EQ6 Hypertune

[peter_4059]

I got underway with my hypertune today. All went pretty smoothly although the RA shaft bearings were on pretty tight and took some convincing to get off - the original bearings will all be replaced with new ones.

I was pleased to find the source of slop in my RA axis - the shaft screws into the motor housing and is held in place with three set screws - these were loose and the shaft was not fully screwed into the housing.

I also found bits of metal mixed in wiht the grease in one of the bearings and the famous black grease in both worm mechanisms.

The spacers in both RA and DEC were cracked.

After a degrease I'm pleased to report that all the gears and worms were in excellent condition.

Tomorrow it's off to a friend with a lathe to ease the RA shaft slightly so assembly should be a bit easier. I'm waiting on some replacement hybrid ceramic worm bearings and spacers to arrive from the states then I'll be putting it all back together.

Here's some picks of progress so far:

[peter_4059]

More pics...

[allan gould]

Nice photos Peter - really documents the process well. Hope it all turns out well. I was pleased with mine and thanks for all the advice, tools and help - it was very much appreciated.

[peter_4059]

Cheers Allan. I'm looking forward to hearing how yours performs. Here's my progress from today. Got the RA shaft eased by a friend who was kind enough to fabricate a bearing puller/pusher for the RA shaft for me. We also discovered more paint overspray on the RA shaft mating surface that has now been removed. The motor spur gear mesh has been adjusted.

This evening I completed the altitude mod and removed a heap of aluminium shavings from within the mount body. Here's the latest pics....

[Rhino1980]

Interesting read. Could you tell me, is there anyone is Oz who performs this upgrade for a fee? I can fix cars, but I would definately bugger this up though lol

[peter_4059]

Ryan,

There are some astro shops that do this (Star Optics in Brisbane and possibly Bintel in Sydney?) however if you can fix a car you will easily handle this - get the instructions from Deep Space Products and take it slowly. It really isn't that hard once you get into it.

Peter

[troypiggo]

Good stuff mate. Glad you found that slop that's been so elusive to date.

[peter_4059]

Thanks Troy. It was a combination of a high spot due to paint overspray and the set screws not being tightened down on to the RA shaft. I would never have found this without pulling it apart. The QC on these mounts is interesting - the machining is generally quite good however they leave paint in places where it really shouldn't be and fail to tighten set screws. I found this also in the altitude mechanism where one of the three set screws was not touching the pressure plate and the other two were really tight.

Today I'm going to check for burs and high points, install the main bearings in their housings and do the spacer measurements.

[peter_4059]

Here's today's progress...installed the new bearings in the RA and DEC housings and in both ring gears. The bearing puller made short work of it avoiding the need for sanding the housings to allow hand installation or use of a hammer.

I reset the altitude scale using a square to ensure the zero position was correct and cleaned the paint overspray off the worm housing surfaces to ensure the worm mesh adjustment is silky smooth. The stepper motors have also had the gear mesh adjusted.

I found an error in the Hypertune video where he determines the spacer thickness for the DEC axis he measures the height of the ring gear before he has installed the main DEC bearing - the spacer sits between the ring gear bearing and the main dec bearing and allows proper mesh of the worm and the ring gear.

[peter_4059]

more pics...

[kinetic]

Hi Peter,

love the pics and thread , great layout of the progress...:thumbsup:
How did you go with the problem you pm'd me about?
Did it end up being a factor?

Edit: (see your reply) ahhh good!

Steve

[peter_4059]

Steve,

I ended up staying with the 2RS style seals (same style seal as original). With the bearing installed in the heavy mount components the seal gets loaded and loosens up so I don't think it will be an issue.

Peter

[peter_4059]

My hybrid ceramic worm wheel bearings finally arrived today so a bit more progress to report. The worm mechanisms are now reassembled and feel nice and smooth.

I've also adjusted the mesh on the idler gear as per recommendations from the EQ6 group. The recommendation is to use a thin piece of paper to set the mesh clearance. I tried a few different thicknesses and settled on 0.07 mm thickness paper as this resulted in no noticable backlash without making the mesh feel too tight.

Hopefully my replacement spacers will arrive tomorrow and I can finish putting the mount back together (just in time for the clouds by the look of it).

[troypiggo]

Can you keep it disassembled for the weekend so we can all have clear skies for that. Once the moon gets to quarter, then you can put it all back together so the clouds roll in. Ok, thanks.

