High loadable turntable

[WalterMo]

This turntable is the Goliath among the other tables which I had posted before:
viewtopic.php?f=6&t=2383
viewtopic.php?f=6&t=4291

It can withstand loads up to 200kg (per producer). But I never have tested the table with such high loads, only up to about 20kg. The (static) load is one thing, the other is that the mass also must be acceletated (against the inertia). Therefore I have implemented acceleration and deceleration ramps of the stepper motor speed.

The gear ring and its carrier ring are mounted together to one device. They are made of a very stable plastic. The upper ring is mechanically assisted by a lot of steel balls:

http://www.ebay.de/itm/Kugellenkkranz-L ... 43c73a7e13

The stepper motor with a planetary gear came from here:
http://nodna.de/nema-17-planetary-518-1-stepper-motor

The black plastic box for the motor is this:
http://www.conrad.de/ce/de/product/5384 ... 1GSBK-1-St

A cogwheel (it comes with the rings unit) is mounted at the gear's output shaft to drive the gear ring. An advantage is that the motor is lying horizontally, so the total height of the device is rather low.

Dimensions: Diameter of the platter: 280mm, overall height: 63mm.
Further specifications:
gear ring: 139 cogs
pinion: 24 cogs
gear ratio ( table gear ring / pinion): 5.79 / 1
gear ratio (motor / planetary gear): 5.1818 / 1
motor driver board: Pololu A4988 (¼ micro step mode)
platter: aluminium, 5mm thick
square plate: 300 x 300 mm, aluminium, 5mm thick
controller: Arduino Uno
power supply: 9V wall wart

Walter

[JDM Dyno]

looks very good Walter


be interesting to see how much It will take without stripping the plastic gears

I've done this one and tested with over 70 kg, turns ok but need a lower gearing to stop it wobbling when it stops turning, only 2:1 at the moment, I was going to put acceleration and deceleration on to help to.

its a bit ruff at the moment but just testing with things I have already, mostly scrap

[hunkatibor2]

Hi Walter
Worthy, precise and beautiful solution.
Tibor

[Jokeri]

Hello Waltermo!

Can you share the code please!

I wish that you posted this sooner!

This is what I ordered

Thanks,
TT

[WalterMo]

The controller hardware (circuit diagram) is very similar to this:
download/file.php?id=6825&mode=view
I forgot to draw in two 1kOhm resistors. Each from the input pins 6 and 7 of the Arduino to 5 Volts. The resistor R3 is optional, for details see my first post here:
viewtopic.php?f=6&t=4291

Only the inputs MS1 and MS2 of the Pololu for micro stepping are a bit different. Means the switch for MS1 = off and for MS2 = on. Don't forget to glue a small heatsink on the Pololu IC. And add a little fan if necessary.
And here is the code:

Edit: Version Leo3_3 doesn't need the two mentioned above resistors. Regarding resistors: There are only 2 resistors at the angle increment switch necessary. See the attached circuit diagram.

[WalterMo]

be interesting to see how much It will take without stripping the plastic gears

I think stripping (ablating) will not be a problem. The plastic of the cog ring is rather hard and the pinion is made of a tough (doughy) plastic (acetate, Delrin). And it will not be used for hours like a „normal“ gear.
A disadvantage is that the toothing is a bit coarse.

[micr0]

Thanks WalterMo.

I've been building a 2ax trunnion that is big enough to hold engine parts for scanning. I'm waiting on the second stepper and drive, and to finish the control panel design, but here are a few pictures of my current progress. I designed to be easily disassembled and laid flat in a storage case.

µ

Youtube video:
http://youtu.be/ndq9JPo3YVI

[JDM Dyno]

looking really good micr0

was thinking of something like that myself https://www.youtube.com/watch?v=HfuM0xw ... DA9BA6D3A5

check out this video to, at about 3 minuets it gives the price

https://www.youtube.com/watch?v=4AypqqyBTWg

[WalterMo]

For those who need a more powerful stepping motor driver board.

Here it is. It has the Toshiba-IC TB6560 AHQ on board which can drive a peak current up to 3.5 A per motor phase. It's coming from China but you can also buy it in Berlin, Germany:
http://www.ebay.de/itm/SainSmart-CNC-Ro ... AQ:DE:1123

Maybe it's even possible to beat down its price. Anyway they offer a price proposal.

It is easy to use, similar to the Pololu A4988. But it has some more features which can simply be adjusted by mini switches. And it is mounted on a sufficiently big heatsink.
Unfortunately it doesn't has the possibility to choose 1/4 step mode, only 1/1, 1/2, 1/8 and 1/16. I mention this because my Arduino code 'Turntable_Leo3_3' some posts above was programmed for 1/4 step mode.

[ThomasSc]

This is my rotation axis.

