Rowan Belt modding NEQ6 - Need help!

[masjstovel]

Hi,

Been supertuning my NEQ-6 the last 2-3 days. stripped it down, cleaned it, and changed all the bearings, added belts to the motors and re-assembled it.

Problem occurs when aligning the wormgear in RA-axis. 
Been at it for hours now and i've found that if i tighten the setscrew to the point that there still is a tiny minor backlash, the motor cannot handle it and starts to grind and stops.
So i slacken it to maybe 1mm backlash (in visual center) and the motor can handle it.

So my question is: do i live with the backlash or is there any other things i could try in addition to the alignment? 

[teoria_del_big_bang]

I fitted new bearings and added the Rowan belt mod to my HEQ5 and assume yours is similar.

The aligning of the worm in Ra is very tricky. I too made it so thee was no backlash and all seemed fine for a while then when I mounted my scope the motor stalled every so often. It took me quite a while fidlling with the two grub screws to get the motor to work without stalling and have the least backlash. Basically I just kept adjusting then moving Ra through the full 360 degrees a few times at full speed to ensure no stalling, when I adjusted it too much so the motor first stalled I then just backed it off ever so slightly and it has been fine since.

I have only owned one Skywatcher mount and as an engineer they are great mounts for the money but are not perfect by any means. I would say all of these mounts to some extent will have some periodic backlash to these gears. They are not perfectly manufactured and there is some cyclic tight spots within this worm gearing so you can set it so at the tightest point there is little, or no, backlash but then as the worm turns it will get less tight and there will be some small amount of backlash.

Points I noted on my HEQ5 (so not sure if exactly the same) are:-

• Do not over-tighten the thrust bearings or the taper roller bearings, I found literally just hand tight was enough. Too tight and that also puts extra load on the motor.
• Take time over setting the worm backlash it is a lengthy job to do right and it will never be perfect.
• With the Rowan belt mod it is even more important to precisely balance your scope.

Regarding the periodic error you will have due to this worm I believe there is something you can do to at least make it better, although as a relative newbie to all this have not done it myself and it is called PEC (Periodic Error Correction).

There are quite a few threads about this (here's one I was looking at recently)

using-pec-with-heq5phd2

Like I say I am relatively new to all this only been imaging for around 14 months and I didn't get a lot of chance to do it anyway due to work and the UK weather 😞 so this is only my experience to date and hope I have not said anything misleading. I am sure some of the many experts on this forum will correct me if I have.

Good luck with it 🙂

Steve

Edited December 19, 2019 by teoria_del_big_bang

[bottletopburly]

There’s always the Rowan  zero backlash mod , https://www.firstlightoptics.com/belt-mod-kits/rowan-astronomy-zero-backlash-worm-mount-for-sky-watcher-neq6.html no reviews yet though but I’m sure top Quality.

 

[masjstovel]

9 hours ago, teoria_del_big_bang said:

I fitted new bearings and added the Rowan belt mod to my HEQ5 and assume yours is similar.

The aligning of the worm in Ra is very tricky. I too made it so thee was no backlash and all seemed fine for a while then when I mounted my scope the motor stalled every so often. It took me quite a while fidlling with the two grub screws to get the motor to work without stalling and have the least backlash. Basically I just kept adjusting then moving Ra through the full 360 degrees a few times at full speed to ensure no stalling, when I adjusted it too much so the motor first stalled I then just backed it off ever so slightly and it has been fine since.

I have only owned one Skywatcher mount and as an engineer they are great mounts for the money but are not perfect by any means. I would say all of these mounts to some extent will have some periodic backlash to these gears. They are not perfectly manufactured and there is some cyclic tight spots within this worm gearing so you can set it so at the tightest point there is little, or no, backlash but then as the worm turns it will get less tight and there will be some small amount of backlash.

Points I noted on my HEQ5 (so not sure if exactly the same) are:-

• Do not over-tighten the thrust bearings or the taper roller bearings, I found literally just hand tight was enough. Too tight and that also puts extra load on the motor.
• Take time over setting the worm backlash it is a lengthy job to do right and it will never be perfect.
• With the Rowan belt mod it is even more important to precisely balance your scope.

