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This morning while the coffee was brewing I fashioned my own spring loaded worms.? The materials:
- Rubber bands cut from an old road bicycle inner tube.? This kind of rubber is very resilient, do not use household rubber bands.
- A strip of sheet metal about 1 cm wide and 5 cm long, just guessing, cut with tin snips.
Installation steps:
- Loosen the outer worm block by loosening two screws:
- The screw at the bottom of the frame that the block is mounted on, just slightly so there is little vertical play.
- The screw on the housing, this can be loosened a bit more.
- Wrap the rubber band twice around the screws at the bottom.? This should provide quite a bit of tangential force that pushes the outer worm block towards the motor side.
- Fashion the sheet metal to wrap around the rear edge of the housing and around to provide slight pressure on the housing screw.? This screw is directly screwed into the worm block so it provides slight lateral pressure inward that keeps the worm engaged without slack.? You can vary the pressure by positioning the screw, or simply bend it a bit more or less.? Not much pressure is required.
- I should note that I don't use the Oldham couplers but flexible aluminum shaft couplings for stepper motors.? These couplers also provide some pressure but I think this should work with the Oldham couplers just as well.
I did this for both RA and DEC and slewed both around at full speed with my OnStep controller.? It seems to work fine, frankly.??I can't wait to try it out under the stars once the fog stops rolling in.? Here are some pictures: The first 4 pictures are of the DEC worm block: I only have one picture of RA, all you can see the rubber band and a glimpse of the sheet metal spring.? The other RA pictures were blurry. As an aside, here's my OnStep controller to the right.? It's a Wemos R32 with a CNC v3 shield.? The Raspberry Pi 2B running Kstars and Ekos (client and server) is to the left.? I run it with 0.9 degree steppers with TMC2130 controllers with SPI for slewing at full step, microstepping 16x for tracking.? I start out using my Android cell phone as a remote over Bluetooth for alignment, then continue with Ekos and Kstars for tracking, guiding, plate solving, etcetera, remotely logged from my Galaxy Tab A with VNC. I'll duck for cover now.? I've been on this board long enough to know what's coming, so fire away...
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HI Henk
Wow that is some McGyvering there, nice work!
i hope you will let us know about the results
>>>I'll duck for cover now.? I've been on this board long enough to know what's coming, so fire away...
I don't see any references to vixen plates, so I think you're safe on that one for now :)
Brian
On Wed, Sep 23, 2020 at 9:29 AM Henk Aling < haling@...> wrote: This morning while the coffee was brewing I fashioned my own spring loaded worms.? The materials:
- Rubber bands cut from an old road bicycle inner tube.? This kind of rubber is very resilient, do not use household rubber bands.
- A strip of sheet metal about 1 cm wide and 5 cm long, just guessing, cut with tin snips.
Installation steps:
- Loosen the outer worm block by loosening two screws:
- The screw at the bottom of the frame that the block is mounted on, just slightly so there is little vertical play.
- The screw on the housing, this can be loosened a bit more.
- Wrap the rubber band twice around the screws at the bottom.? This should provide quite a bit of tangential force that pushes the outer worm block towards the motor side.
- Fashion the sheet metal to wrap around the rear edge of the housing and around to provide slight pressure on the housing screw.? This screw is directly screwed into the worm block so it provides slight lateral pressure inward that keeps the worm engaged without slack.? You can vary the pressure by positioning the screw, or simply bend it a bit more or less.? Not much pressure is required.
- I should note that I don't use the Oldham couplers but flexible aluminum shaft couplings for stepper motors.? These couplers also provide some pressure but I think this should work with the Oldham couplers just as well.
I did this for both RA and DEC and slewed both around at full speed with my OnStep controller.? It seems to work fine, frankly.??I can't wait to try it out under the stars once the fog stops rolling in.? Here are some pictures:
The first 4 pictures are of the DEC worm block:
I only have one picture of RA, all you can see the rubber band and a glimpse of the sheet metal spring.? The other RA pictures were blurry.
