EQ6 Mount, dismantling and maybe timing belt?

[Astrofriend]

Hi,
My EQ6 mount is old now. Very stiff RA and DEC axis, it's time to dismantle it and see how bad the inside is.

I followed the Astro Baby guide and it was not any big problem to dismantle it. It looks fine inside, I suspect some earlier owner already have done this cleaning and put new grease on. But that must be years ago.

When I now have dismantled everything, shall I rebuilt it and install timing belt drives? I feel it's a little to much money to put on this old mount. I have to think about it and see what alternatives there are.

Here is my EQ6 dismantling story:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/01-eq6-dismantling-rebuilding.html

Only first part, now I'm drawing plans.

/Lars

[bojan]

I highly recoomend installing belts and conversiont to ONStep.
I did it on both my mounts (http://www.iceinspace.com.au/forum/showthread.php?t=69560&highlight=timing+belt). it is not hard to do and it is not costly, if ytou do it yourself with components from ebay (used for 3D printers. .that is why they are so cheap).
(please note, the link is not current - in the latest version, I do not have any gears, I am using 400s/rev steppers and 1:5 timing belt pulleys. I am still trying to locate my post with curent version).

[Astrofriend]

Hi Bojan,
Thanks for information and links. Looks you are not afraid to dig deep into the problems :-)

For the moment I do measurement to see what can be fittet inside the mount. With T2.5 timing belt and 6 mm wide belt there are a lot of more to chose from. But it will be tight. I also had a look at the gears if I shall keep them. But first impression is that it will be a big problem to have them run smoth and with low backslash.

Do you have any supplier of T2.5 pulleys with 4 mm belt width ?

What stepper motors with 400 step / rev have you found? Do they work with the original EQ6 driver board?

Lars

[bojan]

Hi Lars,

I purchased belts and pulleys from Sdp-S (https://www.sdp-si.com/)i, but it was quite some time ago and today there are cheaper options (BangGood, ebay...). GT2, 60 (https://www.ebay.com.au/itm/3D-Printer-2GT-Timing-Belt-Pulley-GT2-12-60-Teeth-3-175-12mm-Bore-Select/272340215348?hash=item3f68bde634:m: mS8nBkNtdtFQaGdRkH4T2zA&frcectupt=true)and 12 (https://www.ebay.com.au/itm/3D-Printer-2GT-Timing-Belt-Pulley-GT2-12-60-Teeth-3-175-12mm-Bore-Select/272340215348?hash=item3f68bde634:m: mS8nBkNtdtFQaGdRkH4T2zA&frcectupt=true) teeth (5:1).
It was a tight fit, some machining was necessary, it was pretty fiddly to place belt onto motor pulley, but it is perfectly doable with adequate patience.
Motor (similar) came from ebay (https://www.ebay.com.au/itm/Nema-17-Bipolar-Stepper-0-9deg-400-Steps-1-68A-0-44Nm-42x42x48mm-Nema17-CNC/152371025096?hash=item237a0554c8:g: nJkAAOSwxHlcSezt&frcectupt=true).
There is even a set 4:1 (https://www.ebay.com.au/itm/GT2-60-15-Teeth-Width-6-5-7mm-Timing-Pulley-Belt-Set-Kit-Reduction-Ratio-4-1/262649796727?hash=item3d2725d877:m: mHGYXTOyohX_8fkb_oR0B7A), not sure if bellt length is adequate, it mat be specified... if not you can buy belt of any length on BangGood for ~$5.


As to your existing controller, 400s/rev motors may not work, the problem will be overall mechanical reduction ratio of steps/arcsec.
You will have to find the right pulleys as well - what kind of reduction you have in your mount?

Is it 12 teeth gear on motor, 47 teeth gear on worm (idler (36 teeth) is not relevant for reduction ratio)? It that case, you will have to find timing pulleys with the same number of teeth (12 is OK, 47 teeth pulley may prove to be tricky... however you can print one with 3D printer) - if you want to keep the same controller.

Or, if it is possible to re-program controller for different mechanical reduction ratio, you can use common pulleys.

My EQ6 original controller was old-style (only tracking and fine positioning) so I went straight to Bartels system, and later to OnSTEP (Arduino platform), using 16 ustepping pulse/dir Pololu drivers.

