Actuator Fitting

Breadfan

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#1
This is going to sound like a stupid newbie question i know, but I've looked round for the answer both here and elsewhere on the net with no luck.

This is hard to explain and it's too dark to take a picture... but how does the actuator fit to the polar mount ? I mean I know it bolts to the holes provided, but which way?

Not explaining this well sorry!! Looking from the top of the pole downward the polar mount is kind of 'T' Shaped. Part that the actuator attaches to the holes on either the left or the right of the top of this "T" (near where the dish mounts). The other end attaches to a metal plate, and the plate can be reversed to fit on either the left or right hand side. My plate is currently fitted to the right hand side... so do I connect it staight up to the hole on the right.... or across diagonally to the hole on the left ?? Does it matter? Anything to be gained/lost by changing it.

I've also noticed the actuator 'flaps about a bit' particularly at the extremes of movement. It's held on by ball joints so I suppose it's supposed to do that ?

Any ideas guys? (and girls?)

Tia
Breadfan.
 

Channel Hopper

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#2
The actuator should be mounted as far away from the 'hinge' of the polarmount as possible. The further away it is, the stronger the design will be , but at the expense of travel (actuator needs to extend more, to move the dish further on the arc)

Therefore both mounting places should be on one side of the dish, either East or West.

If you are experiencing floppy action, then you should check the condition of all the bearings, and the wormdrive in the actuator arm, none should have any movement in them, except a smooth turning action.

Its also very important to have the limits in the actuator set correctly. If not, theres a chance of damage to the dish, the actuator, or the chimney.
 

Breadfan

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#3
Cheers CH that makes sense but thanks for confirming:)

The "floppy action" is only occuring at each extreme of movement so setting limits slightly before that should cure it. My entire set up is based on cheap bits snaffled mainly from Ebay so it's a case of "It will have to do" at the moment. Although saying that I'm already pretty much hooked and it's just a matter of time until I splash out on some better kit :D

The actuator/positioner was working just great on the workbench but now it's 3m up in the air the positioner isn't getting the counts... I can move the dish fine using the set East/West but the counts don't change, so that's the only way I can move it!!! Will have a look at it next week and will prob be back here with more questions :confused.

Great forum this, thanks again,

Breadfan
 

Channel Hopper

Suffering fools, so you don't have to.
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#4
Sounds like the actuator wires dealing with the sensor have come adrift when you raised it onto the pole.

As for floppy at one end, with the newer designs, reduction in the size of the polarmount means that usually at a far extreme angle, the actuator arm will run close to the hinge and this weakens the triangular aspect of the moving parts (two sides of the triangle run close to each other) At this extreme a single count of the actuator pulse - if you had one - could move the dish by a couple of degrees.

If the end travel limit is not too important for you , the cheapest method would be to back off the actuator slightly, by changing the cam limit, or simply sliding the worm drive further down the back clamp.
 
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