61 replies to this topic

[Geo31]

OK, I know I may get better response in Cats and Casses (but maybe not), but I haven't been posting there in a long time and y'all know me...

 

So, my C8 took a dive.  Had it on a shelf and came into the closet one day to find it on the floor.  Quickly checked the optics and breathed a sigh of relief.  Until tonight.  Invited neighbors over to look through the C5 and C8.  Went to use my Hotech collimation tool and found the mount on the C8 is busted.  I have NO idea what is wrong at the moment, but he RA axis is cattywompus and and it flops around.  Not good.  At least the C5 is functioning fine.  Had I known before I have a Powerstar fork mount with all the remote control dodads, but I've never used it and it's buried upstairs.

 

So...

 

Does anybody know of a guide for disassembling a Byers drive C8 mount?

 

It may be terminal.  A screw fell out when I pulled it out of the bag (I have a soft case for it).

 

Poop.

[rolo]

Its been many years since I disassembled one but I think there's a 5/8" bolt on the bottom that should be removed. It should be pretty straight forward if you've done this sort of thing before.

[Geo31]

Its been many years since I disassembled one but I think there's a 5/8" bolt on the bottom that should be removed. It should be pretty straight forward if you've done this sort of thing before.

Looks like sometime this weekend I'll at least do a postmortem.  The more I think about it, the more I think it's terminal.  The bolt on the bottom is solidly in place and the fork mechanism partially pulls away from the base.  I suspect some part of the RA shaft is done busted.

 

Like I said, I have another base for a project that I will now likely marry up with the OTA.  Could be worse.

 

Autopsy pics as soon as I dig in.

[Geo31]

Okie dokie...  Couldn't wait until morning.  Turns out bolt on top is the one necessary for disassembling the base.  Once I got that off, everything was easy.

 

First pic is the first look at the damage.  I was thinking the worst.  That just isn't supposed to happen.

 

When I started fussing with the base, two machine screws fell out.  Not a good sign.  Second pic shows where they came from...  The clutch assembly.  I somehow lost one (doh), but the other went right in the hole and tightened up just fine.  I'm guessing these were loose for a LONG time.

 

The gears were assembled with what looks for all the world like automotive bearing grease.  Ick!

 

Last pic is a better pic of the damage to the RA setting circle.

 

Now the good news.  The only real damage I can find is to the RA setting circle.  That is reasonably easy to fix.  But...  I have to tear apart the clutch assembly to get to it.

 

Turns out there were more loose bolts (like on the fork arms).  So with the loose bolts, bearing grease, and God knows how the dec shafts are lubed, this thing will get a complete rebuild and be much better than it was in any time during my ownership.

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Edited by Geo31, 17 June 2017 - 12:59 AM.

[Gil V]

Excellent work, great photos. Nice post.

"Cattywompus". I'm using that.

Keep 'em coming.

Edited by Gil V, 17 June 2017 - 06:09 AM.

[Joe Cepleur]

Glad all will be okay. Perhaps the gods were smiling. Might the loose bolts have allowed enough movement in the mount for it to have absorbed the shock of the fall, protecting the optics?

[Geo31]

Glad all will be okay. Perhaps the gods were smiling. Might the loose bolts have allowed enough movement in the mount for it to have absorbed the shock of the fall, protecting the optics?

You know, that's a good point.  It's entirely possible.

[deSitter]

Okie dokie...  Couldn't wait until morning.  Turns out bolt on top is the one necessary for disassembling the base.  Once I got that off, everything was easy.

 

First pic is the first look at the damage.  I was thinking the worst.  That just isn't supposed to happen.

 

When I started fussing with the base, two machine screws fell out.  Not a good sign.  Second pic shows where they came from...  The clutch assembly.  I somehow lost one (doh), but the other went right in the hole and tightened up just fine.  I'm guessing these were loose for a LONG time.

 

The gears were assembled with what looks for all the world like automotive bearing grease.  Ick!

 

Last pic is a better pic of the damage to the RA setting circle.

 

Now the good news.  The only real damage I can find is to the RA setting circle.  That is reasonably easy to fix.  But...  I have to tear apart the clutch assembly to get to it.

 

Turns out there were more loose bolts (like on the fork arms).  So with the loose bolts, bearing grease, and God knows how the dec shafts are lubed, this thing will get a complete rebuild and be much better than it was in any time during my ownership.

How did this get so strangely bent? Is this crumple from sideways force, or bending? I suspect the former. Probably the circle was forced against something when the innards came loose. If so, there's your shock absorption.

 

-drl

Edited by deSitter, 17 June 2017 - 12:50 PM.