[Astrofriend]

Hi Bojan,
There is so much to think and plan for. Many good alternatives goes away because of too high cost.

But now after I have clean the mount and done some measurement I get a better overview of the alternatives. I wrote them down on the second page:

http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/02-eq6-dismantling-rebuilding.html

Maybe it's easier for me to implement a kind of semidirectdrive on the shaft of the worm gear. But still need a gearbox, a builtin planetary gearbox with low backlash.

I'm waiting for the roller bearings I ordered and still looking for shims, I think I go for steel shims if I find any. Inner diameter 40 mm and outer 56 mm, thickness 0.1 to 0.5 mm.

Many thanks for the links and tips!

/Lars

[bojan]

Lars,
Belt mod (with 4:1 or 5:1 GT2 (12 & 60) belts & pulleys) fits nicely inside EQ6 enclosure (4mm belt width is quite adequate), while for T2.5 you will have to remove the part of housing to fit the larger pulley (it will protrude out of it - some people did that, though). It is also easy(er) to adjust transmission ratio (by varying teet number on pulleys), and Banggood has large number of various timing belt lengts in stock, cost is couple of AUD. And 3D-printing of 47-teeth pulley is a viable option.

Also, OnSTEP electronics is actually very affordable/low cost solution, so it make sense to sell existing controller and maybe recover a significant part of the investment in new electronics.

As to stepper with planetary gearbox, there will be backlash (no backlash is present with timing belt transmission/reduction). This motor is 200steps/rev.. so you will have to use 32 /usteps or even 64.

Also, any gearbox will be louder compared to timing belt transmission. This motor assembly may not fit inside EQ6 either.. External placement is not so good for mount carrying around as it could be easily damaged. And if it does fit inside, you will need belt transmission to couple it to worm anyway...


Have a look at this webpage (http://www.alphageek.co.uk/eq6.html), it is similar to what I have done (I went for 5:1 belt transmission, 60 & 12 GT2, and I did not make those large holes in the aluminium enclosure)

[Astrofriend]

Hi Bojan,
Sorry, didn't understand earlier that GT2 was another standard for timing pulleys. Looks to be more common and then more to choose from.

When you say 4:1 is that 48t and 12t ?

And 5:1 60t and 12t ?

According to the data a 60t has a diameter of 44 mm and I can't see that I have more space then a diameter of 39 mm. Do I missing something?

But a 48t will fit.

Now I'm surfing with my mobile, tomorrow I will do a new search on the computer which is much easier.

Thanks a lot, now I'm back in the timing belt thinking again.

Your comment about planetary gears, do you mean all of them? Some say they are backlash free (special version).

Lars

[bojan]

60t must be fitting inside because I am using it (with other one being 12t, so the timing belt reduction is 5:1). (I will double check, but I am 100% sure it is 5:1)

Planetary gears with small backlash are expensive. And they will always have some introduced periodic error ("noise").
The one you are looking at is US$41..

[bojan]

Yep, it is 5:1. 60-12 teeth..
(Attached is my calculator spreadsheet).

My pulleys came from SDP-Si:
http://shop.sdp-si.com/catalog/produ...A51M012DF0603# (http://shop.sdp-si.com/catalog/product/?id=A_6A51M012DF0603#)
http://shop.sdp-si.com/catalog/produ...6A51M060DF0606 (http://shop.sdp-si.com/catalog/product/?id=A_6A51M060DF0606)

(BTW, SPI-SI catalogue says GT2 60t pulley pitch diameter is ø38.2mm, with belt this is ~same as 47-teeth gear... maybe your ø44mm is with flanges? You don't really need them, belt will not slip from pulley if everithing is square and because it will be guided by slot in the enclosure).

[Astrofriend]

Thanks again Bojan for all information you sheer to me and all other who read this.

Yes it was with flanges, only because that was the only option I found, but the flanges looks easy to remove.

I have found some timing pulleys on Ebay and they have a 12 mm bore. Good for me because when living in a flat I no longer have any machines.

But one more problem, did you use the 60 teeth with out any machining? The link with data say it's 18 mm wide, in my EQ6 chassis there is only space for 16 mm and it looks exactly as your according to the photo you send.

