Precision Polar Mount Project

[Captain Jack]

All inox/stainless steel - I very rarely work with anything other than that. The original bits are galvanised, I believe (at least there's not a spot of rust on it).

 

[timo_w2s]

Because I have crooked arms, which are unable to cut anything straight with an angle grinder, I invested in a mitre saw. Cuts through metal like butter. Just need that welder but maybe for later as it's rather expensive...

View attachment 93016 View attachment 93017

That's weird, I acquired one of these very same units with our new house together with a heavy duty wooden bench it was bolted onto. The previous owner didn't want to take it with him. It's been very useful for cutting up bits of wood but I must admit I never thought about using it for metal. I think he left some spare blades too so will see what was left. The laser line is quite handy too.

 

[moonbase]

@moonbase - the chop saw cuts 6mm stainless steel just about OK but I wouldn't go any thicker. 3-4mm steel is not a problem at all.

CJ,

Thx, have you tried to cut any box section with it yet?

Rgds

 

[Captain Jack]

CJ,

Thx, have you tried to cut any box section with it yet?

Rgds

Not yet. Will give it a go soon.

 

[Captain Jack]

Another thing I need to do is create more mounting points for the actuator. At the moment, there's a real risk of flopping at the extremes. With correct points, I should able to avoid it completely.

 

[Archive4]

At the moment, there's a real risk of flopping at the extremes.

If you don´t get some good answers with that opening line!.......

 

[Captain Jack]

Attached an extra arm to the mount for the various jack mount points. Made it a lot sturdier at the extreme west when the jack is extended.

 

[Archive4]

Attached an extra arm to the mount for the various jack mount points.

Crooked arm, or a straight one!

 

[John]

Another thing I need to do is create more mounting points for the actuator. At the moment, there's a real risk of flopping at the extremes. With correct points, I should able to avoid it completely.

... Let me introduce you to the Flopomatic Calculator Machine, knocked this up when i home brewed my mount for the 1.8 CM. Simple and basic and adjustable at the mounting points to give you options, but also gives you an idea on how much you can go before you get a flop on.

 

[Captain Jack]

Very interesting, John. I kind of winged it with the trial and error approach. Forgot to attach picture from previous post.

 

[Captain Jack]

Finished the mount today and it's up. Need to align the dish now...

 

[Captain Jack]

And today I've been reminded why 1224 rules the roost. The jack that I am using is rock solid - there's only a teeeny bit of play in spheric joints but nothing major beyond that. However, with that on, there's far more play at the extremes (west for me) than there ever was with the Jumbo. Yes, it is more solid in the middle and the east of the arc but... sigh. I can only get down to 49 east until the mount runs into itself. Not a huge deal as I can't see beyond 53 east anyway... and I don't actually know how far west I can go. It looks like 58W should be OK but this is guess-work and the dish is almost about to flop at that extreme.

Lastly, the resolution of this SuperJack XL HQ or whatever it's called, is pathetic. around 10 pulse counts per degree! Which makes it rather prone to miscount. Compare that to 1224, which is about 25-30 counts per degree. Looking online, that ball screw Venture is about 15 pulses per degree (depending on where you are on the arc, of course)...

Ahhh... now the dilemma of whether to put the Jumbo back on or live with this.

 

[John]

And today I've been reminded why 1224 rules the roost. The jack that I am using is rock solid - there's only a teeeny bit of play in spheric joints but nothing major beyond that. However, with that on, there's far more play at the extremes (west for me) than there ever was with the Jumbo. Yes, it is more solid in the middle and the east of the arc but... sigh. I can only get down to 49 east until the mount runs into itself. Not a huge deal as I can't see beyond 53 east anyway... and I don't actually know how far west I can go. It looks like 58W should be OK but this is guess-work and the dish is almost about to flop at that extreme.

Lastly, the resolution of this SuperJack XL HQ or whatever it's called, is pathetic. around 10 pulse counts per degree! Which makes it rather prone to miscount. Compare that to 1224, which is about 25-30 counts per degree. Looking online, that ball screw Venture is about 15 pulses per degree (depending on where you are on the arc, of course)...

Ahhh... now the dilemma of whether to put the Jumbo back on or live with this.

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
I totally agree with your findings re: the jacks, i loved my Jumbo on my 2.2 ali Precision dish with counter balance at the rear, but even that got trashed when a storm came and i wasn't around to lower it all down. This Channel Master 1.8 with all it's lnb's on the changer would have been too much for another Jumbo to handle and thats why i had to go for the stronger but not preferred option of heavy duty jacks .
I'd love to go for an Egis or even a home brew version of an Egis for peace of mind.
I recon you would be ok with your Jumbo on your Lami installation with a rear counter balance fitted, and install some extra ground anchor points either side of the dish to tempory tether it to in the event of any strong storms..... just my two cent's worth.

 

[Captain Jack]

John, it's interesting you mention the counter balance. Do you have any pictures or diagrams as to how you had it attached? Also, what broke in the Jumbo?

 

[John]

John, it's interesting you mention the counter balance. Do you have any pictures or diagrams as to how you had it attached? Also, what broke in the Jumbo?

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Totally shattered internals, the counter balance was a home brew affair. It was made up from a bit of 25 x 25mm steel box with a length of 22mm threaded rod welded inside. A length of shrink tube was put over the whole length.
I had to modify the fixing point to make it fit the 1.8 CM frame / incline jack mount position.
I could only find one pic with it mounted on the Jumbo so knocked up a quick sketch.

 

[Captain Jack]

Wow, that's quite a catastrophic break. I would guess the alu 2.2m didn't weigh much more than my Laminas... Must have been a heck of a storm.

Need to think about the counter weight. I should be able to find a fixing point for something like that. What was the weight of it? In theory it should be heavy enough to centre the dish if the cogs were to snap off.

I like that you reused various parts of the Precision mount and the Jumbo motor ones. And looks like you reused Jumbo bits for the CM polar mount!

 

[moonbase]

...I'd love to go for an Egis or even a home brew version of an Egis for peace of mind...

Would an Ajak H-H motor be an option even if it had to be imported from the USA, there might be availability?

The Egis does have the advantage of dual axis inbuilt into it, however, I am not sure of availability second user and they are fairly expensive brand new.

 

[Captain Jack]

I've been looking at Ajaks and they seem pretty beefy. However, I read somewhere that it's only 8 pulses per degree?

 

[John]

Wow, that's quite a catastrophic break. I would guess the alu 2.2m didn't weigh much more than my Laminas... Must have been a heck of a storm.

Need to think about the counter weight. I should be able to find a fixing point for something like that. What was the weight of it? In theory it should be heavy enough to centre the dish if the cogs were to snap off.

I like that you reused various parts of the Precision mount and the Jumbo motor ones. And looks like you reused Jumbo bits for the CM polar mount!

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
That galvanised triangular mount on the back of the 2.2 was actually off a 1.2 precision i think ..... the black square frame on the back of the 1.8 CM was part of the compulsory "A" frame ground mounting kit that came with the Precision. It has four holes pre-drilled in each corner which aligned up exactly with the four fixing bolts on the CM 1.8 .... weird or what!..... everything else is home brew. No parts were used from the old Jumbo, what was left went to Chris(scopus) for motor spares etc and possibly might be with you now.
@moonbase , i'll have a look into those drives, thanks for heads up.

 

[moonbase]

I've been looking at Ajaks and they seem pretty beefy. However, I read somewhere that it's only 8 pulses per degree?

The other option might be a Birdview mount, they are supposed to be very robust mounts, capable of handling larger antenna than the Ajak?