T-Rex Heavy Duty Alt / Az Mount
Posted 14 February 2011 - 06:45 PM
Reads like a good old fashioned, honest impression of the gear.
I like the fact that you took the time and opportunity to have it side-by-side with a DM6 - much appreciated!
Posted 14 February 2011 - 07:25 PM
I have two of these things now, so you can pretty much guess what I think of the T-Rex.
I've had both a Meade AR-6 and a Meade AR-5 on the mount at different times (each with a 60mm scope attached to it), a C9.25, several smaller scopes, and even a 60mm f16.7 by itself. My favorite combination of scopes on it is an Antares 105mm f14.3 with a 60mm f16.7 riding on the back of it. Moving around the sky with a well-balanced long refractor tube on one of these mounts is a real pleasure.
I've got one of the T-Rex mounts on a Stellarvue wooden tripod that used to carry their M7 mount, and the other is on a Losmandy G11 heavy duty tripod with two pier extensions attached for use with the long Antares scope. Both setups are as solid as a rock.
The ultimate compliment any mount can be paid is to say it gets out the way while you're observing because you simply forget about it -- and that's exactly what happens with this one.
Posted 14 February 2011 - 09:43 PM
Posted 14 February 2011 - 10:55 PM
With the larger OTAs like the newt or the SCT, did the tube width restrict altitude motion, could they all reach zenith?
The SCT reached zenith with no trouble.
The 8" f5 Newt fully loaded (w 72mm WO, 31mm Nagler and SV60 finder), needed to be shuffled a bit and the tripod legs bought in a little.
Fortunately there are a fair number of extension piers that fit the mount (its basically a Synta/Orion base) that will allow complete clearance of a longer, thicker OTA.
Despite not having a terribly big scope, I've ordered one anyway as I find the mass of the (lowered) tripod very useful in balancing a heavy tube - especially with the wind here!
Posted 15 February 2011 - 12:05 AM
I had a DM-6 and loved it. But I used to really struggle with that thing when viewing directly overhead. It works for that kind of viewing, but it can be kind of a wrestling match at times, especially with a short-tubed scope like an SCT. It's much, much easier to do that kind of viewing with the T-Rex.
........ although it can still leave you with a pain in the neck.
Posted 18 February 2011 - 10:03 PM
How will it handle a Mewlon 250?
Good question Mike.
It handled an M210 like it wasn't there, but that's not a particularly heavy scope.
I used the standard, back-heavy configuration to mount it which seemed to have no adverse effect.
I would think that it would handle an M250 well. If memory serves they have a counterweight system that can be adjusted to balance the tube?
At around 13kgs the 250 is well whithin the ballpark weight limit so I think if you can adjust the scopes centre of gravity (or moment or whatever its called this year)
it would be fine.
Just as a BTW, and because I was bored, I filled an 8" ID / 30' long bit of aggy pipe with 20kg of sand, mounted it and was able to move it about with little difficulty.
I had to tighten up the tension levers to almost full, and I couldn't push/pull steadily, but the slo-mo controls worked just fine.
Hope that helps!
Posted 19 February 2011 - 07:18 PM
How will it handle a Mewlon 250?
I've use Vixen VMC260L on T-REX. I think other people use C11 on it. So I think Mewlon 250 should be OK.
I use Intes-Micro MN-86 (8" f/6 MakNewt) on T-REX. The scope setup is about 40lb. With good tripod, it is indeed rock solid.
As you can see, the flexible cable is too short for MN-86.
Barry@Kokusai Kohki is working on longer slow motion control flexible cable.
PS: Peter, nice review
Posted 19 March 2011 - 08:03 AM
Posted 22 March 2011 - 06:09 PM
Posted 23 March 2011 - 12:04 AM
I think a Planewave would be a bit beyond its capacity.
I've had 20kgs (about 4lbs less than your Planewave) on it, but 'free' movement was definately affected as I had to tension the bolts to nearly full lock.
There is, AFAIK, no counterweight system for the T-Rex and I'm not sure if the c-w system on the DM6 actually increases carrying capacity or just helps balance a heavy load.