Is it 6 mm wide belt you using or the 4 mm you wrote about earlier?

How many teeth or length does your belts have?

Almost ready to order now.

Sorry for all questions.

ps.
I read that they prefer the GT2 relative the T2.5 because it gives better precision in 3D printing. Good for ur too.

/Lars

[Astrofriend]

With Bojan's information I have now come closer to a workning rebuilt drive system:

http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/03-eq6-dismantling-rebuilding.html

/Lars

[bojan]

I have to find drawings, please wait a sec...
BTW. they are the same length...

Found the drawing (in dxf format - you can open it in LibreCAD, v 2.13 (F:\Data_disk\PROJ\Astro\Equipment\ Mount\EQ6_mount\Modification\Mechan ical)))
There are some funny issues in the drawing - consequence of conversion from ACAD (dwg) to dxf format, but the drawing itself is reasonably accurate, you will not have any problems with dimensions.

According to my notes (from drawing), belts are:

176mm
88 teeth
B-G2-88-060-NF
A 6R51M088060


I also made new motor plates (as per drawing - there was a problem with motor height and shaft length) and some machining on pulley was necessary to fit it in.

[Astrofriend]

Hi Bojan,
Thanks for the drawing, maybe I already has a CAD software installed, otherwise I follow your link and download.

Now back to the drawing board and start thinking again.

Lars

[Astrofriend]

Hi Bojan,
You helped me a lot with ideas how to proceed, many thanks!

Now I have ordered timing pulleys, I choosed a 60 teeth pulley with no flange and a 16 teeth pulley, it gives a non standard 3.75:1 ratio. Small pitch, wider belt and bigger pulleys should give a bit less elastic and smoother run compare to the normal kits, at least according to my ideas and help from forums. But I can not use the handterminal with this non standard gear ratio, but I never do that anyway.

I bought them at https://www.active-robots.com/ in Great Britian because I live in Europe Union and then I don't have to pay custom fees and taxes. They was one of few that could offer the 60 teeth pulley with a 12 mm diameter bore.

I have done some updates and put in more links with information:

http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/01-eq6-dismantling-rebuilding.html

At page three there is a link to a belt length calculator.

/Lars

[bojan]

Hi Lars,

I am happy I was able to help :-)
As to 16-teeth pulley, it is standard (for 3D printers) and that is why it is low cost. If you intend to use 400s/r stepper and OnSTEP (or similar) with ustepping Pololu module (32 usteps), you will have 0.15 arcsec resolution (100Hz stepping rate for tracking) - more than enough (I have 0.225 arcsec, and no tracking problems with 1000mm FL AP & visual).

[Astrofriend]

Hi Bojan,
Internet is fantastic, Sweden and Australia very far away from each other. 30 years ago it had been much more difficult. You must figure out yourself how to solve problems.

I got also a lot of interesting reading from 3D people.

Maybe my 20 Euro kit will perform better then the standard mod kit :-)

The OneStep driver you mention, I read about it and it sounds really interesting. My EQ6 driver do 64 microsteps, with 200 / rev it gives the same step size. But 400 step / rev with 32 microstep should give better quality.

Do you have any idea if the OneStep with 400 / rev could perform better then the standard EQ6 driver ?

Maybe next time I rebuilt a mount. But I need something better to start with then the EQ6, does a Losmandy G11 perform better if you only look at the mechanics? From what I have read you have to replace a lot of parts on the older G11 to get high performence from it.

Lars

[bojan]

Lars,

OnSTEP is low cost solution because it uses cheap h/w platform (Arduino), and firmware (actually I should use Arduino term "sketch" ;) ) is quite capable and still evolving (I am using 3y old version and it is quite OK for what I do). I have Pololu stepper drivers inside EQ6, and I am driving it from external Ardiono MEGA board via cable (so I can also use other controllers - Bartels, SoundStepper, my own controller....)

As long as you can reprogram your controller (via ASCOM) to suit your belt transmission ratio, you should be OK regardless of 400 or 200 s/rev.
I wouldn't know about G11 - but I know that stronger and heavier the mount is, the better (in principle) it is. The size of the worm gear is also important (bigger = more precise).