[allan gould]

Can't wait til you get the spacers And the final adjUstments made to your mount. We'll have to make a comparison to the guiding and then you can fine tune mine. I think you can spend an age tuning the mount and then the software for the guiding before it all falls into place. In my case it will be knowing when to stop.
The photos look great and maybe you should write it up as an IIS resource

[peter_4059]

Looks like you got your request answered Troy - still waiting on the spacers to arrive. :mad2:

Hopefully they will be in Monday's post.

[peter_4059]

Well the spacers finally arrived today - can't understand why they took so long as they were posted on 6th Jan and marked air mail. Anyway I've now got both the RA and DEC axis back together. A few more parts to install and I can try it out - yippee!

[allan gould]

Peter, you will have to come round and set up on my new deck. Just kidding as today I pulled out all the stops and poured the pier and did all of the decking. Must admit it looks fine and it will be interesting to see if your mount can do long exposures while guiding.
I should thank you as I was finally motivated to get the new observatory after doing the hypertune. Now I just need aset of narrow band filters to make it all worthwhile.

[peter_4059]

Well it's finally all back together now and I've spent quite a bit of time adjusting the worm mesh to minimise backlash. I tested it tonight (indoors) under full load and it seems to be slewing nicely. Friday night is looking clear so hope to get some time under the stars soon.

It was a very rewarding experience to pull it all apart, find the problems, correct them and put it back together. Thoroughly recommended if you have it in you.

[opticalsupports]

Kudos on a job well done. Last year I did a similar rebuild on an Atlas EQ-G. The ceramic bearings are a must-have IMHO.

It looks like your hypertune is a step above most I've seen. Even after the work I put into mine I still had at least four high spots per axis. Paint overspray could have been the culprit for me too.

Your photos make me want to give mine another go around.

[peter_4059]

Cheers Curt. I finally got to try it last night for the first time and I am very happy with how it is performing. I've been capturing pec curves and have +/- 5 arc second average PE according to PECPrep. I've also tried some 15 minute guided subs and have no noticable trailing - the best I could get previously was 2 mins.

Hoping to take some images tonight.

Peter

[opticalsupports]

Fantastic. 15-minute subs is what hypertuning an Atlas is all about. I heard similar numbers reported from folks on the yahoo group, and their testimonials were what persuaded me to give it a try.

[allan gould]

I know its all your fault that this weather is upon us, Peter.
+/- 0.005 arc second PEC and 95 hour subs doesn't cut it when its cloudy.......... Grrrrrrrrr.
Maybe we should take your mount out into a deep dark and lonely place and fill its bearings with sand and Vegemite so that the rest of us can get back to fumbling in the dark.

Glad to see that your efforts have paid off so well. Have to measure the PE of mine sometime when this cloud goes away... But I said that before:sadeyes:

[leinad]

Great work peter.. I'm thinking of acquiring on of these kits myself very shortly.

Did you get a chance to measure the PE prior to the work over?
Some have mentioned the Atlas/EQG-EQpro mounts having a +/-30 PP ?

[peter_4059]

I'm not sure I would recommend buying the whole kit as the tools are pretty basic and the spare parts are readilly available. The instructional DVD's are quite good however there is an error in the DEC re-assembly bit.

I didn't measure the pre workover PE as there were some more fundamental issues with the mount I was trying to address. I was interested in the post PE to see if I'd done a reasonable job putting it all together more than anything.

[leinad]

So the only worthy parts of the whole kit were the worm gear, and ceramic hybrid ball bearing kit? oh.. and extra spacers needed.

[troypiggo]

Hey Peter,

I reckon it'd be extremely useful to make a post here about the best place to get the different parts instead of the kit. Like, if you had to do it all again, how would you do it and where would you get the stuff, links to the websites etc.

[peter_4059]

The basic kit only contains the spacers. You have to pay (quite a lot) more for the ceramic hybrid worm bearings. The bearings can be bought from VXB.com and the spacers are available from one of the members on the Yahoo EQ6 group. The kit doesn't contain a worm gear and you should n't need to replace this. The best part of the kit is the DVD's in my opinion.

[bojan]

It is a pity you did not determine which component was contributing the most..
In my case it was transfer gears (47 peaks 2-3 arcsec in one period) and gearbox (last stage, 1:3, ~5arcsec pp).
Total it was ~35srcsec pp, after tuning (mesh) it is 23 arcsec pp.

[leinad]

How did you conduct your test bojan; with Pempro ?

