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Sqren

HEQ5 pro, RA problem

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Hi! 

I recently did the belt mod and fitted a guide camera on to my HEQ5 pro. After getting the mount up and running, I have noticed that about every 10 min, I get this "bump" on the RA-axis. I am fairly sure this was here before I did the belt mod, it's just that I got the guiding at the same time as the belt, and then actually started paying attention to it. 😅

I have checked both the balance of the scope, and the power supply. Both seems alright. 

 

Have any of you had the same problem? Will switching out the bearings and doing a re-grease fix this? 

 

Thanks in advance

72299074_2458748480869436_6286111471545876480_n.jpg

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I believe think the original worm gear ratio is 135:1 which would equate to about 10 minutes 40 seconds .

So I would have said possibly broken/faulty tooth....

However I dont know if this applies the same ratio applies to the belt drive ?

 

 

Edited by Kev M
typo

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If its the Rowan belt mod then the ratio should remain the same. Could it be grit or dirt in one of the gears? I would strip it down, give it a good clean and try again.

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1 hour ago, Kev M said:

I believe think the original worm gear ratio is 135:1 which would equate to about 10 minutes 40 seconds .

So I would have said possibly broken/faulty tooth....

However I dont know if this applies the same ratio applies to the belt drive ?

 

 

I timed it to be almost exactly 10 minutes and 40 seconds... 😒

Is this something that one can get parts for? If so, do you know where?

Is it normal for these gears to get damaged over time, or would it be more likely for it to be dirt/grit, as Mark suggests? 

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Looking at the slight blip you have, I am not sure if it is even anything to worry about....

Others with more experience may be able to comment further.

 

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Have you had this mount from new or bought 2nd hand?

Having stripped one of these down and replaced the gears myself when I also did the Rowan belt mod I would agree with the comments above it has to be connected with the worm or the gear that meshes with the worm.

It could be a damaged tooth as suggested, It could be dirt but I would expect this to move around a bit and maybe be more intermittent rather than absolutely once per rev.

It  could also just be binding. When I put mine back together I was determined to get rid of any backlash and my first attempt looked fine to begin with absolutely could see no backlash in the worm. But when I mounted the scope and CB weights even when balanced it would bind once per rev of the worm and occasionally would miss a step of the stepper at the tight spot.

I had to slacken everything off just ever so slightly. So for sure on mine I cannot totally eliminate backlash as I have to set it with zero backlash when it was tending to bind which means some slight backlash when the worm is at 180 degrees from this.

Anyway what I mean to say is maybe if it is 2nd hand somebody did the same and the gears are getting very tight once per rev. If you turn the worm by hand when not under power you can feel it. The graphs tends to indicate this I think in that it hits a tight spot then loses position and PHD2 is sending correction pulses but nothing changing for a while then all of a sudden it goes but then goes too far because of the pulses that were sent and so PHD has to back-track and send opposite direction pulses. But again a broken tooth could show the same effect.

Check the worm and the meshing gear as it has to be in there.

You do not need a full strip down to do that is it quite easy to get to and adjust (although fiddly and time consuming because it only needs a very small adjustment each time. 

Look here if you haven't already done so to see how to adjust.

heq5-rebuild

It's basically this section:

image.png.3aae472df36e926855ecc4188f782bfa.png

Steve

 

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7 hours ago, Sqren said:

Hi! 

I recently did the belt mod and fitted a guide camera on to my HEQ5 pro. After getting the mount up and running, I have noticed that about every 10 min, I get this "bump" on the RA-axis. I am fairly sure this was here before I did the belt mod, it's just that I got the guiding at the same time as the belt, and then actually started paying attention to it. 😅

I have checked both the balance of the scope, and the power supply. Both seems alright. 

 

Have any of you had the same problem? Will switching out the bearings and doing a re-grease fix this? 

 

Thanks in advance

72299074_2458748480869436_6286111471545876480_n.jpg

Something is binding and then releasing. 

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3 hours ago, teoria_del_big_bang said:

Have you had this mount from new or bought 2nd hand?

Having stripped one of these down and replaced the gears myself when I also did the Rowan belt mod I would agree with the comments above it has to be connected with the worm or the gear that meshes with the worm.