[Astrofriend]

Hi Bojan,

Now I got my new timing belts and pulleys from England. Looks very good even if it was not exactly the dimension I expected. But it was as close as I could get.

Here are what I got:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/04-eq6-dismantling-rebuilding.html

Not very difficult work to do, just one problem, I living in a flat and does not have a lathe.

/Lars

[bojan]

Yep.. you have to find a friend (with a lathe!) :-)

Living in a flat is not a problem - in my previous life (~30 years ago), we lived in one-bedroom flat (2nd floor), in Zagreb....
And one day I had to replace the head gasket and insert one bolt thread in the engine block of my Fiat 126.. So I removed the engine, placed on the kitchen table (to the rightfull horror of my wife) and did it....
My wife forgave me when she heard the sound of the running engine couple of hours later when I went to test drive around the flat block...

[The_bluester]

You sound like my dad bojan.

It was before I was born but my mum's Fiat 500 apparently used to do a head gasket with some regularity and he had replacing it down to a fine art, doing it on the dining table. A table which we still have and that half a century later still has marks on it to prove it where oil went in to the oak and marked out the corner of where the head was sitting one time, among other things like a clear imprint of a ball bearing.

[bojan]

:thumbsup:I knew I m not the only one :)

[The_bluester]

The table was antique before my parents got it sometime in the late 1960's, it is just like crashing and repairing a race car. A couple of decades later it is just another bit of it's history.

[Astrofriend]

What nice stories you have, once I had a motorcycle engine on the table in the bedroom. I need some thinking of what I could do with it.

http://www.astrofriend.eu/vehicles/my-cars/earlier-vehicles/minibike.html

But now the problem are of smaller physical size.

Today I have found shims washers of steel, m40 ID 50 OD, 0.1 and 0.2 mm thickness. I don't trust these plastic shims, the old are deformed by the pressure. It will come photos later. I will keep one plastic shim on top to have it act as a spring when length of shafts changes because of temperature.

I wrote to the university where I studied once, thay had a terrific workshop. But they didn't have it anymore, I must look for a lathe somewhere else.

Everything are in progress now and I can't see any problem that I can't fix.

Lars

[bojan]

That is good :thumbsup:

[Sunfish]

Sounds familiar.

My dad used to repair the Kombi motor on the kitchen table. In those days there was no garage with a workbench I suppose.

Must run in the family as when I came home from school my brother had his triumph Bonneville in parts on newspaper in the lounge room.

I like the sound of onstep for the EQ6/EQ5 with belt drive. . I should try that next , having tried it on the fork. Just need to get the wireless module to work.

[Astrofriend]

It's always so much to do, but this weekend I got some time to work on my EQ6 mount.

I have removed the paint on the surfaces of the lids that cover the worm gear.

You can follow the work here:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/05-eq6-dismantling-rebuilding.html

To my surpise one of the surfaces was not milled, anyone else that have found that too ?

/Lars

[bojan]

Whenever I have situation like this, I use a large enough sheet of sandpaper on flat surface.
This way the final result is close to what it would be if the paint was removed on milling machine.

[mswhin63]

Have to agree, I have a marble cutting board that is never used as a cutting board and place a large sheet of emery paper of varying grits to get an excellent finish. Not much use for protrusions but can be manipulated to get in some tight places.

[Astrofriend]

Yes I thought about that, but then I need to find a flat surface with a hole to let the RA shaft through. But even better with a lathe, then I get the surface orthogonal to the RA shaft also.

Lars

[Astrofriend]

Now it's time for an update of my timing belt project.

From the beginning I was not convinced that I should modify my EQ6 mount and replacing the spur gears with timing belts. But I do now.

I needed some tools and machines.

I looked for a used desktop lathe but couldn't find any and the time goes on. Later a new friend offer to me to use his lathe, perfect, maybe I can be finished in time and some test later when the darkness comes back.

You can read here what I have done, also added a lot of photos to make it easier to follow:

http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/06-eq6-dismantling-rebuilding.html

I can not recommend any to do this, better to buy a ready made kit that is just to mount. I feel it's more exiting to do things myself, maybe a sickness.

