Losmandy vs Vixen Dovetail

[Sunshine]

Would you have any reservations about mounting your scopes using a Vixen dovetail sideways on an alt azimuth mount? considering there’s only two screws anchoring it to the rings. Or should I be getting a losmandy bracket where I can use 4 screws? I mentioned sideways because I’m assuming those screws are under constant vertical load compared to an equatorial mount where the scope sits over top the screws. Is this paranoia? let me know if I have a point as my local shop has a 9” losmandy in stock.

Edited December 31, 2021 by Sunshine

[johninderby]

A typical M6 bolt will take a load of over 200lg so with two screws a load of over 400kg. Exact loads depend on quality of bolts used of course and type of tube rings

I’ve fitted dual vixen / losmandy saddles to my alt az mounts. The Losmandy dovetails are usually much more solidy made than typical vixen dovetails so less flexing with the losmandy.

[JeremyS]

No worries about 2 screw attachment. I use Vixen dovetails on all my 4-inch and below refractors.
My bigger concern is the securing the dovetail to the holder. I prefer clamps to screws. I use a Losmandy dovetail on my TSA120 not cos it’s attached by more than 2 screws, but because it’s better engineered 

[Mr Spock]

With larger scopes there can be flex in the Vixen dovetail. I was never happy with a C9.25 fixed with a Vixen dovetail; it was much more solid with a larger base dovetail.

[Stu]

3 hours ago, Sunshine said:

Would you have any reservations about mounting your scopes using a Vixen dovetail sideways on an alt azimuth mount? considering there’s only two screws anchoring it to the rings. Or should I be getting a losmandy bracket where I can use 4 screws? I mentioned sideways because I’m assuming those screws are under constant vertical load compared to an equatorial mount where the scope sits over top the screws. Is this paranoia? let me know if I have a point as my local shop has a 9” losmandy in stock.

Which scope is this for, the 115mm? I would think a Vixen would be perfectly adequate for that. I use Vixen dovetails on all my scopes except the LZOS 130mm which is quite a lump and it deserves the extra security of a Losmandy. Like Michael, I also used one on my C925.

[Mr Spock]

I should add my 102mm is rock solid on a Vixen - less mass to secure.

[John]

I've followed a similar approach to others above - my 100, 102mm and 120mm refractors use Vixen-type dovetail bars but the 130mm F/9.2 gets a Losmandy bar. I did use the bigger scope on a strong version of a Vixen-type bar for a short while but decided to move to the larger one and it just seems more solid.

My refractors are all side-mounted on alt-azimuth mounts.

I do use better quality dovetail bars though. Those long stock Skywatcher type bars do seem a more prone to flex and vibration.

 

Edited December 31, 2021 by John

[Sunshine]

Thanks for the replies folks! It seems I have nothing to worry about, the scope I was referring to is my only one, my TSA-102 (the 115 is long gone) with an ADM dovetail which seems to be made of a more solid maderial than the stock dovetails I’ve seen with scopes I’ve had like the skymax 150. 

[johninderby]

The stock Skywatcher dovetails aren’t exactly known for their robustness. The CNC type vixen dovetails like the ADM and others are nice and solid.

[John]

I used to have a William Optics vixen-type dovetail bar which I thought, for a vixen-type, was very solid indeed and allowed a 4 bolt fitting to the tube rings.

https://www.firstlightoptics.com/dovetails-saddles-clamps/william-optics-vixen-compatible-dovetail-plate.html

Mine was the long version of the above.

Edited December 31, 2021 by John