Leveling the mount isn¡¯t really critical. Then get the RA axis pointed at the north celestial pole by using the altitude and azimuth adjustments, regardless of what method you¡¯re using for the alignment (polar scope, drift alignment, rough eyeballing, etc.). Remember, the goal is to align with the north pole, which is about 1 degree away from Polaris. As long as the RA axis is aligned with the NCP, it doesn¡¯t matter how level or not level the mount is. Leveling can help speed up some alignment methods, but if you¡¯re visually aligning ¡ª with a polar scope or the main scope or just looking through the polar scope hole ¡ª leveling is completely unimportant.
-Les
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On 14 Oct 2017, at 6:54, f4chief73@... [Losmandy_users] <Losmandy_users@...> wrote:
Finally had a clear night here in the Florida panhandle so I took the scope out and set it up here in the apartment perimeter on an asphalt road...Think I made a boo-boo during my setup...
First thing I did was point the scope due north towards Polaris. Then I leveled the scope both directions perfectly. Then after leveling I noticed Polaris was too low while looking thru the RA hole. So I tried to realign Polaris by adjusting the mount height again. (1st Mistake) I realized this after I got back home and thought about it. I should have adjusted the altitude knob on the mount. This knocked out my accuracy. (Book also says, never use the Dec and RA knobs to do Polar alignment)
When I went to an object it was about 1 degree off, or just out of the field of view depending on which Eye piece I was using. At this point I should have started over and releveled the mount. Now I know. I put in a 34 degree eyepiece, then went to M31. I was surprised to find it in there.! ! I was pretty tired last night from a very busy mental day I had. So I probably wasn't thinking too good. I will do this again, and this time once I level the mount, I will not touch it again...
Now, after all this explaining, my question, does it sound reasonable that what I did is what messed up the accuracy of my scope wjhile going to different objects? I think so...This BTW is my first EQ mount. I used Dobs before only...
I also just printed out about 15 pages of instructions off the Losmandy web site on the set-up of this mount.
Thanks,
Rodney
|
Yes.? Rodney, when you say RA hole, does your mount have a Polar Alignment Scope (w/ reticle) in the hole? If not, your attempts will be very crude at best. And, you are correct, next time use the? Alt and Az knobs.
As an extra tip, I have always used a small voice recorder in the field to note things (half of which I would forget had I not recorded -ha!) like next time do this or bring that. I also made my own setup checklists -something about typing it in my own words makes it stick in my head better
Hope your good weather holds out?
Jeff
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Re: Mount Clutch Tensions
Yes Brendan, Al on Al will gall quickly given half a chance (even if it's hard anodized). I also recall burnishing the threads and deburing the thread holes on the ID when I got a set of knobed knobs (CKS). That was another example of less than ideal workmanship, but it's ok, I live to wrench! And I am lucky, working in aerospace most of my life I have access to lots of fun lubricants and such
There is definitely a lot of feel and awareness involved it clutch tightening
|
Finally had a clear night here in the Florida panhandle so I took the scope out and set it up here in the apartment perimeter on an asphalt road...Think I made a boo-boo during my setup... First thing I did was point the scope due north towards Polaris. Then I leveled the scope both directions perfectly. Then after leveling I noticed Polaris was too low while looking thru the RA hole. So I tried to realign Polaris by adjusting the mount height again. (1st Mistake) I realized this after I got back home and thought about it. I should have adjusted the altitude knob on the mount. This knocked out my accuracy. (Book also says, never use the Dec and RA knobs to do Polar alignment) When I went to an object it was about 1 degree off, or just out of the field of view depending on which Eye piece I was using. At this point I should have started over and releveled the mount. Now I know. I put in a 34 degree eyepiece, then went to M31. I was surprised to find it in there.! I was pretty tired last night from a very busy mental day I had. So I probably wasn't thinking too good. I will do this again, and this time once I level the mount, I will not touch it again... Now, after all this explaining, my question, does it sound reasonable that what I did is what messed up the accuracy of my scope wjhile going to different objects? I think so...This BTW is my first EQ mount. I used Dobs before only... I also just printed out about 15 pages of instructions off the Losmandy web site on the set-up of this mount. Thanks, Rodney
|
Re: Mount Clutch Tensions
The orthogonality of axes and parallelism of clutch surfaces . ( Michael Siniscalchi?
