"A" axis on cnc machines ...

WilleeCue

WilleeCue

The Barefoot Cuemaker
Silver Member
My little 3020 CNC machine is doing great for pens and has taught me a lot about CNC set up and Mach 3 software but I can see that a larger machine that can taper shafts and butts is what I am going to need for pool cues.
Looking toward this summer and putting together a larger CNC machine that can do all that.

My question is how are others doing the "A" axis so that it can use the stepper motor to position the cue for inlays yet be able to spin the wood at a faster RPM for tapering?
Is the stepper motor fast enough to do that or is some other motor used to get it done?

Past Experience: Unique products used a worm gear drive on their older CueMonster.
It lifted clear and was pined up and out of the way so a speed controlled DC motor and belt pulley could be used for spinning while tapering.
Brian engineered some great pool making equipment that was really well thought out and built heavy duty.
His cue makers lathe is like nothing else out there. (in my avatar the Shiner beer is siting on one)
His smaller Cue Companion is very popular for portable shaft, tip, and ferrule work.


Willee
 
Last edited:
WilleeCue said:
[...]
My question is how are others doing the "A" axis so that it can use the stepper motor to position the cue for inlays yet be able to spin the wood at a faster RPM for tapering?
[...]
Click to expand...

The short answer is, they aren't. Steppers do not lend themselves very well to the smooth rotation required for decent turning applications.

Most light-duty cue-specific machines have some way of switching out between using a stepper motor for rotary positioning and a different motor for higher speed turning. I've seen countless ways of accomplishing this switchover, but the result is the same - one motor is used for rotary machining/engraving and a different motor is used for spinning.

There are more industrial systems - typically servo driven - that use motors capable of turning at high speeds (without the "jerky" action of a stepper), but can also be accurately positioned. Generally speaking these machines are much more expensive than the stepper systems you are used to.

TW

 
I use a stepper as a dedicated "spindle"(direct drive) on my cnc saw machine and I believe Leon Sly does as well. It seems to work just fine in THAT application. Other saw machines I have seen use a DC motor and controller, which I'm pretty sure would be a better solution. If I mount a turning station, I believe DC motor/controller is the direction I would take. I wouldn't want to try and use a 4th axis for everything.

When it comes to 4th axis ANYTHING on a cnc machine, it will BEHOOVE you greatly to listen to any and all advice Thomas has to give you.

This could be the time where Thomas corrects me for giving out wrong information, but even his correction is usually useful.

I'm still not buying him dinner at Aragaw..
 
pescadoman said:
I use a stepper as a dedicated "spindle"(direct drive) on my cnc saw machine and I believe Leon Sly does as well. It seems to work just fine in THAT application.
<snip>
Click to expand...

It is possible that the saw blade has enough rotating mass that it acts as a flywheel smoothing out the steps of the stepper motor.
I am not the sharpest knife in the drawer but when a man with the years of experience and knowledge base of Thomas Wayne speaks I try to pay a bit more attention.

Thanks TW ... for sharing all the information you have posted here to help others.
It is a lot better to learn from the mistakes of others than learn from your own.

You too Randy, its all good and I am grateful for any information you share.

Willee
 
The problem is when you try to get the stepper to rotate at any kind of high speed then it has no torque. I tried to do the same thing with one of Donald Bloodworth's machines and I could get the rpms up but you could touch the item spinning and the stepper would just shut down since it had no torque even when set up in Mach3 as a spindle.

Best to have another motor to use as for spindle on 4th axis.
 
Brickcues said:
The problem is when you try to get the stepper to rotate at any kind of high speed then it has no torque. I tried to do the same thing with one of Donald Bloodworth's machines and I could get the rpms up but you could touch the item spinning and the stepper would just shut down since it had no torque even when set up in Mach3 as a spindle.

Best to have another motor to use as for spindle on 4th axis.
Click to expand...

I own the Bloodworth single head and have no problems at all. I think I spin 600 rpm at 30IPM while taking 1 inch dowels to .750 cones. The ability for the center to maintain adhesion on the center hole is the limiting factor. The spindle never stalls.

I'm not going to argue with anyone on whether it's good or bad, just that I do it without any issues and have never stalled the "spindle". I replaced my controller and all the steppers, so maybe it was the stepper on that particular cnc.
 
WilleeCue said:
It is possible that the saw blade has enough rotating mass that it acts as a flywheel smoothing out the steps of the stepper motor.
I am not the sharpest knife in the drawer but when a man with the years of experience and knowledge base of Thomas Wayne speaks I try to pay a bit more attention.

Thanks TW ... for sharing all the information you have posted here to help others.
It is a lot better to learn from the mistakes of others than learn from your own.

You too Randy, its all good and I am grateful for any information you share.

