Arduino indexer , full project

[rodw]

Pretty sweet build. Its cool for me to see how people use my controller. Awesome to see it working with the nano!

 

[stragenmitsuko]

Rod , I think it's cool that you make this software available for free . There are some issues with the nano , but I'll get to those later .

Stepper motors .
At first I had a beefier stepper in mind .
It fits the planetary gearbox , and it still , altough barely , clears the table when the dividing head
is tilted to 90°

This larger stepper however is a unipolair 6wire .
It can be driven by a bipolar driver if the centre wires not used .

The smaller stepper thatcame with the gearbox is an 8 wire motor .
Can be configured unipolar , bipolar series or bipolar parallel .
Each configuration has it's adavantages and disadvantages .

Unipolair is quite obsolete nowadays , it dates from back in the time when drivers and power transistors or fets were pretty expensive . It's the easiest and was the least expensive way to drive a motor , but it also has the least performance .

Bipolar series , and unipolar without using the centre wire , is used when a higher voltage is available , it needs less current then a bipolar parallel .Performance is better then unipoar , electronics are more complex .

Bipolar parallel can be used with less voltage but higher current .
If however a high voltage source is combined with a current controlled driver the torque and possible speed are at their highest levels . Best of both worlds in matter of speech . As both power supply and decent drivers are dirt cheap these days , the choice is easily made .
Bipolar parallel it is .


And then you have eight wires , without a clue wich is wich .

The connector is an ebay item so even if I had a datasheet that would be meaningless .

To figure it out all you really need is a couple of alligator clips .
First short any two wires and twist the motor shaft using thumb and index finger .
When you have shorted a pair , it will act as a brake and the shaft will be harder to twist .
Mark that pair or write down the colours .
Do this until you have found four pairs .

Next take any two pairs , wire them in parallel and short them .
The braking will be quite hard .
Reverse one of the pairs and short them again .Most likely that will have no effect .
That is not a matching pair . You have 12.5% chance of being right from the first time .

Repeat this with all of the pairs until you find a configuration where the braking effect goes away .

You have now found two matching pairs , and they are wired anti parallel .
Thus their magnetic fields work against each other and there is no or far less braking .
Thesame must be done with the other two pairs .
Does this make sense ?
It's easier done then trying to describe how to do it .

Once all wires determined I made a support for what round here is called an airplaine connector .
4 poles are needed , each pole has 2 wires soldered to it and heat shrink tube insulation .

I've made a little support for the connector and the wiring . Secures the wires , and makes it look good .

 

[stragenmitsuko]

A couple of pictures of the inside of the enclosure .

Many electronic projects fail due to poor wiring .
I know , been there done that got the t shirt .

It's understandable , the project is nearly finished , one is eager to use it and the wiring is done hastly .
Sooner or later something shorts out or comes loose .
Especially when mains voltage is inside ( we have 220v only ) mistakes can be hazardous .
So I took my time to solder it all , insulate it , make little looms of the 220 v wiring and secure them to the case .

Altough my enclosure has plenty of room , it is quite crowded in there ;
It holds everything . All I need to do is plug in a power cord and that's it .

 

[rodw]

Looks great. Be sure to use shielded cable and leave the shield unconnected at the motor end and connect it to frame ground at the other. With my plasma table where electrical noise can be a real issue, I used the same connectors except in a 5 pin version. That let me use one pin to pass the ground through into the control box so it could be earthed right at the stepper controller. But that is overkill here.

 

[stragenmitsuko]

This is how it looks when finished .

The enclosure had two rectangular holes on the left side and two round ones .
So I added three gauges . Not really needed but I did need a way to cover those holes .
The top gauge diplay's the stepper voltage , the middle one the current and the lower one the logic voltage .

Not needed , useless really , but it was all I could think of to close those holes apart from some kind of blind plate .

The centre heartsink is for the stepper driver . Again not needed , but once again it covers the two holes that were already there .

Having to deal with this is offcourse the downside of using used parts .

 

[stragenmitsuko]

Here we are , the arduino controlled indexer has made it's first chips .
A simple hex for a bolt , nothing fancy .

There are a few details left to take care of , and I still need to make that set of hook spanners , and once finished I will make a decent wooden box for it .

 

[stragenmitsuko]

Rod , I noticed you have a version 11 now .
Does it more then add support for the dfrobotshield ?
I made my buttons with the right 2K resistor , so it's compatible with the original .

 

[stragenmitsuko]

A couple of hook wrenches , made on the rotary table and welded together .

I lik working with a rotary table .
The hand crancking of the table gives a feel much like free hand turning on a lathe .
It's different from "just engaging the power feed ".
It can also be quite challenging to clamp the parts . So if it doens't have to be down to the micron precise , I use a piece of wood to hold the part . Woodscrews are added and removed as the cutter advances .
Light cuts only . Nothing agressive !

The body being milled .

A 14mm round welded to the body , and a modified M8 bolt acts as a pin .

Pretty good fit

 

[stragenmitsuko]

It's important that the centreline of the pin and the centreline of the handle more or less intersect at the centre of the disk they are used on .
At least , that is what I can measure from existing commercial hook wrenches .
The angle between hook and handle seems to be 135 a 140° .
So I kept those measurements and adapted the dimensions to fit my chuck and backplate .
Backplate is 100mm , chuck is 112 mm .

The handle is 13mm tubing with an aluminium plug pressed in on both ends .

 

[rodw]

Rod , I noticed you have a version 11 now .
Does it more then add support for the dfrobotshield ?
I made my buttons with the right 2K resistor , so it's compatible with the original .

V 11 just fixes loss of steps on indexing mentioned in the download thread and supports for the DFROBOT shield which i am using on one machine. It had a bit of an upgrade in the last week as I think I got something wrong.

 

[stragenmitsuko]

I see , so I uploaded V11 . Luckily the eeprom content is'n erased by this so I could use the stored parameters ;

Today , altough I promised myself I wouldn't until everything was finished , I started milling the 22T gears .

First a test on a piece of scrap , wich turned out great . Then the two hybrid nylon/aluminium gears that ought
to take care of the problem onace and for all .

Guys , this device is so sweat . No more counting crank turns , no more "did I already move the scissors or not " , no math
needed anymore to calculate the nr of turns ..
Just a press of a button . I was kinda dissapointed I had no more gears to make once the third one was finished .

I can highly recomend this project to anyone who needs dividing whatever . It's well worth the time and investement .

Couple of pictures

This is a test piece .

The "real items "
Up right my test gear ;
Up left an new 3d printed one .
Lower two are the originals . I needed to keep the core because I can't reproduce the internal gearing . So I turned the broken gears down , and pressed/ loctited and bolted a ring to them .
I'm sure that will be the end of the window regulator problem . Unless the larger gears will now start to fail . We'll see ....

Rod another thumbs up and big thank you for making this software available .

 

[rodw]

Thanks for the thumbs up!