HEQ5Pro Rowan Belt Damaged - help diagnosing cause and solution.

[jiberjaber]

Fitted this upgrade to my mount a few weeks ago and all seemed to be going OK apart from my guiding was getting worse on one side of the pier than the other.  All went well with the upgrade and but last night I suffered really badly from elongated stars in my images so decided to investigate as I noticed some noise from the motor gearbox when I was parking the scope last night. I was expecting the issue to be something about balance or worm drive mesh as all was good guiding towards the North (M51) and the issue was on the other side of the pier when guiding to the South (M65).

After checking for backlash in the RA & DEC (though PHD2 indicated it was RA the issue might be in) I would check the belts and here was the sight upon removing the cover:

That explains the noise when parking, the belt had ridden up and the only thing stopping it from coming off was the cover over the motorbox area!

Belt appears pretty ruined, new one ordered from @FLO 

I've flipped and refitted the belt, it works but there is noise in rotation and it is trying to slide down the sprockets now rather than up them.

It's not good and needs replacing, problem is I don't want to ruin another belt but I can't see what I did wrong here, the sprockets are all aligned but the belt still rode up and deformed.  Any pointers would be greatly appreciated.

 

[JamesF]

I think I'd get a new belt and fit it, leaving the motor covers off and then see how it behaves.  Could be that the original belt was always faulty and that a new one will work fine.

The only other thing I can suggest is that perhaps there wasn't sufficient tension in the belt and that allowed it to ride up over the edge of the idler wheel, but that is just a guess.

James

[Tomatobro]

see microbe's post rowan belt mod.....same problem I think

[jiberjaber]

Yep - same tension in the DEC belt which seems to be OK. I'll certainly be keeping an eye on the new belt when fitted!

[jiberjaber]

4 minutes ago, Tomatobro said:

see microbe's post rowan belt mod.....same problem I think

I just looked back to a photo I took when I installed the belt, no touching of the teeth but I will adjust the motor pinion position relative to the idler just in case when the new belt arrives.  The thread does mention damage due to excessive tension so will double check the belt tension when fitting it with that on the DEC motor.  Has anyone got an actual measurement of belt deflection ?

 

[david_taurus83]

Belt looks stretched. Too tight?

[Erling G-P]

I did the conversion on my HEQ5 Pro recently.  While testing with the cover off, I noticed that the belts would creep a little up or down on the sprockets, depending on the direction of travel.  Solution was to loosen the belts - the tighter they were, the worse it seemed.  Never got completely rid of it, but reached a point where it was minimized.   Mount has performed well afterwards, knock on wood...

PS: I can't see your images - shows a 'minus sign' inside a circle.

[jiberjaber]

On 15/05/2020 at 23:09, Erling G-P said:

I did the conversion on my HEQ5 Pro recently.  While testing with the cover off, I noticed that the belts would creep a little up or down on the sprockets, depending on the direction of travel.  Solution was to loosen the belts - the tighter they were, the worse it seemed.  Never got completely rid of it, but reached a point where it was minimized.   Mount has performed well afterwards, knock on wood...

PS: I can't see your images - shows a 'minus sign' inside a circle.

Not sure what's going on with the images, I just pasted them in to the message and the forum is hosting them?

Anyway, I suspect you might be right, my belt finally gave up - hoping the replacement drops through the letterbox tomorrow!

[newbie alert]

Can't see any of the images but does the pinion run true, seen a few that oscillate quite bad, so combined with a over tightened belt could cause some damage

[jiberjaber]

New belt arrived today, fitted it and adjusted tension and got the belt moving up and down again though not as bad. re-adjusted to be 'quite slack', perhaps a little more slack than the DEC belt and all seems fine. I've ran it back and forth for a good few mins and it seems to be behaving itself - hopefully get chance to run some test guidance tonight and see if things are heading in the right direction  

[theropod]

Old fart story warning:

 

My oldest brother was the crew chief on a top fuel dragster (rail) that contended very well here in the USA back in the late 60’s. We talked about the toothed belt driving those huge supercharged engines more than once. His take on the issue that a little too loose was far better than a little too tight. He also said they put a new supercharger belt on with each rebuild of the engine, which was about 6-10 runs. Granted, your mount isn’t cranking >1500 HP, but I would think the same principles are at work. Your old belt looks like it suffered from cord breakdown. A little too tight and those strings in belts give up.

[1parsec]

How were you tensioning the belt that broke ?  The damage is definitely from over tension.

