Re: Gemini 2 response to pulses that are smaller than minimum
Ed,
Two things I suggest you evaluate:
You have the option of using ASCOM pulse guiding (sending commands to the Gemini to move) or using the ST4 port (the autoguide camera sends electrical signals to the Gemini).
I've always read they work identically, but I think it's worth it for you to do a comparison.? I tried both mothods and found good results from either way.? But since you are experiencing some problems perhaps one method is superior and minimizes your issue.
The other factor you might try is this: eliminate the SLW movement if your DEC uses this spring system.? You only need to adjust the worm for smooth jam-free rotation into the ring gear, then tighten down the bottom two worm block mounting bolts so the DEC assembly cannot shift in the pivot hole (left block) and cannot shift in or outward (right block).? This will cut the hysteresis time needed for those motions. Compare your autoguide results.? Use the best method for real practice and don't be concerned about theory.? (Again, friction matters here and for lowest friction of the worm to ring gear I suggest CRC Brake and Caliper Grease ...that has the best technical ratings and I feel the smoothest worm behavior (no chatter) on my G11T RA worm.)
All the best, Michael
On Sat, May 22, 2021, 12:23 PM Edward Beshore via <ebeshore= [email protected]> wrote: Hi Brian,
I was mostly concerned about the Dec axis with my GM811.
The default minmov for PhD2 in Dec is 0.2 pix. I am using my 480mm Pronto (206.265/480 = 0.43"/¦Ì?plate scale) and a Lodestar 2 (8.6?¦Ì?pixels) for my guidescope setup which yields 8.6 ¦Ì * 0.43"/¦Ì?= 3.7"/pix. With a 0.2 pix min move that is 0.2 * 3.7" = 0.74" in Dec. Seems like I should be setting my Dec min move to ~1.15 " / 3.7 "/pix = ?0.32 pix?
Given Paul's response, it sounds like the Dec move commands would be getting ignored until the error gets past the minimum step. In the final analysis, that may be fine, since the error will eventually move past that and a correction will make it through but seems a bit pointless to set a minmov to a value that the mount can't accommodate.
What do you think?
Cheers, Ed
|
Re: Gemini 2 response to pulses that are smaller than minimum
Hi Brian,
I was mostly concerned about the Dec axis with my GM811.
The default minmov for PhD2 in Dec is 0.2 pix. I am using my 480mm Pronto (206.265/480 = 0.43"/¦Ì?plate scale) and a Lodestar 2 (8.6?¦Ì?pixels) for my guidescope setup which yields 8.6 ¦Ì * 0.43"/¦Ì?= 3.7"/pix. With a 0.2 pix min move that is 0.2 * 3.7" = 0.74" in Dec. Seems like I should be setting my Dec min move to ~1.15 " / 3.7 "/pix = ?0.32 pix?
Given Paul's response, it sounds like the Dec move commands would be getting ignored until the error gets past the minimum step. In the final analysis, that may be fine, since the error will eventually move past that and a correction will make it through but seems a bit pointless to set a minmov to a value that the mount can't accommodate.
What do you think?
Cheers, Ed
|
Re: DIY Spring Loaded Worms for the G11
Made a couple of minor changes...
Painted the worm block assembly black.?
Changed to button head socket screws.?
Added very thin washers so the button head screws don't get stuck
in the paint.?
Added nylon washers under the pivot bottom bolt.
Added a longer bolt and spring under the bottom sliding bolt to
apply constant pressure.
|
Re: next up: polar alignment tutorial
Does it have to be the "blessed" Losmandy way?? Which is by polar scope or Gemini I suppose.?
I would suggest that there are several of us using a Pi and OnStep so you may want to bring that up too.? You can have a very simple OnStep controller that just controls the motors and leaves higher level functionality to the Pi such as WiFi/ethernet/USB connectivity, plate solving and polar alignment to the Pi.? The Ekos PA routine is similar to SharpCap so if you mention SharpCap you can mention Ekos too.
For those who don't want to use a computer but who have a scope with DSLR, there is a simple computer-less procedure that works just like SharpCap/Ekos:
1) Align the mount roughly so that when turning the scope around the RA axis, both the center of rotation and the NCP are inside the FOV (use an eyepiece).
2) Rotate the mount around the RA axis while taking a 30 sec exposure at 6400 ISO.
3) Mark the center of the star tracks on the LCD, for instance with a reusable piece of clear tape with a needle hole burnt into it.
4) Start taking 2 second images and move the Alt/Az controls until the hole is on top of the NCP.? ?Do not move DEC or RA during this.
This will give an alignment that is 1' to 2' accurate.? There is a visual asterism to locate the NCP quite accurately, check Stellarium for this.
My 2 cents, FWIW.