Regarding the periodic error you will have due to this worm I believe there is something you can do to at least make it better, although as a relative newbie to all this have not done it myself and it is called PEC (Periodic Error Correction).

There are quite a few threads about this (here's one I was looking at recently)

using-pec-with-heq5phd2

Like I say I am relatively new to all this only been imaging for around 14 months and I didn't get a lot of chance to do it anyway due to work and the UK weather 😞 so this is only my experience to date and hope I have not said anything misleading. I am sure some of the many experts on this forum will correct me if I have.

Good luck with it 🙂

Steve

Thanks for the reply, Steve. 
It seems like alot is simular to my NEQ6.

Regarding your learning points:
Sorry, my English is not the greatest, but which bearings is the thrust-bearings?

• The taper rolling bearings, i presume you mean the ones that keep in place the wormgear (Not the brass one, but the thinner rod)?

          I made these pretty slack - so i could spin them around with my hand, but so there was no slack in it - this is what you mean?

• Been re-adjusting it today. I am down in maybe 0.5mm backlash in the visual center. RA turns 360degrees fully loaded with gear. It sounds great, but I have a feeling the motor is crying for help as it was grinding just a couple of millimeters back on the aligning-setscrew. No grinding - happy astronomer? Or do i need more slack?
   
• About the balancing. I bought SKF bearings and regreased them with SuperLube. All except the 6 bearings keeping both RA and DEC axis in place. I felt i did more damage then good when trying to remove the rubber seal on those, and SKF says it can handle minus 40degrees Celsius so i thought i could just live with it. Anyways, the old bearings were little grease in them - so they span much quicker around than the new ones with grease. Thats normal, i know - but it also makes more resistance when spinning the RA and DEC axis. It is more even all the way around, but its more "slowness" sort of. I had an expectation that i could push the scope and it would spin around forever kind of. Do you understand what I mean, and do you have any thoughts on this - Video attached showing this?
  Lastly, the point im making here is that this "slowness" is making it harder to balance correctly, especially the RA-axis since it takes more force to get feedback kind of. 

Thanks for the PEC-thread, I will go through it!:) I got the first telescope gear in Mars this year so you have 50% more experience than me

5 hours ago, bottletopburly said:

There’s always the Rowan  zero backlash mod , https://www.firstlightoptics.com/belt-mod-kits/rowan-astronomy-zero-backlash-worm-mount-for-sky-watcher-neq6.html no reviews yet though but I’m sure top Quality.

 

I have seen that one yes. Plan is to see how guiding goes with this minor backlash, and if im not satisfied, this will be my next gear! 

 

Here's a video of the spinning: The RA-clutch is veery loose so could be some minor binding of that in the video. Sorry about the mess on the floor. My attict has turned into a workshop

Edited December 19, 2019 by masjstovel

[masjstovel]

@teoria_del_big_bang I think i understand now. Taper roller bearings - you mean those cone-shaped 1 per axis? How you mean handtight now? They must be fully in their slots yes? 
On DEC Axis it is the weight-shaft that determines the tightness i think. I tightened it as hard as i could with my hands, than slackened off like 1/4turn. DEC seems tight still, so i could try slacken it a bit.
On RA Axis its in the polarscope end. I tightened that as hard as i could with my hands, because it was VERY tight to get off when i stripped it down. Should i try loosening it a bit?

[teoria_del_big_bang]

Yes those are the bearings I meant.

They only need to be tight enough that the rollers are always in contact with the race. So I would not say make them loose but it is very east to over tighten them when using tools to tighten them. But unless you are a body builder then I would say it is difficult to over tighten by hand, but do not leave them loose at all.

I do not know if you followed this guide but it is worth a look.

Astro Baby Guide to EQ6 Stripdown

This actually shows tighteneing with a tool but stresses not to overtighten. I did not have such a tool at home so I think used two allen keys in the grooves of the nut and then just tighened by my hands.

Essentially they need very little pre-load, if any, you just need to sure there is no movement at 90 degrees to the bearing (I hope that makes sense). See my very bad quick sketch below.

