Paramount MX out of the box capacity

[Somnium]

So i am looking to put my new OTA, when it comes in, on my paramount MX+, but i am not sure if i need additional counterweights, an extension bar or both. just wondering if anyone knows how much weight (RC or CDK style OTA) the PMX+ can carry with the standard 3 counterweights. additional counterweights are extremely expensive and i cant find anyone who wants to part with one second hand, i don't want to buy more weight then i have to.

[suma126]

the web site says 14 inch with camera for me one day12 half inch with guide scope and gear is the limit I recon:D. I have 2 counter weights on my mx+ with 10inch + all the gear and its close too its limit I will need a 3rd one weight if I upgrade ota.....http://www.facebook.com/shanes.astroshed

[Somnium]

Thanks do you know what the weight of the set up is? i am running an OAG and a pretty like camera so it might be similar.

[raymo]

It would probably be cheaper to get a local machine shop to make you one.[ unless you want it to look precisely like the genuine ones]. If the
originals are of a simple unadorned design like the Skywatcher ones, any
decent machinist could produce one in an hour or so,[including the
threaded hole for the retaining bolt.]
raymo

[Somnium]

That is not a bad idea. i am just wondering if 60lbs of counterweights is enough though. the OTA is 54 ...

[raymo]

Can't answer that question without knowing dimensions. How long is the
counterweight shaft for instance. Being as the mount is rated for a 45kg
payload, which is far heavier than the 54lbs you quoted, I would think that the shaft would be long enough to get the weights far enough out
to balance your OTA.
raymo

[Somnium]

thanks Ray, i have spent the morning looking up tech drawings of the mount and the ota, doing the calculations and it seems that the standard weights are probably not going to cut it. the extension bar seems to be the bes way to go, when you look at what an additional weight does to the capacity, i.e. it moves the centre of mass of the counterweights up the shaft, so adding weight doesn't give you a whole lot more capacity. the extension bar with no additional weights increases the capacity dramatically.

[raymo]

If you think that the supplied weights won't cut it with your gear that is waaay under the mount's max load, I think that's a bit poor on behalf of
the manufacturer, meaning that just about every purchaser would have
to buy extra weights, [which, as you said, are very expensive].
raymo

[ericwbenson]

Hi,
I have a PME extension shaft that I'm not using, let me know if you are interested?
EB

[Somnium]

PM sent

[Paul Haese]

I have both a PME and a PMX. The PMX is currently running the 12" system which has the following on board. 12" GSO RC, 3" Optec Rotator, FLI Atlas focusor, AOX, 8 position integrated guide and filter wheel with filters and STXL camera. Including adapters and cables I am around 37kg I think. It was very tricky getting the guiding right with that load on board.

I am using 4 counter weights on the standard shaft. I have an extension but I am not keen on using it. There are differing opinions on the use of the extension.

Depending on which camera you use, focusor etc, will most likely tip you over the 45kg with a 14" scope. I know if I used the same imaging train with a 14" I would be over. Your system may well be under that, but you need to work out the figures very carefully. With near perfect balance you can get good results with the PMX when it is close to its maximum payload.

[Somnium]

Thanks for your experience Paul, i know you have played around with the limits of your mount so was keen to get your thoughts.

my OTA weights around 24.5kgs, i am using a FLI ML camera with a 2" CFW which all up is around another 3kgs. i have a couple of other bits and pieces, MMOAG, adapters and spaces and then the Optec Gemini focuser which is around 3kgs. all up i am looking at ~31 - 32 kgs. i am thinking that the counterweight extension allows for more options. it has both pros and cons, it does allow for less overall weight on the mount itself but may introduce flex at the joint. my thoughts are that there really shouldn't be much flex if the bar is done up tight but that may be a wrong assumption.

[PRejto]

There were some posts a while back on the Software Bisque board where some users found better guiding performance using more weight vs an extension. I guess the theory is the longer moment might set up an oscillation that takes longer to dampen out. You could probably get a machine shop to make you a weight for less than the cost of buying and shipping a Bisque weight. I've had quite a few parts made up locally (Northern Beaches) by a company called Flame Lily. I didn't ask them to make up a weight but they modified my MX weights to fit the MEII shaft, and another local company (now closed) did make up a weight for me for a different mount.

Peter

[Somnium]

Thanks Peter , I have bought Eric's extension bar , I will see how it goes. If I find that it is not working as well as I am looking for I will have one made locally