Mount for TV 76. Tele-Pod or Something else...?

[Qualia]

Bit of a long shot, but does any know whether TeleVue's Tele-Pod mount could be screwed on to either the Skywatcher's 2" steel tripod (which came with the AZ4) or Celestron's 2" steel tripod which came with the CG 5?

Other than that, I'm trying to sort out a firm and accomodating mount for the TV 76, so I'm open to any suggestions.

At the moment, I'm using an ADM vixen dovetail (VDUP7) on the AZ 4, but for some reason all the screws I've been kindly supplied free of charge from Robtics in Holland and Valkanik in Spain and also those I've hunted out myself in hardwear shops, just don't fit the clamshell too well. That is, even without the dovetail, the screws don't really screw all the way in. They do a couple of fine turns and then there's that nasty 'halting' where you know if you go any further, you are going to cause damage.

In consequence, there's a little play between the clamshell and dovetail which worries me a tad. I have no idea, but this might have something to do with all the screws I find in Europe being metric in design and the clamshell's threads for screws are more than likely imperial. I've just ordered a couple more screws from Teleskop which may work but I'm not holding my breath.

So other than that, does any one have any idea what I can do to set up the 76 in a firm and solid manner?

Thanks for any help

[nightfisher]

How about a set of proper tube rings, Telescope service stock a set of 76mm rings, these fitted to a dovetail bar would make a classic and secure mounting platform

http://www.teleskop-express.de/shop/product_info.php/info/p981_Orion-Cradle-Rings---Aluminium---for-Tubes-with-diameter-76mm.html

[Stu]

Some info on the Telepod here Rob, including some thread sizes.

http://www.televue.com/pdf/literature/Tele-Pod%20Mount%20Instructions.pdf

I would go for a mini giro on the tripod you have. The 2" steel legs are rock solid, and the giro takes the 76 very nicely.

Stu

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[Pig]

Rob,

The TV clamshells I had were the standard "smaller" camera mount thread = 1\4" UNC, maybe someone has been trying 6mm in them

I have recently converted my AZ4 tripod to use with the giro mount and had similar questions / obstacles as you.

The thread size that held the mount onto my AZ4 were a10mm thread (the giro is standard "larger" camera thread = 3\8" UNC)

In simple terms you will be trying to match either a 1/4" UNC for the clamshell and a 3/8 UNC for the mount.

Skywatcher are 1/4"  for the "L" shape bracket and 10mm for the mount.(the mount is different to the EQ5&6 )

I don't know what sizes the Celestron are but the above info combined with Telepod description may help.

[Qualia]

Thanks a lot for the replies

Jules, that's a great find and if all else fails, I'm on to them for Xmas In the end, I reckon they might be the cheapest and soundest purchase.

Stu, thanks a lot for the link. I've had a read of the pdf, but I just can't figure if it screws on to the centre support shaft of the tripods mentioned or not. I'm being dumb here, but I just don't know whether those 3/8" and 1/4" 'attachment holes' mentioned are actually what I need to screw in to and whether they are suitable for the types of tripods mentioned If the centre support shaft of the Skywatcher is 10mm and TV is offering 3/8" (9.52mm) and 1/4" (6.35mm), it doesn't look like there's going to be much joy

Shaun, I've eventually tracked down 1/4" screws in Europe (that took some hunting!) which didn't cost tens of euros to post through and I will see if they fit. I'm sure the previous owner didn't use 6mm screws, for he told me he used to have the 76 set up on a tele-pod.

If I went for a Mini Giro, again, it looks like it isn't going to screw on the tripod. The tripod's support shaft being 10mm and the Giro's thread some 9.52mm (3/8"). 

Oh, what a mess. I know I'm doing something wrong here, but I wish there was a kind of standard here.

Other than Jules suggestion, is the only option remaining to buy a complete mount and tripod set up? 

[jetstream]

It may be cheaper to drill and tap the holes Rob, or maybe even sneak a helicoil in there for the larger one. Getting 2 full turns and then resistance is kind of unusual....

[Stu]

Rob, you can just get a 3/8" 2" bolt or a piece of threaded rod and it should allow you to mount a mini giro to your tripod I think. What does the top plate look like?

I use an EQ 6 tripod and the 3/8 bolt goes through the 10mm hole with no problem, ie the threads don't engage at all

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[Qualia]

Thank you, Gerry. After your words, I had a look again and I think the problem is that the screws are a given length, the dovetail is a given thickness and between these two sizes, there's a little play. It isn't a lot but sufficient for the dovetail to slide just a tad. I've now got quite a collection of 1/4" screws and not one of them is perfect However, if the screws are tight, then hopefully everything will be fine.

Stu, thank you for your kind reply. I think that sounds a good plan of action. When I'm in town, I'll ask about if someone sells that size bolt or rod. If not, I'll hunt about and see if one can be posted. I've read about and searched the forums and noticed that over the years, a couple of regular users here have used the CG5 tripod with the Giro mount, so I might drop them a line to see what they did, if anything.