I guess temperature can make a difference as when very cold I guess the pre load will go up a bit due to the spindle contracting, so I would say if hand-tight at normal room temperature (20 C or so) then they may get a bit tighter when nearer to 0 C but not by much so would be fine they are unlikely to get looser.

I tried to look at the video but I am currently working in China and the internet is really slow despite my VPN so the video is really not easy to watch or download so difficult for me to comment. Just make sure the axis is not stiff at all and that there is no movement as shown above.

Steve

 

 

 

 

[Ishan Mair]

On 20/12/2019 at 14:24, teoria_del_big_bang said:

Yes those are the bearings I meant.

They only need to be tight enough that the rollers are always in contact with the race. So I would not say make them loose but it is very east to over tighten them when using tools to tighten them. But unless you are a body builder then I would say it is difficult to over tighten by hand, but do not leave them loose at all.

I

Essentially they need very little pre-load, if any, you just need to sure there is no movement at 90 degrees to the bearing (I hope that makes sense). See my very bad quick sketch below.

 

I've run into a related problem on my HEQ5 Pro. When I hand tighten the RA nut with a little force, the RA axis rotates very easily during balancing. Thats the good part. Now the bad one. It is so free to rotate that a little wind or even a thin cable can rotate it. So even with axis locked, it does slip. It takes a lot of time to balance. Gets frustrating.

So I was thinking that I could keep RA nut a little loose because that seems to make axis a little rough to rotate. What would happen if  the RA nut is a little loose? Would that damage the gear teeth or motors?

Or is there any other solution to this problem?

[teoria_del_big_bang]

Ishan,

I am not fully sure what you mean, but those taper roller bearings are there as thrust bearings and as I said above are there to stop any movement in the direction of the double arrow on my very crude drawing. There are other bearings there to take care of the rotational movement. Certainly do not leave them so loose that thee is any chance of movement in that direction and  possible a small amount of nip to give some pre-load but really not very much. By all means use some sort of tool on it I am not saying only use your hands as it is difficult to turn a castellated nut by hand but I use the expression hand-tight to convey the sort of force to apply when tightening.

Also how free it rotates should only aid the balancing because to balance well if it is tight at all then there can still be some small out of balance but you will not see the axis move.

However, neither of the above should have anything to do with the axis slipping when the locknut is tightened. I would say something is not set right with that or something missing. Make sure the brass button is there under the locking screw, also ensure the screw is wound in enough before screwing on the lever, from memory you need to screw the screw in till you just feel it start to tighten up then back off about 1/8 turn and then fit the lever so that 1/4 turn or so on the lever totally lock the axis in place. But make sure the brass button is there otherwise you will damage the spindle with the end of the screw.

See here:-

heq5-rebuild

 

Steve

[masjstovel]

On 20/12/2019 at 09:54, teoria_del_big_bang said:

Yes those are the bearings I meant.

They only need to be tight enough that the rollers are always in contact with the race. So I would not say make them loose but it is very east to over tighten them when using tools to tighten them. But unless you are a body builder then I would say it is difficult to over tighten by hand, but do not leave them loose at all.

I do not know if you followed this guide but it is worth a look.

Astro Baby Guide to EQ6 Stripdown

This actually shows tighteneing with a tool but stresses not to overtighten. I did not have such a tool at home so I think used two allen keys in the grooves of the nut and then just tighened by my hands.

Essentially they need very little pre-load, if any, you just need to sure there is no movement at 90 degrees to the bearing (I hope that makes sense). See my very bad quick sketch below.

I guess temperature can make a difference as when very cold I guess the pre load will go up a bit due to the spindle contracting, so I would say if hand-tight at normal room temperature (20 C or so) then they may get a bit tighter when nearer to 0 C but not by much so would be fine they are unlikely to get looser.

I tried to look at the video but I am currently working in China and the internet is really slow despite my VPN so the video is really not easy to watch or download so difficult for me to comment. Just make sure the axis is not stiff at all and that there is no movement as shown above.

Steve

 

 

 

 

I get what you mean yes. I followed astro-babys and Martin Pyott youtube videos during the supertune. Really helpful with the videos in addition as they shows some nitty-gritty good details thats hard to do with text and pictures.