[Joe Cepleur]

deSitter, good eye! I bet you're right, but was it a little of each? The loose bolts allowed parts to move, so that the setting circle could absorb the blow.

[Geo31]

If you look at the first photo you can see what happened.  The RA circle jammed against the worm.  Not sure about the second bend.  Joe is right, the the bolts fell out of the clutch mechanism, allowing the forks to move, taking the RA circle with them. 

 

I bought some bolts to put this back together.  Haven't had a chance yet today, but I'm hoping to tear it down the rest of the way and check it all out.

[Joe Cepleur]

Classic telescope forensics!

[Geo31]

I was able to steal away a few minutes tonight to tear down the Super C8 a bit more.  I removed what I believe to be the clutch and pulled out the drive gear and RA shaft "housing."  I put housing in quotes because it's this part that actually rotates on a fixed shaft.

 

The first photo is of the RA shaft "housing."  You can see two witness marks where it contacted the upper plate that the forks mount to.

 

The second photo is the underside of the upper plate.  I've circled the witness marks where the RA "housing" contacted the plate.  This occurred because three of the clutch screws were loose and two fell completely out.  This allowed the upper plate to move in relation to the housing.

 

Interestingly enough, the clutch is simply metal on coated metal.  I'll post more pics as I actually get things assembled.

 

After I post this, I think I'm going to separate the drive gear from the coated plate (that actually holds the gear used for RA slow motion.  I've cleaned up what I can so far.  This final disassembly will allow me to fully clean everything, remove and repair the RA setting circle,  and relube with a much better lube (haven't decided what to use yet).

 

The last photo is of the RA locking mechanism from inside the housing.  The whole thing locks with half a turn what looks to be a 1/4-20 thread.  IOW, just 1/40" from free turning to lock (if my tired monkey brain did the math right).

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[Geo31]

Finished the disassembly, mainly because I could squeeze in a few more minutes to do so and who knows when I'd get to it next.  No more pics tonight, but I'll try to take really good pics of how each piece goes together.

 

It's a pretty exquisite mount, and the machining of the pieces quite good.  The drive gear took some doing to get it off the hub.

 

I believe the grease is from the factory.  I doubt anybody else tore this thing down this far in the past.  I need to decide what grease/lube I'm going to use on reassembly.  I'm thinking seriously of using anti-sieze.  The stuff is pretty slick and shouldn't gum up like old grease.  Still not sure though.

 

Given how many bolts were loose on this thing, I'm expecting when I get done for it to perform better than ever and be much much more stable.  I'm hoping so.

 

Next up (next time I get to this) is pics of the damage to the RA SC and after fixing.  Not sure how I'm going to flatten it just yet, but I suspect clamps and wood will be involved.

[NMBob]

When you put it back together put the knob on the RA slow motion spur gear (your third picture) before you put the body pieces back together. It's hard to get that gear pulled up (out of the body) while you are pushing down trying to put the knob on, and if the gear is in all of the way (like it would end up if you put the body back together and then tried to put the knob on) it will sit on top of the main gear(? can't remember which part) and make a grinding dragging scratching noise when you release the clutch and move the mount by hand. Not that I've had that happen more than once.

 

I use regular SuperLube. It seems to work fine. None of these parts are spinning at 1000 RPM. You mainly just need to have something that doesn't turn to ice or melt. There are monumental threads on the subject.

[deSitter]

That's a nice looking casting, like a motorcycle part, which I guess is what saved it from shattering. You can of course sand down those dings on the RA thing if they threaten to touch those ribs.

 

-drl

[Geo31]

I don't think there will be any risk of contact, but I'll of course check that carefully.

 

I must say I'm really pleased with the quality that went into this.  It's not a Questar and not machined from billet, but it's well designed and as I said, the machining is excellent.  I'm looking forward to putting it back together with extra care.  I like what I see from Super Lube, so I'll try to get some at lunch time.  I may pick up some removable thread lock as well, given how many bolts came loose.

[Brian Risley]

Interesting.  Nice pics of the internals. They used the same RA lock as they used on the spur gear setup.  (The early OT's had a metal plate instead of the nylon you see and that would develop a dimple that cut down on the area that contacted the flat gear side.)  This is why you should never force the RA lock lever beyond the point that it grips good.

[Geo31]

OK, a little update tonight.  I tackled what I think will be the hardest part of this repair and rebuild...

 

I flattened the RA setting circle.

 

In the first pic you can see the RA circle on my messy workbench and see out bent up it is.  What you cannot see in that pic is how bent the RA circle is on the ID.  It was turned up quite a bit and had me concerned.

