Well, had it setup with new calibration using the guide scope. Guiding started, and. Drumroll..... The clouds rolled in. Boo hisss. I'll have to try when it clears up.
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Re: Yup its the 75 second cycle
Hello Henk, the high precision worm should give a periodic error of about +/-5¡± so it all looks ok to me (and the period would be 239 seconds). I found misalignment of motor and worm could give extra harmonics (and this would include any bearing misalignment), so I would also check if everything is aligned well. To get lower values you would need to use PEC. Don¡¯t know what focal length you are imaging at but autoguiding should work well with that level of periodic error.
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Re: Yup its the 75 second cycle
Hi John,? thanks for the advice and the pictures of your bearing fitting in Alan's thread.? I believe the explanation by John Goetz about the 76 second cycle. Just spring loading will not fix it because the bearings are still misaligned.? Both the worm and the crown wheel are uneven so the spring loaded worm must be moving constantly to compensate.? Therefore the bearings must follow so Belleville washers are the solution.
If I widen the holes in the blocks I should be able to reuse the bearings that I have, should I not?? If yes, why did you buy new bearings?
Also, my outer block bearings should realign themselves because mine float and are pressed by a tangential spring.? So I think the inner block needs the Belleville washer not the outer.? Maybe it's best to do both if there is enough space.? Any thoughts?
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Re: Yup its the 75 second cycle
To make sure what the frequencies are I imported Ekos' .csv file of the 2nd plot into Scilab and ran an optimization over the sum of a linear and 2 sines (8 parameters altogether).? The outcome is? amazingly clear:? One cycle is 75.63 seconds, the other 240.62 seconds.? The amplitudes are 1.66 and 3.61 arc seconds, respectively.? The fit is like this:
So, by relinquishing the spring loaded worms I get stuck with a significant worm cycle of 1 turn per 4 minutes, Earth's rotation.
Wow!? I thought I was provided with a "high precision worm"?
Ok well my DIY spring loading apparently takes care of it.? So my next quest is to fix the 76 second cycle due to the ball bearings in the worm blocks.? Ugh.
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Re: Yup its the 75 second cycle
Henk,
Just saw your additional post made while I was typing. Seems like you may have two separate occurrences with overlapping periods. So a glitch with both bearings? Wondering if some additional block to block tension may be needed. Or perhaps to much pressure on the worm towards the ring gear is overcoming the axial tension, and you are again riding too much on the outer races. Perhaps starting a bearing purchase may be in order. I bought a pack of 10 the last time round so I would have extras at home to experiment with, or to see if one is better than another.
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More looking at brass reactions to CRC MolyD lube
Hi gang,
Just want to report that I see no reaction after almost a month of room temp exposure of brass shim stock to CRC Caliper grease with MolyD, graphite, and teflon lube.??
The theory put forward by the AP coming on their mounts is to avoid MolyD based lubes over a concern over sulphur reacting with the brass of the worm.??
The Losmandy company has used MolyD and other lubes fir years with no reports if any trouble from that.? They recommend avoiding Lithium based greases but I'm not sure if there was chemical issue of concern.??
To test the AP sulphur reaction on brass hypothesis, I have been immersing a section of brass shim stock into a good amount of CRC "quieting" brake and caliper lube.? That lube has MolyD (molybdenum disulphide), graphite, and teflon particles in an oily lubricant.? I found this CRC stuff works better than SuperLube on my G11T titan brass worm and it's massive anodized ring gear.? The worm was "chattering" on the ring gear with only Superlube, but the chatter is gone using the CRC grease.??
Another local buddy told me about the AP forum getting concerned about sulphur from the MolyD crystals...somehow Sulphur breaking molecularly off from the molybdenum, and reacting with the copper in the brass.? But so far, even in hot weather, there is no reaction observed.? The MolyD is stable and is not reacting with the brass test strip.?
?See the attached photos of the brass, and the dark grey CRC lube.? The round end of the strip was immersed in the dark lube for a month.? I cannot detect and etch edge or discoloration line.??
