Topics

OnStep on my G11S


Henk Aling
 

I mounted the controller, Wemos R32/CNCv3/TMC2130,  on my G11S.  With my Pi it is strapped on a plank that fits in the original controller location of the G11S.  The system works beautifully.  It slews at 4 degrees per second, tracks so quietly and silently I can't even hear it and have to watch it spin the worm very slowly to convince myself that it works. 

Here's a photo.  I like this open setup for now just in case I need to fix something but will be thinking about an enclosure.



I have not taken it under the stars because tonight there are none.  Today we were covered in the haze of fires all day.  It was very warm and as humid as in a sauna, then the fog rolled in too from the ocean.

Maybe I will order another Wemos R32 with a USB micro instead of USB-B, it's a big cable and the connector hits the top board.  I isolated it with some tape.  The height of the 2 boards plus driver pin base plus drivers plus heat sink is about 2 inches, more than I like.  I am wondering if I should use a plain Arduino development shield.to solder everything on and replace the CNCv3 with it.  But, this works now, I am ready to take it out under the stars.


Mike Wagner
 

Very cool! What motors and couplers did you end up going with? Can you get a picture of the mounting you did for that?

I have had my system out under the stars twice but waiting for better couplers.

Also, you might want to think about the board having a cover, just to keep away any dew. 

Pretty exciting to see your set up up and running!

Mike


Alexander Varakin
 

Very nice! 
I would keep the USB connector as is - USB micro is very flimsy. 


Henk Aling
 

I am using "Nema 17 Bipolar 1.8deg 60Ncm (85oz.in) 0.64A 10V 42x42x60mm 4 Wires".  I may get some 400 step motors though depending on how it goes.

Here's a picture of the mounting:


Mike Wagner
 

That looks pretty good. Your motor mounts seem a little thin, are they 3d printed?

I designed a version of Howard's mount that is thicker and houses the RJ45 breakout boards. The housing for the breakout is against the underside of the base plate so that gives it extra stability.

Will post up some pictures of mine as well since I just got the bellows couplers :)

Mike


Howard Dutton
 

When you build a Max series controller (MaxPCB2 etc.) the FreeCAD files (Files area here on the group) are setup allow creating STL's for 3D printing case panels that allow attaching the controller to the G11 using the factory mounts that came with my 492 Digital Drive.  The little white box is the BME280 ambient TPH... newer Max version 3.6 controllers will allow that sensor to be wired into the DB15 connector on the other side (prior to 3.6 the Max uses a DB9 that often doesn't bring out I2C.)  The Max PCB slides into the aluminum case which is an eBay item that costs me about $12 delivered.  Each of those DIN socket/plug sets were more than that.


Henk Aling
 

That looks pretty good. Your motor mounts seem a little thin, are they 3d printed?
They are made of steel not plastic, and are rock solid.

The mounting is inherited fro  my previous kit although I replaced the motors with larger ones (and will replace them again).  The older ones simply had crimped rubber around them, that's an easy and nice solution that I will look into some day.


Butchf
 

Very nice and clean, Good Job.


Henk Aling
 

When you build a Max series controller (MaxPCB2 etc.) the FreeCAD files (Files area here on the group) are setup allow creating STL's for 3D printing case panels that allow attaching the controller to the G11 using the factory mounts that came with my 492 Digital Drive.  The little white box is the BME280 ambient TPH... newer Max version 3.6 controllers will allow that sensor to be wired into the DB15 connector on the other side (prior to 3.6 the Max uses a DB9 that often doesn't bring out I2C.)  The Max PCB slides into the aluminum case which is an eBay item that costs me about $12 delivered.  Each of those DIN socket/plug sets were more than that.
That looks great but I like the DIY look with the Pi running Ekos included, it is a personal touch and will be a topic of conversation. Meanwhile I glued the RJ45 connectors on the Pi and pinned the parts in place on the plank with screws.  I may add a simple enclosure like a transparent plastic one or one of cardboard sealed with red duct tape.