Once again, thank you for the swift and informative replies

[Dannae]

Just a few possibly unrelated points Qualia as I have a mini giro and a TV-76: The TV-76 gets focuser-end heavy very quickly with the diagonal and eyepiece and even with the AVT-1011 dovetail I still had to buy the telescope balance aid to move the balance point further forward.

http://www.televue.com/engine/TV3b_page.asp?id=43&Tab=_avt#.VHMZNa1F2Hs

The mini giro is pretty much at it's limits in ALT as the TV-76 is pretty heavy to start with so you might want to go 'up a size' to the regular giro if you go down this route.

Regards

Dannae

[Stu]

I agree that balance can be challenging, but the mini giro is rated to 9kg and takes my TV85 with no problem with a counter weight.

With a longer Dovetail and the clamshell pushed back towards the focuser balance is usually possible to find.

Like Dannae though, I've used an additional weight towards the front at times to help when using much heavier eyepieces.

The Giro-WR is worth looking at too, rated at 10kg.

Stu

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[Qualia]

This is really helpful!

The dovetail I bought for the opperation was the ADM VDUP7. It's 7" long and I thought it should cover my back with such a relatively weighty telescope. It was also recommended as being suitable for TV clamshells.

If you look at the picture, there are many holes on the dovetail, but I can't use them due to the peculiar spacing of holes on the TV clamshell. So I have screwed the clamshell onto that longish slot in the middle. Here, no matter what screws I'm able to find, there is a little play, so the dovetail does slide up and down. However, even though there is this feeling of 'sloppiness' between the clam and dovetail, I have found that so long as the edge of the dovetail slot hits against the screw, once I've set up on the AZ 4 and point the scope up more than 0º the telescope doesn't race down the groove.

I've copied Stu, and also bought a little 2" to 1.25" adapter from TS to be able to screw in the Herschel Wedge and do a little solar work.

The main worry, then, isn't so much the mount (for I will go with Stu's idea and either look at the Mini Giro or WR) and set it up on the CG 5's tripod, but of that play with the dovetail. If you guys think I should be okay, I'm happy, but if you think there is sufficient room for concern, I really need to do something. The two screws I use are 1/4" and go well into the clamshell's hole and when I give a tug, everything seems okay. It's just the case of the dovetail still being able to slide up and down that concerns me a tad. 

Sorry about this over explanation and blathering. Although I picked up the TV for a very reasonable price, it would break my heart if it crashed to the floor while using it   

[Stu]

Hi Rob,

I have one of those ADM dovetails so can try it out on the 85. I'm sure you should be able to get a good tight fit so will see what is needed.

Cheers

Stu

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[Qualia]

Thanks a lot, Stu. Maybe it's just a case of finding a tad longer screw or drilling into the dovetail to get a closer, snugger fit

[ollypenrice]

The clamshells frequently become butchered as people try metric threads in the holes. I've had this with two second hand TV mounts. The easiest solution, though it doesn't make the setup as quick to dismantle, is to drill right through the clamshell, countersink the holes on the telescope side and put in machine screws from the inside with nuts on the outside to hold the clamshell to the mount. That way there's no tapping.

Or you can bond a couple of studs into the butchered holes and use nuts on the bottom.

The Americans really need to get with it and lose this addiction to Shakespearian units. Anybody say Mars Lander? 

Olly

[Qualia]

Thanks for the input, Olly.

I think the clamshell is okay. I got hold of a small 1/4" UNC screw and it went in like a glove, so I'm assuming the threads are still in good order. Now all I've got to do is find 2 1/4" UNC screws of the correct length and the dovetail should fit okay. This isn't as easy as it sounds, so I'll probably have to just hang on until something crops up. If the worst comes to the worst, I could always drill into the dovetail and deepen the groove so the screws I do have make for a snugger fit. In the meantime, I figure the dovetail will hold on the AZ 4 and it would be quite a freak accident if the suddenly slipped from the dovetail, but until I get this part of the gear sorted, I can't really look into mounts.

It's a right pain. I've never come across a problem like this which seems so easy to fix in theory but near impossible in practice due to the peculiar design of the clamshell and the sheer lack of screws that can actually fit it where I live. Weird is a little of an understatement

[Qualia]

Think I've sussed the problem. I've just tied soft metal around the end of the screws and have tighten them into the dovetail. Bingo...it seems like a really solid, non-budging fit And with any damage to the dovetail

[Pig]

know where your coming from Ron, I had similar issues a few weeks back  I think it is too small a market to have any kind of standardisation. I also think telescope accessories are deigned by the same folk who design cycles  similar issues lie there also.

[Helen]

For reference, if anyone needs access to various screws etc of odd sizes there are great options here http://stargazerslounge.com/topic/51503-socket-head-screws-bolts/

Helen