It could be a damaged tooth as suggested, It could be dirt but I would expect this to move around a bit and maybe be more intermittent rather than absolutely once per rev.

It  could also just be binding. When I put mine back together I was determined to get rid of any backlash and my first attempt looked fine to begin with absolutely could see no backlash in the worm. But when I mounted the scope and CB weights even when balanced it would bind once per rev of the worm and occasionally would miss a step of the stepper at the tight spot.

I had to slacken everything off just ever so slightly. So for sure on mine I cannot totally eliminate backlash as I have to set it with zero backlash when it was tending to bind which means some slight backlash when the worm is at 180 degrees from this.

Anyway what I mean to say is maybe if it is 2nd hand somebody did the same and the gears are getting very tight once per rev. If you turn the worm by hand when not under power you can feel it. The graphs tends to indicate this I think in that it hits a tight spot then loses position and PHD2 is sending correction pulses but nothing changing for a while then all of a sudden it goes but then goes too far because of the pulses that were sent and so PHD has to back-track and send opposite direction pulses. But again a broken tooth could show the same effect.

Check the worm and the meshing gear as it has to be in there.

You do not need a full strip down to do that is it quite easy to get to and adjust (although fiddly and time consuming because it only needs a very small adjustment each time. 

Look here if you haven't already done so to see how to adjust.

heq5-rebuild

It's basically this section:

image.png.3aae472df36e926855ecc4188f782bfa.png

Steve

 

This is a 2nd hand mount. And yes, it also seems to be moving a little. The spikes seems to be almost non-existent when it's around time for a meridian flip. Though the timing varies from 10min 20 sec, to 40 sec-ish. 

Thanks alot for the advice, Steve!

I will try this in the next couple of days and get back to this thread with the results 😃

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On 15/10/2019 at 14:56, teoria_del_big_bang said:

mean to say is maybe if it is 2nd hand somebody did the same and the gears are getting very tight once per rev. If you turn the worm by hand when not under power you can feel it. The graphs tends to indicate this I think in that it hits a tight spot then loses position and PHD2 is sending correction pulses but nothing changing for a while then all of a sudden it goes but then goes too far because of the pulses that were sent and so PHD has to back-track and send opposite direction pulses. But again a broken tooth could show the same effect.

Check the worm and the meshing gear as it has to be in there.

You do not need a full strip down to do that is it quite easy to get to and adjust (although fiddly and time consuming because it only needs a very small adjustment each time. 

Look here if you haven't already done so to see how to adjust.

heq5-rebuild

It's basically this section:

image.png.3aae472df36e926855ecc4188f782bfa.png

Steve

 

So I'm just done fiddling with this for a couple of hours. I kinda got it better, but it didn't get rid of the problem. After alot of adjusting and playing with the worm gear, I'm 90% sure it's a damaged bearing or some dirt. When passing a certain point, it almost feels like it's "grinding" and uneven for a small part. 

I have decided to just go for the stripdown, and also switch out all the bearings for something higher quality (SKF/FAG etc.). 

Do you know what kind of grease is best to use here? The store I get the bearings from also sells SKF LGMT 2, mineral oil based, lithium soap thickened grease. Should be good enough? 

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I seem to recall that a lot of people use white lithium grease.  You don't really need to go mad because the bearings are hardly handling huge loads for extended periods at high temperatures...

James

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I ended up using some tf2 grease when I did mine. seems okay so far after 12 months +.

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More or less as above none of the bearings are under any real load and do not move with speed so most good quality grease will do. I would say do not use really thick grease and do not pack them so tight with grease, they do not need a lot.

Also get normal clearance bearings not C3 bearings. C3 bearings have a bigger clearance means that the bearing has room for expansion if needed between the races of the bearing. These are meant for high speed operation where the bearing may get hot and so need that room for expansion. You may think you are getting better quality bearings if you buy C3 but all you end up with is bearings that have play in them that is not required. You will get better precision with the normal, cheaper bearings.

May not be of much use to you as you are not in the UK but this is what I bought when I did mine.