And the ino:

#include <AccelStepper.h>

// Define a stepper and the pins it will use

AccelStepper stepper(1, 3, 2);

#define STEP_PIN 3
#define DIR_PIN 2

int pos = 1600; // steps pro round (1600, 1/8 step)
int i = 6; // gear ratio
int val; //Variable to store the content of the COM port
int count = 0; // Variable to count the scans
int limit = 16; // Means the number of scans/round

void setup(){
pinMode(DIR_PIN, OUTPUT);
pinMode(STEP_PIN, OUTPUT);

stepper.setMaxSpeed(10000);
stepper.setAcceleration(5000);

Serial.begin(9600); // set up Serial library at 9600 bps
}

void loop(){
if (Serial.available() > 0) {
val = Serial.read(); // read if theres a message in the port and store it in the communication variable
}
if (val == 'T' && count < limit){

delay(500); // pause
stepper.move(pos*i/limit); // = deg

count +=1;
}
if (val == '2' && count > 0 && count < limit){
Serial.println("S"); // Triggers the next scan when DAVID has sent its "ready" message
}
if (val == '2' && count == limit){
count = 0; //Just to reset things when you finished a whole round
}
if (val == '1'){
count = 0; //To reset the counter after a faulty try switch to DAVID#s Calibration mode and return to ScanningMode
}
val = 0; // To refresh the COM port input

stepper.run();

}

[micr0]

For those who need a more powerful stepping motor driver board.

Here it is. It has the Toshiba-IC TB6560 AHQ on board which can drive a peak current up to 3.5 A per motor phase. It's coming from China but you can also buy it in Berlin, Germany:
http://www.ebay.de/itm/SainSmart-CNC-Ro ... AQ:DE:1123

Maybe it's even possible to beat down its price.

It is easy to use, similar to the Pololu A4988. But it has some more features which can simply be adjusted by mini switches. And it is mounted on a sufficiently big heatsink.
Unfortunately it doesn't has the possibility to choose 1/4 step mode, only 1/1, 1/2, 1/8 and 1/16. I mention this because my Arduino code Turntable_Leo3_3 some posts above was programmed for 1/4 step mode.

Thanks Walter.

I've been using steppers and drives from these guys: http://www.wantmotor.com/ again from china (available on ebay) but the shipping is pretty quick and the prices are reasonable.
I'm using one of their power supplies and one NEMA 43 and 23 stepper with drivers for my trunnion and they work well.

FWIW I'm using a fairly large NEMA 34 with a 4:1 reduction mostly for the holding power as a number of the pieces I've been working with are hard to mount with the center of mass near the center of rotation.

µ

P.S.
Thank you for the leo3 code. I'm trying to adapt it to do 2ax. I'll post it if/when I get it working.

[WalterMo]

Hi micr0,

3 years ago I had built a 2 axis positioner:
viewtopic.php?f=6&t=4154

Maybe you can take some ideas from the design/code. There are 2 pins free on the Arduino Uno for your special modification.

I have just looked on ThomasSc's design and code (2 posts above). He is already using the powerful motor driver from SainSmart. And I thought I would be the very first user/pioneer on this forum.

Thomas has used an elegant way to program the code. Simply by calling up the Arduino pre-built library 'AccelStepper'. I didn't know it before.
This subroutine contains already accelelation and deceleration for the motor speed.

Walter

[micr0]

Hi micr0,

3 years ago I had built a 2 axis positioner:
viewtopic.php?f=6&t=4154

Maybe you can take some ideas from the design/code. There are 2 pins free on the Arduino Uno for your special modification.

I have just looked on ThomasSc's design and code (2 posts above). He is already using the powerful motor driver from SainSmart. And I thought I would be the very first user/pioneer on this forum.

Thomas has used an elegant way to program the code. Simply by calling up the Arduino pre-built library 'AccelStepper'. I didn't know it before.
This subroutine contains already accelelation and deceleration for the motor speed.

Walter

I was going to use accelstepper.h which I do have installed, but was having a bit of trouble getting my code together without having to get through the accelstepper documentation and try to incorporate those unfamiliar structures. I planned to get there eventually but I wanted to make something that was a bit more universal. I had the same problem with the addafruit motorshield (which I also happen to have. Thomas's code is very simple and I do understand what he did there. I just haven't gotten to that point yet. That said i probably should rethink that.

µ

[micr0]

Over the weekend I started building the control pendant for my turntable. I wired it very similarly to Walters original 2 axis table. The most notable exception being that I replaced the 3 position angle increment switch with a 6 position rotary switch to give a greater range of angle selections. After designing and building everything I realized I should have used a 20x4 LCD display instead of the 16x2 and the next iteration that is what I plan to do. I'm starting to work on the code and I'll post that when I get there. Right now I finished testing all the hardware with the help of a little sketch that returns pin values to the serial monitor. the only hardware problem is that the back light on the LCD isn't working but everything else seems to check out.

Here's the serial monitor"

Code: Select all

void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}

void loop() {
  // read the input on analog pin:
  int sensorValue = analogRead(A3);
  // Convert the analog reading to a voltage (0 - 5V):
  float voltage = sensorValue * (5.0 / 1023.0);
  // Send the value to the serial monitor:
  Serial.println(voltage);
}

One of the rotary switches. 5) 1K resistors allow the voltage to be divided by 1v increments to 0.

You cant see it but it is displaying Walters welcome message.

[JDM Dyno]

like the panel very cool

I have a 128 x 64 lcd that I am going to use if I get time, already done an ECU display with one and a Haldex controller with another with arduino