Eliminating Backlash in HEQ5

[Jasp05 (Aaron)]

I'm having a play with adjusting the backlash on my mount. and I have a few questions regarding the process.

Firstly, if I grab the head of the dec axis I can feel a "knock" as I spin side to side. (Clutch is engaged, and the knock feels like its the slop between worm drive and ring gear teeth.)

I can remove this knock by engaging the worm gear tighter in the mesh. So I assume this knock is due to improper meshing of the worm drive. ( I should mention my mount has had the rowan belt kit installed by the previous owner).

I'm assuming you would ideally have no movement left/right on the dec axis when clutch is engaged with no sticking/ tight points throughout a 360 degree travel of the axis?

And in regards to no sticking/ tight points throughout the travel of the worm gear. How much is too tight? I can press one finger tip against the spur gear and spin it freely. some spots are very slightly tighter (Not sure if there actually tighter or if its me imagining things). I generally test these spots by going back and forth over them which usually doesn't reproduce the sticky spot.

Is it ok to have a few slightly stickier spots throughout the travel of the gear?(I assume not as this would play into periodic errors).

Or should it be completely consistent in the full 360 degree travel? (to be completely consistent the knock mentioned above cannot be eliminated). Although now that I think about it, having the mount weighted slightly in one direction should stop that being an issue? by taking out the slop that allows the knock?.

Hope this made sense. If not let me know and I'll try and explain further.

Thanks in advance.

[brian nordstrom (As avatar)]

Hi Aaron, it sounds like ' End play ' in the worm drive just do a google as there are plenty of good articals and video's on utube on how to adjust these , I had one for years and after a bit of adjusting it never needed touching again , these are good work horse mounts .

Dont be tempted to adjust anything until you have studied up a lot as if you over tighten the block you will damage the gear ( it's only alloy , not brass and the worm drive is stainless ) and its stuffed so it will need replacing .

Good luck , it's not hard .

Brian.

[ChrisV (Chris)]

Astrobaby
http://www.astro-baby.com/heq5-rebuild/heq5-m1.htm

[Jasp05 (Aaron)]

I should mention ive used astro baby's guide during this whole process.

And i don't believe it is end play Brian. (I am most likely wrong here). But i only adjusted one of the float caps on the worm drive. And whether its tight or loose that knock is still there. (Maybe its not tight enough? Only got it done up firm i guess. Havent really tightened it up hard yet. Didnt think there was a need. If side to side movement is out of the worm drive that should be it no? )

Only way the knock disappears is to tighten the engagement between worm and gear.

If someone knows something to the contrary im all ears.

Should i try adjusting the float bearing on the other end of the worm drive??

As asked below should the gears be butter smooth when turning by hand? Or as in astrobaby's guide as long as its smooth and doesn't bind thats sufficient? Im assuming some parts of the rotation will be a bit stickier than others and this is normal?

I had adjusted the worm meshing the other day and eliminated the knocking. And the motors spun just fine through 360 degrees. I hadnt tested it by hand through the full 360 degrees tbh, but used the hand controller to spin it through.
I took the mount out to see how it performed and upon calibration was told i either had very bad polar alignment, huge dec backlash or something wrong in ra. The calibration data showed the dec and ra axis were around 39 degrees to each other if i remember correctly. Hence why i've decided to tear this mount down regrease and set everything properly.

[Jasp05 (Aaron)]

As an update.

I think I have got it figured. Dec axis does not spin when clutch is not engaged which was one problem solved. Just had to really thin the coating in the housing down. like a film more so than anything.

And I seem to have eliminated that knock and not have any point bind on the worm drive.

So at this point everything is at it should be I believe. One last test is take it out and do some calibrating with PHD2 and see if I fixed my dec backlash issue for certain...

Will report back for further help If its not fixed