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Re: motor question- G-11 hit tripod
Another indoor trialing trick is to switch the tracking mode to ¡°terrestrial¡±. you can slew around but dont have to worry about it tracking into furniture. That mode will stick across a gemini restart.
--
Edward
|
Re: next up: polar alignment tutorial
JMD:
You posed this puzzle:
? ?How to eliminate or minimize the variation in polar alignment when you loosen and re-tighten the AZ and EL locking bolts.??
_______
Here is what I did to help minimize this problem:
When you loosen the AZ bolts, the only mechanical element holding the vertical axis firm is a large center bolt under the bottom of the RA axis.? I think this is 3/8-16 thread on the G11 and GM8 and GM811.? This must be loose to allow the AZ to be rotated.
1. I install one or more heavy Belleville spring washers under that bolt head.? The compressed Belleville washers provided a constant force on the AZ axis.? ?
2. I also put a pair of face to face Belleville spring washers surrounded by flat stainless steel washers on each of the AZ and EL bolts.
4. I put either Black or (better for dim lighting) color (Red or Yellow) T handle bolts that are slightly longer, to accommodate the needed vertical space.
When you then slightly loosen the AZ or EL locks, the springs keep these AZ and EL axes under a constant force that is easily adjustable.? Then the polar axis adjustments have less play.? ?Perhaps you will see near zero play....depending on your scope FL.??
Here are photos...
I have these parts, for a modest fee.? I will make up the bolts in the color T handle you prefer (or you can just use your existing T handles of course).? Contact me if interested, and let me know your mount type.??
Best, Michael
On Sat, May 22, 2021, 7:43 AM Les Niles < les@...> wrote: It¡¯s complicated.? Because refraction varies continuously across the sky, there is no combination of polar alignment and tracking rate that will give perfect tracking everywhere.? In fact, there is no combination that will given perfect tracking of any single object as it moves across the sky, though it¡¯s possible to get close by aligning on the refracted pole and using a drive with a proper adaptive King rate.? At least in the middle latitudes, aligning to the refracted pole actually works better than trying to align to the true pole.? There¡¯s a detailed discussion at?, including formulae and spreadsheets to calculate the theoretical drift, which you could compare with what you¡¯re actually seeing. ?
The bottom line is that guiding is always going to be necessary.? The purpose of polar alignment is to get close enough that guiding is smooth and field rotation is not significant. ??
What I would like to see some day is: Polar Alignment, part 2 - very accurate polar alignment
I can get extremely precise PA with sharpcap, but the accuracy seems to be a bit off since I still get a very slow RA drift.? I dunno it's either due to refracted vs real pole, king rate, equipment flex, etc.? I think I'd need to do some kind of a drift alignment to trim to the final value, or just cheat and adjust the RA divisor rate.
|
Re: next up: polar alignment tutorial
It¡¯s complicated. ?Because refraction varies continuously across the sky, there is no combination of polar alignment and tracking rate that will give perfect tracking everywhere. ?In fact, there is no combination that will given perfect tracking of any single object as it moves across the sky, though it¡¯s possible to get close by aligning on the refracted pole and using a drive with a proper adaptive King rate. ?At least in the middle latitudes, aligning to the refracted pole actually works better than trying to align to the true pole. ?There¡¯s a detailed discussion at?, including formulae and spreadsheets to calculate the theoretical drift, which you could compare with what you¡¯re actually seeing. ?
The bottom line is that guiding is always going to be necessary. ?The purpose of polar alignment is to get close enough that guiding is smooth and field rotation is not significant. ??
toggle quoted message
Show quoted text
What I would like to see some day is: Polar Alignment, part 2 - very accurate polar alignment
I can get extremely precise PA with sharpcap, but the accuracy seems to be a bit off since I still get a very slow RA drift.? I dunno it's either due to refracted vs real pole, king rate, equipment flex, etc.? I think I'd need to do some kind of a drift alignment to trim to the final value, or just cheat and adjust the RA divisor rate.
|
Re: next up: polar alignment tutorial
Hi Brian!
? ? ? I use Pole master and generally that is pretty good. ?The ONE area that I find I have to really pay attention to is when I go to tighten the Alt and Az axis back down. ?If I do not take care to adjust the torque equally on each side for both axis, I find I can mess up that last little bit of fine alignment. ? Would be interested in hearing how you guys suggest handling that. ?
JMD?
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Re: DIY Spring Loaded Worms for the G11
Hello Henk -
Thanks for your comments.? I'm of course familiar with your SLW
modifications, and were part of the inspiration in trying this for
myself.? Your use of the sideways spring to apply both the worm
pressure as well as locating the worm block was especially clever.