[bojan]

Just 15 minutes exposure using 1000mm lens with slightly mis-aligned mount. Then I analysed the image pixel by pixel (tedious job ! )
I did not use the K3CCD then, unfortunately.

The images are after and before tuning (and replacement of motors and gearboxes)

[peter_4059]

OK Troy here goes:

Spacer kit - join the Yahoo EQ6 group and find the post from Doug - he sells Delrin EQ6 spacer kits for US$13 including post to Aus.

http://tech.groups.yahoo.com/group/EQ6/message/32554

Worm Bearings (2 on each axis) - These are 608 deep groove ball bearings. The standard ones are steel but the recommendation is to get some hybrid ceramics. I got mine (ABEC7 ceramic hybrid low friction in a set of 8 for US$70) from VXB.com although I've seen posts where people got the same ones on ebay for less. http://www.vxb.com/page/bearings/PROD/Kit8344

There are quite a few different ceramic hybrid bearings to choose from apart from these - key is to get some good ones. I was told to go for ABEC 7 or ABEC 9 by someone I trust.

Grease - I got Superlube synthetic grease (3oz - 85g) from a local locksmith http://www.toplock.com/

It was about $10

http://www.super-lube.com/synthetic-multipurpose-grease-ez-49.htm

I chose to replace the main bearings also although some say this is not necessary. I decided upon SKF bearings as follows:

6008-2RS1 - 6 in the mount although you can choose to re-use the original 2 DEC ring gear bearings as these don't rotate when the DEC clutch is locked
30206 J2/Q - 1 required
32208 J2/Q - 1 required

http://www.skf.com/skf/productcatalogue/Forwarder?action=PPP&lang=en&imperial=false&windowName=null&perfid=105027&prodid=1050270008

http://www.skf.com/skf/productcatalogue/Forwarder?action=PPP&lang=en&imperial=false&windowName=null&perfid=131000&prodid=1310000206

http://www.skf.com/skf/productcatalogue/Forwarder?action=PPP&lang=en&imperial=false&windowName=null&perfid=131000&prodid=1310002208


All up these main bearings cost $179


You can get the instructions from Beevo for free although it isn't a step by step DVD:

http://www.beevo.com/rework.htm


You need the following tools:
a set of metric allen keys
a set of phillips head and straight screw drivers
a shifter
some needle nose pliers to remove the worm shaft covers and to adjust the wom thrust ring.
possibly some vice grips if the locking rings are done up really tight.

some fine wet and dry sand paper.
a craft knife for scraping paint off the mating surfaces.
a small length of 6mm ID tubing to rotate the worm shaft by hand.

Finally - a lot of patience when you adjust the worm mesh.

Peter

[peter_4059]

Based on my post tuneup PE curves, most of the PE is coming from the transfer gear and the worm (about 50% each). The transfer gear has an o-ring either side of the gear as a bearing and this is obviously not quite right. Luckily this is easy to adjust without pulling the mount apart again. There are also a number of modification options that can be looked at to replace the o-rings with spacers, or proper bearings. I just haven't got there yet.

[leinad]

Thanks for all that information peter :thumbsup:

[bojan]

Yep, this was my conclusion also, and it is quite visible on images above..
The transfer gears contribution can not be tuned out - I wanted to replace the gears with timing belts, everything is ready for the task but I do not have time...:sadeyes:

PS: my mount is classic, with gearboxes (yours has only 200 s/r motors and transfer gears)

[allan gould]

Peter and Bojan

which is the actual transfer gear you are referring to?

[bojan]

I was referring to two 47-teeth gears - one is on the worm, another one is on the output shaft of the gear box of my classic EQ6 (gearbox with 131 reduction).
Also, I mentioned the last stage of the reduction in the gearbox that is 1:3, and the effect of this is visible as 3x higher frequency un the PE photos..

The Synscan EQ6 mount has slightly different reduction: 200s/rev motor, 12 (or 20?) teeth gear on motor shaft, then there is middle-size transfer gear (with rubber spacers?) and finally larger gear on the worm shaft. The reduction ratio is determined by gears on motor and worm axle [middle gear size (transfer gear) is irrelevant]

[peter_4059]

Allan,

On our EQ6 the transfer gear is the larger of the gears on the motor mounting. Mine has rubber o-rings and yours has a bush.

