# CNC 4th Axis



## Alexander (Feb 3, 2019)

I want to start a build thread for my stepper controlled rotary table.  This will be a copy of the @Johnwa rotary indexer project. I have attached a photo so you can see what i am talking about.
I could definitely use some pointers on the design.


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## Alexander (Feb 3, 2019)

This is the block i will use to make the body.




This is the chuck I will use. It is a 6 inch 4 jaw self centering chuck from aliexpress.


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## Janger (Feb 3, 2019)

Will it be tied in to your milltronics mill? Or independently controlled?


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## Janger (Feb 3, 2019)

Are you joining the make a tailstock party?


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## Alexander (Feb 3, 2019)

It will be independently controlled for the first tests but if i am able to get it to work with the milltronics ill control it with that. I did start a foot stock already. Just need to finish it


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## Johnwa (Feb 3, 2019)

I was motivated to do mine by this thread
https://www.homemodelenginemachinist.com/threads/arduino-rotary-table-for-dummies.26744/

There are a few different builds in that thread.
There are a few direct drives, some of which use geared steppers.  I have a 4:1 belt drive on mine with a 400 oz-in stepper.  I’ve accidentally milled while it was turning but it would occasionally lose steps.


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## PeterT (Feb 3, 2019)

Not sure if you saw Stefans video, description starts about min 15


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## Alexander (Feb 3, 2019)

Thanks for the links guys ill go in the house and read those after i get done roughing this chunk to size. I think this will push my setup to the limit. There is allot of material to remove here.


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## Alexander (Feb 3, 2019)




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## Alexander (Feb 3, 2019)

This was very satisfying to watch


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## Janger (Feb 3, 2019)

Hogging out! wow. You have a big mill Alex. very nice. You seemed to shim the block? 

Do you anticipate being able to turn the table under power while milling? What kind of parts do you anticipate? Turbine Blades? Custom Scooter turbos? Only tongue in cheek a little. I think that could be really interesting. 

Will Fusion 360 support 4th axis CAM?


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## Alexander (Feb 3, 2019)

I used shims under the block to get the side perpendicular to the bottom. I also used a shim on the movable jaw because the front and back are not parallel,  yet. I really didn't want the block to shift during milling. Those were some heavy cuts.


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## Alexander (Feb 3, 2019)

Yes i belive fusion 360 cam allows for 4th axis. I actually plan on using the 4 jaw chuck to machine 4 sides of my parts without reaching inside the machine. Why you ask? If you machine the 5 sides without removing the block from the chuck then everything will be square and you won't need to dial anything in.


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## Alexander (Feb 3, 2019)

@PeterT as for the idea of attaching the stepper motor to a rotary table i thought about it. I do have an 8 inch rotary table. But it is not what i would call fast, or accurate. I know allot of people would disagree. I think the design of cnc lathes with live tooling could be copied.  They use the spindle motor as a servo. It is basically an electric motor when turning, an accurate servo for continuous machining and an electric brake when indexing. I am sort of experimenting here with a very large stepper motor and hopefully it can replicate those capabilities.


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## YYCHM (Feb 3, 2019)

I'm an old fart engineer here.  What the heck is the 4th axis?  X, Y, Z is my norm?


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## Janger (Feb 4, 2019)

Mount a rotary table on its side on the mill -  attach a chuck, and a stepper motor for automated control and you’ve got a 4th axis. You can now mill 4 sides of a square part without taking it out of a vise etc. 

Alex if you put the rotary table down flat is it still called 4th axis?


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## Janger (Feb 4, 2019)

Janger said:


> Mount a rotary table on its side on the mill -  attach a chuck, and a stepper motor for automated control and you’ve got a 4th axis. You can now mill 4 sides of a square part without taking it out of a vise etc.
> 
> Alex if you put the rotary table down flat is it still called 4th axis?
> 
> This will be really interesting keep posting Alex as you progress.


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## Alexander (Feb 4, 2019)

If you assign a letter to the 4th axis is called C axis. When axis of the C is parallel to the spindle you have a rotary table not a 4th axis. Most big VMC machines use a rotary table because it is hard to rotate big parts on there side.


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## Alexander (Feb 4, 2019)

Also the machine in my profile picture is a 5 axis VMC with a rotary table.


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## PeterT (Feb 4, 2019)

I always thought 4th axis meant about a rotational axis over & above the 3 normal linear axis. But I think there is a more robust definition like below. I found this definition on the internet, so it must be true LOL. I guess you could have a machine with no rotary component but some other 'direction the cutting tool could move' and that might also be a 4th axis? (Although I cant think of one off hand).