Thank you for your suggestions on mitigating the periodic forces
from the flex couplers.? I was looking into the belville washers
for both the bottom bolts, as well as potentially to keep the worm
from walking (bearing preload).? I may first try a regular
compression spring and longer bolt under the sliding bolt.? I was
also thinking about using some delrin or low friction plastic
under the pivot, both for the small bit of compression, and the
anti friction properties.
I do agree with you that the biggest room for improvement is how
the worm bock is located by? the loose pivot bolt.? It's less than
ideal.? The spring is a novel approach.? A set screw with a
rounded nose may also be an option to push the worm block assembly
to one side.? It's been something I've been pondering since the
beginning, but haven't settled on a solution yet, at least not
before seeing how the current m4 plastic washer works.? But its
certainly my primary suspect from any large backlash.
I'm lucky that my static worms were pretty good.? I had somewhere
around 8 to 10 arc sec peak to peak of native PE in the worm.? Not
sure if swapping them would have improved things or not.? But
guiding wise, it was relatively easy to get under 1 arc-sec RMS
when? the conditions supported it.? In trying to dial the backlash
out with the static worms, I also had some occasional binding,
though only when running the worms quite tight.? Still, the
backlash would vary depending on where you were on the worm ring.?
I'm also hoping the SLW will help the mount handle just a tiny bit
more wind without having to resort to excessive intentional weight
imbalance.
Thanks again for your comments, and I'd love to hear your
thoughts on my results or any other unexpected difficulties I may
encounter.? Thanks again.
-Tony
On 5/21/2021 11:42 PM, Henk Aling
wrote:
toggle quoted message
Show quoted text
Hi Tony that looks great.? The basic idea is not that different
from my humble construct below (for DEC)
Namely, both blocks are screwed fixed against the aluminum cover
(and are aligned to prevent the 75 Hz vibration), both bottoms
screws are loose and the one nearest the motor serves as the
pivot.? I added 2 Belleville washers tightened lightly at the
bottom one near the motor to keep the blocks flat against the
plate and prevent wobble.? Note that the flex couplings are not
quite symmetric around the axis because there is always some play
and the setting screws pull them off center.? That in addition to
the not perfectly centered motor axis yields significant periodic
forces that try to wobble the block assembly.
That's the balancing part.? On top of that there is the additional
friction because of the continuous spring pressure as compared to
a fixed worm position with some play.? That will cause stronger up
and down vibrations and may also push the worm away from the RA
axis if the pressure is not right.? I've noticed that the Losmandy
SLW have a setting screw, is that because of this perhaps?? So
it's not really full time spring loaded, only at high points.?
Altogether a lot of forces that need to be managed.
Here's the RA one,
The idea is that the pivot screw in its hole is pushed against the
side away from the motor and stays there.? For RA, since the worm
pulls itself away from the motor during tracking, this will
hopefully be true.? But nevertheless we have two screws floating
of which one is only loosely fixed in position.? Same with yours
if I understand it right.? My spring system is more of the
Flintstone kind than your professional looking tunable spring.? I
regulate the force by the position of the screw around which it
sits.? Further outside, more momentum.
So far it has worked very well for slewing.? This used to be my
main problem (the ring gear is not round enough to work with a
tight fixed setting and binds up), and it solved that.? As far as
RMS is concerned, when I get less than 1" total RMS I'm happy (it
happened once).? I have not had the chance to do much testing
because I bought a lot of electronic gear that I am learning how
to use so the focus has been elsewhere.
So far I'm still hopeful that this system will work.? If not, all
I have to do is turn the bottom screws tight and I'm back to the
old fixed system so it can't hurt to try.? Or just use the spring
loaded configuration for slewing and the fixed on for tracking.?
Good luck and keep us posted on how it works!
|
Re: next up: polar alignment tutorial
What I would like to see some day is: Polar Alignment, part 2 - very accurate polar alignment
I can get extremely precise PA with sharpcap, but the accuracy seems to be a bit off since I still get a very slow RA drift.? I dunno it's either due to refracted vs real pole, king rate, equipment flex, etc.? I think I'd need to do some kind of a drift alignment to trim to the final value, or just cheat and adjust the RA divisor rate.
|
Re: motor question- G-11 hit tripod
Whew!? Good to hear.? Thank you Michael. Regards,
John
On Sat, 22 May 2021 at 3:12 pm, Michael Herman <mherman346@...> wrote: John,
There are several protections built into the Gemini system.
If the motor gets stuck (or worm gear jams, or scope is trapped by a wall or a snagged cable), the Gemini is designed to detect this high current and report a "Lags" or "Stalled" motor.??
The L6295PD motor dual "H bridge" chip has also a current sensor and limit of 2.8 amps. It will shut down if it tries to drive a higher current.??
Since your system went back to Park ok, All the parts are likely just fine.??
All the best, Michael Responding to this old post as a similar thing happened to me last night.