[allan gould]

Thats why I was confused as I couldn't remember anything with rubber O-rings in the mount.
Thanks for that

[opticalsupports]

Pete, thanks for posting all of that info. It appears I will be following in your footsteps in the near future. Your thorough documenting of the hypertune is truly inspiring.

Where did you get the instructional DVD?

[peter_4059]

I got mine from Deep Space products

http://www.deepspaceproducts.com/default.asp?Q=New_Atlas_DIY_HyperTu ne_DVD

It is the same as the one Astro Rubylith sells

http://www.astro-rubylith.com/category.sc?categoryId=5

[opticalsupports]

Pete,

I probably won't ask this question very cleary so please pardon my stumbling through the wording.

When I hypertuned my first Atlas there was a point in the reassembly where everything but the motors had been installed. The instructions I used directed me to reach into the motor compartment and feel where the worm spur gears protrude into the compartment via the slots in the walls. If I could turn them with my finger tips and thus make that axis slowly move, then supposedly that meant everything was meshed welll. On the other hand if one or both spurs could not be moved with my fingers it supposedly meant the meshes were too tight, and therefor the motors would have difficulty moving them as well.

Did you go through a similar process in appraising the tightness or looseness of your gear meshes after reassembling the mount?

The problem I had was annoying. As I turned the spur with my fingers, it would go smoothly until reaching what felt like a sticky spot. I had to push harder to get past that sticky spot, then it got smooth again until the next one. On the RA axis I had one or two spots, but on the DEC it was more like 4-6.

[bojan]

Curt,
That looks bad.
Either the worm shaft is bent (that would explain one sticky spot) or the worm is damaged (couple of bumps on threads) or (less likely) you have hard particles/dirt in grease which are now pressed into worm surface.
Is this happening at every position of the worm gear (I know.. you have to turn it 140 times to find out. If yes, at least you know the gear is OK)
Anyway, all this will result in increased periodic error,

[peter_4059]

Curt,

I left two (RA and DEC) of the worm shaft caps off (the ones on the side of the mount where the power and hand control connections are as this end of the worm shaft is retained in place by a screw-in ring. I then inserted a small length of plastic tube over the end of the shaft so the tube was protruding out of the mount. You can then turn this either with your fingers (without reaching into the housing) or with an electric drill.

Using this tube to rotate the worm I found the high (tight) point on the worm ring gear (I think pretty much all of these mounts have some degree of run out). I then adjusted the gear mesh at this point. I also found the feel of this adjustment was easier if the mount was somwhat balanced (I extended the counterweight shaft).

Hope this makes sense - if not let me know and I'll post a picture.

Peter

[bojan]

Ah, yes, the mount MUST be balanced when doing this.
Because, when you rotate the worm against load, the mount will behave more or lees OK (except for increased friction resistance due to pressure on worm threads).
But if you do it in the same direction (where mount wants to go because of unbalance) the mount first tends to stay where it was due to friction. But when the worm touches and pushes the teeth of the gear, the friction will "get free" and the mount will "fall" due to the unbalance until it hits the other side of the teeth, where it will stop (friction again).
And so on. So the balance is paramount here.

Also, I forgot to mention, your "sticky spots" may be due to too much pressure on worm ball bearings, or dirt inside them... or both.

[opticalsupports]

Ah, I need to leave a cap off as well so I can observe the worm cycle while manually turning the gearing for each axis. Last year when I went through this process I had already installed both caps, so when I turned the spurs manually after reassembling the mount I didn't have a way to see where the worm was rotationally.

Still I'm not sure it could have been the worms that were the problem. My diagnosis was that those sticky spots were problems with the large cogs rather than the worms. If were the worm instead I would have expected A LOT more sticky spots. Here's why - I literally sat there and spun each axis 360º with my finger on the spur. It took a long time for each axis but I wanted to feel where the problems were. If the sticky spot had been a single point on the worm, I should have felt it at regular intervals. Also, I should have felt more than just three or four in a full 360º of each axis.

Does that make sense?

I really appreciate your feedback on this. My new EQ-G arrived today and I'm determined to lick my hypertuning mystery this time around.