).
My guess the clutch has a purposes there must be some tension but not to much to stop slip if axes clash...as I have done more than once. Oh I don't have a CKS knobs...but I noticed my std knobs galling between the different surfaces.? This made it really difficult to adj clutch tension, some zinc anti size fixed this.
FWIW
Brendan
|
Re: New G11 / Gemini 2 user with issues..
Say what?? Did I miss something
somewhere??
?
Derek
?
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From: Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Friday, October 13, 2017
3:48 PM
To: Losmandy_users@...
Subject: [Losmandy_users] Re: New
G11 / Gemini 2 user with issues..
?
?
Derek,
I meant the original hardware that was used to attach the gearboxes and
servomotors to each other and to the plate on the mount itself. Sorry for the
confusion.
|
Re: Mount Clutch Tensions
I'm getting the feeling (maybe a little late- hehe) that there are a whole lot of Losmandy mounts with potential axis to thrust bearing face alignment issues. (meaning thrust bearing face to axis squareness)?
Obviously grease covered clutches account for many of the reported slippage vs tightening problems reported but, having my GM-8 apart and seeing my RA axis with >.003" out of parallel remaining (across <2" Dia, despite some serious mallet action and the best efforts of a #3 arbor press - no gaps ever detectable) I can only guess that is the machining consistency we get at this price point. (Grrrr) The fact that I have also encountered metal on metal contact adjacent to the altitude scale which explained why the Alt knob was so hard to turn when I traveled north for totality also reinforces this conclusion.
FWIW? ? -Jeff
|
Re: Mount Clutch Tensions
With that I agree Chip, and I may look into a set of those pads just out of curiosity as my own out of square issue persists despite my best efforts.?
Jeff
|
Re: Mount Clutch Tensions
I think we are all under too much pressure!
We must stop beating ourselves up... there is certainly a design issue with the plastic clutch disks.? They slip for a variety of reasons:? ??
? ?1. the plastic is slippery or worse, has an oily surface (plastics have an oily plasticizer anyway, but oils from the bearings creep up too)
? ?2. the clutch metal faces may not be flat or if flat, not parallel.? ? ? ? ? ?It is an open question as to whether torquing down too hard on the clutch knobs can distort the aluminum plates.??
? ?3. the clutch knob has a coarse thread.? It takes more torque to get a hard grip on the (plastic) clutch disk.
? ?4. some people report the clutch knob cannot get to "bottom" and even Mark Crossley says he had to put on two plastic spacers? ? ? ? ? (see his site:? ? ? ? ) ? ? ? ?this means there are or were at one time clearly some mechanical aspects that were not held in spec.? A few washers of the right size and voila... perfect.??
? ?5. some people overload their G11, like me... and still expect miraculous performance....and we still get it.? Company7 wrote that the G11 holds C14s fine...maybe not for AP...
? ?6. wonder why these sell for $125 if they are not needed?? ?
If you look at Mark Crossley's site, , he notes that the clutch disks he uses are cardboard.? He mentions that many other owners use strap wrenches to tighten down the clutches for AP work.? I was once one of those folks.? ?I am settled on a better material now and think this is it.? Now if my skies would only stay clear and I could get back home to play...
All the best and happy imaging...!
- Michael
On Fri, Oct 13, 2017 at 3:38 PM, chiplouie@... [Losmandy_users] <Losmandy_users@...> wrote:
?
Hi Jeff,
Well we can't help it if people don't know what "tight enough" means. For those people Michael Herman has some trick clutch pads which are much grippier than the slick hard plastic discs used by Losmandy. I think he sells them for a bit more than the Losmandy clutch discs but this material will do the trick.?
I know there have been some G11 and GM8 mounts which people cannot lock their slip-clutch on no matter how much they torque the clutch knobs down. I suspect there is another issue which nobody has addressed which is unique to a slip-clutch mount. The clutch surfaces must be nearly perfectly perpendicular to the RA or DEC axis and parallel to one another for the hard plastic clutch discs to clamp effectively. The more surface you have for a given friction coefficient clutch disc material the higher the grip and better the lock up. If the plates are not parallel the surface area is significantly reduced and the working clutch surface area will become too small to hold the load. If there is no mechanical interference limiting free movement of the clutch plates and the clutch does not hold with a reasonable amount of torque on the clutch knobs the only possible problem can be the clutch plates are not parallel enough to allow the clutch pad material for supply enough friction for lock up. It doesn't take much for this to become an issue given that the clutch disc material is a hard plastic material and Michael Herman's solution is two fold, the clutch disc material has a higher friction coefficient and the material is slightly more compressible. This material solves the friction issue by having more friction and addresses the lack of perfectly parallel surfaces with the compressibility of the disc material. The combined characteristics of this material should resolve these issues without having to resort to sending the mount to Losmandy for resurfacing. Of course at some point if the clutch plates are out of spec excessively even an large increase in friction coefficient will not allow the clutches to lock up fully.?
