Hypertuning the EQ6

[Euan]

I want to spend a lot of time this summer really preparing for next season by eliminating a lot of the gremlins that takes up valuable imaging time in the darker months.

One of the things I would like to do is really go to town on the EQ6 and get the guiding as good as it can possibly get. This is in anticipation of moving to a higher focal length at some point.

The obvious thing is to do PEC through EQMOD, but has anyone ever tried any of the worm gear options that are available?

Things like this?: Orion Atlas EQ-G Hypertune - Rubylith | Saves Your Night Vision

[Bizibilder]

Don't get carried away with fancy bearings that can do thousands of rpm. Your scope does 1 rev per DAY!!. By all means upgrade - but reasonable quality steel bearings from a reputable supplier are just as likely to do the job at a fraction of the price. You can find your local bearing supplier in Yellow pages or on the web.

The problem with some (but NOT all) Chinese bearings is that they are packed with awful grease and this is often contaminated with grit - it doesn't take long for them to get scratched and start to wear.

The bearings we use could do with a little "preload" to tighten the balls in the races. This does not mean tight! just enough to remove ALL play at all points in a complete revolution of the axis.

[Astro_Baby]

Having stripped an EQ6 and an HEQ5, which were releatively new units, I found the bearings to be pretty well lubed. The rest of the mount wasnt though and in both cases had nasty bits of flaked up paint and assorted drek inside. The bearings were ok as they were sealed.

A standard strip and rebuild replacing any old lub with white lithium and a thorough clean out of the internal plus adjusting the worm gears seems to work wonders.

Cant say how effective a hypertune would be. When I did the EQ6 I did notice some rough maching in parts and smoothed that out on the way through.

[daz]

I did the full monty on mine, replaced all the bearings, etc.. I also took all the paint off the housing faces and polished them smooth.

It's fairly straightforward following the excellent guides by Mel, and taking your time. Watch the bearings of you replace them though - I found my replacements to be very tight when re-seating and required some additional, er, leverage to get them in!!

Glad I did though, the whole things is much smoother. I took PEC measurements before I started, but have not done them since! Really must do......

[daz]

You will need the spacers, though. I could not find a UK supplier for them at all....

[Euan]

You will need the spacers, though. I could not find a UK supplier for them at all....

That's my first step, I've just bought some digital callipers and I'm going to try and set the worm spacing properly, like this: DEC Assemble

I'm not to bothered about the bearings, I've stripped it all down and lubed it properly and it seems really smooth, I just want to concentrate on the worms.

I've noticed a little play in the mating of the two gears on each of my stepper motors, so I'm going to look into this as well

[Euan]

I've noticed a little play in the mating of the two gears on each of my stepper motors, so I'm going to look into this as well

The mount is now stripped to bits and I've started looking at the stepper motors.

I have the same problem as shown here:

QXOI_Lk6UhM

There is a good thread where someone has eliminated this on Ice In Space: EQ6 - Transfer gear fix - IceInSpace

I'm going to try the same solution, so have now started to look for some decent washers to replace the brass ones.

[Euan]

There is a really easy way to get rid of the backlash in the stepper motor transfer gear

Just loosen the three hex screws holding the top section in place and adjust it until there is no play between the gears. Here is someone setting it with a 0.02mm spacer sheet

[Astro_Baby]

Yup - I did that on the mounts I rebuilt but used a foil spacer to get the distance. I didnt document it in the strip downs. I am working on a hypertune guide at the moment to cover the twiddly bits like making the motors dhut up as they spool up.

[Euan]

Yup - I did that on the mounts I rebuilt but used a foil spacer to get the distance. I didnt document it in the strip downs. I am working on a hypertune guide at the moment to cover the twiddly bits like making the motors dhut up as they spool up.

Oh cool. How long do you think it will take you? If it's anything like your strip down guide it will be worth keeping my mount in bits for the moment

[Euan]

I rebuilt but used a foil spacer to get the distance.

