I am working on building my own MaxSTM v3. I know I will have more questions as I build, so hope this can be that thread.

My current question is around the "Stepper driver section". I don't see which resistors to use. I bought all of my resistors, capacitors, and other parts from LCSC. 

These are the stepper motors I bought:

• 2 x "3D MKS TMC2130 Stepper Motor Driver+Heatsink With Sticker Reprap" from ebay (https://www.ebay.com/itm/142753579926?var=441756660926)
• 2x "TMC5160 V1.2 SPI Stepper Motor Driver S5160 Stepstick Mute Driver Flying Wire" (https://www.ebay.com/itm/184428066147)

The questions I have are

1. Do I need to add the R19, R20 resistors? If I do, I am not certain which ones to use. Any drawback adding them anyway?
2. For some reason, my TMC2130 had 4 pins on top. I flipped them over so they are all pointing downwards. The ebay listing showed them pointing down.
3. I also don't seem to see any stl's that I can use to 3d print a case. I tried printing a few that I thought were it, but they didn't fit. Maybe I missed something.

I should also add, I am building this: https://onstep.groups.io/g/main/wiki/26597

I bought some PCB boards from LCSC. I had to buy them in a set of 5. 

here are some pictures.

On Sun, Mar 6, 2022 at 12:41 PM, Sam S. wrote:

Do I need to add the R19, R20 resistors? If I do, I am not certain which ones to use. Any drawback adding them anyway?

No drawback to adding them, but not needed.

From the MaxSTM3.6 Wiki:

Two resistors R19 and R20 are to pull the DCO/CLK pin of TMC5160 drivers low so you can use any TMC5160 without modification.  If using TMC5160's where you are sure the DCO/CLK pin is already pulled low (Bigtree TMC5160 v1.2) or TMC2130's you can omit these resistors.  Solder where indicated, there is no polarity.

On Mon, Mar 7, 2022 at 03:11 AM, Howard Dutton wrote:

No drawback to adding them, but not needed.

Sorry, that TMC5160 stepper driver actually does need those resistors.

On Mon, Mar 7, 2022 at 03:11 AM, Howard Dutton wrote:

If I do, I am not certain which ones to use.

As for which ones they are 1/8 watt 4.7K Ohm, any resistor close to that will work, not critical.

On Sun, Mar 6, 2022 at 12:41 PM, Sam S. wrote:

I also don't seem to see any stl's that I can use to 3d print a case. I tried printing a few that I thought were it, but they didn't fit. Maybe I missed something.

Guess I never got around to designing that front panel.  I made it up this morning though, pretty sure it'll be ok (if not let me know.)  Its in the Files section:
https://onstep.groups.io/g/main/files/3D-printables/Board%20enclosures%20%28Cases%29/MaxSTM%20Version%203.6%20panels

For the buzzer. I'm using an active buzzer. It says I can ditch the resistor and use a wire. It also said I could omit the diode.  Does this mean to also just replace the diode with a wire?  any issues if I use the diode anyway?

On Mon, Mar 21, 2022 at 05:41 PM, Sam S. wrote:

Does this mean to also just replace the diode with a wire?  any issues if I use the diode anyway?

No, omit the diode or leave it is fine, but adding a wire there would be bad (shorting the pin to ground!)

I had put this project on hold, but I'm back on it now.  I actually 3D printed some parts and mounted 2 planetary gears with gt2 pulleys.

I'm in the process of printing a case for the device, along with the face plates provided by Howard.

I'll post a few pictures.

1. I need to figure out how to wire the planetary gears into the MaxSTM. I have the ethernet type connectors on the board.
2. I need to figure out how to install the firmware.

I'm sure I'll have some questions as well.

I am reading through the firmware update section. It's a bit overwhelming.
1) It is recommended to use OnStepX vs OnStep?

I am going through the spreadsheet to try and figure out the numbers to use on the online tool to produce a Configuration.h file.
2) Is this same file used in OnStepX?

I am also trying to understand the numbers that I need. I am pretty much using the exact items on the wiki for the build.
Axis 1 & 2 us using "TMC5160" and "Nema 17 Stepper Motor L=39mm Gear Ratio 100:1 High Precision Planetary Gearbox" for motors.

The stepper motors say they have 256 native microsteps
3) Should the spreadsheet numbers for microsteps be 64, which is the max allowed?

I don't know what "stepper-steps" should be. default has it as 400 on the spreadsheet.

I also am not too sure what to put in the gear reduction columns. 
What I have is a 20 tooth gt2 pulley on both of the gearboxes. 
The base rotates (Azimuth?) on a lazy suzan (VERY smooth) with a 120 Teeth gt2 pulley.  I connect these with a timing belt.
The tube movement (Altitude?) has a timing belt set up as well. it's not really a gt2 pulley, but instead a half circle, where I wrap the timing belt around. In essence, it's a gt2 pulley with way more teeth. I need to figure out that number. but a quick rough count makes it be around a 400 tooth pulley. You can see the piece here: https://www.thingiverse.com/thing:1350940.

I need some help with the values, and where they go. I am not sure what the "slew rate" number is.

 

A few photos of how my build is going. I 3D printed a case and used the panels provided here .

Curious if anyone has set up a dobsonian with planetary gears lately that could help me out?

Thanks,

No, I have not finished it.  I am still trying to finish the configuration.  I'm not sure what values to set.

My planetary gears are 100:1.  I assume that "GR1 Ratio = 100" for both?

For "GR2 Ratio", I have 24 for the big one, and 14 for the smaller one.  I calculated these measurements by measuring the outer radius and divided it by the inner radius of the gears. not sure if that's right.   Maybe it should be the ratio between how many teeth the planetary gear has vs the bigger outer gear (or the one used for left/right movement) ??

This is what I have so far.  

Maybe I'm calculating things wrong.  Here' more info.

each planetary gear has a 100:1 ratio

each planetary gear has a 20T pulley on them.

Azimuth gear has 120T.

Altitude gear has about 380T.  I could be off by a few teeth here because it's not really a pulley... it's more like a guide for a tooth belt.. you can see the photos up top. I tried to find where 1/4 of the full rotation would be, then laid some belt and counted how many teeth. i then multiplied it by 4.

correct. I have teethed pulleys, with a belt connecting them.  the motors have 20 teeth.   then one has 120 teeth.... the other has 380 teeth.

seems like I need to have axis1 GR2 as 6, and axis2 GR2 as 19?

I am also having issues even uploading my firmware to my Blackpill F411CE. It's very frustrating... getting "Write failed at address: 0x8000000 "