Adding declination control (Fibo 90)

Hakon said:
I guess there's a heavy load on the DiSEqC motor in this setup ?
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Not really. I think that in the pictures it is difficult to tell how small the shortened actuator is, but only weighs 1 kilo, and it is behind the bearing axis, so if anything it is acting as a counter-weight. The dish is only a 90cm so not too much weight there. And the motor sounds pretty much the same when it is driving up the arc as driving down. When I get a spare minute I'll do a video and post the link here.
 
Huevos said:
Here's what it looks like when it's altogether and on the arc. Hardware limits set 11º above and below the arc.
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I like the colour of the angle iron, very NASA-esk. Do you think the balance of the installation will be acceptable with that extra weight off centre?
 
smiffie said:
Do you think the balance of the installation will be acceptable with that extra weight off centre?
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Seems to work ok. What potential problem do you see?
 
Huevos said:
Seems to work ok. What potential problem do you see?
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It's just the stability really, as you've a lot of weight off centre from the pole. So you may have issues with repeatability in terms of the dish returning to the same position. So what are you targeting with the declination mount?
 
smiffie said:
It's just the stability really, as you've a lot of weight off centre from the pole.
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Only about 1 kilo, and anyway it's not as if a dish bolted to a DiSEqC motor is balanced. A lot of the weight is stuck out in front of the bearing axis and as the motor turns towards the ends of the arc gravity really shows itself. If you have ever set up a big dish on a polar mount you'll know what I mean. When you push the dish up the arc manually you have to push like mad near the ends of the arc, and where it crosses the meridian it is pretty unstable, trying to fall one way and then the other. If anything this is acting as a counter balance.
smiffie said:
what are you targeting with the declination mount?
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Anything that is inclined and has feeds starting with 2ºE, although that does appear as strong here as people in northern Europe have suggested.
 
Was cutting down the actuator a straight forward job? On your photos there appears to be some punch marks, were they holding two sections together and how did you part them? My next project is to add declination to my 1.2 but I may need to cut down one down to fit, I could even get a used longer one cheap and cut that down.
 
aceb said:
Was cutting down the actuator a straight forward job? On your photos there appears to be some punch marks, were they holding two sections together and how did you part them? My next project is to add declination to my 1.2 but I may need to cut down one down to fit, I could even get a used longer one cheap and cut that down.
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Pretty simple. Just cut straight through it with the angle grinder. If you are going to do it I can talk you through it... but I think you are not going to need to cut anything down. How far apart are the hole centres (of the fixed adjuster) as the motor is currently set up?

Motor is a DARL 3608 (76 pulses per inch). Cost is 19.90€ from HM-sat.
 
Have you thaught about fixing a counter-weight to reduce the strain on the motor and the declination jack at extreme limits of the dish?
 
BM300 said:
the strain on the motor
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What strain? And don't you think the actuator is acting as a counterweight? At the ends of the arc it is helping lift the dish.
 
Huevos said:
What strain? And don't you think the actuator is acting as a counterweight? At the ends of the arc it is helping lift the dish.
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The actuator weight is not enough to act as a counter weight.
It is your system and you can do with it what you wish.
 
At that price it's not worth messing about chopping down anything larger I may as well buy new from there, thanks for the link. How on earth is it possible to buy and ship an actuator from Germany for 30% less than I'd pay buying it in the UK???

I'm even going to take a punt on the 36" Superjack for €37, I only need 22" of travel on the C band dish so that will leave plenty of thread inside.
 
BM300 said:
The actuator weight is not enough to act as a counter weight.
It is your system and you can do with it what you wish.
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It's just a 90cm dish hanging on a DiSEqC motor. What makes you think that would need a counterweight?
 
Huevos said:
It's just a 90cm dish hanging on a DiSEqC motor. What makes you think that would need a counterweight?
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Thanks for the information.
I had a wrong impression of the dish and thought that it was lager than that.
From the picture, It looked to me like a 1.2 m.

You right about not needing a counter-weight.
Best wishes.
 
BM300 said:
I had a wrong impression of the dish and thought that it was lager than that.
From the picture, It looked to me like a 1.2 m.
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It's aluminium too.
 
BM300 said:
Thanks for the information.
I had a wrong impression of the dish and thought that it was lager than that.
From the picture, It looked to me like a 1.2 m.

You right about not needing a counter-weight.
Best wishes.
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With a 1.2 m dish , I think a counterweight is useful .
For my (Dutch) friend PaulvR , I build a diseqcmotor on top of the original mount of his 1.2 m fibo .
Also changed the reach of that mount from 140º to 150º , to make it possible to receive ABS 1 at 75º E .
Moving back from that position was very hard to do with a lot of noise for that disecqmotor and in a few weeks there was a lot of play in the (nylon) gear of that motor .
So I build a counterweight to it and changed the motor for another one , now its turning smooth and with less noise .

On the stand you see a counterweight used at a 3.10 M mesh dish attached to a Egis 2 axis rotor
 
Trust1 said:
With a 1.2 m dish , I think a counterweight is useful .
For my (Dutch) friend PaulvR , I build a diseqcmotor on top of the original mount of his 1.2 m fibo .
Also changed the reach of that mount from 140º to 150º , to make it possible to receive ABS 1 at 75º E .
Moving back from that position was very hard to do with a lot of noise for that disecqmotor and in a few weeks there was a lot of play in the (nylon) gear of that motor .
So I build a counterweight to it and changed the motor for another one , now its turning smooth and with less noise .

On the stand you see a counterweight used at a 3.10 M mesh dish attached to a Egis 2 axis rotor
Click to expand...

As you made it clear, the benefits of the counterweight (in larger dishes) is most noticeable at the extreme dish positions. It also allows for extra dish travel (so we can catch the signal from lower satellites easily).
It also prolongs the motor life and helps in smooth dish movement.

Regards
 
martin-f said:
Hi huevos, I think I will cut the one I have down what sort of a job is it please.
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It's going to depend on the manufacturer. On my one the spherical joint is just held in by centre punch marks. Take that out. Unscrew the bolt that holds the motor to the tube. And then just unscrew the tube from the worm drive. And then just cut off the amount you don't want from the tube and the worm drive. After that just reassemble. Then insert the spherical joint back in the tube and centre punch it to hold it in. It's pretty simple really. Took me about 15 minutes start to finish, to figure out how to do it and complete the job.
 
Thanks Huevos, it is a 12inch superjack so it should be the same as yours, I will set to work on it in the next few days, thanks m8 :)
 
martin-f said:
Thanks Huevos, it is a 12inch superjack so it should be the same as yours, I will set to work on it in the next few days, thanks m8 :)
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Mine is a light duty 8" (72ppi). In 12" there's also a medium duty one (56ppi).
 
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