 

Yes i understand your sketch. I did it a couple of nights ago on the DEC axis. Its not movement in the 90degrees direction, but its also not very tight i would say. Tight is subjective:)

What i did discover was that the axis "breaks free" from the bearing from time to time. Its the bearing that its not coneshaped in the DECaxis in top of the picture below. Meaning the axis-shaft is spinning and the bearing does not over 10-15degrees aproximately. So i thing there is some grease on the inside-ring of thst bearing. Will try some drops of loctite and reassemble the axis.

Regarding the video: it has very much approved since then:)

Edited December 21, 2019 by masjstovel

[Ishan Mair]

Masjstovel, congratulations for making progress in solving your problem. I hope you wont mind if I continue discussions for my problem in this topic as the drawing and video provide good help.

To Steve... Thank you for the drawing. It did its job very well.

15 hours ago, teoria_del_big_bang said:

However, neither of the above should have anything to do with the axis slipping when the locknut is tightened. I would say something is not set right with that or something missing. Make sure the brass button is there under the locking screw, also ensure the screw is wound in enough before screwing on the lever, from memory you need to screw the screw in till you just feel it start to tighten up then back off about 1/8 turn and then fit the lever so that 1/4 turn or so on the lever totally lock the axis in place. But make sure the brass button is there otherwise you will damage the spindle with the end of the screw.

See here:-

heq5-rebuild

 

Steve

I am sure the brass button is there. I've also adjusted the lever, it does indeed contact the RA axis spindle before it hits the stop.

I must confess that I am quite surprised by what I will mention now. While you say that RA black nut should not have anything to do with axis rotation or slipping, I've noticed that if I keep the RA black nut hand tight, axis becomes very free to rotate by hand. Thus clutch/brass button cant stop the rotation of RA axis even against a small force. Is it possible that RA worm spindle (made of brass) and or housing is too smooth that brass button doesn't cause enough friction? 

[masjstovel]

@Ishan Mair i am still not 100% satisfied with my problems yet, but i dont mind at if you're posting about your problem too:)

I might have a sollution for you.

In Martin Pyotts videos on youtube he mentions the exact problem you describe. Its a common mistake that the whole brass-wheel gets greased, when its just the teeth that need greasing. Symptoms when greasing the whole part, is as you describe: The clutch dont brake very well.

I too had the problem like you, just not as bad as you describe. When i did the supertuning there was alot of grease on that brasswheel where the clutch grips (factory grease - 2nd owner but saw no signs that the mount had been disassembled before), which i removed. Now the clutches grip very well. 

Edited December 22, 2019 by masjstovel

[teoria_del_big_bang]

27 minutes ago, masjstovel said:

@Ishan Mair i am still not 100% satisfied with my problems yet, but i dont mind at if you're posting about your problem too:)

I might have a sollution for you.

In Martin Pyotts videos on youtube he mentions the exact problem you describe. Its a common mistake that the whole brass-wheel gets greased, when its just the teeth that need greasing. Symptoms when greasing the whole part, is as you describe: The clutch dont brake very well.

I too had the problem like you, just not as bad as you describe. When i did the supertuning there was alot of grease on that brasswheel where the clutch grips (factory grease - 2nd owner but saw no signs that the mount had been disassembled before), which i removed. Now the clutches grip very well. 

Never thought of that, but yes that could cause the issue.

Steve

[Ishan Mair]

On 22/12/2019 at 16:20, masjstovel said:

@Ishan Mair i am still not 100% satisfied with my problems yet, but i dont mind at if you're posting about your problem too:)

I might have a sollution for you.

In Martin Pyotts videos on youtube he mentions the exact problem you describe. Its a common mistake that the whole brass-wheel gets greased, when its just the teeth that need greasing. Symptoms when greasing the whole part, is as you describe: The clutch dont brake very well.

I too had the problem like you, just not as bad as you describe. When i did the supertuning there was alot of grease on that brasswheel where the clutch grips (factory grease - 2nd owner but saw no signs that the mount had been disassembled before), which i removed. Now the clutches grip very well. 

