EQ3-2 DEC axis direct drive mod.....

[JamesF]

Stan,

I've taken the gearbox off the stepper motor for the DEC drive on my own EQ3-2, but it's far from clear to me how to separate the two halves of the gearbox to get at the actual gears. Do they just pull apart?

My gearbox has five sets of gears connecting the stepper motor output to the DEC drive shaft most of which are brass. There's one plastic gear that is driven by the stepper motor output gear. All are covered in black "grease". Does that sound the same as yours, or do you have a simpler arrangement of gears?

Thanks,

James

[stan26]

Stan,

I've taken the gearbox off the stepper motor for the DEC drive on my own EQ3-2, but it's far from clear to me how to separate the two halves of the gearbox to get at the actual gears. Do they just pull apart?

My gearbox has five sets of gears connecting the stepper motor output to the DEC drive shaft most of which are brass. There's one plastic gear that is driven by the stepper motor output gear. All are covered in black "grease". Does that sound the same as yours, or do you have a simpler arrangement of gears?

Thanks,

James

James, I never took the gearbox apart, just removed it from the motor unit as you have done. I think you would have to knock the pins through to get it apart but I wouldn't advise that in case you damage it. I used motor industry brake cleaner to remove the old grease stuff. This then allowed me to check all the little cogs for play. You will never get rid of all the backlash in there, we're talking tolerances on a miniature scale here. I did notice a fair bit of play on the last gear (output shaft cog) on mine. For this I simply used superglue applied through a fine tip nozzle to get down in there to where the shaft goes through the gear. If you look carefully and turn the silver output shaft back and forward you will probably see the slop in there. If I was you I would put a SMALL dab of superglue on the tip of a nail (as in hardware nail) and use that to get down into it. No need to take the thing apart. I then finished by putting a good chuck of clear lithium grease in there and turning the gears to work it around, then put it all back together.....

HTH

Stan:)

[Rob L]

No worries Rob, What problems are you having I may be able to help..? (guiding related that is, not other personal problems:D)

Stan

Don't worry Stan I've got netmums for all my personal issues

I built Sam's simple gpusb to control the eq3 hand controller which was very easy to do and works just fine.

I think the issues I'm having are down to backlash/slop in the gears. The mount tracks fine, but as soon as I use the control buttons either directly or via PHD controlling, things start to go wrong.

I'll strip down, degrease and try and eliminate as much of the backlash as possible and see if that improves things.

The 9x50 finderscope combined with SPC900nc seems good and PHD hasn't had any trouble finding guide stars.

Rob

[JamesF]

I've disassembled the DEC drive again this evening and separated the gearbox from the stepper motor once more.

The first spindle (driven by the stepper motor) carries a pair of plastic gears. All the other gears, including the one driving the output shaft, are brass. For the benefit of those who haven't done this, the gearbox contains five spindles with two gears on each except the final output shaft (which only needs one). Each spindle is driven by one gear and driving the next with the other.

If I hold the "output" gear of the spindle carrying the plastic gears fixed, then there's "some" play through the gearbox when I attempt to turn the gearbox output shaft, but I can't see there's anything I can do about that.

When I held the second spindle in place and moved the driven plastic gear (the one the stepper motor drives) with a screwdriver, I could move that gear about half a tooth, but I couldn't see if the spindle was moving as well. I took a tiny bit of the goopy black lubricant and marked half of the end of the spindle with it and then repeated the test. I couldn't see any movement whatsoever in the spindle, so it seems the plastic wheels may well be slightly loose on the spindle.

I don't have any IPA yet (soon) for cleaning the grease off. Once I've cleaned the gears I'll repeat the test under a magnifying glass just to make sure, and see if I can find some way to apply a little superglue to the plastic wheels and spindle. Stan's method sounds good, but at the moment the lubricant is preventing me from seeing what's really going on.

James

[Quatermass]

It will be worth it when your done James and with the weather so cold doing that is good project

Sent from my GT-S5670 using Tapatalk

[JamesF]

Well, today I've done my own direct drive mod on my EQ3-2. I'll write it up and post some pictures later.

[stan26]

look forward to it James, get it up on here. It think all these tweaks transform the EQ3-2 into a very capable short FL imaging platform!

stan

[JamesF]

It's done:

http://stargazerslounge.com/diy-astronomer/174649-my-eq3-2-dec-axis-direct-drive-mod.html

James