Best, Michael
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Re: Yup its the 75 second cycle
Henk,
You have probably seen the discussion. Other than replacing the bearings, or honing out the right bearing block fit and compressing with a Belville washer, you might try squeezing the blocks toward each other along the worm axis. This may allow the balls to ride smoothly along the inside track, and not ride on the outside race where there could be some rough spots. That seems to be the best theory by consensus.
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Re: Yup its the 75 second cycle
When I tighten the outer block (so both blocks are tightened) I have the standard non-spring-loaded Losmandy G11S mount.? It gives me an extra harmonic of 225 seconds (=3*75).? Hmm.?
I can't get the size of the images right, maybe there's a limitation.? Here are just the error plots:
This one has the DIY springs enabled.? The outer block is floating and is pressed by a strong tangential spring and a weak radial spring.
This one has both blocks tightened.? This is the standard non-spring-loaded G11S - except that I had my hands on all screws I could find.
Clearly the DIY spring loaded worms got rid of one harmonic.? But what would cause it, thoughts anyone?
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Re: Mount takes off when guiding is turned on
Michael, I would agree except I did a calibration in PHD before I tried guiding so it didn't reuse an old calibration.
I'll try again tomorrow night... Fingers crossed.
Jim
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Re: Mount takes off when guiding is turned on
That's an interesting puzzle. If you chose a hot pixel, the PHD2 should never have calibrated, as the "star" would never have ever moved.??
If it calibrated then locked onto a hot pixel in the image field ... maybe.
You can avoid the possibility if hotbpixejs by going under the brain icon, find the "noise reduction" and pick 3x3 median.? ?That will eliminate all hot pixels.??
I'll still keep my money in the bet that you have checked the box "reuse last calibration" and this messes up things nicely as you move around to different parts of the sky.
Have fun, and good luck finding your real cause of tonight's riddle.
Best, Michael
Ok...I just kicked myself in the you know what.
I should have thought of that but I didn't.
You're probably right on with the hot pixel.
That would explain everything.
On a side note.
I had just went out to tear down and gave guiding another try.
I use Metaguide but i did a full calibration and tried again and it started guiding like normal.
This is probably the third different time I calibrated in MG plus the one time in PHD.
Sorry for bugging everyone tonight.
I had visions of a board going out or something major like that.
Thanks again
Jim P
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Re: Mount takes off when guiding is turned on
Ok...I just kicked myself in the you know what.
I should have thought of that but I didn't.
You're probably right on with the hot pixel.
That would explain everything.
On a side note.
I had just went out to tear down and gave guiding another try.
I use Metaguide but i did a full calibration and tried again and it started guiding like normal.
This is probably the third different time I calibrated in MG plus the one time in PHD.
Sorry for bugging everyone tonight.
I had visions of a board going out or something major like that.
Thanks again
Jim P
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Re: Mount takes off when guiding is turned on
Hi Jim
that's not a lot of guiding there, but my guess is that you are locking on to a hot pixel?
there is a lot of lost star events, and this is a good example:?
make sure you do a dark library, enable noise reduction, increase min star HFD (pixels) to 2
There's probably not very much info in the logs.
Since the mount started to act up in Metaguide, I stopped that software and started up PHD2.
I did a calibration run where I was pointing and not near the meridian.
I did do a GA run though.
Hope that will help.
When I say it takes off, it's not going wild or anything like that.
It may just stop tracking.
I can do 30 second exposures without guiding on and I get round stars.
When I turn guiding on I get star trails in the same exposure lengths.
-- Brian?
Brian Valente portfolio
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Yup its the 75 second cycle
Just testing with RA and DEC control turned off in the guider. Running with multiple stars. And to be sure that OnStep has no secret cross talk, disconnected the DEC cable.? After reading about the 76 second cycle, guess what we have here.? It's 75 seconds according to my estimate but I may be off.
