NEQ6 Pro Belt Mod

glend (Glen) · #1 04-09-2015, 09:36 AM

I have a belt mod kit coming from Rowan Engineering in the UK:

http://www.rowanastronomy.com/productsa2.htm

I'd like to hear from anyone who has installed this kit in their mount, with any advice, tips, etc that someone who has never opened up a mount would need to do it successfully.
I do have a number of the install links provided by Rowan on their site, but need some first hand feedback on things to watch out for, shortcuts (if any), and other things to do while I have it opened up (shims?).

codemonkey (Lee) · #2 04-09-2015, 09:49 AM

I've actually just done this myself, using the same kit. The belt mod itself is quite straight forward; I've got zero experience with anything remotely like this, so if I can do it anyone can. I started late morning and got it all back together in the mid-evening.

That's including a couple of hours I spent after getting the RA axis jammed trying to dismantle it. My own fault, but something to note: where it says that you may need to gently tap the shaft out with a mallet, watch that you don't end up with it out of square or you may get it jammed like I did.

Also watch out for the tapered bearings falling out when you're dismantling the axes. It does mention it in the guide, but mine fell out before I got to that point.

The hard part for me is getting the gear meshing right after putting it back together. I've got horrible backlash after reassembling that I still haven't resolved. I'm hoping to fix that over the next few days.

peter_4059 (Peter) · #3 04-09-2015, 12:10 PM

here's my experience:

http://www.iceinspace.com.au/forum/s...highlight=belt

codemonkey (Lee) · #4 04-09-2015, 12:59 PM

Looks like I spoke too soon.

Went up the back to try and tweak the meshing, seemed to be getting close, then it bound up. Backed it off, still bound. Backed it off some more, same result, then even more, where the axis had very noticeable slop, and now the worm isn't moving, even though I can hear the motor going and it's not binding. I think the belt must have come off the worm/motor, so maybe it was never backlash to begin with, maybe I didn't tension the belt(s) properly.

billdan (Bill) · #5 04-09-2015, 05:18 PM

Must admit I received the belt drive mod from Rowan Astronomy and a set of SKF worm bearings from RS Components back in June. Still I haven't had the guts to strip the EQ6 down yet.

You know "if it aint broke etc"

Bill

codemonkey (Lee) · #6 04-09-2015, 07:04 PM

I had bad "backlash" issues in DEC before I bought the kit, and I'd heard somewhere that belt mods can help that, and since I want to squeeze the most out of the mount in addition to fixing up that backlash issue I figured I'd give it a shot.

Not sure how I managed this, but the pulley on the DEC motor had come off, and the pulley on the DEC worm was loose as well, which could explain what I thought was backlash.

Fixed it back up today/tonight, guess I'll see how it goes the next time I get it out under the stars.

I also learned not to tighten the worm end float too much. Astro baby's guide suggests tightening that until it binds and backing it off, but after moving the worm myself with it all open, there doesn't seem to be any value it tightening that nut beyond the point where it's not loose, beyond that the worm starts to move awkwardly.

I also upgraded the counter-weight shaft at the same time as I'd heard that it helps with guiding.

RobF (Rob) · #7 05-09-2015, 12:06 PM

Just take it slow Glen. Have lots of clear clean space to lay things out on. Take lots of pics as you go.

I have no particular engineering/mechanical experience, but found the exercise extremely helpful to better understand the weaknesses in the design and see what all the adjustment options are. Getting rid of the transfer gears has got to be a help. Nice to have quiet purring during slews, rather than grinding punctuating the start and end of each movement as it was pre-mod.

Key things to watch in assembly include tension on worm bearings, worm/gear adjustments making sure to keep rotating by DEC and RA as much as possible (there will be some parts of the worm tighter than others). Follow the tips on getting the belts on, putting bit of plastic over allen keys etc.