?
I have a G11G with a SLW on the RA assembly.? I was trialing N.I.N.A. indoors just to check connection to my mount, guider, focuser and camera, and had forgotten to switch off the Gemini 2 after I was done.? This morning I found the telescope leaning against a bookshelf.? I quickly switched off the Gemini-2 and felt the RA motor.? It was just slightly warm to the touch.? I hadn't read the last message on the Gemini 2 before switching it off.? I switched the Gemini 2 on again and tried slewing east/west and the motor seemed fine.
?
Does anyone know if this would have damaged the RA motor in any way, or any gear in the RA assembly?? My son said he heard a "clicking" sound every few seconds.? Would this have been a gear slipping, or the Gemini 2 resetting itself?
?
The owner from the original post said his RA motor was red hot, but otherwise fine.? Mine was just slightly warm.? I'm wondering whether the SLW would have handled this better, or whether the Gemini 2 some logic to stop the motor if the current exceeds a certain level.
Thank you and regards,
John
|
Re: Max Current Draw for GM811G?
Thanks Mark
------------------------
Jim W
Phoenix, AZ. USA
|
Re: motor question- G-11 hit tripod
Correction: L6205PD chip...
Spec sheet attached...
Michael
On Fri, May 21, 2021, 10:12 PM Michael Herman via <mherman346= [email protected]> wrote: John,
There are several protections built into the Gemini system.
If the motor gets stuck (or worm gear jams, or scope is trapped by a wall or a snagged cable), the Gemini is designed to detect this high current and report a "Lags" or "Stalled" motor.??
The L6295PD motor dual "H bridge" chip has also a current sensor and limit of 2.8 amps. It will shut down if it tries to drive a higher current.??
Since your system went back to Park ok, All the parts are likely just fine.??
All the best, Michael
Responding to this old post as a similar thing happened to me last night.
?
I have a G11G with a SLW on the RA assembly.? I was trialing N.I.N.A. indoors just to check connection to my mount, guider, focuser and camera, and had forgotten to switch off the Gemini 2 after I was done.? This morning I found the telescope leaning against a bookshelf.? I quickly switched off the Gemini-2 and felt the RA motor.? It was just slightly warm to the touch.? I hadn't read the last message on the Gemini 2 before switching it off.? I switched the Gemini 2 on again and tried slewing east/west and the motor seemed fine.
?
Does anyone know if this would have damaged the RA motor in any way, or any gear in the RA assembly?? My son said he heard a "clicking" sound every few seconds.? Would this have been a gear slipping, or the Gemini 2 resetting itself?
?
The owner from the original post said his RA motor was red hot, but otherwise fine.? Mine was just slightly warm.? I'm wondering whether the SLW would have handled this better, or whether the Gemini 2 some logic to stop the motor if the current exceeds a certain level.
Thank you and regards,
John
|
Re: motor question- G-11 hit tripod
John,
There are several protections built into the Gemini system.
If the motor gets stuck (or worm gear jams, or scope is trapped by a wall or a snagged cable), the Gemini is designed to detect this high current and report a "Lags" or "Stalled" motor.??
The L6295PD motor dual "H bridge" chip has also a current sensor and limit of 2.8 amps. It will shut down if it tries to drive a higher current.??
Since your system went back to Park ok, All the parts are likely just fine.??
All the best, Michael
Responding to this old post as a similar thing happened to me last night.
?
I have a G11G with a SLW on the RA assembly.? I was trialing N.I.N.A. indoors just to check connection to my mount, guider, focuser and camera, and had forgotten to switch off the Gemini 2 after I was done.? This morning I found the telescope leaning against a bookshelf.? I quickly switched off the Gemini-2 and felt the RA motor.? It was just slightly warm to the touch.? I hadn't read the last message on the Gemini 2 before switching it off.? I switched the Gemini 2 on again and tried slewing east/west and the motor seemed fine.
?
Does anyone know if this would have damaged the RA motor in any way, or any gear in the RA assembly?? My son said he heard a "clicking" sound every few seconds.? Would this have been a gear slipping, or the Gemini 2 resetting itself?
?
The owner from the original post said his RA motor was red hot, but otherwise fine.? Mine was just slightly warm.? I'm wondering whether the SLW would have handled this better, or whether the Gemini 2 some logic to stop the motor if the current exceeds a certain level.
Thank you and regards,
John
|
Re: motor question- G-11 hit tripod
Responding to this old post as a similar thing happened to me last night.
?
I have a G11G with a SLW on the RA assembly.? I was trialing N.I.N.A. indoors just to check connection to my mount, guider, focuser and camera, and had forgotten to switch off the Gemini 2 after I was done.? This morning I found the telescope leaning against a bookshelf.? I quickly switched off the Gemini-2 and felt the RA motor.? It was just slightly warm to the touch.? I hadn't read the last message on the Gemini 2 before switching it off.? I switched the Gemini 2 on again and tried slewing east/west and the motor seemed fine.