[allan gould]

The main reason for leaving the cap off is that you can attach a piece of hollow plastic tubing over the spindle of the worm gear and use this to turn the worm gear rather than getting your hand inside the mount housing to turn the gear attached to the worm gear. Its easier to do and just as sensitive.
One thing that happened to me was that after assembing my EQ6 mount, the dec axis was perfect but I suddenly had a 7-8 sec lag before the ra axis would reverse direction at slowest speed. The reason that I finally found is that there are 2 grub screws on the worm gear that hold the worm and the gear together. One of these was not sitting on the absolute flat point of the worm gear. While testing the backlash etc of both axis - perfect but once I loaded it up with the scope and counterweights it was enough to dislodge the grub screw so that it oscillated on the worm gear giving me the 7-8 sec delay between motor reversals. So if you have NO backlash but get a delay in axis movement this is your probable cause. I had to strip the axis back down again to fix this and then re-adjust all the backlash etc again. About an hour job.

[opticalsupports]

Allan, thanks for the heads-up. It makes perfect sense what you're describing. I didn't have that exact problem because I obsessed over aligning the flat spots with the set screws. It was tough because you can't see it very well as I remember.

[allan gould]

Curt, I thought that I had also been obsessively careful as I marked it with a "sharpy" to know where the flat was but I must have been just a bit off and with the scope load rocking it back and forth, the screw gradually worked itself loose so that it went from perfect (No backlash or delay in reversing the motors) to a 7-8 sec delay in reversing the motors. Just something to be aware of.

[acropolite]

Peter, do you have any contact details for Doug Dieter, none of the links in the Yahoo spacer thread work, I'd like to contact him to see if he still supplies the Delrin spacer kits.

[asimov]

Thank you all for the very (to me) important information in this thread. I have the basic EQ6 that I have stripped & tuned the best I could without any part replacements as such. I have these tight spots on the ring gear too. I'm only concerned with the RA axis & it's PE. Does anyone make a better quality ring gear & worm for these mounts? Sorry If I have missed any info. related to this in this thread.

[peter_4059]

Phil,

Try this email address:

skygazer at kennaquhair dot com (skygazer@kennaquhair.com)

[peter_4059]

John,

You can purchase replacement ring gears and worms from:

http://www.aeroquest-machining.com/index.html

I've also seen references to Gierlinger gears from Germany but don't know the website address. Check out this thread:

http://www.iceinspace.com.au/forum/showthread.php?t=19091

[bojan]

Just be aware that the main problem with EQ6 is not PE per se.. the real problem are the sudden jumps 1-3arcsec, due to gear transfer.
PE caused by worm is relatively large (~20arcsec pp) but this can be guided out, as it is smooth in most cases.
PE analysis (to determine the cause of the problem) is essential before spending money un-necessarily.

[acropolite]

Thanks Peter.

[asimov]

Thanks Peter & Bojan:thumbsup:

[acropolite]

Some of the links on Beevo's stripdown site are not functional I found a more comprehensive alternative here (http://www.astro-baby.com/EQ6%20rebuild%20guide/EQ6%20worm%20alignment.htm).

[Poita]

Is there anything that can be done about the gear transfer problem?

[bojan]

Yes, apart from cleaning or replacing them with high-precision gears (expensive!), you can have a look what I have done about it. However, this was not hyper-tuning - this was modification, so my reply is somewhat OT..
http://www.iceinspace.com.au/forum/showthread.php?t=69560&highlight=timing+belt
Many others before me did it (I was just following their example), with good results.

The presented mod still have one gear transfer stage (1:4) but currently I got rid of this one as well, so now the motor drives the timing belt directly.
I only need some free time and nice weather to test it.
The processor h/w & f/w used at the moment are according to Darren's mod presented on his website (http://projects.gbdt.com.au/eq6-1/ , it supports various transfer reduction rates), but my final intention is to use Mel Bartel's software with this, once the mount is permanently set up.

[joncarruthers]

apart from belt mods we've had some improvement by fitting better constant velocity profile gears. These along with a PierAstro kit (ceramic hybrid bearings all round, steel shims, motor nose bearings, etc) made a huge difference. Lapping the Gerlinger worms was the final touch, about as good as it gets now. The main sorce of grief in these mounts is the worm end float control. I'd like to drill/tap the end covers and fir either a pointed hardened grub screw or a small spherical saphire lens to make a jewelled movement ;-)

[Poita]

John, does replacing the gears mean that the sysncan features no longer work?

What are the issues with the worm end float control? I'm opening mine up this weekend to get a better understanding of the internals, so reading up as much as I can. I have access to a local hi-tech CNC shop, so am interested in messing around with modifications.

[bmitchell82]

Just a quick question about lapping of the gears are you able to point me to some literature regarding the type of lapping compound and how you connected to the worm to go though all the revolutions?

Brendan

[salimant]

thanks for the info