[jiberjaber]

Tensioned using a flat blade screw driver to gently move the motor mount to get (what I thought was) the right tension and then nipped up the holding bolts.  I was pretty sure I had the tension equal at both axis - I've slackened both off since replacing the RA one 

[SimM]

7 hours ago, jiberjaber said:

Tensioned using a flat blade screw driver to gently move the motor mount to get (what I thought was) the right tension and then nipped up the holding bolts.  I was pretty sure I had the tension equal at both axis - I've slackened both off since replacing the RA one 

Did you ask the manufacturer for more guidance on what is the optimum tension (how to get it right)?

On 19/05/2020 at 17:46, jiberjaber said:

New belt arrived today, fitted it and adjusted tension and got the belt moving up and down again though not as bad. re-adjusted to be 'quite slack', perhaps a little more slack than the DEC belt and all seems fine. I've ran it back and forth for a good few mins and it seems to be behaving itself - hopefully get chance to run some test guidance tonight and see if things are heading in the right direction  

Was it replaced under the guarantee? Is it the same as the original or OEM? Is the toothed belt marked with a part number e.g. can it be bought elsewhere such as a motorcycle parts supplier with different qualities available?

Did the failing axis have a “wobble” on the spindle? Did you fix this? Are the new spindles the same e.g. swapping them may result in a better fit on one - so less future issues?

Simon

[jiberjaber]

Hi Simon,

I asked the supplier, FLO and the advice was "The tension should be 1 to 2mm of movement. When tensioned correctly the drive should be smooth, if you hear any kicky noises it is ether to tight or to loose" I guess it's quite hard to describe what good looks like because that movement depends on how much pressure is applied to the belt to get the deflection.

My replacement was a new one from FLO which I paid for - I am not aware of an alternative supplier and I am hoping that this isn't a frequent consumable part once the tension is right

Both axis have a very slight wobble on the spindle I hadn't considered swapping them because they came in separate marked bags of components for each axis, so assumed they might be different, I do have an issue still on teh RA axis so might try swapping over to see if the issue changes - I've done what I can in terms of grease and worm mesh on the RA so that might be an avenue to explore.

 

[billhinge]

On 29/05/2020 at 12:19, jiberjaber said:

Hi Simon,

 

My replacement was a new one from FLO which I paid for - I am not aware of an alternative supplier and I am hoping that this isn't a frequent consumable part once the tension is right

 

 

You can DIY and get the belt quality you  want,  there are different  types of belt , prices and strengths

 I ordered the  parts from here

https://www.beltingonline.com/belt-tension-meter-1266/?zenid=2fhn20f4c3vlbf7054use3s2c7

 

 

 

[Neil H]

Hi my HEQ5 with the rowan belt upgrade was fine to start off but after a few weeks had a strange clicking , that was the belt running to high I adjusted the large tooth gear  this then stopped the belt from riding up , your may be the same and just needs a tiny adjustment it take a few goes to get it right so the belt does not move up or down in use 

[jiberjaber]

49 minutes ago, Neil H said:

Hi my HEQ5 with the rowan belt upgrade was fine to start off but after a few weeks had a strange clicking , that was the belt running to high I adjusted the large tooth gear  this then stopped the belt from riding up , your may be the same and just needs a tiny adjustment it take a few goes to get it right so the belt does not move up or down in use 

My DEC belt is a fraction of a mm proud to the top at the moment so might look in to that, I assume if the belt is riding up, then the large gear needs moving up?

[Neil H]

the belt height seem to be more controlled by the idler pulley so you need to get the gears to run in line but the larger gear will make the belt run high or low , the larger  gear can be moved on the shaft or place washers between the motor and mounting plate to make motor sit deeper in the housing , Rowan did send washers out to a customer who was having this problem

But all I did was move the large gear out about 0.5 of a mm  on the motor shaft so when I run the mount the belt did not ride up towards the cover that fits on top, it may take a few tiny adjustments till it runs as you want it 

Edited June 2, 2020 by Neil H

[jiberjaber]

11 hours ago, Neil H said:

the belt height seem to be more controlled by the idler pulley so you need to get the gears to run in line but the larger gear will make the belt run high or low , the larger  gear can be moved on the shaft or place washers between the motor and mounting plate to make motor sit deeper in the housing , Rowan did send washers out to a customer who was having this problem

But all I did was move the large gear out about 0.5 of a mm  on the motor shaft so when I run the mount the belt did not ride up towards the cover that fits on top, it may take a few tiny adjustments till it runs as you want it 

Yes - moving larger sounds easier though I do have a load of M3 washers here but it would involve more removal than the larger gear, however the larger gear is quite a tight fit, so washers I think... cheers for the info.