Sg2100 Motor Bracket Flex

[stogie5150]

I have a motor problem, fellas, and I need some engineering help.

One of my setups WILL NOT track the arc. I can zero it on my TS satellite (G-11), run it to AMC6 eastward and I have ZERO quality. Run it to G10R westward...NO quality. I have to adjust the elevation to get it to come in. What works on the west side elevation-wise won't work in the middle of the arc, and what works on the east end wont work on the center or west.

Obviously I checked the plumb of the pole, I am alright there....I am with in 3/32 or so all the way around, no better or worse than my other setup that does fine.

The difference in the two setups is the motor itself. The one I am having problems with is the new style with the thinner brackets and u-bolts. The u-bolts are clearly bent from tightening them to the pole so they are tight. So I put a torpedo level on the bracket itself, and the results startled me. The bracket is clearly not plumb to the pole! See pics below.

 

[stogie5150]

So that has me thinking. is the 1m dish setup too heavy for this new motor? I am sure it weighs about at the limit of the sg2100,being that is a Primestar CM antenna, they are heavy, afterall. Plus my homebrew mount probably adds 5 pounds or so to the mix.

So, whadya think? I have the mounting plate of the dish already drilled for a P* 84E reflector, and I have a pile of those, should I swap it out and see?

I am strongly considering re-engineering the u-bolts some kind of way, although if the bracket iself is bending, new u-bolts aren't going to help.

I eagerly await YOUR opinion.

 

[starman345]

So that has me thinking. is the 1m dish setup too heavy for this new motor? I am sure it weighs about at the limit of the sg2100,being that is a Primestar CM antenna, they are heavy, afterall. Plus my homebrew mount probably adds 5 pounds or so to the mix.

So, whadya think? I have the mounting plate of the dish already drilled for a P* 84E reflector, and I have a pile of those, should I swap it out and see?

I am strongly considering re-engineering the u-bolts some kind of way, although if the bracket iself is bending, new u-bolts aren't going to help.

I eagerly await YOUR opinion.

I had that happen to me with a 1 meter Winegard on a SG-2100, I found the motor was strong enough to handle the dish but like you say the bracket wasn't up to the task. I clamped the bracket to a flat piece of 1/8" plate and drilled the u-bolt holes then added some washers to give the bracket distance from the pole. It isn't perfect, but it keeps the bracket from bending. I'll try to attach some pictures of it. Picture is worth 1000 words

 

[stogie5150]

I had that happen to me with a 1 meter Winegard on a SG-2100, I found the motor was strong enough to handle the dish but like you say the bracket wasn't up to the task. I clamped the bracket to a flat piece of 1/8" plate and drilled the u-bolt holes then added some washers to give the bracket distance from the pole. It isn't perfect, but it keeps the bracket from bending. I'll try to attach some pictures of it. Picture is worth 1000 words

Outstanding!

I had thought of that, But I still don't know if the u-bolts will hold up if you really crank down on them, which I am going to need to do because of the weight of the dish. I think I will go remove the dish, plumb the motor bracket the best I can, and see if that helps. Thanks for the idea!
:up

 

[lumpkin666]

If your motor would allow room between the bracket and the back of the motor, you could add to starman's setup but cutting another steel plate and positioning it on the other side of the bracket.. then using some heavy-duty bolts instead of the u-bolts... then your only worry would be craking it down fo far that you crush the mount itself or the pole

 

[Anole]

I M O

It appears that the back side of the bracket (where it is against the pole) is subject to flex under the tremendous stress of the U-bolts.
And, the design of the bracket back-side, is such that it can and will rubber-band under this tension.
It may well permanently deform... I don't know.

I'll take these pictures to some of my more mechanical friends and try to come up with a better fix and design, after the 1st of the year.
Right now, I'm not sure the plate shown is all the answer, but certainly anything that stiffens the structure is a good thing.

For now, I'd take the Devil's Advocate role and say you have over torqued the U-bolts.
That's what strips 'em, that's what bends 'em, and that's what has bent your bracket.
So,... don't do that.

For an immediate fix to this problem, and not a general solution, please raise the elevation of the motor by exactly 2º, and run your arc again.
That will work only if you don't re-torque the bracket U-bolts.
If you do, then you're on your own.
I've measured the tilt of your bracket relative to the pole using your excellent pictures, and that is the current error.

 

[stogie5150]

Here's what I did. .375 aluminum plate.

Does it work? I don't know.

Haven't tried yet. Will do tomorrow morning.

The first couple detail what the bracket looked like when I released the bolts. BOINNGGGGGGGGG!

After that, in, order, is how I put it back together with the plate.

Sorry Brother Anole, I couldn't use your solution....I had already taken it apart...things happen QUICKLY around here...

Thanks again to all who replied, we'll see what happens tomorrow. :up

 

[starman345]

Nice looking setup you have there. Just a few comments:
I found that the plate moved against the pole whenever I was adjusting the dish/motor. The SG-2100 bracket has a V in the back that sits against the pole, that keeps the bracket straight up and down with the pole, when you put a plate in there, you lose that V, thus the plate will shift on the pole. It wasn't a huge problem but I had to re-check the plate for plumb every time after making any adjustments on the dish/motor because it would shift slightly. I had thought about welding a piece of 2" angle on the back of the plate to keep it straight with the pole but like I said it wasn't a huge problem and I never got around to it.
I tried using hardened straight bolts instead of u-bolts but found I liked the u-bolts better, they seemed a lot easier to work with when aligning things.