?
Does anyone know if this would have damaged the RA motor in any way, or any gear in the RA assembly?? My son said he heard a "clicking" sound every few seconds.? Would this have been a gear slipping, or the Gemini 2 resetting itself?
?
The owner from the original post said his RA motor was red hot, but otherwise fine.? Mine was just slightly warm.? I'm wondering whether the SLW would have handled this better, or whether the Gemini 2 some logic to stop the motor if the current exceeds a certain level.
Thank you and regards,
John
|
Re: next up: polar alignment tutorial
My input Brian One of My factory installed level seem to be inaccurate ¨C so where to place the level ? -? a bubble in the center of the base? Over the top edge of the azimuth screw and along the top with a std level? ( ?BTW Laying on top with std seems to be best/easiest for me ¨C parallel to ea leg) Of course I use SharpCap? but? ¡??? when using the factory polar scope ?really would like suggestions on how to tighten and install the illuminated button seems to get in the way and the shaft seems to have is a lot of play in it Ron Sent from for Windows 10 ?
toggle quoted message
Show quoted text
From: Brian ValenteSent: Thursday, May 20, 2021 11:12 AM To: [email protected]; [email protected]Subject: [Losmandy_users_io] next up: polar alignment tutorial ? Hi folks we're planning and shooting the polar alignment tutorial for our next one in the support series Just wanted to check and see if anyone had specific comments or questions on this process
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Re: DIY Spring Loaded Worms for the G11
Hi Tony that looks great.? The basic idea is not that different from my humble construct below (for DEC)
Namely, both blocks are screwed fixed against the aluminum cover (and are aligned to prevent the 75 Hz vibration), both bottoms screws are loose and the one nearest the motor serves as the pivot.? I added 2 Belleville washers tightened lightly at the bottom one near the motor to keep the blocks flat against the plate and prevent wobble.? Note that the flex couplings are not quite symmetric around the axis because there is always some play and the setting screws pull them off center.? That in addition to the not perfectly centered motor axis yields significant periodic forces that try to wobble the block assembly.
That's the balancing part.? On top of that there is the additional friction because of the continuous spring pressure as compared to a fixed worm position with some play.? That will cause stronger up and down vibrations and may also push the worm away from the RA axis if the pressure is not right.? I've noticed that the Losmandy SLW have a setting screw, is that because of this perhaps?? So it's not really full time spring loaded, only at high points.? Altogether a lot of forces that need to be managed.
Here's the RA one,
The idea is that the pivot screw in its hole is pushed against the side away from the motor and stays there.? For RA, since the worm pulls itself away from the motor during tracking, this will hopefully be true.? But nevertheless we have two screws floating of which one is only loosely fixed in position.? Same with yours if I understand it right.? My spring system is more of the Flintstone kind than your professional looking tunable spring.? I regulate the force by the position of the screw around which it sits.? Further outside, more momentum.
So far it has worked very well for slewing.? This used to be my main problem (the ring gear is not round enough to work with a tight fixed setting and binds up), and it solved that.? As far as RMS is concerned, when I get less than 1" total RMS I'm happy (it happened once).? I have not had the chance to do much testing because I bought a lot of electronic gear that I am learning how to use so the focus has been elsewhere.
So far I'm still hopeful that this system will work.? If not, all I have to do is turn the bottom screws tight and I'm back to the old fixed system so it can't hurt to try.? Or just use the spring loaded configuration for slewing and the fixed on for tracking.?
Good luck and keep us posted on how it works!
|
Re: DIY Spring Loaded Worms for the G11
Hi Tony,
Marc Aragnou in Australia also made his own SLW.? He used one or more rubber O-rings as springs.? They are a shorter range spring.? I wondered if the rubber would be temperature dependent or dry up over time.? However, easy enough to replace them and he said they work fine...he said he gets very good guiding.??
He also used a 50:1 McLennan gearbox on his (old version 2mm drive shaft) motors and he found the 50:1 better than the 25:1.? But the McLennan factory told me not to try the 50:1 as the high torque motor has a larger 1/8th inch (~3.2mm) drive shaft...the 50:1 takes a smaller OD pinion gear and they thought it would bore too close to the teeth.??
Anyway ..more ideas to consider.? Many ways to skin a cat...
Best, Michael
On Fri, May 21, 2021, 5:08 PM GuitsBoy < guitsboy@...> wrote:
Hi Michael -
Please, no apologies necessary.? I'm one to find the humor in a
good autocorrect fail, but not quite sure I've spotted the gaffe.?