It will be very interesting to see if I get any advanteges of using a wider 6 mm belt for more stiffness and the GT2 profile pulleys that they use in 3D printers to reduce the backlash.

/Lars

[bojan]

You did a very good job, I would say.
Yes, generally kits are easier to install (but as we know, anything can (and will) go wrong), but they are also much more expensive.. and they are (probably) using the same sources for components... so why not try to DIY, it is always fun.

[Astrofriend]

Hi Bojan,
Thanks for the coment.

I have a question for you, you looks to be a big DIY. Do you have any experience of 3D-printing, and maybe Carbon fiber filament?

/Lars

[bojan]

I have used PLA at the beginning, and ABS ever since. Never tried Carbon filament.

[Astrofriend]

Hi Bojan,
I'm on the move to buy a 3D printer, just need to collect more information what's important.

I setup a new page with 3D related links, the last link is an info page about 3D printing and carbon fiber.

http://www.astrofriend.eu/links/links-astronomy-3d-printing.html

See also the spectrograph, very interesting.

There must be many parts that I could 3D print and use in my telescope and others.

I start a new thread later when I have something more to tell about 3D printing and what I do. Lots of ideas in my head for the moment.

The 3D printer I'm interesting in is this one:
https://www.anycubic.com/collections/kossel-series

Maybe more safe to buy a traditional XYZ printer.

/Lars

[bojan]

Yes, there are many thngs you can 3D print.. however you always have to keep in your mind the limitations:
- structural strength is always lower compared to injection moulding of the same material
- dimensional tolerances are usually > +/-0.15mm or even more

I usually apply post-printing machining where needed... of course that means the model must be appropriatelly dimensioned (by 0.5mm or so on surfaces to be machined)

The printer you linked is OK (price is certainly attractive)... judging by reports from some of my friends who also use similar concept (my printer is DIY, cartesian type. Firmware is Repetier, which also support Delta geometry, which is potentially capable of moves Cartesian printer cannot do ).

[Astrofriend]

I found a lot of interesting information about 3D printers. One link is about parametric CAD model of pulleys.

All links are collected here, this link is the second last:

http://www.astrofriend.eu/links/links-astronomy-3d-printing.html

If I can 3D print pulleys with enough accuracy it's fantastic. I can then print odd dimension and teeth numbers. If it not possiblie today it will be soon.

Next time I need a gearbox or timing belt drive I will give it a try.

/Lars

[bojan]

I was printing pulleys and gears, see here (http://www.iceinspace.com.au/forum/showthread.php?t=171309&page=2&highlight=printed+pulleys), here (http://www.iceinspace.com.au/forum/showthread.php?t=12171&highlight=dobson+pulley) and here (http://www.iceinspace.com.au/forum/showthread.php?t=12171&page=2&highlight=dobson+pulley).
Parametric designs (using OpenSCAD) are a good way to go, especially because it is easy to taka care of details like tolerances where needed... And printer settings are also VERY important... Once I even needed to alter the design to get desired outcome on my printer.

[bojan]

BTW, this guy (https://www.thingiverse.com/janssen86/designs) published VERY useful parametric designs for all sorts of gears.. I used one of them for my dobson encoder (large helicoidal sector).

Also, I used this design (https://www.thingiverse.com/thing:36568) for my timing pulley (for encoder).. However, there was an error (IMO) in the design, the timing belt thickness was not treated in calculations as it should have, resulting in wrong teeth pitch (2.4% smaller.. I notified the author about this, and it is easy to correct the design to the pulley turns out OK).

[Astrofriend]

Hi Bojan,
Thanks for the links, I added them to my link list about 3D printers: http://www.astrofriend.eu/links/links-astronomy-3d-printing.html

What filament (material) have you found that works best when printing pulleys and gears?

I have no experience yet but have read that carbon fiber filament are strong but give a rough surface. PETG I have seen recommended for this purpose.

I got the printer delivered yesterday, now I assembling it. Looks to be of very high quality, but not better then I found some small details to improve. I will setup a page about it later when I'm finished.