Astrobaby has a good guide on EQ mounts too, and Peter's previously linked page has lots of great background to get you in the zone and build confidence.

glend (Glen) · #8 05-09-2015, 12:16 PM

Thanks Rob, it's mounted on the pier in the observatory so it will be done in there and I will have a table setup next to the mount to lay things out. I can leave it on the pier as I take it apart so I won't be fighting with the heavy chassis along the way and I get leverage for removing things and putting things back on. I will have all the Astrobaby instructions printed out as well as live access via wifi to the Rowan Engineering links page. No rush to get it done. I am suppose to go out to the dark site by mid-week so it may have to wait until I return.

codemonkey (Lee) · #9 05-09-2015, 12:31 PM

I took apart my dec yesterday and did the ra this morning. Much quicker now that I have a vague idea what I'm doing.

One thing I found today is that getting the wedge off the ra axis (something I jammed badly in my first attempt) was much easier done by laying the main casing down, with the black polar scope cover that's on the "front" of the main casing flat on the table, then lifting the wedge off that way.

I only point this out because you've mentioned that you want to do this on the pier, and I did this part on my tripod the first time around and got it jammed. You might not, but I think it's easier laying it down for this part. Up to you!

codemonkey (Lee) · #10 12-09-2015, 12:37 PM

Quote:

Originally Posted by codemonkey

I also learned not to tighten the worm end float too much. Astro baby's guide suggests tightening that until it binds and backing it off, but after moving the worm myself with it all open, there doesn't seem to be any value it tightening that nut beyond the point where it's not loose, beyond that the worm starts to move awkwardly.

Whatever you do, don't listen to my previous advice here, I was way off. In trying to work out my dec issues I've discovered that the worm end float adjustment is in fact critical.

Today I backed off the grub screws that adjust the worm/ring meshing as I suspected this was too tight; it wasn't binding, but it didn't sound "smooth." After doing that, I adjusted the worm end float and found that, visually, the backlash is massively better after tightening this up. May need to adjust it a little still once I get it under the stars, but I can tell by watching the end of the worm when I slew in dec that the backlash is way better.

RobF (Rob) · #11 12-09-2015, 12:53 PM

Quote:

Originally Posted by codemonkey

Whatever you do, don't listen to my previous advice here, I was way off. In trying to work out my dec issues I've discovered that the worm end float adjustment is in fact critical.

Today I backed off the grub screws that adjust the worm/ring meshing as I suspected this was too tight; it wasn't binding, but it didn't sound "smooth." After doing that, I adjusted the worm end float and found that, visually, the backlash is massively better after tightening this up. May need to adjust it a little still once I get it under the stars, but I can tell by watching the end of the worm when I slew in dec that the backlash is way better.

I'd certainly agree the tension on the end of the worm/bearing is every bit as critical as the grub screw tension on the worm/gear. Has to be firm, but not so tight that you get binding as the assembly is rotated all the way around (there is usually a tight spot somewhere if you get it too tight).

What about padding the worm/bearing ends though - is that possible or required to optimise the worm/gear mesh? Be interested to hear from gurus?

glend (Glen) · #12 23-09-2015, 04:31 PM

Well I did the tear down today and mostly it was uneventful, but the sadistic person that put that RA worm together really P'd me off.

The driven RA gear on the end of the worm has two grub screws which were buried in some sort of lock-tight compound, one came out ok but the other was a real trial - I was worried about breaking off the Allen key inside the grub screw it was bending so much, I finally had to heat up the screw with a soldering iron to get it to break loose. Then I found that they had painted lock-tight all around inside of the opposite end where the Worm Shaft end bearing nut is located, and the black cap was also held tight by lock-tight. After I finally got the black cap loose I found the bearing tool I bought with the kit would not move the shaft lock nut at all, the notches were filled with lock-tight. I spent an hour scraping lock-tight out of the threads and the notches on the end cap so that the bearing tool could get some purchase. Finally got it to move and eventually all the way out. I dread what I will find on the DEC Worm Shaft.

