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How to achieve a Losmandy mounting for 250mm Quattro


SteveA
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So...a wet Saturday afternoon and sitting at work slightly bored....always dangerous!

I got to thinking about mounting my F4 Quattro on a Losmandy style mounting plate.  I upgraded the EQ6 dovetail mounting clamp to an Altair dual Vixen/Losmandy clamp a while back and although this clamp is a seriously beefy bit of kit,  the Vixen/Synta dovetail seems fairly flimsy in comparison. It seemed like a fairly obvious thing to consider just replacing the standard dovetail with a nice wide and presumably more stable Losmandy plate. However, this doesn't seem as easy, possibly not even feasible with the Skywatcher tube rings, which are obviously designed for the standard dovetail. The attachment between the tube rings and the dovetail is on a remarkably small base and even if it were possible to attach these rings to a Losmandy plate, this small attachment base would likely not increase the stability of the mounting to any degree. So.....how about upgrading the tube rings? I almost had it when I stumbled across the Primaluce tube rings. Unfortunately....not available for tubes with 288mm OD! Very anoying as these would have been just right.

https://www.primalucelab.com/astronomy/250mm-plus-support-rings.html

So...the big question....Losmandy plate and a Skywatcher 250 Quattro...is it possible?

Steve

 

 

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I’ve been considering this for my Quattro, but since it’s 200mm, there’s clearly some options.  Even this size scope makes one wonder about the rigidity of the Vixen bar. 

Given the price of the smaller PrimaLuce rings, surely an option is to get a local machine shop to make something robust?

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That is a possibility I guess. As you say the PrimaLuce rings are really rather expensive, especially when you consider the fact that a set of rings of this size from Skywatcher are only about £50. 

It seems to me that Synta are missing a trick here. Their latest mounts are equipped with dual Vixen/Losmandy clamps, but all their OTAs come with only a Vixen dovetail (I assume that statement is correct?). I know Synta have drawn criticism on certain aspects of their hardware over the years and in some cases have addressed these, strangely I've never heard complaints relating to mounting bars etc.

Steve

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  • 1 year later...

Hi Subdwarf, I realise we're a bit further down the time line since your original post regarding the SkyWatcher 250mm Quattro OTA Tube ring set versus upgrading to a Losmandy dovetail bar for extra stability.

Firstly I must confess to experiencing exactly the same probem with my 250mm Quattro and after one night set up with an 80mm guidscope on pick a backed on top of the reflector, I noticed the wobbly nature of the setup from side to side. I use a S.W. EQ6 Pro mount so it will take the wider bar, but as you said, the bosses on the bottom of the rings are too narrow to take the upgrade.

I am at present in discussion with Sales at RotherValley Optics, regarding this, though i don't think I'll get far. What set me off thinking is, the SkyWatcher 300mm PDS reflector appears to have the sturdy Losmandy bar fitted as standard, so why not the same option for the 250 PDS? (Its got the weeny Vixen style bar, same at the Quattro.

Anyway, I'm still thinking about it and make have to visit a workshop to add a bigger metal boss to my ring set.

I'll let you know if I get anywhere. I take it that since the 'thread' didn't get any further, you're still in the same place with it?

Regards

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  • 1 year later...

Good to finally report some progress on this old thread. I really never expected to take quite so long to get this sorted, but very nearly three years on, I have.

To be honest I had pretty much given up on the whole idea as I couldn't find anywhere that could supply these and I didn't really know where to start getting some bespoke ones fabricated. But just a few weeks back now I found that Parallax Instruments in the USA do a massive range of tube rings including their 11.3" rings which are the exact size for the SW 250 OTA. 

Parallax Instruments, Inc. - Telescope Mounting Rings, Rotating Telescope Rings, and Tube Rings

I emailed Joe at Parallax and got a quote for the rings and shipping. Unfortunately they were quite pricey! The initial $310 dollars for the rings worked out to around £220 with the exchange rate, then there was an additional £50 for shipping. Parallax also quoted me for the cost of an ADM DUP15 dovetail, which I had intended to source in the UK, however this worked out marginally cheaper route, though I don't really think that with the shipping and duty I really saved anything on this to be honest.  All together I was looking at around £330, I mulled it over and almost pulled the plug as it did seem a lot to pay for tube rings, but in the end I obviously went ahead! 

Parallax use UPS for shipping. I've never really had any issues with UPS before, but on this occasion it was a bit of a mess. There was an eye watering £87 of import duty to pay, I knew there would be some duty to pay but I hadn't really banked on it being this much and to be honest I probably wouldn't have gone ahead if I had known how much this was going to be. This is where things got messy! I attempted to pay the duty online at the UPS site using PayPal, for some reason the transaction failed and I then attempted payment a second time using a credit card, but this failed as well and I got a message on the UPS site that the duty had already been paid? I double checked both my PayPal account and credit card transactions, but neither showed any activity. The UPS "Virtual Assistant on their website is worse than useless and so I resorted to contacting UPS by phone. My explanation of failed online payment transactions completely flummoxed them for some reason and all they wanted to do was take payment using my card on the phone. This in itself wasn't particularly problematic and I got an authorisation code that thankfully I kept a record of. The parcel took around a week to arrive in the UK and I watched its progress on line, worryingly though the tracking tool continued to show that the £87 import duty was still to be paid and I knew I was going to have problems. UPS do not give you any kind of time slot for delivery and I inevitably missed the UPS delivery as I was at work. Very weird stuff began happening at this point. I got a status update from UPS by email saying that I had refused delivery and didn't want the goods! When I got home I found the missed delivery card through the door which suggested they would try again the next day, but also showed £87 duty to pay. I tried entering the code off the card on the UPS site, but this was unrecognised. By this stage the status of the goods was "being held at UPS facility awaiting instructions and agreement".  So, I called UPS, and clearly again had to deal with operators in the USA, I explained the whole thing twice to two different people. In the end UPS did accept that payment had been taken and promised to update this. I also got them to change the delivery address to my workplace to avoid missing the delivery a second time. I got several status updates from UPS by email and it did seem that they hade actually managed to change the delivery address... but again the UPS site still showed that there was duty to pay. I had been keeping Joe at Parallax updated with all of this and he was quite surprised to hear of these issues. Later that evening however he mailed me to say that the "US government had called him, saying that my address and phone number were wrong and asked for my email address". A mild sense of panic ensued and I had visions of being deported to the states for some major infringement of US law, okay possibly a slight exaggeration, but at this stage I doubted I was ever going to get the damn tube rings at all! Quite what was going on was beyond me, it all seemed a real screw up.

The next day however, UPS turned up at work with the package. Of course they wanted the £87 again! However I had a copy of my credit card statement and a note of the authorisation code I had been issued with. The very reasonable driver accepted this and I am now the proud owner of a new set of tube rings.

The rings themselves are nicely made and finished. They are cast aluminium with a dark grey paint finish and felt lined. I've attached the ADM plate and the scope is now attached to my mount. I've a small issue with the vixen plate on the top of the OTA I use for power bar and USB hub, but that will require and additional hole for bolting to the top of the rings. 

I'm pretty pleased with these rings, they are rock solid on the mount with the bigger dove tail. Despite the cost I'm hoping they will be a good investment, though I could have done with out the UPS problems!

I've attached a few pics below..

Steve

 

Rings1.jpg

rings2.jpg

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