/Lars

[bojan]

I was using ABS for everything.. it is strong enough, but you need to know what and why you are doing.
When you need strength, you should use metal.
Carbon fibre is OK (so I am told) but it is ver abrasive, it wears nozzle (there are nozzles made of ruby for that)

[Astrofriend]

Hi Bojan,
Yes, I read about the carbon fibre that it nail down the surfaces.

Working hard here to assemble the 3D printer. Took some photos for you who find it interesting to follow:
http://www.astrofriend.eu/3d-printing/3d-printer-setup/01-3d-printer-setup.html

For you who have experience of 3D printing, is it a good machine? The printer didn't cost much.

Working space 230 mm diameter and 300 mm high with a cone at the top.

I start a new 3D thread later about this when I print my first adapter.

This evening I shall visit a friend with a lathe, doing some work on the pulleys.

/Lars

[Astrofriend]

Now at last, I can start assembling the EQ6 mount again.

I started with installing the 60 teeth timing pulleys. Some small adjustment I had to do once again, of course :-)

Here it is:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/07-eq6-dismantling-rebuilding.html

/Lars

[bojan]

I think 3-D printed timing pulley would work....

Please note, any PE introduced by pulley will be divided by 180 in EQ-6, and errors generated by gears will always be larger... IMO.

[Astrofriend]

Today I have assembling more items on the EQ6 mount. I have measure the needed thickness of the RA and DEC shafts shims. I also checked if the length of the timing belts are correct, amost but have to do some modifications.

Here is photo and info of todays work on the EQ6 mount:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/08-eq6-dismantling-rebuilding.html

/Lars

[Astrofriend]

The last days I have test assembled the EQ6 mount, belive it or not, but after a few modifications everything looks to fit together and the timing belt when rotating it gives a fantastic smoth feeling.

See the latest here:

http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/09-eq6-dismantling-rebuilding.html

Now I just have to unmount it clean it once more, put on grease and then assembling it again.

/Lars

[Astrofriend]

Now I have come as long that I can do the first test.

One thing I found is that the RA and DEC shaft doesn't revolve as smooth that I has thought. It's much better than earlier but still, when revolve a turn I can feel that about 1/3 it makes a little bit more resistence. And it doesn't rotate by itself, but I can easily rotate it by my finger tip. The gap between the scale ring and chassis is enough all the way around, at least 0.1 mm.

The big 6 roller bearings felt perfect to me, only resitance I could felt was the gasket. Even the two conical bearings felt ok. Didn't replace them, only the 4 small roller bearings to the worm drive.

How low is the friction in your EQ6 mount that you have regreased?

Latest:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/11-eq6-dismantling-rebuilding.html

/Lars

[Astrofriend]

Now I found what happens in the mount and cause the friction.

It's only when the cluthes are open I have friction. When closed and tracking it rotates with the two other roller bearings and then it's almost no friction. Good!

Some photos from when I testing this:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/12-eq6-dismantling-rebuilding.html

For me it had been better without these clutches, less complicated and more compact, save some kg also.

If I ever build my own mount it shall not have any clutches and no gearboxes. It shall have direct driven 3-phases DC motors. For the moment only a dream.

Until then I collect information:
http://www.astrofriend.eu/links/links-astronomy-directdrivemount.html

/Lars

[Astrofriend]

Now at last, I could power up the EQ6 mount again.

Really exiting to do this first test. One important thing was to setup the EQMOD with custom gear ratios, never done it before. It looks to work with the indoors test I did.

Here it is:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/13-eq6-dismantling-rebuilding.html

To my surprise the sound / noise was almost as high as before. Maybe others with standard spur gear has very high noise.

I hope we get a clear sky soon so I can do real test.

/Lars

[bojan]

Lars,
The noise you hear is generated by PWM (Sawtooth waveform current, flowing in motor coils), that is why the change in sound was not significant..
However, what you will find is the significantly smoother tracking, because you removed the transfer gears, so the only potential issue for PE and un-even moving remained will be the worm and worm gear.
In case you need/want to improve that, you will have to lap it with diamond paste (available on ebay for couple of $$).

[Astrofriend]

Hi Bojan,
The noise reduction wasn't that important, my neighbours will sleep anyway. But I noticed that the old spur gears hade very lot of grease on them, maybe that damped the noise earlier and that's way it isn't that much difference.