Thanks @masjstovel. I will watch the video series again. I will clear the surface of housing and brass-wheel when I disassemble it. Could you please shoot a video that shows how easy and smooth is rotation of axis while balancing? I hope its not too much to ask for.

[spillage]

Would grease on the brass wheel also cause the mount be poor when rotating with the clutch released?

[tooth_dr]

7 minutes ago, spillage said:

Would grease on the brass wheel also cause the mount be poor when rotating with the clutch released?

Mark, I also still suffer from stiffness in my dec axis, when the clutch is opened (or even removed altogether).  Even with 15kg on it it doesn't spin that freely.  Im still getting guiding at 0.6 or less RMS in dec axis, sometimes no corrections are needed over extended periods of time.  But it's very hard to balance effectively.  I do it by feel but I cant be sure if it's balanced.  I sanded down the inside of my Dec bell housing but I think I should have went more when I did it.  Never had an issues with my clutch though.

[spillage]

Thanks for the info Adam. Mine seems to be in RA and is better with a bit more weight loaded. With the quattro I can see .5 but with the 130pds I am struggling to get .8.  I might bite the bullet and replace some of the bearing and give is a quick service if I can find the time. I must admit the stars are not too bad but feel it could be a bit better.

[masjstovel]

3 hours ago, Ishan Mair said:

Thanks @masjstovel. I will watch the video series again. I will clear the surface of housing and brass-wheel when I disassemble it. Could you please shoot a video that shows how easy and smooth is rotation of axis while balancing? I hope its not too much to ask for.

I think it is in part 4. I can post a video yes, but im away until 2.January. I slackened off the DEC axis to the point of satisfaction before i left, and it spins very freely now. Only thing is what I mentioned  that the axis loosen from the bearing in some positions. I will loosen the RA axis, and use some drops of loctight between the bearing and axis in DEC when i get home, and you will see the result. Sholdnt take more than an hour or so to fix.

2 hours ago, spillage said:

Would grease on the brass wheel also cause the mount be poor when rotating with the clutch released?

Good question. Out from what i could see on the construction when i took it apart, i would say no. I would guess that tightness to be either the bearings or that the axies are too tightened together. I am not qualified to say that though.

You could just try unscrewing the 3 set-screws on the weightshaft - loosen it a little bit but ensuring that its not loose 90degrees according to @teoria_del_big_bang 's drawing and try:) 

Edited December 23, 2019 by masjstovel

[masjstovel]

@Ishan Mair if you disassemble, please have 100% control of the white/blank teflon washers - which, where and how many etc.. Be aware that it can be 2  greased together that looks like 1 and so on:)

[Ishan Mair]

On 23/12/2019 at 22:52, tooth_dr said:

Mark, I also still suffer from stiffness in my dec axis, when the clutch is opened (or even removed altogether).  Even with 15kg on it it doesn't spin that freely.  Im still getting guiding at 0.6 or less RMS in dec axis, sometimes no corrections are needed over extended periods of time.  But it's very hard to balance effectively.  I do it by feel but I cant be sure if it's balanced.  I sanded down the inside of my Dec bell housing but I think I should have went more when I did it.  Never had an issues with my clutch though.

Can our mounts be averaged out? That would make the both of us happy !!
 I would not try sanding it down more than that if does guide good in declination.

On 24/12/2019 at 00:16, spillage said:

Thanks for the info Adam. Mine seems to be in RA and is better with a bit more weight loaded. With the quattro I can see .5 but with the 130pds I am struggling to get .8.  I might bite the bullet and replace some of the bearing and give is a quick service if I can find the time. I must admit the stars are not too bad but feel it could be a bit better.

My HEQ5 rarely achieves less than 1" with 130pds.

On 24/12/2019 at 16:32, masjstovel said:

@Ishan Mair if you disassemble, please have 100% control of the white/blank teflon washers - which, where and how many etc.. Be aware that it can be 2  greased together that looks like 1 and so on:)

Heq5 just has just one red washer so I wont have to worry about it.

[masjstovel]

On 23/12/2019 at 16:57, Ishan Mair said:

Thanks @masjstovel. I will watch the video series again. I will clear the surface of housing and brass-wheel when I disassemble it. Could you please shoot a video that shows how easy and smooth is rotation of axis while balancing? I hope its not too much to ask for.