As an aside, here's my OnStep controller to the right.? It's a Wemos R32 with a CNC v3 shield.? The Raspberry Pi 2B running Kstars and Ekos (client and server) is to the left.? I run it with 0.9 degree steppers with TMC2130 controllers with SPI for slewing at full step, microstepping 16x for tracking.? I start out using my Android cell phone as a remote over Bluetooth for alignment, then continue with Ekos and Kstars for tracking, guiding, plate solving, etcetera, remotely logged from my Galaxy Tab A with VNC.
I'll duck for cover now.? I've been on this board long enough to know what's coming, so fire away...
-- Brian?
Brian Valente portfolio
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That's out of the box thinking. I don't feel as bad using neoprene washers now ;0
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On Wed, Sep 23, 2020 at 09:29 AM, Henk Aling wrote:
As an aside, here's my OnStep controller to the right.? It's a Wemos R32 with a CNC v3 shield.? The Raspberry Pi 2B running Kstars and Ekos (client and server) is to the left.? I run it with 0.9 degree steppers with TMC2130 controllers with SPI for slewing at full step, microstepping 16x for tracking.? I start out using my Android cell phone as a remote over Bluetooth for alignment, then continue with Ekos and Kstars for tracking, guiding, plate solving, etcetera, remotely logged from my Galaxy Tab A with VNC.
Nice, I also have the??Wemos R32 with a CNC v3 shield for an OnStep using the original hurst stepper motor. I just have a GM8 RA base so it serves as a heavy duty star tracker and solar scope mount. The whole OnStep was also a 5 minute mod :)?
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Nice, I also have the??Wemos R32 with a CNC v3 shield for an OnStep using the original hurst stepper motor. I just have a GM8 RA base so it serves as a heavy duty star tracker and solar scope mount. The whole OnStep was also a 5 minute mod :)?
The OnStep part can be a few minutes but what took me a lot of time is debugging my CNC v3 board (I had two, not all pins were working as advertised) and making cables for SPI, etcetera.? Plus, one of my two Wemoses was broken as well (but not badly enough to make it obvious).? Debugging all that took a lot of time.? But it's OK, I enjoyed learning everything. Last night I took the system under the stars and found that it was not tracking well (unrelated to the mod of this thread, I ran it with and without).? So I have more debugging to do.? The battery was at 11.5 V so maybe that was it, otherwise I may need to increase the Vref of the stepper drivers, check the connections, etcetera.? I will figure it out but it always takes more time.
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Well I tried again and found that OnStep is moving in DEC for some reason, I am checking with the OnStep group.?
After unplugging the DEC cable I got this image of Andromeda by Moonlight.? I don't think I can salvage the colors but what matters is that the stars are very crisp and round.? ?G11S with OnStep and DIY SL Worms unguided, Fuji X-a1 @ 6400 ISO, 178x30s lights, 24 flats, DSS (stack+edit).
I can't get the image any larger maybe there's a limit so just take my word for it.? Thanks for looking.
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On Thu, Sep 24, 2020 at 06:55 AM, Henk Aling wrote:
The OnStep part can be a few minutes but what took me a lot of time is debugging my CNC v3 board (I had two, not all pins were working as advertised) and making cables for SPI, etcetera.? Plus, one of my two Wemoses was broken as well (but not badly enough to make it obvious).? Debugging all that took a lot of time.? But it's OK, I enjoyed learning everything.
Well in theory, 5 minutes. I spent a day trying to figure out what was not working to find out I had the wrong pin map defined. I also waited 5 days to get new CNC board because I thought my old one was broke, it was not plugged in :)?
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The attachment worked, it is larger than the inline image but still smaller than when I look at it on my screen.? That was actually not full size but this one is, attached.? You can see the lack of dithering, I can't recall having that with an unguided image, I guess that means something.
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i took a stab at fixing the color, it was a pretty low res jpg ;)
On Fri, Sep 25, 2020 at 1:09 AM Henk Aling < haling@...> wrote: Well I tried again and found that OnStep is moving in DEC for some reason, I am checking with the OnStep group.?
After unplugging the DEC cable I got this image of Andromeda by Moonlight.? I don't think I can salvage the colors but what matters is that the stars are very crisp and round.? ?G11S with OnStep and DIY SL Worms unguided, Fuji X-a1 @ 6400 ISO, 178x30s lights, 24 flats, DSS (stack+edit).
