Arduino Rotary Table for Dummies

[dnalot]

OK

Well the number one mark on my keypad when wired to the number 11 terminal on the arduino did not work so I reversed all 8 wires and the unit now responds correctly.

 

[dnalot]

OK, powered up and the motor is moving. Now I just need to calibrate my setup.

I have mounted a group 17 stepper motor with a 27-1 reduction that turns a 2.5 - 1 belt drive reduction that turns my indexer. To make it a bit more difficult its not an even 27 to 1 on the gearbox, but 26 with a fraction of 103 over 121 to 1

The drive system has .4 degree of backlash but that should not be a problem as I can manually press on the belt before locking the indexer with its locking screw.

I still have the current set to its minim value at 12 V without losing steps so the motor should easily be able to do the job.

Next step will have to wait till tomorrow as today is my 67th birthday and I have to party with friends and family.

Mark T

 

[bmac2]

Well happy birthday Mark! :thumbup:
Glad it worked out.

 

[dnalot]

OK. I have a small problem in that my geared stepper motor does not give me a whole number for the reduction and the sketch does not accept numbers with a decimal place. My reduction comes out to 67.1281. To overcome this problem I lied and entered 404 steps per revolution of the motor in place of the actual 400 steps. This gets me very very close to a full 360 at the indexer when I command a 360 degree movement. I think the system will work as long as I don't make more than one revolution of the indexer. I will need to cut a gear to find out.

I will post photos when I get the electronics mounted in a box.

Mark T

 

[bmac2]

I’ve corrected post #12 so it has the correct library.

 

[Maxmekker50]

Hi everyone here is my version Of rotary table in small box All honor to bob. Had some issues along the way. With programming problems, etc. Seeing there are several who have had problems researching it a bit and just looking like it may have been awkward in some wires. But now happy and everything seems as it should. And again big thanks to bob

Link for CHINA ARDUINO DRIVER ; http://0xcf.com/2015/03/13/chinese-arduinos-with-ch340-ch341-serial-usb-chip-on-os-x-yosemite/


link to box: https://www.aliexpress.com/item/Fre...32717034004.html?spm=2114.13010608.0.0.hjyaKH

 

[bmac2]

Looks good Max. I like that project box and good call on not getting the white one .

How do you find Aliexpress? When I first heard of them I couldn’t believe the prices and placed a small test order (4 items in 4 different categories) to try them out. The fastest arrived in 63 days and the last one took 4 months. That was back in March and I haven’t used them since.

Here in Canada something changed back in November and anything coming from China is taking 1 to 2 months to clear Canada Post.

 

[Maxmekker50]

HI bob I have used Import from china last 15 years When i ordere i ordere 10 pcs ore more and i collect all in one store and use dhl And get in 5 to 6 days
Some time i use the e shipping that take 14 days .

If bigger i use the seway on my lathe and mill i used seway take 39 days to norway . More pictures comming up now i convert the uno card and driver to wire up all in the box then pictures comming.

 

[chucketn]

I have a 3d printer coming in the mail. I'd like to print an enclosure for my setup(I built the same RT Controller and love it).

Chuck

 

[grapegro]

Hello Chuck,
I got mine in the post yesterday in kit form. It is an Anet A8 . It seems a very sound unit and am looking forward to using it. Norm

 

[bmac2]

Oh the 3D printer. Now there’s a sirens call that keeps niggling at the back of my brain.

 

[rodw]

I thought I'd just poke my nose in after reading about concerns regarding accuracy when dividing. You should not be using floating point maths anywhere because you will end up with accumulated rounding errors. It like using a micrometer with a coarse scale. Accuracy can not be better than 0.5 of the smallest division as I was taught and we had to accumulate the error +- the measuring unit when doing maths with such readings. It is far better to reduce everything to the smallest discrete unit you can measure. So if you measure divisions in seconds rather than the much coarser degree, a lot of problems go away. Others will appear though as you need to present the angle to the user. I chose to do this in degrees minutes and seconds.