Chip?
|
Hi Tom,
They are out there if you look on some of the European sites and there are several US web pages with these issues too but usually they are resolved by returning the worm to Ovision and getting a replacement. Some continued to have issues and ultimately returned them for refund and later corrected the problem with a Losmandy OPW and HP worm. This was all a few years ago now but there definitely have been some issues with the Ovision worms that were confirmed by replacement with Ovision or Losmandy worms.
Chip?
|
Re: New G11 / Gemini 2 user with issues..
Derek,
I meant the original hardware that was used to attach the gearboxes and servomotors to each other and to the plate on the mount itself. Sorry for the confusion.
Chip ?
|
Re: GM8 Saddle with bent bolt
Hi Tony,
That top contraption is not a Losmandy part, remove it by loosening the large silver knob under the wacko bolt and knob. If the resulting saddle is 3" wide then you should buy a used or new saddle for your GM8 that has the Losmandy "D" and the smaller Vixen style saddle clamps. The current GM8 saddle is designed to accept both Losmandy and Vixen dovetails correctly, it looks like this:??
 ?
This part is only $55 plus shipping so not too bad and is the right way to solve the problem.?
Cheers/Chip
|
Re: Mount Clutch Tensions
Hi Jeff,
Well we can't help it if people don't know what "tight enough" means. For those people Michael Herman has some trick clutch pads which are much grippier than the slick hard plastic discs used by Losmandy. I think he sells them for a bit more than the Losmandy clutch discs but this material will do the trick.?
I know there have been some G11 and GM8 mounts which people cannot lock their slip-clutch on no matter how much they torque the clutch knobs down. I suspect there is another issue which nobody has addressed which is unique to a slip-clutch mount. The clutch surfaces must be nearly perfectly perpendicular to the RA or DEC axis and parallel to one another for the hard plastic clutch discs to clamp effectively. The more surface you have for a given friction coefficient clutch disc material the higher the grip and better the lock up. If the plates are not parallel the surface area is significantly reduced and the working clutch surface area will become too small to hold the load. If there is no mechanical interference limiting free movement of the clutch plates and the clutch does not hold with a reasonable amount of torque on the clutch knobs the only possible problem can be the clutch plates are not parallel enough to allow the clutch pad material for supply enough friction for lock up. It doesn't take much for this to become an issue given that the clutch disc material is a hard plastic material and Michael Herman's solution is two fold, the clutch disc material has a higher friction coefficient and the material is slightly more compressible. This material solves the friction issue by having more friction and addresses the lack of perfectly parallel surfaces with the compressibility of the disc material. The combined characteristics of this material should resolve these issues without having to resort to sending the mount to Losmandy for resurfacing. Of course at some point if the clutch plates are out of spec excessively even an large increase in friction coefficient will not allow the clutches to lock up fully.?
Chip?
|
GM8 Saddle with bent bolt
Hello everyone,?
I just bought a GM8 used off of craigslist and it's a fantastic mount. I'm excited to be part of the losmandy owner's club!?
I do have one issue, I noticed that the saddle has the losmandy plate on the bottom and the vixen style on top. Is this the standard for mounts produced in the early 2000's? The reason I'm asking is the top tensioning screw for the vixen saddle is bent and I can only get it tight enough to hold my scope if I use a wrench. I'm hoping I don't have to buy a new saddle, and only replace the screw, but I don't see anywhere online where I can buy a bolt that has a screw hole in the end to fix the angled clamp to it.
Any advise on how to replace this bolt?
-Tony
|
Re: Mount Clutch Tensions
" the fact remains that you can easily turn the RA or DEC axles with the clutches fully locked up"
And you can keep twisting the knobs far past that point Chip. That's my whole point.