Here you go. I feel RA is very nice. In DEC it sort of "brakes up" ever so slightly from time to time, and i found out thats because the axis-rod losenes itself from the bearing nearest the polar scope top opening. I can see it through the opening, the axis-rod sort of slips alittle and rotates without the bearing. Maybe i didnt clean the inner bearing-ring enough. I havent tried guiding yet as the weather hasnt been right, but i imagine it wouldnt affect the guiding. If it does i will poor a couple of loc-tite drops on the axis where the bearing sits.

[m.tweedy]

Have you watched this YouTube set of videos.

probably the best guide I have seen about this mod (my NEQ6 was modded by a friend using this).

 

[newbie alert]

15 hours ago, masjstovel said:

Here you go. I feel RA is very nice. In DEC it sort of "brakes up" ever so slightly from time to time, and i found out thats because the axis-rod losenes itself from the bearing nearest the polar scope top opening. I can see it through the opening, the axis-rod sort of slips alittle and rotates without the bearing. Maybe i didnt clean the inner bearing-ring enough. I havent tried guiding yet as the weather hasnt been right, but i imagine it wouldnt affect the guiding. If it does i will poor a couple of loc-tite drops on the axis where the bearing sits.

 

15 hours ago, masjstovel said:

Here you go. I feel RA is very nice. In DEC it sort of "brakes up" ever so slightly from time to time, and i found out thats because the axis-rod losenes itself from the bearing nearest the polar scope top opening. I can see it through the opening, the axis-rod sort of slips alittle and rotates without the bearing. Maybe i didnt clean the inner bearing-ring enough. I havent tried guiding yet as the weather hasnt been right, but i imagine it wouldnt affect the guiding. If it does i will poor a couple of loc-tite drops on the axis where the bearing sits.

That looks far better in this video from the last.. had you over tightened the taper bearing locking nut?

 On setting the worm a good way is to do it by sound.. make sure the gears are meshed nice and snug but not too tight and with your Allen keys tighten until you hear it slightly bind and then back it off.. make sure that the big Allen bolts in the worm housing are loose and once tightened the sound doesn't change.. 

[masjstovel]

3 hours ago, newbie alert said:

 

That looks far better in this video from the last.. had you over tightened the taper bearing locking nut?

 On setting the worm a good way is to do it by sound.. make sure the gears are meshed nice and snug but not too tight and with your Allen keys tighten until you hear it slightly bind and then back it off.. make sure that the big Allen bolts in the worm housing are loose and once tightened the sound doesn't change.. 

Yes in both axis it was too tight to get proper balancing when i reassembled, so i loosened both the weight-shaft end (DEC) and polar scope end (RA) making sure no movement 90degrees, and its much better.

Interesting procedure. Is it an actual sound? Im not sure i understand how you mean

Edited February 2, 2020 by masjstovel

[newbie alert]

18 minutes ago, masjstovel said:

Yes in both axis it was too tight to get proper balancing when i reassembled, so i loosened both the weight-shaft end (DEC) and polar scope end (RA) making sure no movement 90degrees, and its much better.

Interesting procedure. Is it an actual sound? Im not sure i understand how you mean

Sent a pm to you

[Ishan Mair]

On 01/02/2020 at 22:21, masjstovel said:

Here you go. I feel RA is very nice. In DEC it sort of "brakes up" ever so slightly from time to time, and i found out thats because the axis-rod losenes itself from the bearing nearest the polar scope top opening. I can see it through the opening, the axis-rod sort of slips alittle and rotates without the bearing. Maybe i didnt clean the inner bearing-ring enough. I havent tried guiding yet as the weather hasnt been right, but i imagine it wouldnt affect the guiding. If it does i will poor a couple of loc-tite drops on the axis where the bearing sits.

 

Thank you for the video  . Gives me a chance to compare. Mine is perhaps a little more free in RA. Same as yours in Dec though. So I dont have a lot of problems balancing on Dec. May be I should disassemble RA and try again. How did you check for  the "90  degree" movement  for axis-shaft mentioned by @teoria_del_big_bang in this sketch in topic earlier ?