Let me check what happens if I tighten the blocks thereby disabling the DIY spring loaded worms.? Regardless, I need to check the block alignment.
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Re: Mount takes off when guiding is turned on
There's probably not very much info in the logs.
Since the mount started to act up in Metaguide, I stopped that software and started up PHD2.
I did a calibration run where I was pointing and not near the meridian.
I did do a GA run though.
Hope that will help.
When I say it takes off, it's not going wild or anything like that.
It may just stop tracking.
I can do 30 second exposures without guiding on and I get round stars.
When I turn guiding on I get star trails in the same exposure lengths.
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Re: Mount takes off when guiding is turned on
Jim,
My guess #1:
Your PHD2 is using an existing calibration and it's the wrong calibration for that part of the sky. Maybe you did a meridian flip....?
Do this:
At the top PHD2 menu under tools choose review calibration and sehect Erase calibration.?? Then select a star and let PHD2 calibrate again.? Then your auto guiding should be good.
Guess #2: If that's not it your clutches may be slipping and you are forever lost.? Contact me for high friction clutch disks and get rid of that issue.??
Best of luck, Michael
All of a sudden my G11 has decided to take off when I activate software guiding.
It tracks fine and I get 30 second images with not star trailing but as soon as start guiding in PHD2 or Metaguide the mount starts drifting off.
A 30 second image with guiding turned on shows LARGE star trails.
This is with a Gemini 1.
I tried parking then turning the electronics off and cold stating it but the same issue is there.
Any ideas?
Last night it worked fine.
Jim P
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Re: Mount takes off when guiding is turned on
i don't know.?
i don't know what "RA is taking off" means
yes some PHD logs would help
Brian, it's not just in one program though.
It does the same thing in Metaguide, which is my main guiding software.
I went out again and checked and it's RA that's taking off.
I'm taking 30 subs now just to salvage something out of the night.
I can post PHD log later if you think it'll help.
-- Brian?
Brian Valente portfolio
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Re: Mount takes off when guiding is turned on
Brian, it's not just in one program though.
It does the same thing in Metaguide, which is my main guiding software.
I went out again and checked and it's RA that's taking off.
I'm taking 30 subs now just to salvage something out of the night.
I can post PHD log later if you think it'll help.
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Re: Mount takes off when guiding is turned on
Hi Jim
that's not a lot to go on - It would be better if you uploaded guidelog to look
my wild guess would be you have reverse dec enabled in PHD? when it shouldn't be
All of a sudden my G11 has decided to take off when I activate software guiding.
It tracks fine and I get 30 second images with not star trailing but as soon as start guiding in PHD2 or Metaguide the mount starts drifting off.
A 30 second image with guiding turned on shows LARGE star trails.
This is with a Gemini 1.
I tried parking then turning the electronics off and cold stating it but the same issue is there.
Any ideas?
Last night it worked fine.
Jim P
-- Brian?
Brian Valente portfolio
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if you want to upload some guidelogs i'm happy to look at them
On Fri, Apr 2, 2021 at 8:04 PM Henk Aling < haling@...> wrote: What calibration problems are you having?
I want to get to 0.5" RMS total but 1.2 is the closest I got, with the 12".? I'm looking at mechanical problems first.? The DIY spring loaded worms seem to work but I will check again, need to check the effect of tightening the clutches too.? I have equal errors in DEC and RA so it could just be poor seeing.? I will find out more tonight with the 6", just guiding no imaging.? Until it works.
-- Brian?
Brian Valente portfolio
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Mount takes off when guiding is turned on
All of a sudden my G11 has decided to take off when I activate software guiding.
It tracks fine and I get 30 second images with not star trailing but as soon as start guiding in PHD2 or Metaguide the mount starts drifting off.
A 30 second image with guiding turned on shows LARGE star trails.
This is with a Gemini 1.
I tried parking then turning the electronics off and cold stating it but the same issue is there.
Any ideas?
Last night it worked fine.
Jim P
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Jamie Amendolagine
Michael Herman