So it this a common issue with modding these mounts? Or did I just get a 'special' one.

peter_4059 (Peter) · #13 23-09-2015, 05:00 PM

Have you had it since new or has it been "hyper-glued" by someone?

codemonkey (Lee) · #14 23-09-2015, 05:11 PM

I'm assuming you bought that secondhand? Mine (a few months old, bought brand new) definitely wasn't like that. Sounds like a royal PITA.

glend (Glen) · #15 23-09-2015, 05:52 PM

Quote:

Originally Posted by peter_4059

Have you had it since new or has it been "hyper-glued" by someone?

I bought it new just two years ago and this is the first time I've opened it up. I like the term 'hyper-glued' an accurate description.

glend (Glen) · #16 27-09-2015, 09:35 AM

Well I thought that I had the belt mod completed but when I tried to adjust the worm mesh I found that the RA belt drive wheel was rubbing on the housing (this despite being installed exactly to the Rown Engineering directions for spacing); not just rubbing but refusing to turn. I had to tear it down again to remove the worm shaft housing and check that, but the spec distances were correct. I then had to machine (Dremel) some of the aluminium from the housing lugs just below the motors on both RA and DEC to get better mesh gear clearance. Re-assembled and both RA and DEC worm gears now rotate freely. This is something that people doing this mod might want to check before they button up the mount.

Second issue is the RA lock shaft brake pad. On my mount there is a small round spacer or sacrifical brake pad that sits on the end of the shaft - only held there by the fact that it's inside the hole and a little grease on it on the lock shaft side. This spacer/brake pad presses against the side of the turning axis gear face to lock the axis. When I disassembled the RA shaft, this locking spacer fell down into the bottom of the mount housing, and I did not see it. When I reassembled the RA the unit would not go all the way down, it was only slightly out, with the setting circle wheel showing too much gap. On disassembly again, I found this small piece of metal spacer sitting down in the bottom of the casing where it was preventing the RA shaft assembly from seating properly. So keep an eye on those little brake pads.

Hopefully today I will get it all back together.

RobF (Rob) · #17 27-09-2015, 10:49 AM

Good on you Glen for persevering and sharing those tips.

Doesn't sound like its been the easiest of upgrades, but I did find it helpful to have some idea what's going on under the hood, and understand exactly what all those adjustment grub screws on the outside housing are really doing. Also the importance of bearing tension.

glend (Glen) · #18 28-09-2015, 09:53 AM

Finished everything last night. The RA worm adjustment gave me the most issues and I had to pull it out again to adjust the Worm Belt sprocket further inward on the shaft. With the RA it would help alot if there was a window or a couple of holes in the RA housing and the RA Worm housing so that you could actually see the alignment of the belt in relation to the motor sprocket and the RA worm sprocket, as without that your relying on the directions from Rowan and not all of the cases seem to be the same. Certainly mine needed some machining. I am really tempted to drill holes in the RA Case and RA Worm case so that I can see the belt alignment, but for now its working fine and I'll see how it goes under load.

I ran a complete 360 degree cycle on both DEC and RA and tuned it for no binding or slipage. Nice and smooth now. testing with a payload tonight I hope.

RobF (Rob) · #19 28-09-2015, 12:49 PM

Will be interest to hear if you think you've got better PE or backlash.

glend (Glen) · #20 02-10-2015, 09:28 AM

Did a first light test on the new belt drive NEQ6 last night and boy what a difference it makes. I had the RC08 setup on the mount along with my heavy cooled DSLR, guidescope etc. Did initial guide calibration on a star near Sculptor at about 40+ degrees in the east and once guiding was surprised at how flat the X/Y graph (in Metaguide) was now. I suspect that my mount previously had alot of slop in the gearing and the graphs used to show overcorrection. The load was balanced exactly the same as previous gear drive sessions. I had not changed any software setup on the mount. Ran a series of 8 minute 25 second test subs on Sculptor (a duration just not possible previously) and the star shapes were great (no tails, trails, etc). So I'm pretty happy with the result, and at this point no further adjustment appears necessary. I need to get the 10" imaging newt on the mount in the next few days to see how that behaves but for now it seems to be money well spent.