Help with refurbishing Edscorp Motor Drive
Posted 27 March 2009 - 02:33 PM
When I got it, the mount motor drive was completely locked up. I have since taken it completely apart and re-greased it.
Everything now moves very smoothly, but the mount does not engage and track. So - now I need to know how this drive works.
1. The motor works. The assembly below works - you can see the worm-drive shaft rotate.
Posted 27 March 2009 - 02:37 PM
There are two thin nuts which screw onto the black threaded rods in the picture (those aren't pictured here).
Here you can see a picture of the assembled motor drive. I'll include a few pictures from several different angles.
Posted 27 March 2009 - 02:45 PM
Posted 27 March 2009 - 02:47 PM
By unscrewing this, the end assembly can be removed. I am assuming that this might serve as some type of clutch mechanism, pushing against the drive gear. Here is a pic of the end pieces.
Posted 27 March 2009 - 02:50 PM
The gear is not threaded - it slides up the threaded shaft to the smooth portion of the smaller shaft, pressing against the larger part of the shaft.
Posted 27 March 2009 - 02:50 PM
but the shaft is not your clutch is slipping.
on my meade you tighten the screws on the end
until you can still turn mount by hand but the motor will grab enough to turn the shaft.
did you have nuts on those bolts on the end of your shaft.
if so try putting them back on and do some adjusting
and try again.
i put a mark in the gear so you can tell its turning.
hope this helps and i am sure someone here knows
more about this mount than me.
Posted 27 March 2009 - 02:52 PM
Posted 27 March 2009 - 02:57 PM
Posted 27 March 2009 - 03:09 PM
Just unlock the RA shaft knob and see if it rotates freely with the drive motor in place.
Then replace your ring gear and check to see that it is not pressing up against the drive motor housing...if it is this will bind the ring gear against the drive motor housing not allowing the shaft to turn when the gear is engaging the clutch.
There needs to be adequate clearnace for the ring gear to press against the RA shaft, but freely spin. It is the clutch.. and the clutch plate applies pressure against it and it, against the RA shaft. Once there is adequate contact the drive motor will turn the ring gear and subsequently the RA shaft. If the ring gear is contacting the drive motor housing...you'll bind.
Check it out.
Posted 27 March 2009 - 04:21 PM
So I took everything apart all they way up to the top bracket (which - by the way, has a small ball bearing on top of it that I had to put the mount upside down to re-install correctly). Everything turns very smoothly now.
I didn't know what should be tight, and what should move.
I did have the leather washer, and it is on the piece of the clutch that pushes against the gear. I took it off and wiped it down, and put it back in.
I believe the clutch was slipping for multiple reasons outlined above:
1. I didn't have the lock nut on the shaft
2. The two small black threaded rods actually thread all the way through the first of the three clutch pieces, I tightened them down against the knob behind.
3. I found a nut that fit the center bolt, and tightened down the clutch assembly, then tightened down the nut a bit.
4. I made sure that the fine adjustment knob was tight against the shaft.
I drew a line on the clutch gear, and lined it up with one of the screws on the worm gear. After several minutes, you could clearly see that the gear has turned.
The gear turned, but the shaft and scope did not turn. I have tightened things down a bit, and will try again.
Now running - Test 2:
I lined up the shaft so I could see one of the mounting bolts through a hole in the motor cover, and aligned the digital setting circles at 0.0
I'll let it run for 15 minutes and then see if there is a change in shaft position.
Posted 27 March 2009 - 05:56 PM
Posted 27 March 2009 - 06:13 PM
Yours has a disk or wheel on the end of it - right? So how much do you tighten it down when you engage the clutch?
Posted 27 March 2009 - 08:09 PM
Posted 27 March 2009 - 08:57 PM
Posted 28 March 2009 - 11:44 AM
I am looking at my drive which is the same as yours and it is mounted to a 1.5" stub on the casting with set screws, on the smaller Edmund mount.
If I tried to put this drive on my large Edmund mount the 1.5" shaft is where the casting stub would be and the whole drive assy. would be mounted and rotating with the shaft!
Can I see a picture of your mount with no drive, or the back of the drive casting?
Posted 28 March 2009 - 12:39 PM
A replacement motor cleared mine up.
Posted 28 March 2009 - 01:18 PM
First - I am glad you asked for these pics. I found I hadn't cleaned the bearing surfaces pictured here at the top of the shaft. The shaft floats on a teflon sleeve, as well as the teflon disk.
On my mount, there is a small gap when this is pushed back together. Don't know if it should be there or not...
Posted 28 March 2009 - 01:22 PM
At the bottom, the shaft steps down from 1.5" to 1" at the end.
You can also see two bolt holes that the first piece of the drive bolts to.
Posted 28 March 2009 - 01:31 PM
This piece has the clamp for locking the shaft down, and on the right in the picture is the end of the fine adjusting knob, which will move the mount just a bit to center an object.
This is an 8" f8 OTA, so the eyepiece is a solid 46" away from the control rod. Unfortunately for this design, my hand is only 36" away from my eye, so I haven't figured out exactly how you are supposed to use the "fine adjustment knob"
Posted 28 March 2009 - 01:35 PM
It is threaded on the other end. There is also a small ball bearing that fits into the hole on the end of the shaft. You actually have to move the mount and shaft so that it is angled up in order to re-install the ball bearing.
Posted 28 March 2009 - 01:36 PM
It has two hex screws in the flange that bolt the assembly to the shaft. So - again what does that ball bearing do exactly?
Posted 28 March 2009 - 01:43 PM
At the bottom of the assembly in the picture are two short rods. These will fit on both sides of the fine adjusting knob. The fine adjusting knob is bolted onto the mount frame, so it won't turn.
When the motor assembly slides on, the two short rogs fit on both sides of the fine adjustming knob. This locks the motor assembly down so it doesn't rotate, and puts the worm gear into the correct position to mount up to the drive gear.
Posted 28 March 2009 - 01:47 PM
There are two hex nuts (hard to see, on the right side) that hold a small mounting plate in place.
Posted 28 March 2009 - 01:49 PM
The assembly is only held in place by friction from the adjusting knob. It only locks in place when the clutch disks are screwed down.