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Author Topic: EQ6 Strip-Down and Rowan Astronomy Belt Modification  (Read 7176 times)

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Online chris.bailey

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EQ6 Strip-Down and Rowan Astronomy Belt Modification
« on: 08:59:54, 02 May, 2015 »
My EQ6 is now 8 year old. It has been a trusty companion but started showing signs of age. The Dec axis had tightened up, both clutches slipped and tracking showed the odd lurch. I had previously done a partial strip down to re-grease the worms and ring gears but decided this time to do a full strip down. It also seemed a good idea to do a belt modification and swap out the worm end bearings, which are known to be of dubious quality.

The belt modification I choose to use based on good reviews was the one by Rowan Engineering http://www.rowanastronomy.com/productsa2.htm. Delivery was swift (next day) and the kit well packaged and complete. The big advantage of the Rowan kit is that it maintains ratios allowing the handset to be used. Some Belt mods change this meaning EQMod has to be used exclusively with a custom setup. The handset is useful for solar work so I wanted to maintain it.

The replacement bearings were sourced from Bearing King http://www.bearing-king.co.uk/bearing/608-2rsh-skf/3554 and again delivery was swift.

The instruction pdf on the Rowan website is comprehensive and easy to follow (a copy is provided as part of the kit but the pdf includes higher resolution images that allow zooming in). The first issue was that one of the motor bolts seized part way out. Applying a little more 'welly' sheared the head off the bolt. As it is deep inside the mount head, its an awkward beggar to get to but with the aid of an easy-out extractor and some judicious drilling I managed to remove it without damaging too much thread to prevent the motors being bolted back down. I ran an M5 x 0.8 tap through the others to make sure.

The two thrust bearings and main shaft bearings all looked and felt in good condition though the one on the RA shaft was quite dry so were cleaned and re-greased. The worm and ring gears where degreased and cleaned up. There was quite a lot of 'gunk' in the bottom of the ring gear threads so these were also degreased and thoroughly cleaned. They showed no signs of damage or scoring.

The second problem came in removing the Dec axis worm spur gear. The grub screw used to secure it to the worm shaft was seized solid so had to be drilled out. As the gear was superfluous to the modification this mattered little. One of the Dec axis worm gear end bearings felt decidedly 'gritty' on removal so I was glad I had opted for replacement.

The standard EQ6 includes transfer gears between the motor and worm. These are the source of a lot of backlash and noise and a higher frequency harmonic that sits over the periodic error. Dismantling one shows they are brass gears running on a brass collar with lots of play between them. Definitely one of the weak links in the drive chain

Re-assembly is quite straightforward though feeding the timing belt through the guide pulleys deep inside the mount head is a little fiddly (a tool is provided as part of the kit to assist). It is also tricky gauging how much tension to apply to the timing belts as with the motor and new motor plates installed, this is done blind. It is then a matter of adjusting the worm mesh to remove any play but prevent stalling.

As the worms and ring gears had been re-lubricated, I followed the Bisque recommendations for the MX of following any adjustment or re-lubrication with a thorough exercise by slewing from limit to limit repeatedly. The mount is now MUCH quieter with none of the gear chatter at the commencement and completion of slews.

A very quick visual test on the stars shows that slews are a lot smoother with less overshoot and though I only observed for a short period, tracking seems much smoother as well.

All in all the Rowan belt modification is highly recommended. It is well thought through and accurately machined with all parts need included. Without the issues above (which are totally separate from the kit), installation would have taken an hour or so. Stripping down further and carrying out some deeper cleaning added a further hour but having to drill out seized elements probably added four more.

If your EQ6 is more than a couple of years old then a strip down and re-grease is warranted. At the same time swapping out suspect bearings and going over to belt drive seems to me like a no-brainer.

