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
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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 ??
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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 ?
|
Thanks Chip...I just have not seen the number of Ovision worm returns and very mixed reviews. Must have missed them.
Tom
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Show quoted text
On 10/12/2017 7:43 PM, chiplouie@... [Losmandy_users] wrote: Tom,
Scott doesn't need to characterise his worms, obviously measuring them is not particularly valuable as many Ovision worms with glowing certificates performed very poorly. If you get a Losmandy HP worm that is not up to snuff Losmandy usually will help you tune your mount and if it is bad replace the suspect part.
Chip
|
Tom,?
Scott doesn't need to characterise his worms, obviously measuring them is not particularly valuable as many Ovision worms with glowing certificates performed very poorly. If you get a Losmandy HP worm that is not up to snuff Losmandy usually will help you tune your mount and if it is bad replace the suspect part.?
Chip
|
Re: Mount Clutch Tensions
Hi Jeff,
Yes of course, as you apply pressure on the clutch discs the load on the thrust bearings naturally is increased. 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. I have not run the calculator to check the forces involved but the bearings are good for at least 4,900lbs per bearing and up to 6,000RPM so a few extra pounds shared between the two bearings would seem to represent a fairly low load. Also consider that the servomotor output is reduced 25:1 before the worm gear reduction which is something like an additional 360:1 reduction so the additional load should not represent a big change in load.?
As I said above, if you have a Gemini 2 you can monitor the servo feedback data using the Gemini's web server. Or you can try this, easy demonstration: remove the worm block from the DEC axis and loosen the clutch knob and feel the force needed to rotate the DEC axis. Now tighten the DEC axis clutch knob and rotate the DEC axis, it will still rotate freely, if you can feel an increase in force it will not be much and the DEC shaft will still rotate freely. This is what bearings do, they reduce friction and the force necessary to rotate the axes even while loaded up.?
Chip
|
Re: Super greasy worm gears on my GM8
Hm build a cable? I have a QHY5L-II and I've been using the cable that was provided for autoguiding. It worked before but I'm kind of anxious that it won't now for some reason. It should be fine though. If I get dithering sorted out I'll be good to go I think.
|
Re: New G11 / Gemini 2 user with issues..
well, since I'll see you for sure, please get me one and put it on my ever-growing tab!??
Michael?
On Oct 12, 2017 15:44, " chiplouie@... [Losmandy_users]" < Losmandy_users@...> wrote:
?
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.?
Chip ?
|
Hi Chip,
I think you hit it that time. I cannot speak first-hand about the Ovision worm but have thought about going that route and as I understand it they document the PE of the worm and Scott does not. I was hoping medium/long term users of the Ovision worm would chime in with their experience.
Tom
toggle quoted message
Show quoted text
On 10/12/2017 6:37 PM, chiplouie@... [Losmandy_users] wrote: Hi Tom,
Based on the number of Ovision worm returns and the often very mixed reviews in testing by people who spent a lot of money for often no better results or worse results than a carefully tuned Losmandy 2-piece worm block setup I think the Ovision worm is an very pricey significantly less reliable option.
The new Losmandy OPW design offers similar performance to an Ovision worm that tests good but the Losmandy OPWs seem to have more consistent real world test results. Additionally with the the addition of improved worm mesh adjustability with the threaded adjuster and the ability to buy a PAIR of new Losmandy OPWs with a brand new HP worms installed for less than the cost of a single Ovision I think the new design Losmandy OPW is the better way to go. Most imagers are using an autoguider and the results using an autoguider do not seem to get much better than 0.3-0.4 arcseconds RMS which is typically much better than the seeing will allow under ideal conditions.
If this doesn't clearly answer the OP's questions I'm not sure what the OP is asking.
Chip
|
Hey gang,
I privately emailed the originator with this opinion also...
--------------------
I'll attach a writeup on improvements that I made to the Losmandy OPW and why I added a Belleville spring washer to it. The Ovision product has one of these already designed in at the far end, I think.
Chip Louie is correct in that the Ovision mounting does not also line up the gearbox and Oldham coupler.? That lineup is done by the Losmandy OPW system.? An offset in angle between the gearbox shaft and the worm shaft can result in additional oscillation that I think can be corrected by PEC, because the offset creates a 2X worm frequency.? However, it is always better not to have these oscillations in the system.??
------------------- I no longer know the prices of these things... but once one is going for the ultimate in what the system can do, I don't think that matters. The question is:? what gets you the ultimate capability if you also put effort into it. The way the mount is designed, and what was left out of the design, I can see why the really well engineered Ovision system could end up not meeting its PE capability.? The interaction of the worm PE with the Oldham coupler angle or offset is a fundamental issue that is simply not treated by the machinists.? But careful owners can adjust it and test the PE; PEC and autoguiding take you the rest of way below the atmospheric seeing level.??
- Michael
On Thu, Oct 12, 2017 at 3:37 PM, chiplouie@... [Losmandy_users] <Losmandy_users@...> wrote:
?
Hi Tom,
Based on the number of Ovision worm returns and the often very mixed reviews in testing by people who spent a lot of money for often no better results or worse results than a carefully tuned Losmandy 2-piece worm block setup I think the Ovision worm is an very pricey significantly less reliable option.?