Regardless, no worries at all, I never gave it a second thought
(or a first for that matter).
Thanks for the comments and suggestions, and I'll be sure to roll
it into a PDF once I finalize it and get some baseline results.?
It may still be a dud.? Anyway, since the clouds rolled in, its
getting painted flat black right now in the garage, and have
proper stainless button head screws coming tomorrow.? I'm sure
I'll continue to tweak and make revisions before I'm ready to
leave it be.
Thanks again,
-Tony
On 5/21/2021 7:39 PM, Michael Herman
wrote:
...sorry for the not so humerous typos...
I meant your ... clever design...
I don't know how the Android programmers made
the autocorrect pick the worst possible words to use.? Maybe
the Android system has Turette syndrome.
(It can't be me can it?)
All the best, and apologies...!
Michael
On Fri, May 21, 2021, 4:20 PM
Michael Herman via <mherman346= [email protected]>
wrote:
Very nice work.
Please put your steps and photos into a PDF,
as the email will become lost over time.? You can then
upload your PDF instructions into the group files....and
you will be famous forever!? ?Over time,? many people will
study your best dead and try it out.
The final step is the most critical.? You
just measure your PE from.s star tracking...show the PE is
smooth and get the Peak to Peak and RMS PE.? If those are
low, you have succeeded well.
Have fun, and thank you again for showing a
nice way to upgrade with a DIY spring loaded system, and
easy to fabricate parts.? ??
Michael
On Fri, May 21, 2021, 1:58
PM GuitsBoy < guitsboy@...> wrote:
I've had about a half dozen or so nights out imaging
with my OnStep converted G11.? My guiding has been
pretty good, averaging around .65 to .75 with the old
two piece worm blocks and HP brass worms.? After
seeing a few posts here and on cloudy nights about DIY
spring loaded worm mods, I decided to give it a try
myself.?
![]()
The raw materials were some 3/4 inch aluminum 90?
angle stock, 1/8 thick, some 3D printed attachment
points,? a 3D printed drill jig, and some off the
shelf hardware.?? Here is the aluminum angle stock
marked up for drilling.
![]()
I ordered fresh worm blocks so if this mod doesn't
quite work out, I can always go back to stock.? I
already had extra bearings.? The new blocks were
drilled front and top, but only tapped on the front
side.? I tapped the top holes to match the front,
10-24 threads.? I also had to file down the corner to
get the worm blocks to sit flat in the angle stock.?
There is a tiny radius in the extruded aluminum you
need to accommodate.
![]()
Drilling into a nice mount can be a bit unnerving.? I
3D printed up a jig to make sure I drilled straight,
and got the depth right.
![]()
A 6-32 tap cuts the threads.?? The rear drill hole
does go into the worm block mounting hole, but the
bolt does not protrude into it.? No big deal.
![]()
One side done, one more to go.
![]()
The 3D printed attachment point is in place.
![]()
The finished assembly on the DEC side.? The empty
outboard hole next to the spring is for a push set
screw, if I find it's needed.
![]()
And here's the RA side.
![]()
Hello little worm, I see you!? You can also see my
DIY RA extension I needed to clear the motor
brackets.? I'm using 1-1/4 aluminum spacers, and a 3D
printed trim ring.?? You can see I did something
similar with the DEC as well.
So far, so good.? The pivot point is the bottom worm
block bolt closest to the motor.? It's located in
place with an m4 x 10mm OD plastic washer.? It is very
lightly snugged in place.?? The worm block bolt away
from the motor is the sliding side.? It's left loose,
only tight enough to keep the worm from walking
upward.?
When testing the worm in the OPWB, if I snugged the
stock worm blocks into the aluminum angle stock, the
worm was difficult to turn.? It could be a burr or
defect on both pieces of angle stock, but more likely,
the worm blocks / bearings are just off by a fraction
of a degree.? I found that torquing the top bolts
tightly first, then lightly snugging the front bolts
allows the worm to spin freely.
I can just barely get to the motor couplings without
taking everything apart, which is nice.? I'm using
flexible couplings attached to the belt drive
brackets, courtesy of Rockmover on Thingiverse.? I
have 16:60 belt reduction, and I'm running the 0.9?
stepper motors at 1/16 microsteps, which gives me 0.15
arc-sec or resolution.? Control is handled by OnStep.?
Personally, my gut feeling is that attaching the
motors directly to the OPWB is unnecessary for the
microscopic amount of runout the worm wheels have.?
The flexible couplers are more than adequate for
taking up any angular error.? I could probably even
get away with a rigid coupler and rely on the shaft to
flex a tiny bit.? And that's to say nothing of all the
plastic. :)
There's clouds in the foreseeable forecast, but I'm
hoping there's a break in the weather soon so I can
get some testing done.