I can't get the image any larger maybe there's a limit so just take my word for it.? Thanks for looking.
-- Brian?
Brian Valente portfolio
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Wow nice Brian!? Even when I load up the full resolution, when clicking on the attachment it is still only 1024 times something.
I figured I'll wait until the Moon is gone, my main goal was to test the equipment.
I am stoked about how well everything worked though while not even trying hard.
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Henk,
That is a very wonky system done long ago by others and found wanting in reliability and consistency. But I offer you a much better solution here for the insult.
It looks like you have already drilled and tapped the worm cover to hold the worm bearing blocks in place, if this is true you will get better consistency by installing a in the outer bearing block using the well proven methods of either reducing the 4RZZ bearing's outer shell OD just enough to allow the bearing to float in the outer bearing block or by honing the outer bearing block enough to do the same thing, floating the bearings on a layer of fine lube, both work well. The Belleville spring disc is oriented with the large cone pressing on the worm bearing outer shell, you may need to put a shim under the small cone to get some preload depending on your particular outer bearing block cavity. Next you snug down the fasteners to tie the blocks firmly in the worm cover now acting as a bearing block carrier and at this point your worm should have zero endplay in the carrier and the entire assembly should behave as a solid single piece. You can stop here and you will have a massively improved worm carrier system and then just adjust the backlash on the mount after it has been chilled outside on a cold night in the usual way.??
But this next step should get you pretty close to where those with sprung gen II OPWs are. Your mount appears to have a drilled and tapped hole in the deck/base plate in line with the outer bearing block. If this hole has been drilled and tapped all the way through to the outer bearing block post you might find a to fit the tapped hole to make this setup behave as a spring loaded loaded worm system. The spring plunger if you find one small enough yet long enough would act on the outer bearing block post in the hole preloading the now mechanically bridged bearing blocks. You would need to use a fine grease under both blocks and under the bottom cap screws and set the cap screws the tiniest bit loose to allow the 0.001-0.002" movement needed to float the worm, it should not be loose but just able to move in and out. You will also want to use a mild thread adhesive on the retaining cap screws. If you cannot find a spring plunger small enough, I don't know the hole and thread size, you can in essence make your own by using a short piece of solid SS rod with an OD to closely fit the threaded hole and chased by a small block of rubber and caped with a long inside hex cap screw for an adjuster. Again you only need to allow 0.001"-0.002" of movement so this should be nearly as effective as the real spring OPWs.?
Cheers!
--
Chip Louie Chief Daydreamer Imagination Hardware?
? ?Astropheric Weather Forecast - South Pasadena, CA?
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I think I understand what you mean Chip, relative to the rotation axis, tangential pressure by the Belleville washer and radial pressure by a spring plunger.? It seems like part 1 requires the outer block to be in a fixed position by attaching it to the cover, while part 2 requires the outer block to be movable.? I did not quite get that part, a verbal description can do so much.?
Regardless, I'm not ready for placing McMaster-Carr orders.? What I have works, it's non-destructive and I had fun doing it. And I took the sharpest image I ever took, with it BTW.? I could change it to a sheet metal brace that encloses a tangential spring for perpendicular pressure instead of pulling on a screw.
In the end, using the worm cover for spring loading is an afterthought and a kludge.? That worm cover has 4 screws that need to be positioned carefully, and that also serve to protect the motor couplings from being pulled on.? I just spent over an hour getting the RA motors attached and having the the worm positioned such that it moves freely.? The aluminum flexible couplers that I use make the tolerances even tighter.? It is enough trouble by itself let alone adding a loaded spring in the mix.? A good spring loaded worm system should be designed up front and center so it can be installed and adjusted independently of the other parts.
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I found and fixed the DEC movement bug in my OnStep system.? I had assigned the DEC step pin to the same pin used for LED controls.? As a result, every time the LED was blinked, it turned my DEC motor instead.? Redefining the LED pin fixed it so I can declare victory on the OnStep front, everything seems to be working quite well as far as I can tell. I created an album for the image I described earlier in this thread, at least it shows the same resolution as the image on my laptop.? I can't get it to show properly otherwise so? here's the link.? Again I'm very pleased with the stars especially as it was unguided.? I hope to take many good images with my G11S now that it works well.