I bought the larger bearings from Bearings R Us

image.png.cbba82b0705cfe4f65decfee2544c47f.png

and the small bearings for the worm from Simply Bearings as that was the cheapest option.

image.png.09b885d6954daa287c8f6d13b8ae2c4c.png

 Steve

Edited by teoria_del_big_bang

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And do not tighten the taper bearings too much. It just needs to take up any play and does not need a lot of pre-load. Basically tighten as much as you can by hand then maybe just an 1/8 turn more with a spanner (at most).

Regarding the grease as well although I see no need really for any specialised grease most people seem to recommend lithium grease, but I notice that now even on the Astro-Baby site which most people use as the bible for doing this they give a caution about using white lithium grease:-

NOTE 2: When this guide was originally written the accepted wisdom was that white lithium grease was an overall good lubricant. However it would appear that
standard white lithium grease may cause problems under some extremes of damp/temperature. All of the mounts I have rebuilt have been done with white
lithium that is stable and often mixed with a syntehtic like Teflon or PTFE. It is best to consult the manufacturer on the quality of the product.

heq5-rebuild

Steve

Edited by teoria_del_big_bang

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Hei Sqren,

A couple of years ago I gave my HEQ5 Pro the Rowan belt mod, and recently I did the RA overhaul. I never replaced the big bearings, just the two small ones, and I did not touch the DEC department at all. For lubrication I used ("Biltema 36-1861 ") chain lube for bike chains which is very sticky.  It works very well now.

I would say that with the symptoms you describe, the most important parts to focus on are 1) the two small worm bearings (just a small axial tension after you put in the new ones), 2) the worm belt pulley (do the belt tooths engage perfectly over the whole circumference ?) and 3) too little backlash may cause intermittent binding when temperature falls.

Also, the taper bearings - I only tensioned them by hand (without adrenaline =:)

Ragnar

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So I am back after doing a stripdown of the RA-axis, changing out the bearings, cleaning and re-greasing. First night out - lo and behold - the problem is still here. The guiding got rediculously better though, if we ignore the bump. 

Any other suggestions? Kinda running out of ideas. ☹️

 

-Aleksander

Skjermbilde.PNG

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Eliminate risk of binding (too little backlash is bad).  Try swapping the RA & DEC belts - in case of some defect on the RA belt. Inspect the big RA pulley teeth with a magnifying glass. Make sure the belt is not "climbing" up the edge of the tension wheel.

When you see this guiding "jump", slew backwards a tiny bit and see if you can repeat it (try to find the bad spot). Then stop tracking, take off the cover plate and mark the position of the big RA pulley with a pen or a piece of tape. Take off the RA belt (just take a small screwdriver and slide the belt sideways while rotating the pulleys a bit, and the belt will slip off) then feel with your fingers how the pulley rotates. Check this immediately, without unloading the mount. 

Ragnar

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Hi,

I won't be the belt as it has 71 teeth and this doesn't match the period of the error you're measuring. ( The belt makes a full rev for every 1.51 turns of the worm)

If you're fairly sure the error was there before the belt mod then it will be a defect on the worm or one of the worm bearings has a damaged outer race.
Try swapping the worms over from RA to DEC and if no luck there, swap the worm bearings From RA to DEC.

ATB  Dave.

 

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On 17/10/2019 at 10:01, teoria_del_big_bang said:

Regarding the grease as well although I see no need really for any specialised grease most people seem to recommend lithium grease, but I notice that now even on the Astro-Baby site which most people use as the bible for doing this they give a caution about using white lithium grease:-

I use white lithium grease on a completely different application and after repeated exposure to cold weather it turns to something resembling stale cheese.

A much better alternative is 'SuperLube' - https://www.rapidonline.com/Loctite-399420-Super-Lube-Grease-Tube-85g-87-7279?IncVat=1&pdg=pla-530220220992:kwd-530220220992:cmp-757438067:adg-44804851896:crv-207912323492:pid-87-7279:dev-c&gclid=Cj0KCQjwjOrtBRCcARIsAEq4rW7F-ORhnXZA5gY-NksfFey87oFNo-Xa6Y-Bk16K7jAdxz7IwD2KvlcaArslEALw_wcB

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