might be nice, but that would mean a dec worm and ring gear instead of the tangent arm...so not a good idea.
So far so good...onto the tangent arm.
Matt
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Last edited by MattT; 17-10-2014 at 08:05 AM. Reason: clarity & spelling
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  #2  
Old 15-10-2014, 11:58 AM
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Now for the Tangent Arm. Gotta admit I had heard the term before but had no idea what this was or how it worked....ATMing is a learning curve for sure
As with the RA slip clutch it was read read read look and try to understand what's what. I came across a nice idea from Jim Sapp. The penny dropped some where along the way and it was into the shed for aluminium shavings everywhere again. Building a pillow block mount from scratch would have made all this so easy...retro fitting means I'm limited with what I could do, so this is what I came up with.
Photo time: L to R Tangent arm showing the cylinder block with the threaded rod through it. The cylinder block is two cylinders one in the other that keeps the threaded rod straight as the arm moves through an arc....simple right?
From the front and next the solid blocks that are part of the clamping mechanism around the mounts DEC axis. Last photo the dovetail and tube rings which are bolted to the Dec shaft...turning the threaded rod moves the dovetail around 10º in either direction while the clamp keeps it all clamped down on the dec housing with cork inserts for a bit of grip. Whew.
A lot harder to describe than it really is.
Thinking of putting an electric motor on this too and as I can move it by hand quite easily, possibly a focus motor will do the job? Gonna try it any way. My first version of the arm was twice as long as it is now and it sagged under it's own weight. Rather than rebuild it with a counterweight out the front of the dec axis a I have seen on some old 19th Century refractor's I went with the shorter length and a motor will make adjustments easy...I hope.

Still need to get the scope up on this but it works with a smaller scope on it in my shed.
I feel that I have missed out on quite a few details of the build here so I'll add more along the way.
Matt
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  #3  
Old 15-10-2014, 08:02 PM
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Looks great matt.
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Old 15-10-2014, 09:01 PM
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Good going there Matt.

So long as you paint in black enamel (surely there is some lead based black oil enamel out there still, SOMEWHERE ), you'd never know it was 21st century aluminium. Brass would be great - prohibitively expensive - but.... no one will know under a coat of black

Or brass coloured spray enamel
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  #5  
Old 16-10-2014, 06:17 AM
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Nice going Matt, your work on that beautiful setup is awesome !!!
(I did get your email, just haven't had a moment away from grandfather duties to respond ...... )

You definitely should be taking the whole lot to Nhill !!!! It would be the star of the star-party.
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Old 16-10-2014, 09:23 AM
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mental4astro (Alexander)
kids+wife+scopes=happyman

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OOOOHHH, I doooo love a bit of Steam Punk...

Progressing slowly but surely, Matt.

Yep, gotta love a bit of old school Gaunt, er, grunt.

That set up is one of the most beautiful in the country. And it's still a work in progress. Marvelous stuff,

Mental.
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  #7  
Old 16-10-2014, 11:43 AM
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Steam Punk...l like it Thanks for the kind words....many hours of cutting, drilling and grinding in this project.
Raining here so I set the scope up in my shed and it works as I hoped. Slewed around with my cordless drill as a motor as much as possible, the slip clutch doing it's job on the RA and the Dec clamp hanging on too.
Paint...yes gloss black same stuff Matt used on the rest of the mount, pretty tuff stuff it is too. I do have a can of Brass spray and will experiment on some scraps.
Sadly won't be on the road to Nhill or anywhere else this year, next year definitely, as there are a couple of niggles in the worm gear to iron out...nothing major but I built in a bit too much adjustability to the worm blocks. The worm rides on skateboard wheel bearings that are the perfect fit for the shaft but I drilled slightly over size holes for the M6 bolts on the blocks so there is a tiny bit of movement i.e. more backlash than I would like. More aluminium shavings coming up!
The counterweight shaft is new too....almost forgot this one. The old shaft was a bit of plumbing with 15kg's of gym weights. It worked looked a bit ugly but had no adjustability(there is that word again) so had to go. This is a brass collar with internal threads and a couple of grub screws to hold it in place. The shaft is the extension from my NEQ6 and 3 brand new Skywatcher 5kg weights. I quite like the white though black would fit in better???
Some photos of the whole shebang.
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  #8  
Old 16-10-2014, 11:56 AM
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Questions....
1. Where do I start with adding a simple stepper motor drive to the RA 360 tooth gear? Would like it to track at sideral solar and lunar rates, slewing fast doesn't matter as I'll use muscle power there.
Could be simple as a box with an on/off switch and a potentiometer plus a reversing switch??? My knowledge about electronics is very limited

The scope on top weighs in around 18 kg's with everything included....my thoughts so far...get an old EQ6 syntek stepper motor and controller and hopefully with the correct gearing it'll drive at least at sidereal rate...am I close

2. Argo Navis? Yes or No? Looked into it and Gary tells it can be added and I like the idea, as this set up stays very much in the backyard...for now.
Matt
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  #9  
Old 16-10-2014, 12:22 PM
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traveller (Bo)
Not enough time and money

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Wow, it's looking great Matt,
Not sure if my puny focus motor can cope with the load.
Will catch you tonight (I hope the clouds clear!)
Bo
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  #10  
Old 16-10-2014, 12:28 PM
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In case you haven't seen this
http://www.gumtree.com.au/s-ad/melbo...rts/1058982136
Not sure if these motors can be salvaged?
Bo
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  #11  
Old 17-10-2014, 10:35 AM
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ZeroID (Brent)
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Quote:
Originally Posted by mental4astro View Post
OOOOHHH, I doooo love a bit of Steam Punk...
Mental.
Another afficianardo of the Genre !
Do you have a SP name ?
Have you checked out Brassgoggles website ?