Posted 23 March 2011 - 11:12 AM
Thanks for the information about your experience with your 20 kg scope and the T Rex. Tammy Homma's comments about his 44 lb MN 86 scope and the T Rex suggests that that combination is "rock solid" though no two scopes have the same geometry. The Planewave weighs 2-3 pounds more, but does not require as much mounting hardware (no rings needed) so the weight has to be fairly close. Also, the tube length of the Planewave is only 31" vs. 46" for the MN86 which may make it easier to handle in that respect. The only thing I can thing of going against the Planewave vs the MN86 is the larger diameter optical tube which puts it's center of gravity 2-3 inches further away from the center of the tripod.
Supposedly, there are folks who use C-14's with the DM6 + counterweights. As I understand it, the weights not only help balance the load across the tripod, but in doing this, weight gets distributed more evenly across the bearings which makes them more functional with higher loads. Of course, the fact that some people do this doesn't say anything about how well it works in practice.
The only option I can think of that is specifically designed for heavy loads like a Planewave 12.5 and more is APM's maxload alt ax mount. Unfortunately, they do not appear to offer a DSC option. I suppose there might be some way to install encoders. Anyway, thanks for the feedback.
Posted 24 March 2011 - 10:33 PM
I also contacted Tom Peters at DM6 who said there is a counterweight option for that mount, but he does not publicize this on his web site because he does not want people to think that it is needed it for scopes up to C-11 or TEC-180 size. He said there are a few C-14 owners who use them. The counterweights are supposed to make the DM6 serviceable with this kind of load as it evens weight distribtuion across the bearings.
The heavyweight king among portable alt az mounts appears to be the APM Maxload which is supposedly capable of handling loads of 120 pounds without difficulty.
Posted 05 April 2011 - 07:30 PM
I've fine-tuned the gears a couple of times because initially when I got the mount, when utilizing the slo-mo controls they were too tight causing stiction, which in turn caused the scope to vibrate with every little minute adjustment of the controls. After adjusting the gears I was able to eliminate the stiction so everything moved nicely, but this was at the cost of creating slight back-lash on the azimuth which is where I think the movement is coming from in windy conditions. I suppose it may come from the Stellarvue tripod, as such I may have to try it on another tripod to rule out that variable. Does anybody else have slight azimuth back-lash that doesn't cause them problems in windy conditions? If so, maybe I need to rule that out as the problem. I'm just trying to figure out where the weak link is and if I can fix it.
Posted 05 April 2011 - 10:31 PM
The only time I get vibration is when I've mis-balanced the tube. I am using the EQ6/Atlas Tripod and its very solid and effectively wind-proof. As a result I've been able to view succesfully in winds up to 35mph. Trying a heavier tpod might indeed work.
What I have noticed is that the mount responds more easily with a heavier scope. It will move my TOA130 with all the trimmings much more smoothly than it does my AT106.
However it is not as "stictiony" (I can't call it [i]stiff[/i} exactly :) )as when I first got it. I'm not very good at fiddling with things, so I've left mine stock, but I suspect some fine tuning might just ease it up.
Posted 05 April 2011 - 11:48 PM
So the tripod is not the issue (shouldn't be, anyway), and you should have more than enough weight with the TSA-120 on it.
There are two things that you might check. The first one is to make sure the T-Rex mount head is very tightly in place on the tripod pier. When I put the mount on the pier, at the point where the head stops turning on the stud, I loosen it a bit, and then give it a good, strong twist to make sure it's really tightly in place. Grab hold of the bottom half of the mount head (the part that doesn't turn when the azimuth clutch is loose) when you do that. And I check that periodically, too, to make sure it hasn't become loose.
The other is to check your azimuth clutch and make sure it's locked down tight when the wind is blowing. I normally leave mine loose and move the scope in azimuth by hand. But if it's windy, I'll get a lot of motion also unless I lock the clutch down tight. There are instructions with the mount on adjusting the tension of the clutches, so you might check that, too.
Hope one of those two things helps.
Posted 07 April 2011 - 01:03 AM
Posted 07 April 2011 - 12:44 PM
There is just a bit of backlash in the vertical movement of one of the two T-Rex mounts I've got - none in the horizontal movement on either mount, though.
Might try sending a message to Barry at T-Rex, also. He's very responsive, and since he designed the mount, he knows it better than anyone else.
Posted 26 April 2011 - 03:45 PM
A friend of mine have had the idea to install a Synscan Goto and after Barry gave me all details we checked what we need and it seems to be not difficult.Is this something other owners would be interested too ? If a few kids could be made, it may cut down a bit the cost
enjoy your T-Rex
Posted 31 October 2011 - 10:46 AM