_The term “*5*-*axis*” refers to the number of directions in which the cutting tool can move. On a *5*-*axis* machining center, the cutting tool moves across the X, Y and Z linear *axes* as well as rotates on the A and B *axes* to approach the workpiece from any direction._


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## Alexander (Feb 4, 2019)

This is starting to get off topic lol.
Lathe, 2 axis   x and z





3 axis mill       x,yand z





4 axis mill       x, y, z and part rotates





5 axis mill       x,y, z the part rotates on 4th axis and the head tilts,


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## Alexander (Feb 4, 2019)

I did some roughing tonight it is starting to take shape


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## Alexander (Feb 7, 2019)

PeterT said:


> I always thought 4th axis meant about a rotational axis over & above the 3 normal linear axis. But I think there is a more robust definition like below. I found this definition on the internet, so it must be true LOL. I guess you could have a machine with no rotary component but some other 'direction the cutting tool could move' and that might also be a 4th axis? (Although I cant think of one off hand).
> 
> _The term “*5*-*axis*” refers to the number of directions in which the cutting tool can move. On a *5*-*axis* machining center, the cutting tool moves across the X, Y and Z linear *axes* as well as rotates on the A and B *axes* to approach the workpiece from any direction._





 I borrowed this image from my machines manual.


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## Alexander (Apr 20, 2022)

I am starting this project back up. I started following the tutorial @Johnwa linked. Realized my LCD and controller aren't soldered together yet. I'm not very good at soldering but I'll try. If it doesn't turn out good I'll buy the one that is already soldered together


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## Degen (Apr 21, 2022)

The easiest way to understand axis on cnc is the direction the cutter moves, where it gets complicated is when the work piece moves in conjunction with the cutter and or transfers to secondary holder (lathe mill centers) at this point the the axis count climbs fast.

As an example, x, y, z 3 axis, 1 rotary 4th, 2nd rotary 5th (simple so far) tooling head pivots 6th, tooling rotates around z 7th, transfer to a second cutter head and so on.  Seeing some of these machines in action is absolutely amazing.

4 plus a manual 5th can meet most applications that we have.


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## Alexander (Apr 21, 2022)

I soldered these parts together but I can not get an address on the serial monitor. I think ill order another I2c display this time ill get one which is pre assembled.


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## Alexander (Apr 25, 2022)

I got my new screen. As soon as I opened it I realized my mistake. The LCD I was trying to use for the tutorial was smaller than it should have been. Once I had the right parts the tutorial @Johnwa shared was easy. Doh! Next step is wiring up a keypad. I have two! Just like before the one I wanted to use is wrong  this time I'll start with the right one. Maybe later I'll try the other one.


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## Alexander (Apr 26, 2022)

The good news is the program and the number pad work. The bad news is I ordered a DC power supply but this stepper driver is AC Doh! This Microstep Driver also has the inputs labeled differently than the one in Arduino table for dummies guide . I'm hoping it will just work? This might be wishful thinking.


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## gerritv (Apr 27, 2022)

The manual says AC or DC: http://www.sah.rs/media/sah/techdocs/hb860h_manual.pdf


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## Mcgyver (Apr 27, 2022)

Is there a harmonic drive in between the stepper and chuck?


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## Alexander (Apr 27, 2022)

gerritv said:


> The manual says AC or DC: http://www.sah.rs/media/sah/techdocs/hb860h_manual.pdf


Although that has the same name. I dont think it is the same part. the manual talks about the closed loop system with encoder. I dont have any of that.


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## Alexander (Apr 27, 2022)

Mcgyver said:


> Is there a harmonic drive in between the stepper and chuck?


I had to Google what you were referring to. I am not exactly sure how I am going to use this just yet. I kind of want to try direct drive, timing belts or worm and worm wheel. Might test it on a big rotary table first. To see how that works


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## Alexander (Apr 27, 2022)

I attached some pictures of my first two stepper projects I completed tonight. One rotates the stepper back and forth one turn and the other rotates the stepper with a 10k potentiometer. I learned a little bit with these tiny parts and I'll try to apply that to the large Microstep Driver over the weekend. I kinda wish the inputs were the same on the big stepper driver but they see to function differently.


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## Mcgyver (Apr 28, 2022)

Alexander said:


> I had to Google what you were referring to. I am not exactly sure how I am going to use this just yet. I kind of want to try direct drive, timing belts or worm and worm wheel. Might test it on a big rotary table first. To see how that works



I thought it might be given how compact the one in your photo was.  They are a great thing and I thought of building a fourth axis based on one, but they are so  darn expensive, even from China.  imo for dividing you need some sort of gearing, i.e. you need more than micro stepping,  else you'll have some large errors between divisions.   All depends what you are trying to do of course.


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## Alexander (Apr 30, 2022)

Alright this works! Now I need to figure out how to adjust the steps. The power supply I have for bench testing things will be good enough for now. I didn't try DC power because I believe my driver is actually a cheaper hb860 labeled as the more expensive hybrid version. That is about what I expect from Aliexpress


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