EQ6 - Transfer gear fix

aokman · #1 11-04-2010, 01:52 AM

Hey everyone, just thought id share some experience i had with my new EQ6 over the weekend.

Got it off the forums but i wasn't really happy with the slewing noise so i thought i would poke around and see what makes it tick

So i popped out both motors. To my surprise i found both had quite a bit of backlash and 1 had excessive deflection up and down.

http://www.chipcontrol.com.au/Video/IMG_0145.MOV
http://www.chipcontrol.com.au/Video/IMG_0146.MOV

Why? For some reason they decided that O-rings would be fine for securing a transfer gear in place...the results speak for themselves with the gear flopping around, even after tightening you still cannot eliminate all of it. Also the transfer gear is not a perfect size for the shaft and does have a slight movement.

My solution to the problem was to rummage around in my spare bits and i found some washers that are a perfect fit for the holders and the shaft. They are a solid plastic bushing normally so they can handle the work but i packed them with plasguard just to play it safe.

www.chipcontrol.com.au/Video/IMG_0150.MOV

The other gearbox's transfer gear was directly rubbing on the base plate? it had a brass washer under it but it was sitting in the recessed area and never actually makes contract with the transfer gear? Solution for this was again to add a nice washer but thicker to raise the gear off the base plate.

In both cases i needed to adjust the motor gear slightly higher to mesh normally. Once the transfer gear is sorted, loosen all the screws on the motor mounting and adjust the gear mesh so there is little-no freeplay...

So far its much better, ive eliminated startup noise on 1 axis, i should have the other fixed tomorrow with some more tension adjustments.

BC · #2 11-04-2010, 07:42 AM

Hi there aokman,

Good on you for having the guts to delve deeply and show others how it is. I bought a new EQ6 Pro a year ago and have the same horrid sounds as it slews my 10" newt around. I followed a number of articles to do a strip down of the bearings and re-greased and backlash adjustment, but to be honest, it didn't have as big an impact on the noises as I wanted. I did not, however venture into the motor gearboxes. It looks like you've identified the source. I shall save these pics and give it a go when I feel brave.

Thanks,
Bruce

koputai (Jason) · #3 11-04-2010, 08:30 AM

AOK, do you think your EQ6 was that bad from the factory, or was it due to lots of use by previous owners?

If they come like that from the factory I would be amazed. My EQ6 that I bought 2nd hand here on IIS makes no grinding or chattering noises, everything sounds perfect.

Cheers,
Jason.

MuntiNZ (Daz) · #4 11-04-2010, 08:58 AM

Quote:

Originally Posted by koputai

AOK, do you think your EQ6 was that bad from the factory, or was it due to lots of use by previous owners?

If they come like that from the factory I would be amazed. My EQ6 that I bought 2nd hand here on IIS makes no grinding or chattering noises, everything sounds perfect.

Cheers,
Jason.

Yep same here mate my kiwi flatmate brought a new EQ6 pro a few months and it is sweet for a cheapo chinese thing.
No bad noises or any thing and tracks awesome.

peter_4059 (Peter) · #5 11-04-2010, 09:08 AM

aokman,

You have two generations of motors in that mount - the o-ring version is the same as my black EQ6 and the brass bush version is what they are putting in the new white EQ6 pro's.

Looks like you have done a nice job of fixing the slop. The tasco rep told me to be careful not to make the gears too tight so I've not completely eliminated the wobble in mine yet. What material did you use for the plastic bushes? I've seen some pictures on the EQ6 group where someone has installed a minature ball bearing in place of the o-rings - another elegant solution.

Peter

aokman · #6 11-04-2010, 11:51 AM

Quote:

Originally Posted by koputai

AOK, do you think your EQ6 was that bad from the factory, or was it due to lots of use by previous owners?

If they come like that from the factory I would be amazed. My EQ6 that I bought 2nd hand here on IIS makes no grinding or chattering noises, everything sounds perfect.

Cheers,
Jason.

Im unsure on that part, apparently it was untouched but i can see marks from removal. The black O-rings look factory as ive seen bits of them in other images on the net. The newer designed motor is improved but still has a little backlash. Both are equal now.

The noise is hit and miss, all the mounts are the same, some are just tigher than others and you might get the noise on day when something works loose. What stops the noise is the pressure on the transfer gear and the grub screw on the side as it actually bends the shaft to 1 side.

With the noise i think its a combination of the stepper motor and transfer gear, if i push on the motor shaft it has some movement up and down which is a sign of a cheap stepper motor and increasing preload on the gears seems to stop it also. I have other motors here in the same dimensions and shaft size that have 0 movement from japan servo, i just wish they were the same bipolar motor

No sure why the gearboxes are different, maybe they had them laying around. Also another unusual thing is 1 wiring header on the board for one of the motors is 5 pin with 1 not in use as the motors are 4 pin headers.

I would love to hear what tasco say on the issue as the noise is a very very fine line between too tight and noise, personally i can live with the noise but not the movement in the gears. With my plastic washers the takeup point where it goes tight is very small so it takes a while to get the tension right.

Not sure on the bushing material but they come from production printers in the fusing unit as shaft holders so they are rated for 200c and holding a spinning load. I would love to replace it with ball bearings actually and i do have some nice sized ones. However i might stop in at a bearing shop and see what they have... a thrust bearing with around 4.95mm ID and 12.02mm OD would do the trick

bojan · #7 11-04-2010, 02:07 PM

Perhaps you should have used ball bearings.. I would if I had this mount (mine was clasic EQ6.. so I made completely new transfer with gears and new motors, all shafts equipped with ball bearings).

aokman · #8 11-04-2010, 02:34 PM

Quote:

Originally Posted by bojan

Perhaps you should have used ball bearings.. I would if I had this mount (mine was clasic EQ6.. so I made completely new transfer with gears and new motors, all shafts equipped with ball bearings).