Great idea!!

I noticed that if you push the gears together, there is usually a point on the turn that they start to bind slightly

I was still getting it on one strip of tin foil, but put two in and there's now no backlash and no binding

[Bizibilder]

Gears are quite tricky to get to mesh correctly! The main problem that we face is that a tiny error in manufacture can cause real headaches.

Consider a gear where there is a 0.02mm (about 1 "thou" for us oldies!) error in the central hole (ie it is not perfectly centered with respect to the teeth) mashing with a second gear with a similar error.

If they are set up at the correct "mesh" there is a very good chance that as they rotate the "errors" will add and subtract to give a relative movement of +/- 2 thou. So you have to set the gears far enough apart to compensate for the worst case - where there may be zero clearance - so you may need the gears 3-4 thou further apart than theoretical.

You have, by doing that, introduced backlash!! And you can fiddle around for hours trying to get the "best fit". Manufacturing errors of gears are quite likely to be greater than the dimensions mentioned, so we are in a viscous circle!!

The only advantage that we have, as astronomers, is that our gear systems are "one way only" and that once the gears are driving (ie all the backlash is taken out of the system) we should only see the usual periodic errors caused by the slightly "out of round" of the gears themselves. Until, of course, our not quite perfectly balanced tube starts to operate under the influence of gravity rather than the gear box!!

I think we have arrived at the answer - the whole thing has to be a compromise designed to get the best result from each individual set of gears / mount / scope etc.

[Euan]

That's a really good explanation, I hadn't thought about the tiny tolerances on these things

[Euan]

Yup - I did that on the mounts I rebuilt but used a foil spacer to get the distance. I didnt document it in the strip downs. I am working on a hypertune guide at the moment to cover the twiddly bits like making the motors dhut up as they spool up.

What have you used to stop the rattling? I don't want to put too much pressure on the transfer gear shaft with the original brass washers in place so I'm trying to find something else, some kind of small teflon washer maybe?

[Euan]

What have you used to stop the rattling? I don't want to put too much pressure on the transfer gear shaft with the original brass washers in place so I'm trying to find something else, some kind of small teflon washer maybe?

I went around a few model & diy shops this afternoon looking for plastic washers. Nothing to be had

I then noticed these panel mount phono sockets in Maplin. They are insulated with Teflon washers, which just happen to be EXACTLY the correct size and are also very low friction!

[Astro_Baby]

Thye motor rattle is controlled by tightening down the big hex nut on top of the motor cogs BUT you have to loosen a small set screw on the side of the motor first. The small set screw is visible in the picture in post #8 of this thread and is below the gear cogs on the left side (as pictured) of the motor housing.

You can adjust the gear cogs tension to the motor spindle using that BUT you have to exercise extreme care because you can easily strip things badly.

The guide for doing all of this is behind the rebuild of the polar alignment guide which is due a rewrite, behind the 'what scope to buy' article and both of those are behind the 'Strip a TAL 1 to bits and rebuild it/budget astronomy guide' which is taking all the time so I guess the short answer is not anytime soon

[Euan]

The one in post #8 is a picture from somewhere else, my motors are different and are in post #15. I bought the upgrade kit a few months ago, so this may be how all the new motors are.

It's the same idea but without the thread, to tighten it up you have to put pressure on the top of the shaft and then tighten the two grub screws

[Euan]

I'm doing the worm gear spacing just now using the Teflon spacers from here:

Set of Worm Wheel Spacers - Rubylith | Saves Your Night Vision

They took about 2 weeks to ship from the US but they are really good.

With the RA the centre of the worm and the gear were off by 0.42mm, one of the spacers were that exact size

I'm doing the DEC just now and I just noticed something that probably explains the dodgy DEC guiding I've had with this mount. The bearing that sits inside the worm gear and connects it to the main body of the mount wasn't totally flush inside the gear. It was off ever so slightly, so this will cause about a 1mm wobble as it rotates!