People speak of using tools on the knob. I have read it here and seen them grossly over tighten in the field myself. Over tightening is what I was addressing.
Jeff
|
Re: Mount Clutch Tensions
Jeff,
My comment was with the clutch loose, the lower bearing carries zero load. once you start to apply clutch pressure the lower thrust bearing starts to carry some of the load. As clutch pressure is increased the load on both bearings is increased until you reach the point where both bearings are each carrying about 1/2 of the total on axis load. That point is where can be no additional movement on the thrust axis, no more compression of the clutch material can be made and all bearing surfaces are in full contact, this not a small load in terms of PSI but the axle will still turn freely. You can disagree all you want to, the fact remains that you can easily turn the RA or DEC axles with the clutches fully locked up. Try it or alternately, as mentioned previously monitor the Gemini's power and encoder feedback from the servomotors.?
Yes but 50 in/lb is much less than is needed to lock up the clutches fully. The average adult barehanded can achieve approximately 7-13 ft/lb of torque and the winged clutch knobs increases this at least double, possibly three times.. Here is a quick bearing force calculator you can use. ? have fun.
Chip ??
|
Re: Losmandy pickup? Re: New G11 / Gemini 2 user with issues..
Derek,
Nice to read you already put in a Losmandy order...but wish Chip to do a pickup if possible.? I plan to stop at his place tomorrow evening.? ?
Chip planned to go there tomorrow.? He was going to buy a new gearbox (I told him I'd pay for that, thinking you needed one).??
please call Chip at: 626-823-4546
and I'll copy him on this email too.??
Very best, Michael?
?
Hey there Mike..
?
If you are able to swing by Losmandy
before you return, let me know! That would be fantastic!!! I will send you a
shopping list, as I ¡®placed an order¡¯ a week ago, but heard nothing
from Losmandy.. I then found the Losmandy ¡®store¡¯ website and
almost everything is shown as out of stock..
?
Derek
?
?
?
?
Great thinking, Chip.
Derek... let me know if you want that... sounds like a reasonable thing
to pick up and save the $$$ from the shipping.
Question: is there more than one gearbox model to choose
from???
?
On Thu, Oct 12, 2017 at 11:37 AM, chiplouie@...
[Losmandy_users] <Losmandy_users@...m> wrote:
?
Hi Derek,
Hmm, Michael is here or going to be here in L.A., you could ask
Michael to bring you back a new gearbox from Losmandy when he returns next
week, gearboxes are only $35 and this would likely fully resolve the issue. As
far as learning to use the Gemini there is not all that much to figure out once
you get all the data entered correctly into the system. The hardest part is to
get it polar aligned, I forgot, did you get a polar scope? If you have a polar
scope after you verify or align it all you need to do for visual use is point
the mount at Polaris using the polar scope crosshairs. I would not worry about
really getting it perfect as for visual work that is close enough. For imaging
work PoleMaster alignment saves you so much dark sky time? IMO it is the
only way to go in my experience. Then a quick mount alignment using a few
bright stars and you are GTG.?
I had/have similar DEC axis balance with the ES
ED127mm APO I had even with the heavy 2.5" Moonlite focuser hung off the
back. The two solutions I found worked well and will also work for you. First
and easiest is to buy a longer Losmandy dovetail plate so you can attach the
scope rings closer to the focuser end of the dovetail so you have enough meat
to slide the dovetail down in the saddle to achieve proper balance on the DEC
axis. I used a Losmandy DUP14 but you may need to use a DUP19 because you don't
have the heavy 2.5" Moonlite focuser and stepper motor on your optical
tube. The other option is to add weight to the back end of the scope, I used an
ADM counterweight kit for an SCT which worked wonders and allowed me to move
the scope much more forward in the saddle and much improved the clearance
between my camera and tripod legs!?
--
|
Re: New G11 / Gemini 2 user with issues..
I will have to look, but I am pretty
sure I do not have the ¡®old hardware¡¯.. My Mount is not very old..
?
I will check into tomorrow and work it
out with Michael via offline emails..
?
Thanks for the Great Idea!
?
Derek
?
From:
Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Thursday, October 12, 2017
3:42 PM
To: Losmandy_users@...
Subject: [Losmandy_users] Re: New
G11 / Gemini 2 user with issues..
?
?