The new Losmandy OPW design offers similar performance to an Ovision worm that tests good but the Losmandy OPWs seem to have more consistent real world test results. Additionally with the the addition of improved worm mesh adjustability with the threaded adjuster and the ability to buy a PAIR of new Losmandy OPWs with a brand new HP worms installed for less than the cost of a single Ovision I think the new design Losmandy OPW is the better way to go. Most imagers are using an autoguider and the results using an autoguider do not seem to get much better than 0.3-0.4 arcseconds RMS which is typically much better than the seeing will allow under ideal conditions.?
If this doesn't clearly answer the OP's questions I'm not sure what the OP is asking.?
Chip?
?? ??
|
Re: Super greasy worm gears on my GM8
Hi Fredrik,
The #492 digital drive system can definitely be autoguided using PHD2 and any good mono autoguider camera. You just need to build a cable and get a good USB to RS232 converter like the ATEN converter.?
Chip
|
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.?
Chip ?
|
Hi Tom,
Based on the number of Ovision worm returns and the often very mixed reviews in testing by people who spent a lot of money for often no better results or worse results than a carefully tuned Losmandy 2-piece worm block setup I think the Ovision worm is an very pricey significantly less reliable option.?
The new Losmandy OPW design offers similar performance to an Ovision worm that tests good but the Losmandy OPWs seem to have more consistent real world test results. Additionally with the the addition of improved worm mesh adjustability with the threaded adjuster and the ability to buy a PAIR of new Losmandy OPWs with a brand new HP worms installed for less than the cost of a single Ovision I think the new design Losmandy OPW is the better way to go. Most imagers are using an autoguider and the results using an autoguider do not seem to get much better than 0.3-0.4 arcseconds RMS which is typically much better than the seeing will allow under ideal conditions.?
If this doesn't clearly answer the OP's questions I'm not sure what the OP is asking.?
Chip?
?? ??
|
Re: Super greasy worm gears on my GM8
Chip,
Yes, it is indeed a model 492. I agree with you, it's an awesome mount and I think the design is one of the best out there. It looks so slim yet sturdy. I use it as my main mount though and I hope it will keep working to capture some fairly long deep sky exposures.
I have now cleaned the clutches and relubed the RA and DEC bearings. I also cleaned as much excessive grease as I could from the worm gears. I'm sure I didn't do everything correctly but it feels a lot smother now.
Now, more challenges await. The biggest ones being autoguiding and getting automated dithering to work. Since I neither have the Gemini nor an astro-friendly camera (I use Sony A7) I'll have to dither with the PHD2 dither app. I have no idea of what parameters to use either. I guess I'll find out eventually.
Anyway, thank you so much for the help. This is a huge step forward towards making my own little amateur observatory :)
|
I don't think that answers his question...
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Show quoted text
On 10/12/2017 2:10 PM, chiplouie@... [Losmandy_users] wrote: Hi nmatxin,
If you already have the brass worm gears installed in your mount you already have high precision worms installed and I highly recommend buying the newly redesigned Losmandy one piece worm block for BOTH RA and DEC axes. If your mount has the old silver colored standard precision worms then I suggest buying the new Losmandy OPW with a new high precision worm installed and install it on the RA axis and an additional new Losmandy OPW for the DEC axis using your existing worm gear. This configuration will get your tracking PE way down and save you $100 over buying a new pair of HP worm OPWs. If money is not an issue bring your G11 up to the current standard with a pair of HP worm loaded OPWs.
My thinking is this: the first generation Losmandy OPW may have had slightly higher potential to reduce periodic errors because the old OPW fully aligned the gearbox and worm gears on the same axis to eliminate the very small velocity differences inherent when an Oldham coupler is misaligned, this is inherent to the Oldham coupler design. The potential error improvement was very small but cost TWICE as much as the new Losmandy OPW. IMO the still perfect worm bearing alignment, added ease of worm mesh adjustability and the 50% reduction in cost of the new Losmandy OPW design overcomes the slight loss in potential PE reduction and allows mounts without HP worms on the RA axis (the important axis for imagers) to buy the OPW and HP worm for less than the cost of an EMPTY first generation OPW alone!
This thinking was proven on my own G11 mount. I had previously tested my standard Gemini 2-mini powered G11 mount with 2-piece worm blocks and HP worms on both RA and DEC axes with a Stellarvue 50mm f/4 guidescope, QHY5L-II Mono autoguider camera and PHD2 doing the honors. I typically saw unguided error in the 3.5-5.0 arcsecond range before I did the usual Losmandy G11 modifications and 0.34-0.5 arcseconds RMS when autoguided. After Scott updated my 15 year old G11 to full current G11G specs with the new tucked-in motors, RA Extension Kit, newly redesigned OPWs and reusing my existing worm gears. The mount turned in slightly better results (3.5 arcseconds unguided and 0.31-0.46 arcseconds RMS guided) using the same QHY5L-II Mono autoguider at the prime focus of a Meade 10" f/6.3 SCT OTA on a very cold night which had my mount lagging severely requiring that I adjust the worm mesh to free up both the RA and DEC axis to test.
This of course is just one mount but I imaging your results would be about the same.
Chip
|
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!
- Michael
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!?
Chip? ? ??
|
Re: New G11 / Gemini 2 user with issues..
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!?
Chip? ? ??
|
photon_trap
Michael Herman