 

[digiblur]

Do you have another dish to attach to it to make sure it is the dish causing it not to track?

You could do something like a 18inch'er if you can get it on the motor with perforated aluminum over the LNB to attenuate the signal so you'll have to have it dead on like a KU rig.

 

[turbosat]

I like starman's fix, I was thinking along the lines of Anole (stogie using too much cajun power on those chinese-lead ubolts). That big thick 12dollar piece of aluminum should fix it. I think I've seen brackets like that at Marvins Bldg supply too, might check out Lowe's or someplace for better brackets to go in it. Thanks for posting the problem pics, when I decide to buy one of those motors I think I'll go for another brand.

 

[Larry1]

A simular solution would be to use the U brackets (not the bolts) off of a muffler clamp where you have your metal plate. (like the brackets on the other side of the pole where the nuts are) That way you would have a greater contact area to the pole, would help centre it to the pole and would not need so much force on the bolts to keep it in place. Also remember that the order you tighten the bolts down can twist the mount on the pole. In some cases, loosening off one side and tightening the other side can help in the fine adjustments.

 

[Anole]

I've searched the forum six ways from Sunday, looking for the thread with this picture so I would not have to post it again.
Well, somewhere...probably in a discussion with JsatTV, we talked about his HH120 motor and Fortec Star 120 dish.
Here is one of his pictures, after I marked it up.

While not an exact side view, it appears to suffer from the same problem as Stogie has described.
Namely, that the motor bracket is sagging.
If you put your level at the yellow L-mark, the motor bracket should be 0º level, and 90º to the post.
What I described back then as a fix, was to tilt the motor up, in the direction of the red arrow, to compensate.

It's hard to see how this bracket design could sag, so I always wondered if it was an optical illusion?
Or, . . . Maybe this is a more common problem than we thought?

After looking at Stogie's plate, I'm pretty sure he'll be quite happy when he torques it down tomorrow.

Larry's comments above about the muffler clamps and the order-of-tightening should be heeded, too.

 

[stogie5150]

Its already torqued.

Well far as the level, it is level side to side, now whether or not its 90 degress to the pole is another thing entirely. it didnt change when I hung the dish on it.

Yeah I noticed that when I tightened the bolts that tightening one side too much would affect the levelness of the bracket.

Oh, and..

CAJUN POWER!

 

[Tron]

Just be careful on those U-bolts! I know from experience, at least with the older ones, they are extremely fragile. I love the new ones I got from you, wouldn't want to have to give 'em back if yours get stripped

 

[stogie5150]

Just be careful on those U-bolts! I know from experience, at least with the older ones, they are extremely fragile. I love the new ones I got from you, wouldn't want to have to give 'em back if yours get stripped

My wife and I were just talking about that.....about how I let ya have that stuff and then I could have used the new motor bracket about now...oh well....that's how it goes sometime.... ...the ubolts are plenty strong I think, you musta got some bad ones because I really cranked mine down because of the weight of the dish.....

I am NOT looking forward to going outside...its dropped about 30 degrees last night.......COLD for South Louisiana...

 

[stogie5150]

Same thing this morning.Set the middle, both ends are whacked. The motor is square with the pole. I'll have pics directly.

Anole I am gonna try your elevation trick.

 

[stogie5150]

I tried one degree, and two degrees on both directions. no dice.

Digi, I am going to do what you suggested. Completely re-engineer my mount, make a new backing plate and try one of the P* 84e dishes.

Next week.

I am just glad this isn't my main dish.

 

[linuxman]

You don't have the real sweet spot on the dish elevation.

Make sure the elevation on the motor is set correctly with a protractor or digital inclinometer.

Then move the dish elevation on the tube up or down plus or minus 10 degrees from where you are now and see if you can find a sweeter spot on your TS satellite.

If that is indeed the problem, all others will be solved.

Fred

 

[stogie5150]

You don't have the real sweet spot on the dish elevation.

Make sure the elevation on the motor is set correctly with a protractor or digital inclinometer.

Then move the dish elevation on the tube up or down plus or minus 10 degrees from where you are now and see if you can find a sweeter spot on your TS satellite.

If that is indeed the problem, all others will be solved.

Fred

I am not sure I follow you. This dish was woking fine last week, but it was not performing as well as my other one. SO i decided to tweak it.

When setting up a dish, I usually reset the motor, then run the motor to my TS satellite VIA USALS. I then adjust the motor on the pole until I get the best SQ on the satellite. Then tighten the U-bolts. That's the way I've done it for a year now and its always worked.

Until NOW.

Before I do all that work re-engineering the mount I might start from scratch again and see if that helps. It may well not be right. Hell I've been wrong before...

 

[linuxman]

When setting up a dish, I usually reset the motor, then run the motor to my TS satellite VIA USALS. I then adjust the motor on the pole until I get the best SQ on the satellite. Then tighten the U-bolts. That's the way I've done it for a year now and its always worked.

First move the motor manually with the buttons to the zero position.

Reset the motor. Then enter the USALS numbers and let the motor move the dish to where it thinks the satellite is supposed to be. If the satellite isn't there, then adjust the whole assembly on the pole and dish up or down until it is there.

Make sure it is on the real sweet spot. A dish can have more than one which gives pretty good signal, but not the best.

Once you have the TS satellite tuned in the best you can, then everything else should fall in place.

Fred