About the Max PCB, it has parts that I don't need such as Wifi (I prefer Bluetooth since I control it from Android, and an access point is a hassle), I  don't  need the RTC / EEPROM (if I want one, my Teensy 4.0 has it, the Wemos perhaps too, but really Ekos passes the time in), and I don't need ST4.  I kind of like the COTS idea.

There's a mechanical problem though, my crown wheel still gets stuck in some places especially when slewing at high speed so some day I need to visit Losmandy and see what can be done about it.  If I turn it super loose it won't get stuck but I have too much play, which causes nasty resonances.  Before that I need to try 400 step motors, see if that helps.


Mike Wagner
 

I had a similar problem , i would get stalled motors at higher slew speeds. slow speeds it was fine. 

I just put a 24v power supply on mine and can slew at higher speeds with no stalling. i have it at about 3.5 degrees/sec with 50 pounds of scope and 50 lbs of counterweights.

Oh, also one other thing - my couplers i had originally i turned down to fit - but the one i did not turn down quite far enough, so it rubbed on the worm block ever so slightly - check for that too. I'd also check that your motor shafts and the worms line up very closely - the brackets out of the files section were slightly offset for my mount, making the couplers bend more than they should have. this makes the motors work harder, introduces PE, and can make the collars fail (mine did) the good couplers i have no state the parallel misalignment can be like .1 mm or something like that - I printed up custom mounts on my printer, but you could slot the mounting holes too.

For your case, you could make yourself a set of sides with a slot, then you could put a piece of clear plexi or acrylic in there so you could still see everything, which would be cool. I use my CNC router to cut out some arms that hold my control box on the mount. the oak with the boiled linseed oil looks nice against the mount. If you had a clear cover you could add some extra red led's so you could see it and show it of in the dark. Might prevent you stubbing your toe on the tripod.  :)

Mike


Henk Aling
 

On Fri, Sep 11, 2020 at 10:40 AM, Butchf wrote:
Very nice and clean, Good Job.
You must be referring to Howard's box, not mine lol.  Thanks for chiming in though!


Henk Aling
 

I had a similar problem , i would get stalled motors at higher slew speeds. slow speeds it was fine. I just put a 24v power supply on mine and can slew at higher speeds with no stalling. i have it at about 3.5 degrees/sec with 50 pounds of scope and 50 lbs of counterweights.
Thanks that's good information.  I ordered the 0.9 degree steppers recommended by Khalid, let me see what happens when they get here in a week.

Oh, also one other thing - my couplers i had originally i turned down to fit - but the one i did not turn down quite far enough, so it rubbed on the worm block ever so slightly - check for that too.
I checked the couplers, they are not rubbing against the worm blocks.

I'd also check that your motor shafts and the worms line up very closely - the brackets out of the files section were slightly offset for my mount, making the couplers bend more than they should have. this makes the motors work harder, introduces PE, and can make the collars fail (mine did) the good couplers i have no state the parallel misalignment can be like .1 mm or something like that - I printed up custom mounts on my printer, but you could slot the mounting holes too.
I have flex couplers that seem to line up OK but I am not betting it's 0.1 mm accurate.

For your case, you could make yourself a set of sides with a slot, then you could put a piece of clear plexi or acrylic in there so you could still see everything, which would be cool. I use my CNC router to cut out some arms that hold my control box on the mount. the oak with the boiled linseed oil looks nice against the mount. If you had a clear cover you could add some extra red led's so you could see it and show it of in the dark. Might prevent you stubbing your toe on the tripod.  :)Mike
I have a case now, made from a biscotti container, see below.  It feels sufficiently strong to protect it.  I simply left the front open for the connectors.  It looks finished enough for me.

Still waiting for the smoke clouds to go away so I can show some results...




Mike Wagner
 

I like your case, very clever and simple!

Let is know if slowing the motors stops your stalling, if it runs well but slow that’s still pretty good.

i just had mine out Friday night. Guiding was ok, using a 400mm guide scope with a 10” SCT is not the best combo but work alright. Have some tweaking I can still do.

hope the skies clear up for you soon

Mike
Mike