Prof Zero I.D. Stellarius, Astronomer Emeriticus, Royal Dirigible Navigation Corps.

(wheres the SP smiley ?)
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  #12  
Old 17-10-2014, 01:16 PM
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Thanks to Bo the SW electric focuser idea is now dead. Tried Bo's one and gave up after a 1/4 of a turn as I'm sure the motor would have given up the ghost after a few minutes of operation Thanks for the loan Bo

So have attended to a worm gear problem and now the scope awaits a real star test. Tonight is looking reasonable here in sunny Melbourne for once...
In the daylight the RA works, the slip clutch works and the tangent arm works.
Have taken the plunge and bought the HEQ5 motors controller etc and will see about gearing this up or down for my RA gear which has 2.6666x as many teeth I think.
All tricked out awaiting nightfall....
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Last edited by MattT; 21-10-2014 at 06:55 AM. Reason: details
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Old 17-10-2014, 01:19 PM
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Not enough time and money

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No problems Matt,
It was a thrill to see the beast in the flesh (or metal). Good luck with your next stage of experimentation and keep the posts coming!
Bo
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  #14  
Old 20-10-2014, 05:40 PM
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Matt I may have my old g11 stepper motors and drive unit, there yours if I can locate them, will search this weekend. They have made a few trips around Aus on loan and they are likely still boxed up. No idea if they will work on your setup but they are very similar if not identical to my friend Peter's GM200 mount whic is tangent arm setup. I just take my hat of to people who restore these old mounts it's awesome to see. Best of luck.

Edit just saw your last post you got it going that's great. If you still want the Losmandy stepper drive let me know.
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  #15  
Old 22-10-2014, 07:10 PM
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Well it works as I hoped. With my Bosch cordless drill it slews the scope all over the place without the clutch slipping, unless I want it to. I wonder if a disc of teflon might help as there is a fine line between too much and not enough stiction. The tangent does it's job.
Slowly getting my head around gear ratios etc.
One way or another this will get a simple non GOTO drive, using setting circles to find things….fancy that, or Argo Navis...
To be continued…
Matt
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Old 09-11-2014, 03:00 PM
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I have taken up generous offer from Fahim, aka Netwolf, and he has sent down two G11 motors from the orgional G11 Gemini 1 driver and controller.
Just brilliant. As the Losmandy G11 uses a 360 tooth gear these are a straight bolt on, according to my reasearch on the subject. The best bit is all that is needed is a single flat plate of aluminium bolted to the mount, then the motors bolt on to that. No 90º angels just simple flat plate and a collar.
Here is a photo of the bits Fahim has posted down...I have made a trip to Jaycar and bought the needed connectors for the motors. One question, the RJ45 connector on the hand control is miising the locking clip, is it easy to replace the connector? I know it needs a crimping tool that costs $20 from Jaycar. Anyone done these connections?
Matt
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Last edited by MattT; 09-11-2014 at 05:00 PM. Reason: spelling
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Old 10-11-2014, 01:22 PM
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Yeah, looks to be the same configuration as a network cable connection. The tool we have at work has got a proper wee stripper that does it all. Easy as to do.
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Old 11-11-2014, 07:55 PM
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Thanks Brent. Droped into Jaycar who said it's possible but maybe an electrical repairer would do the job, so asked a couple of local ones only to get the reply....no I can't do that.

That's code for...not interested too much effort thanks....struck this before in this 'Industry' so I've bought the crimping tool and a bunch of connectors and some cable to practice on before I do the real thing.
Will post a pic of the final result soon I hope. In the mean time I have ordered a couple of connectors for the motors to worm gears etc. Then I'll cut the appropriate thickness plate and mount the motors and Driver, wire it up and that's it!.....That will leave Argo Navis for the final bit of non goto technology.
The future is looking good for this mount from the past.
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Old 11-11-2014, 09:11 PM
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Shame not in Perth, I have the connectors and the tool. Hope you get it sorted though.

Quote:
Originally Posted by MattT View Post
Thanks Brent. Droped into Jaycar who said it's possible but maybe an electrical repairer would do the job, so asked a couple of local ones only to get the reply....no I can't do that.

That's code for...not interested too much effort thanks....struck this before in this 'Industry' so I've bought the crimping tool and a bunch of connectors and some cable to practice on before I do the real thing.
Will post a pic of the final result soon I hope. In the mean time I have ordered a couple of connectors for the motors to worm gears etc. Then I'll cut the appropriate thickness plate and mount the motors and Driver, wire it up and that's it!.....That will leave Argo Navis for the final bit of non goto technology.
The future is looking good for this mount from the past.
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Old 14-11-2014, 07:19 PM
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Got it all sorted just fine and very easy to do. Really glad I bought the crimping tool. From Jaycar I bought two 1 metre cables with RJ45 6 pin connections from the motors to driver.
The motors chugged along, which I thought at first meant they worked.
Then I replaced the RJ45 on the hand control no problems. On my pratice piece of cable I did RJ45 connections on both ends....just as well as it turns out.
The shop bought connections didn't allow any speed variation to the motors...strange, so in a moment of inspiration I tried my pratice cable and it worked, slewing speed changes, reverse's etc all worked. A close inspection of both shop bought cables showed both cables had been reversed on opposite ends if you see what I mean. Had enough RJ45 ends to start again, cut off both connectors and atttached new ones...now it all works
Amazing that there is so little QC, or are telescope controls different from normal
Now I'm waiting on a couple of collars to fit the motors to the RA and Dec shafts.

Last edited by MattT; 15-11-2014 at 04:02 PM. Reason: spelling....
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