I am in the process of ordering bearings now

ordering brass bearings, quite pricy but the exact size i need for the older gearbox, currently trying to spec bearings for the other one due to the thicker shaft... replacing the gears and motors sounds great as i have noticed a high spot in one of the transfer gears. The motors especially need replacing with something from japan servo, hopefully i come across one in the correct wiring config

It sure would be good with some of these 0.6deg steppers i have though

Anyway aside from the bearings i think i have the backlash sorted, i had some mylar spacer sheets with a thickness of 0.05mm. I adjusted the backlash while feeding it through and its finally given me a perfect adjustment each time and the gear mesh is spot on

aokman · #9 15-04-2010, 09:48 PM

Well after seeing some of the grease on the transfer gear i decided to go deeper into the puzzle and do a rebuild. I pulled down 1 axis and the grease was horrid, lumped up and definitely not rated for the job. Washed down all the gears with a mix of detergent and 10% citrus concentrate with a toothbrush. Then i moved onto the hideous mating surfaces, i had seen pics but didn't know it got this bad. Honestly who goes to the trouble of machining the surfaces then screwing it up with brushed on paint. I would love the see the arguments at the factory

Anyway i went at the top plate with carby cleaner and it took it off with some decent rubbing. The body however had enamel over the top so i had to hit it with acetone to remove most of it then finish it up with a rub of carby cleaner

Next up is the other set of gears then i need to realign the transfer gear on the worm for the new motor gear positions (due to the bushings) dial in transfer gear and worm backlash and rebuild. Im thinking Molykote 33 medium low temp grease

bojan · #10 15-04-2010, 09:54 PM

Since you have all this dismantled, could you measure the diameter of the worm shaft where the gears are and let me know the result?
I am planning a mod with new timing pulleys and I need to know this to decide how to machine the pulleys.. Thank you in advance!

aokman · #11 15-04-2010, 09:59 PM

the transfer gear section of the worm shaft has a diameter of 11.98mm

toryglen-boy (Duncan) · #12 15-04-2010, 10:15 PM

Dude, maybe you should offer this as a service, you would make a mint !!

bojan · #13 16-04-2010, 06:12 AM

Quote:

Originally Posted by aokman

the transfer gear section of the worm shaft has a diameter of 11.98mm

Thank you mate :-)

My timing pulleys have 6mm hole, so it seems I will have to machine the shaft as well.. something I do not like much..

aokman · #14 18-04-2010, 11:37 AM

Well i finally managed to reassemble the DEC axis, was a but of a challenge getting it spot on. Overall i cleaned up all the gears and coated them with superlube. I had Lithium spray / lithium grease with 3% moly and molykote medium 33 but superlube seems like a nice compromise...

First thing was to remount the worm in the carrier bearings, basically i seated 1 bearing and locked it in place, slid the other one in and fitted a washer over the top and pressed it down with a socket tool until the worm shaft was snug with a little bit more tighness. But more importantly - 0 sideways movement then locked the bearings in place.

Next up was the worm-transfer gear, now this was a pain. The shaft is not a perfect fit for it so if you lock it down you will end up with wobble in the gear. After stuffing around with it for about 45 minutes i added a rubber compression washer and a hard alignment washer on the other side to provide even pressure across the face of the gear. While spinning it around you slowly tighten the worms down for a perfect alignment.

http://www.chipcontrol.com.au/Video/IMG_0156.MOV

http://www.chipcontrol.com.au/Video/IMG_0158.MOV

Bear in mind i had to do this while also making sure that the 2 transfer gears aligned perfectly when brought together...

Once this was done it was time for the ring gear. I fitted the plate back on and started with the top set screw. I tightened it until the drive went tight on the worm shaft then backed it off very slightly to lossen it up, i had to do this 3 times as it went hard again after a rotation but i hit the sweet spot eventually.

Finally i cut up another mylar, stuck it on the end of a probe and wedged it in between the 2 transfer gears, with this in place i brought the gears together for a perfect mesh

. I then refitted all parts and repacked the bottom bearing with moly grease and sealed it up.

Overall the results are very impressive, the axis now has 0 freeplay not even a tiny bit. There are no harmonics in the drive anymore its just a constant whine from the gears the whole way. The run up and run down noise is there still slightly by choice however as it requires too much tension in the 1st transfer gear to eliminate totally and has no effect on operation.

Next up is the other half

Shiraz (Ray) · #15 19-04-2010, 09:10 PM

Thanks for the informative posts. I have a HEQ5pro and had the same issues with the transfer gears - had to leave in a little bit of clearance resulting in slight wobble and chatter on start up and run down to get best performance. Also, mine has 2 grub screws to lock each transfer gear shaft (no thread) - suggest if pulling the gear off that the shaft be carefully deburred to remove the grub screw marks and protect the gear inner bearing surface.

aokman · #16 19-04-2010, 10:08 PM

Yup i have one of each gearbox so they were different but a little play seems to be required to keep it loose however i got rid of the freeplay up and down easily.

That said however i did the other axis last night and it was an absolute pain in the ass to put back together, the main ring gear likes to get wedged on the housing and once it sticks you have to knock it back out again and again lol...