 

The second pic is my flattening jib.  Pretty basic.  Two piece of maple, judiciously placed, and a common pipe clamp.  I probably clamped it down in about 10 (give or take) positions, moving it as necessary to flatten whatever wasn't right.  Truly the first couple of clampings had it at about 90%+ flat.  The rest was tweaking.  Finally, I used a rubber mallet in a few spots to fine tune the flattening.  Worked bloody well I'd say.

 

The last two pics are of the flattened RA circle.  The first you can see about 1.5 hours either side of the post, the witness marks from hitting the worm.  Compare that with the first pic.  The last pic is from the other side so you can see just how flat it really is.  The ID came good too.

 

It's not perfect, but it's actually better than I expected.  I'm VERY pleased.

 

I wasn't able to get the Super Lube this week despite 3 attempts.  I have a couple of places to try tomorrow.  Once I have that, I will begin reassembly, assuming other responsibilities (don't ya just hate that) take priority.  I was supposed to have a nice, relaxed 3 day weekend with a day of driving through the woods on Monday.  Instead, my project that keeps finding ways to go off the tracks found yet another today, the day we were supposed to wrap it.  Don't know if I'll get to this or not.  It may turn out to be cheaper and more effective than therapy.... 

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[Geo31]

Oh, BTW, the reason the SC doesn't lay completely flat is the posts extend slightly through the SC.

[deSitter]

OK, a little update tonight.  I tackled what I think will be the hardest part of this repair and rebuild...

 

I flattened the RA setting circle.

 

In the first pic you can see the RA circle on my messy workbench and see out bent up it is.  What you cannot see in that pic is how bent the RA circle is on the ID.  It was turned up quite a bit and had me concerned.

 

The second pic is my flattening jib.  Pretty basic.  Two piece of maple, judiciously placed, and a common pipe clamp.  I probably clamped it down in about 10 (give or take) positions, moving it as necessary to flatten whatever wasn't right.  Truly the first couple of clampings had it at about 90%+ flat.  The rest was tweaking.  Finally, I used a rubber mallet in a few spots to fine tune the flattening.  Worked bloody well I'd say.

 

The last two pics are of the flattened RA circle.  The first you can see about 1.5 hours either side of the post, the witness marks from hitting the worm.  Compare that with the first pic.  The last pic is from the other side so you can see just how flat it really is.  The ID came good too.

 

It's not perfect, but it's actually better than I expected.  I'm VERY pleased.

 

I wasn't able to get the Super Lube this week despite 3 attempts.  I have a couple of places to try tomorrow.  Once I have that, I will begin reassembly, assuming other responsibilities (don't ya just hate that) take priority.  I was supposed to have a nice, relaxed 3 day weekend with a day of driving through the woods on Monday.  Instead, my project that keeps finding ways to go off the tracks found yet another today, the day we were supposed to wrap it.  Don't know if I'll get to this or not.  It may turn out to be cheaper and more effective than therapy.... 

Nice!!

 

-drl

[TOM KIEHL]

Super Lube >>>>>>>>>>>>>>>>>>>>>>>> Harbor Fright  

                                                                                      ^e

 

Edited by TOM KIEHL, 23 June 2017 - 11:10 PM.

[NMBob]

Nice job! You'll know if it's flat enough when you start putting it back together. The only hard part will be keeping that big C spring in place until you can get a screw or two started.

 

There's a Harbor Fright in Conroe. Fright...Haha.

[Geo31]

Super Lube >>>>>>>>>>>>>>>>>>>>>>>> Harbor Fright  

                                                                                      ^e

 

 

Nice job! You'll know if it's flat enough when you start putting it back together. The only hard part will be keeping that big C spring in place until you can get a screw or two started.

 

There's a Harbor Fright in Conroe. Fright...Haha.

Hehe.  Yep, that's where I plan to go tomorrow.  They just opened about a month ago.

 

Question:  The C-spring goes under or over the SC?  It's the only thing that caught me by surprise taking it apart.  My thought was under.

[NMBob]

I didn't take enough pictures. Yup. If the mount was all together sitting on a table it goes below the dial with the RA numbers (that you flattened). It's there just to put friction against that RA dial so it doesn't spin freely. A little grease on the spring helps glue it in place while you are working.

 

Get the non-lithium grease. The tube I have is grey. I think the lithium stuff is in a white tube?

[Geo31]

I didn't take enough pictures. Yup. If the mount was all together sitting on a table it goes below the dial with the RA numbers (that you flattened). It's there just to put friction against that RA dial so it doesn't spin freely. A little grease on the spring helps glue it in place while you are working.

 

Get the non-lithium grease. The tube I have is grey. I think the lithium stuff is in a white tube?

Thanks Bob, that's exactly what I thought.

 

I'll get some grease and some removable thread lock today and should be good to reassemble.