Chris
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Online Roger B

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #1 on: 09:22:02, 02 May, 2015 »
Well done Chris,

something I've thought about but I'm not going to attempt it at the mo,  Just don't have the guts to strip it down. TBH

Rog
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Offline swashy

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #2 on: 09:51:28, 02 May, 2015 »
Good write up Chris, I'm sure I will tackle this sometime in the future
Ade

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Offline Nomis Elfactem

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #3 on: 11:14:39, 02 May, 2015 »
Yeap, great write up Chris... with the noise mine makes it is defo something on the list to do... if ya fancy a weekend in the Cotswolds just let us know  :laugh: :yes: ;) :thumbup:

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
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Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline PaulB

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #4 on: 20:01:49, 02 May, 2015 »
I agree with everybody.
Nice report.

I have a G11 not an EQ6. And I have often thought of a major service on my mount. I'd do this during the Summer.
I might give it ago, if my nerves can stand it!
Paul.
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Offline Eccoskies

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #5 on: 20:40:27, 02 May, 2015 »
I did my Eq6 last year and it's not as bad as you think. Just take your time, keep everything together, and go for it  :thumbup: there's not much in there you can hurt unless you lose something  :rofl:

Mark
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Online chris.bailey

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #6 on: 08:41:48, 03 May, 2015 »
I agree Mark (as long as everything comes apart easily). Without bolts sticking it would have been pretty plain sailing.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
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Offline psjshep

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #7 on: 16:20:56, 10 May, 2015 »
Stonking write-up, Chris.... and inspired me to do mine...
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Online chris.bailey

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #8 on: 19:27:20, 13 May, 2015 »
Used it for the first time today on some Solar imaging and it is chalk and cheese. Prior to the conversion a nudge would result in a jerky guess at how long to keep the button pushed needing a fair bit of backwards and forwards presses to get what you want. Post mod the nudges are instant and smooth starts and stops. Its a different mount altogether.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
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Offline psjshep

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #9 on: 20:05:17, 13 May, 2015 »
:thumbup:

I am hoping to test it tonight.....

Phil
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Offline markarian

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #10 on: 18:02:27, 12 July, 2016 »
Thanks this info Chris. I'm in the process of doing this to my old white EQ6 Pro right now. Just took it all apart and cleaned it up. The info on the bearings was especially useful as I damaged one of the RA worm bearings getting it off so will replace all 4. Fortunately disassembling everything else was very straightforward and nothing else was seized or damaged. Waiting for the kit to arrive for the next stage.
Mark
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Online chris.bailey

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #11 on: 22:19:32, 12 July, 2016 »
Cheers Mark

For the price of replacing the worm bearings its a no-brainer. The SK bearings run so much smoother and with no cage wobble. The original ones are plain nasty. You were lucky to get your part fairly simply, mine was a bit of a pain.

Chris
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Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
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Offline markarian

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #12 on: 11:43:23, 25 July, 2016 »
All went remarkably well. It is a tight fit getting the motors back in place but no real problems (apart from dropping the occasional washer or screw down the RA axis  :ugly: ). Replaced a lot of the icky grease with some nice white lithium stuff too.

Took some time to carefully get the worms to mesh properly again but it's all so much quieter and smoother now. I hope it works as well as I hope.

I'll test it all out once we're out of the Scottish towilight zone next month.
Cheers
Mark
Altair Astro RC8 // 200P // Skymax 180 // C80ED // EQ6 // Atik 460EX // Canon EOS 600D // DBK 21AU618.as
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Online chris.bailey

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #13 on: 12:12:37, 25 July, 2016 »
Glad it went smoothly Mark.

Quieter, smoother, less backlash and a lower periodic error with less second order short duration harmonics is what I found.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo

Offline Nomis Elfactem

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Re: EQ6 Strip-Down and Rowan Astronomy Belt Modification
« Reply #14 on: 16:47:29, 25 July, 2016 »
Quieter, smoother, less backlash and a lower periodic error with less second order short duration harmonics is what I found.

Oooh, I do love it when you talk dirty Chris !

I've still not quite sorted my meshing/backlash (I get it right then it changes - wondering if it's temperature dependent with the very hot weather we've had lately ?) but it's a lovely mod and highly recommended to anyone thinking of doing it !

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

 

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