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Hi JoAnn,
I've built an old MiniPCB for a GM-8 owner. I have to make up cables for the mount's Hursts. Can you give me the pin-outs you used to connect yours? I only have a Hurst without the RJ-12 connector. Also did you wire half or full coil?
Thanks, George
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Henk,
How did you get the RJ couplers open? I tried to find a way, but they beat me.
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Lol, I broke the first one open with a screw driver just to see how the innards held everything together.? While doing that I noticed one side had slid off without me deliberately doing that.? Then I found that it's a matter of continuous massaging from the outside to get them to open up.
With the pins sticking out I wiggled 2 strips of inner bicycle tube between them to separate them in pairs and soldered on that.? ?The only way to keep the plastic from melting and keep the pairs of wire in place and separated.
I also used them for my OnStep controller but there I did not have to open them.? I glued them on the Pi to hold them in place.
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Henk,
Thanks for sharing your description and photos of your innovations.
Marc Aragnou also created his own SLW.? He is in Australia could not send his G11 in to the factory for the SLW addition, as shipping cost would be prohibitive.??
So he did this: he made a hole like you show in your photos just under the right side worm block....he put in a bolt and used his existing OPW's back off screw hole,? and used its metal vertical down tab, then used rubber ORings or rubber washers to act as a spring to push the far block into the ring gear.? The design of the OPW makes this possible.
As he already has an OPW that has the downward back off bolt ...he removed that small bolt and used that existing downward tab.??
I didn't see an easy way to accomplish this without an OPW.? But maybe your photos show a possible way to do it from a hole added to the front or below the mounting flange, and a metal bracket.?
Anyway... there is room for clever advancements.??
Thanks again,
Michael
On Wed, Sep 23, 2020, 9:29 AM Henk Aling < haling@...> wrote: This morning while the coffee was brewing I fashioned my own spring loaded worms.? The materials:
- Rubber bands cut from an old road bicycle inner tube.? This kind of rubber is very resilient, do not use household rubber bands.
- A strip of sheet metal about 1 cm wide and 5 cm long, just guessing, cut with tin snips.
Installation steps:
- Loosen the outer worm block by loosening two screws:
- The screw at the bottom of the frame that the block is mounted on, just slightly so there is little vertical play.
- The screw on the housing, this can be loosened a bit more.
- Wrap the rubber band twice around the screws at the bottom.? This should provide quite a bit of tangential force that pushes the outer worm block towards the motor side.
- Fashion the sheet metal to wrap around the rear edge of the housing and around to provide slight pressure on the housing screw.? This screw is directly screwed into the worm block so it provides slight lateral pressure inward that keeps the worm engaged without slack.? You can vary the pressure by positioning the screw, or simply bend it a bit more or less.? Not much pressure is required.
- I should note that I don't use the Oldham couplers but flexible aluminum shaft couplings for stepper motors.? These couplers also provide some pressure but I think this should work with the Oldham couplers just as well.
I did this for both RA and DEC and slewed both around at full speed with my OnStep controller.? It seems to work fine, frankly.??I can't wait to try it out under the stars once the fog stops rolling in.? Here are some pictures:
The first 4 pictures are of the DEC worm block:
I only have one picture of RA, all you can see the rubber band and a glimpse of the sheet metal spring.? The other RA pictures were blurry.
As an aside, here's my OnStep controller to the right.? It's a Wemos R32 with a CNC v3 shield.? The Raspberry Pi 2B running Kstars and Ekos (client and server) is to the left.? I run it with 0.9 degree steppers with TMC2130 controllers with SPI for slewing at full step, microstepping 16x for tracking.? I start out using my Android cell phone as a remote over Bluetooth for alignment, then continue with Ekos and Kstars for tracking, guiding, plate solving, etcetera, remotely logged from my Galaxy Tab A with VNC.
I'll duck for cover now.? I've been on this board long enough to know what's coming, so fire away...
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Chip Louie
Michael Herman