Now I have adjusted the worm gear play and the worm driva axial play to be very tight. Indoors it woorks like a charm, but maybe problem out in the coldness later. Then I have to fine adjust it a bit.

Two new pages:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/14-eq6-dismantling-rebuilding.html

On page 15 I have added a stop for the dovetail rail to fit in correct position where the DEC balance point is. It will help a lot in the cold and darkness. Very simple done but very useful.


I have now almost eliminated the play and backlash so it will be very interesting to see how it behave in reality.

/Lars

[Astrofriend]

The last night we got a clear sky and I could do some testing of the EQ6 mount with its new timing belt.

At least everything started up and it moved as it should.

But when doing auto guide calibration in PHD2 I got a varning about the orthogonality bewteen the RA axis and the DEC axis.

I also have a little strange behavior of the RA axis, it looks to rotate too fast. I compensated it with the drift compensating in EQMOD, set it to -18.

And about the most interesting, the auto guidning error ? Well, if not perfect it was below 1", the tot rms error. The drifting looks to be slow and smoth so with tweaking of the guide parameters it maybe is possible to get lower.

Here it is:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/16-eq6-dismantling-rebuilding.html

Any idea why I get that high orthogonality error (more then 10 degrees) between the RA axis and the DEC axis ? Do I have to setup the new gear ratio in more places then the EQMOD setup window ?

/Lars from cold and dark Sweden

[bojan]

Lars.

I wouldn't know why you have issues with EQMOD and orthogonality error, I am not using it (someone on forum should know..).

[Sunfish]

When I had problems with that error in PHD and HEQ5 the two issues were cone error, the scope not parallel with the axis, and play in my dec axis and mount plate fixings.

[bojan]

Cone error of 10° is huge... and must be induced by software bug or some mistake with settings.

Even 1° would be too large, those mounts are mechanically much more accurate.

[ChrisV]

Its been intersting following this reconstruction. Hope you get it sorted

[Sunfish]

PHD reports a orthogonality error which is a combination of many mount errors I am guessing so the 10 degrees is almost ok and not the true cone error I think. PHD still works at that I think.

When using Argonavis I discovered there is a plethora of Mount errors which it adapts for in a very complex way as it uses 10000 step encoders to give very precise pointing. Alas , PHD with poor encoders and sloppy worms on HEQ5 can not hope to compensate for these. That’s what guiders are for, adapting to poor hardware.

That is my take , but I am happy to be corrected.

[Astrofriend]

Hi,
Yes it's strange, but after some playing with the parameters it auto guided with less than 1" tot rms error. But still I want to know what cause this orthogonal error.

One thing that I don't have control over or any deep insight in is what exactly the Drift Compensation do. When I use GOTO command it stop at correct position according to the RA and DEC scales on the mount. But when tracking it does not run at correct speed until I adjust the drift compensation. I just remember something about a bug in the stepper motors driver board. Anyone else knows something about why the Drift Compensation is needed ?

Now I need a clear sky so I can continue testing the PHD2 and auto guiding.

I just say, just do this rebuilding if you find it interesting, otherwise buy a complet kit.

For me the advantage is that I learn a lot to next time I do something simular and I have learned a lot from this rebuilding.

But now I must end this project and start using the equipment. I also have my new 3D printer waiting. Two new project to start with.

1, an adapter between my angled viewer and Star Adventurer polar finder.

2, Solve my EQ6 rpoblem with adjusting the altitude polar align (living at 60 degree latitude). I think I can do it with 3D printed plastic part, at least I have to test it.

Here I collect information: http://www.astrofriend.eu/astronomy/projects/project-eq6-wedge-rebuilding/01-eq6-wedge-rebuilding.html

If I can learn how to CAD advanced drawings with threads and other things I will have a lot of things to do in the future.

I thank all people here for all the comments and tips, great help !

/Lars

[Astrofriend]

Hi,
I found a very good info about how to setup PHD2 and EQMOD. I follow it and redo the setup, what was very different was the RA / DEC Ratio, I had it earlier set to 0.3 but now increased it to 0.7 according to the reccomendations I got. I don't remember why I set it to that low value in my old setup.