So by working in smaller units you may only be one step out per division and if you want to go one step further to improve accuracy, you can add and subtract a step or two every alternate division to make the error go away by the time you get round the circle.

Finally, let me just say if you are old enough to remember programming on an 8 bit PC, using floating point maths was fraught with danger due to ongoing errors accumulated from converting to and from decimal numbers and hexadecimal numbers used internally in the machine architecture. 16 bit is not as bad but the issue is still there. Most accounting programs will use a binary coded decimal as the numerical unit to ensure accurate results. Regrettably, few programming languages support such a data type.

 

[dnalot]

Hi

Well after trying to fudge the numbers to get my indexer to work with an odd reduction without success, I gave up the idea of using a stepper motor with a gear box. Digging through my odds and ends box I came up with a 36 to 1 worm gear set. Coupled with the existing 2.5 to 1 timing belt reduction I came out with 90 to 1 reduction.

Note that when choosing a reduction your steps times your reduction must divide evenly by 360. I am using 200 steps per rotation, 90 to 1 reduction so 200 * 90 / 360 = 50, and that works. I tried using half steps 400 * 90 / 360 = 100 but that didn't work,


The worm gear has about the same amount of backlash as the stepper with a gearbox. To eliminate that I am using a counter weight. Will need to cast a better weight, the one in the photo is just to test the idea. Will also need to provide a second idler wheel to hold the weight off when the table is cranked all the way back.

The electronics as well as the 12 volt power supply were fitted inside a project box. The fitting for the 110 volt inlet also provided a fuse and an off on switch. To keep the box from heating up a 1.5” computer fan was installed in the backside of the box.

All and all I'm very pleased with the system.

Mark T

 

[chucketn]

Nice job, Mark. Can you share the source and specs of the project box? Is it perchance, 3d printed?

Chuck

 

[dnalot]

Hi Chucketn

Here is a link to amazon. com for the box. Note it took a few weeks to get

https://www.amazon.com/gp/product/B06XSMK61Q/?tag=skimlinks_replacement-20

And here is the link for the power inlet

https://www.amazon.com/gp/product/B00ME5YAPK/?tag=skimlinks_replacement-20

And the power supply

https://www.amazon.com/gp/product/B00UHI3NGS/?tag=skimlinks_replacement-20

Mark T

 

[chucketn]

Thanks, Mark. I asked because I also built an Arduino based set up and need a box to finish it off. I also just built a 3d printer and would like to print same.

Chuck

 

[Flopearedmule]

Bob, that is awesome! thanks for the lesson and example.
is there a way to tell the Arduino you want a specific number of index? say for example, you want 48 teeth....can you just type 48 in the LCD and it will figure out the angle to move? (7.5degrees)
Also, I PM'd you on a question I have with my project. I don't want to hijack your thread with my project.
thanks

 

[chucketn]

is there a way to tell the Arduino you want a specific number of index? say for example, you want 48 teeth....can you just type 48 in the LCD and it will figure out the angle to move? (7.5degrees)

The sketch allows selecting divisions or degrees, then you enter the value via the keypad. I built the same setup for my rotary table, but it's still rough. I need to print an enclosure and add a connector for the power and the stepper.

 

[billanygard]

Hello all of you!
Sometimes when you see something it says clonk in the head "That should i build".
This was such a thing.
Ordered missed components, draw a nice box and 3d printed it, hooked it up and its working.
BUT!
I use it for my 4th axels thing to my cnc router. 200steps/rot, beltgear 1:3 and it is impossible to get the controller to give the right steps. I need 1200 and get 1040. Fiddeling with numbers in the script only change between 1040 and 1440steps.

Any tips?

 

[Foozer]

Quick and Dirty for 1200 steps . . .
change line 'for(int i = 0; i < tm; i++)' to 'for(int i = 0; i < 1200; i++)'

steps [200] and table ratio [3:1] look to be too coarse for an accurate 'Multiplier' value.
Multiplier = (StepsPerRotation * TableRatio)/360;