Any thoughts, comments or criticism are both welcome
and appreciated.
-Tony
|
Re: DIY Spring Loaded Worms for the G11
Hi Michael -
Please, no apologies necessary.? I'm one to find the humor in a
good autocorrect fail, but not quite sure I've spotted the gaffe.?
Regardless, no worries at all, I never gave it a second thought
(or a first for that matter).
Thanks for the comments and suggestions, and I'll be sure to roll
it into a PDF once I finalize it and get some baseline results.?
It may still be a dud.? Anyway, since the clouds rolled in, its
getting painted flat black right now in the garage, and have
proper stainless button head screws coming tomorrow.? I'm sure
I'll continue to tweak and make revisions before I'm ready to
leave it be.
Thanks again,
-Tony
On 5/21/2021 7:39 PM, Michael Herman
wrote:
toggle quoted message
Show quoted text
...sorry for the not so humerous typos...
I meant your ... clever design...
I don't know how the Android programmers made
the autocorrect pick the worst possible words to use.? Maybe
the Android system has Turette syndrome.
(It can't be me can it?)
All the best, and apologies...!
Michael
On Fri, May 21, 2021, 4:20 PM
Michael Herman via <mherman346= [email protected]>
wrote:
Very nice work.
Please put your steps and photos into a PDF,
as the email will become lost over time.? You can then
upload your PDF instructions into the group files....and
you will be famous forever!? ?Over time,? many people will
study your best dead and try it out.
The final step is the most critical.? You
just measure your PE from.s star tracking...show the PE is
smooth and get the Peak to Peak and RMS PE.? If those are
low, you have succeeded well.
Have fun, and thank you again for showing a
nice way to upgrade with a DIY spring loaded system, and
easy to fabricate parts.? ??
Michael
On Fri, May 21, 2021, 1:58
PM GuitsBoy < guitsboy@...> wrote:
I've had about a half dozen or so nights out imaging
with my OnStep converted G11.? My guiding has been
pretty good, averaging around .65 to .75 with the old
two piece worm blocks and HP brass worms.? After
seeing a few posts here and on cloudy nights about DIY
spring loaded worm mods, I decided to give it a try
myself.?
![]()
The raw materials were some 3/4 inch aluminum 90?
angle stock, 1/8 thick, some 3D printed attachment
points,? a 3D printed drill jig, and some off the
shelf hardware.?? Here is the aluminum angle stock
marked up for drilling.
![]()
I ordered fresh worm blocks so if this mod doesn't
quite work out, I can always go back to stock.? I
already had extra bearings.? The new blocks were
drilled front and top, but only tapped on the front
side.? I tapped the top holes to match the front,
10-24 threads.? I also had to file down the corner to
get the worm blocks to sit flat in the angle stock.?
There is a tiny radius in the extruded aluminum you
need to accommodate.
![]()
Drilling into a nice mount can be a bit unnerving.? I
3D printed up a jig to make sure I drilled straight,
and got the depth right.
![]()
A 6-32 tap cuts the threads.?? The rear drill hole
does go into the worm block mounting hole, but the
bolt does not protrude into it.? No big deal.
![]()
One side done, one more to go.
![]()
The 3D printed attachment point is in place.
![]()
The finished assembly on the DEC side.? The empty
outboard hole next to the spring is for a push set
screw, if I find it's needed.
![]()
And here's the RA side.
![]()
Hello little worm, I see you!? You can also see my
DIY RA extension I needed to clear the motor
brackets.? I'm using 1-1/4 aluminum spacers, and a 3D
printed trim ring.?? You can see I did something
similar with the DEC as well.
So far, so good.? The pivot point is the bottom worm
block bolt closest to the motor.? It's located in
place with an m4 x 10mm OD plastic washer.? It is very
lightly snugged in place.?? The worm block bolt away
from the motor is the sliding side.? It's left loose,
only tight enough to keep the worm from walking
upward.?
When testing the worm in the OPWB, if I snugged the
stock worm blocks into the aluminum angle stock, the
worm was difficult to turn.? It could be a burr or
defect on both pieces of angle stock, but more likely,
the worm blocks / bearings are just off by a fraction
of a degree.? I found that torquing the top bolts
tightly first, then lightly snugging the front bolts
allows the worm to spin freely.
I can just barely get to the motor couplings without
taking everything apart, which is nice.? I'm using
flexible couplings attached to the belt drive
brackets, courtesy of Rockmover on Thingiverse.? I
have 16:60 belt reduction, and I'm running the 0.9?
stepper motors at 1/16 microsteps, which gives me 0.15
arc-sec or resolution.? Control is handled by OnStep.?
Personally, my gut feeling is that attaching the
motors directly to the OPWB is unnecessary for the
microscopic amount of runout the worm wheels have.?