Here is how I set it up as far I could come:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/17-eq6-dismantling-rebuilding.html

I couldn't do any test because of clouds.

What speed ratio are you using ?

Lars

[Astrofriend]

Hi,
At last I could do a test of the mount during environment I had control over.

I did a simple auto guiding test with PHD2 and got a tot rms error of 0.69". I',m sure I can tweak it to be better than that later.

Here are some screen dumps with graphs:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/18-eq6-dismantling-rebuilding.html

Long time ago I had even lower rms error, something like 0.5" to 0.8", in that time I had an off-axis adapter, same EQ6 mount but no belt drive.

A lot of people say they could auto guide with a guide telescope with shorter focal lengths, as low as 1/4 of the main telescope.

My main telescope has 910 mm FL and the guide telescope has 400 mm FL. The pixel size is smaller in the guide camera (QHY5 mono chrome) but not very much difference compare to the Canon 6D pixelsize. I have no IR block filter on the guide camera so the focus is really soft. But that doesn't look to be a problem, it's more that it even out pixel to pixel differences.

What are your experience from guide / main telescope focal length relation ?

/Lars

[Astrofriend]

My EQ6 projects continue forever.

I had a lot of problems with the hardware driver in the EQ6 mount. There is some bug in the driver I had understand, that's why there is a RA drift compensation in EQMOD. With my custom gear ratio this problem got worse. Now I decided to replace the original driver with an external driver. I already have an AstroEQ driver that I want to test.

I need some space where to place it, I have here started 3D-print a new lid for the EQ6 mount:

http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/20-eq6-dismantling-rebuilding.html

I have also ordered some connectors and cables to make adaptercables between the RJ11 6/4 to the JST connector that the stepper motors have.

/Lars

[bojan]

Lars,

Why bother? Just go for OnStep. Or my design (stepper motors drivers only, external controller (could also be PC or laptop) supplies STEP-DIR pulses from variety of applications). You can place it inside the mount instead of original driver board.

I can send you the design if you wish.. it works in both EQ6 I own for almost 10 years now.

[Astrofriend]

Hi Bojan,
Sorry for late answer, I missed it. My friend using a OStep to his motor focuser and looks promissing. Now I already have the AstroEQ and want to test it first.

Your own design, doesn't it load the computer a lot when it has to part of the work to drive the stepper motor ?

/Lars

[bojan]

Lars,
My design featured in the post #61 (https://www.iceinspace.com.au/forum/showpost.php?p=1522562&postcount=61) is just stepper driver that fits inside EQ6.
Obviously, something has to supply STEP-DIR pulses to move motors. For that purpose I have OnStep controller that runs on MEGA (https://www.iceinspace.com.au/forum/showpost.php?p=1281802&postcount=10) or STM32 boards, I mounted them in separate hand-paddles with buttons and other necessary connectors and h/w. But it can be anything, including PC running applications like Bartels, SoundStepper.. or whatever else.I was also playing with AstroEQ, I even have PCB design and actual board(s) that fits inside EQ6 done, but never used it because roughly at the same time I found OnSTEP to be more flexible and cheaper to build.

[Astrofriend]

Now at last I can control my EQ6 mount with custom gear ratio from EQMOD Indi version which I use with my Raspberry computer. Lot of work and lot of help to modify the Indi driver to accept custom gear ratio.

Here is some instruction how I made it:
http://www.astrofriend.eu/astronomy/projects/project-indi-drivers/01-project-indi-driver.html

Note: The gear raitio must be setup for one fixed custom gear ratio. It's done in the source code as it's now.

The driver can distinguish between an EQ6 mount with custom gear ratio and a HEQ5 with standard gear ratio. I use the same control computer for both mounts.

Lars

[Astrofriend]

When looking at my old projects I noticed that I have a lot of readers on my project about the EQ6 mount. I have gone through the text and correct mistakes and moved out some of the pages to separate projects/tutorials.

Here is the updated version:
http://www.astrofriend.eu/astronomy/projects/project-eq6-dismantling-rebuilding/01-eq6-dismantling-rebuilding.html

Let me know if there is something that is unclear and I try to complement the information.

It works very well nowadays, both on Windows ASCOM and Linux KStar system.

Lars