Hi
Michael & Derek,
There is only one gearbox offered and it is an improved version of the
same thing but with a heavier metal base and metal rivets holding the assembly
together. The old hardware will work just fine, bring $35 and you are
GTG.?
|
Re: New G11 / Gemini 2 user with issues..
Hey there Mike..
?
If you are able to swing by Losmandy
before you return, let me know! That would be fantastic!!! I will send you a
shopping list, as I ¡®placed an order¡¯ a week ago, but heard nothing
from Losmandy.. I then found the Losmandy ¡®store¡¯ website and
almost everything is shown as out of stock..
?
Derek
?
?
From:
Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Thursday, October 12, 2017
11:41 AM
To: Losmandy_users@...
Subject: Re: [Losmandy_users] Re:
New G11 / Gemini 2 user with issues..
?
?
Great thinking, Chip.
Derek... let me know if you want that... sounds like a reasonable thing
to pick up and save the $$$ from the shipping.
Question: is there more than one gearbox model to choose
from???
Or ... call me at 408 421-1239!
toggle quoted message
Show quoted text
On Thu, Oct 12, 2017 at 11:37 AM, chiplouie@...
[Losmandy_users] <Losmandy_users@...> wrote:
?
Hi Derek,
Hmm, Michael is here or going to be here in L.A., you could ask
Michael to bring you back a new gearbox from Losmandy when he returns next
week, gearboxes are only $35 and this would likely fully resolve the issue. As
far as learning to use the Gemini there is not all that much to figure out once
you get all the data entered correctly into the system. The hardest part is to
get it polar aligned, I forgot, did you get a polar scope? If you have a polar
scope after you verify or align it all you need to do for visual use is point
the mount at Polaris using the polar scope crosshairs. I would not worry about
really getting it perfect as for visual work that is close enough. For imaging
work PoleMaster alignment saves you so much dark sky time? IMO it is the
only way to go in my experience. Then a quick mount alignment using a few
bright stars and you are GTG.?
I had/have similar DEC axis balance with the ES
ED127mm APO I had even with the heavy 2.5" Moonlite focuser hung off the
back. The two solutions I found worked well and will also work for you. First
and easiest is to buy a longer Losmandy dovetail plate so you can attach the
scope rings closer to the focuser end of the dovetail so you have enough meat
to slide the dovetail down in the saddle to achieve proper balance on the DEC
axis. I used a Losmandy DUP14 but you may need to use a DUP19 because you don't
have the heavy 2.5" Moonlite focuser and stepper motor on your optical
tube. The other option is to add weight to the back end of the scope, I used an
ADM counterweight kit for an SCT which worked wonders and allowed me to move
the scope much more forward in the saddle and much improved the clearance
between my camera and tripod legs!?
--
|
Re: Mount Clutch Tensions
Hey Chip, regarding your first comment... ?"The thing is there are two thrust bearings and as you increase the total load the lower thrust bearing reduces the load on the upper bearing."?
Huh? My logic suggests load applied to a nut at one end would be evenly distributed between the two thrust washers that are being loaded together. As for the loads being within the capacity of the motors and drive train, I am not arguing that, But, not having the calculator out either, I'm gonna assume that 50 in lbs is easily done by hand on a 1 1/4 inch well lubricated nut and I'm gonna also guess that puts a couple hundred pounds load on Mr. and Mrs, thrust bearing. Within its capacity? Absolutely. Does it add drag? As I said only a couple hundred percent increase. Does it hinder smoothness? You better believe it does. Big time. I have one apart on my bench right now, (with perfect, very low hour bearings) ?I have personally?applied 10,000 + pound loads to the same bearings (in larger sizes) in structural testing applications (it's what I do) and know just how the feel changes as load is slowly applied. BTW, these bearings were well within? their advertised limits and lived to see another day but at? max load, it tool probably a 200?Ft. Lbs. to turn the loading nut ! That's what bearings do, they reduce friction, they do not eliminate it ! Remember, we are dealing with two wimpy little bearings with stamped steel races, not sweet high end tapered roller bearings. (unfortunately)
Back to my original statement, doing all we do to achieve the best tracking possible ($), I would consider it foolish to have any load on any bearing in any direction that was not absolutely necessary. Even if the gains seem trivial, it's free! But that's just me. All good.?May your clutches remain grease free -
Jeff ?
|
photon_trap
Michael Herman