The flexible couplers are more than adequate for
taking up any angular error.? I could probably even
get away with a rigid coupler and rely on the shaft to
flex a tiny bit.? And that's to say nothing of all the
plastic. :)
There's clouds in the foreseeable forecast, but I'm
hoping there's a break in the weather soon so I can
get some testing done.
Any thoughts, comments or criticism are both welcome
and appreciated.
-Tony
|
Re: DIY Spring Loaded Worms for the G11
...sorry for the not so humerous typos...
I meant your ... clever design...
I don't know how the Android programmers made the autocorrect pick the worst possible words to use.? Maybe the Android system has Turette syndrome.
(It can't be me can it?)
All the best, and apologies...!
Michael
On Fri, May 21, 2021, 4:20 PM Michael Herman via <mherman346= [email protected]> wrote: Very nice work.
Please put your steps and photos into a PDF, as the email will become lost over time.? You can then upload your PDF instructions into the group files....and you will be famous forever!? ?Over time,? many people will study your best dead and try it out.
The final step is the most critical.? You just measure your PE from.s star tracking...show the PE is smooth and get the Peak to Peak and RMS PE.? If those are low, you have succeeded well.
Have fun, and thank you again for showing a nice way to upgrade with a DIY spring loaded system, and easy to fabricate parts.? ??
Michael
On Fri, May 21, 2021, 1:58 PM GuitsBoy < guitsboy@...> wrote:
I've had about a half dozen or so nights out imaging with my
OnStep converted G11.? My guiding has been pretty good, averaging
around .65 to .75 with the old two piece worm blocks and HP brass
worms.? After seeing a few posts here and on cloudy nights about
DIY spring loaded worm mods, I decided to give it a try myself.?
![]()
The raw materials were some 3/4 inch aluminum 90? angle stock,
1/8 thick, some 3D printed attachment points,? a 3D printed drill
jig, and some off the shelf hardware.?? Here is the aluminum angle
stock marked up for drilling.
![]()
I ordered fresh worm blocks so if this mod doesn't quite work
out, I can always go back to stock.? I already had extra
bearings.? The new blocks were drilled front and top, but only
tapped on the front side.? I tapped the top holes to match the
front, 10-24 threads.? I also had to file down the corner to get
the worm blocks to sit flat in the angle stock.? There is a tiny
radius in the extruded aluminum you need to accommodate.
![]()
Drilling into a nice mount can be a bit unnerving.? I 3D printed
up a jig to make sure I drilled straight, and got the depth right.
![]()
A 6-32 tap cuts the threads.?? The rear drill hole does go into
the worm block mounting hole, but the bolt does not protrude into
it.? No big deal.
![]()
One side done, one more to go.
![]()
The 3D printed attachment point is in place.
![]()
The finished assembly on the DEC side.? The empty outboard hole
next to the spring is for a push set screw, if I find it's needed.
![]()
And here's the RA side.
![]()
Hello little worm, I see you!? You can also see my DIY RA
extension I needed to clear the motor brackets.? I'm using 1-1/4
aluminum spacers, and a 3D printed trim ring.?? You can see I did
something similar with the DEC as well.
So far, so good.? The pivot point is the bottom worm block bolt
closest to the motor.? It's located in place with an m4 x 10mm OD
plastic washer.? It is very lightly snugged in place.?? The worm
block bolt away from the motor is the sliding side.? It's left
loose, only tight enough to keep the worm from walking upward.?
When testing the worm in the OPWB, if I snugged the stock worm
blocks into the aluminum angle stock, the worm was difficult to
turn.? It could be a burr or defect on both pieces of angle stock,
but more likely, the worm blocks / bearings are just off by a
fraction of a degree.? I found that torquing the top bolts tightly
first, then lightly snugging the front bolts allows the worm to
spin freely.
I can just barely get to the motor couplings without taking
everything apart, which is nice.? I'm using flexible couplings
attached to the belt drive brackets, courtesy of Rockmover on
Thingiverse.? I have 16:60 belt reduction, and I'm running the
0.9? stepper motors at 1/16 microsteps, which gives me 0.15
arc-sec or resolution.? Control is handled by OnStep.? Personally,
my gut feeling is that attaching the motors directly to the OPWB
is unnecessary for the microscopic amount of runout the worm
wheels have.? The flexible couplers are more than adequate for
taking up any angular error.? I could probably even get away with
a rigid coupler and rely on the shaft to flex a tiny bit.? And
that's to say nothing of all the plastic. :)
There's clouds in the foreseeable forecast, but I'm hoping
there's a break in the weather soon so I can get some testing
done.
Any thoughts, comments or criticism are both welcome and
appreciated.
-Tony
|
Michael Herman
Edward Plumer
Ron