Willee
Click to expand...

WAIT...WAIT.....WAIT
Are you asking if one can use a stepper like an A/rotating axis OR as a spindle to spin a blade?????

If you are asking if you would want to mount a blade to a stepper then......NO.

In this instance, when I say spindle, I am referring to the stepper spinning the part and not the cutter.
 
pescadoman said:
WAIT...WAIT.....WAIT
Are you asking if one can use a stepper like an A/rotating axis OR as a spindle to spin a blade?????

If you are asking if you would want to mount a blade to a stepper then......NO.

In this instance, when I say spindle, I am referring to the stepper spinning the part and not the cutter.
Click to expand...

You understood the question correctly, Randy.
Set up the "A" axis to rotate and position the cue during inlays.
Then switch the machine over for tapering shafts.

From the advice given here one should use a separate DC motor to spin the shaft for tapering ... not the stepper motor.
Disconnecting the stepper motor and connecting the DC motor seems the biggest challenge to this.
As I stated in my original post here Unique Products did that in a very clever way.

Willee
 
Only servo driven axis drive have smooth rotation, like been said, steppers do steps.There is micro stepping that smooths it out but is still steps.
My suggestion is that you need 2 setups on the one machine. 1 for doing the inlays and pockets with the stepped position A/4th axis.
Have another that has either a regular motor or small servo motor drive for the tapering/turning.
The tapering could be as simple as getting the Taig type dove tail rail and headstock etc and tailstock, and make that the tapering setup. Or make up your own head spindle for the drive end and some end support, there are lots of ways of doing it. You only need to make sure you have the motor turned on before you start the machine and can then turn it off manually after, it does not matter how long the work head keeps rotating for. With VFD's and a 3 phase motor, they can be controlled from Mach 3, I have not done it,but have seen it done.Not the cheapest way to spin a shaft, but does give you very good rpm control of the motor, and will allow for reverse spindle direction if required.
Advantages of servo motors is the ability to time it's position so threading like on a cnc lathe become possible.But more money though.
You might find that the axis you have spins fast enough to do some trials and may not be so bad. If it does only 100 rpm, then slow down the rest of the process to the feed rate and cut per tooth rate work out for you. If it is an automatic operation and time per part is not critical, just let it run. Your time in measuring and getting the right taper won't change if it takes 1 min to pass or takes 30 min to pass. Sometimes when you have an auto operation going that takes a while to process, that will give you time to be doing something else meaningful instead of watching the spindle run.
Neil

I am a slow typer.
 
conetip said:
Only servo driven axis drive have smooth rotation, like been said, steppers do steps.There is micro stepping that smooths it out but is still steps.
My suggestion is that you need 2 setups on the one machine. 1 for doing the inlays and pockets with the stepped position A/4th axis.
Have another that has either a regular motor or small servo motor drive for the tapering/turning.
The tapering could be as simple as getting the Taig type dove tail rail and headstock etc and tailstock, and make that the tapering setup. Or make up your own head spindle for the drive end and some end support, there are lots of ways of doing it. You only need to make sure you have the motor turned on before you start the machine and can then turn it off manually after, it does not matter how long the work head keeps rotating for. With VFD's and a 3 phase motor, they can be controlled from Mach 3, I have not done it,but have seen it done.Not the cheapest way to spin a shaft, but does give you very good rpm control of the motor, and will allow for reverse spindle direction if required.
Advantages of servo motors is the ability to time it's position so threading like on a cnc lathe become possible.But more money though.
You might find that the axis you have spins fast enough to do some trials and may not be so bad. If it does only 100 rpm, then slow down the rest of the process to the feed rate and cut per tooth rate work out for you. If it is an automatic operation and time per part is not critical, just let it run. Your time in measuring and getting the right taper won't change if it takes 1 min to pass or takes 30 min to pass. Sometimes when you have an auto operation going that takes a while to process, that will give you time to be doing something else meaningful instead of watching the spindle run.
Neil

I am a slow typer.
Click to expand...
How about if you attach a pulley on the X axis leadscrew ?
 
conetip said:
Only servo driven axis drive have smooth rotation, like been said, steppers do steps.There is micro stepping that smooths it out but is still steps.
My suggestion is that you need 2 setups on the one machine. 1 for doing the inlays and pockets with the stepped position A/4th axis.
Have another that has either a regular motor or small servo motor drive for the tapering/turning.
The tapering could be as simple as getting the Taig type dove tail rail and headstock etc and tailstock, and make that the tapering setup. Or make up your own head spindle for the drive end and some end support, there are lots of ways of doing it. You only need to make sure you have the motor turned on before you start the machine and can then turn it off manually after, it does not matter how long the work head keeps rotating for. With VFD's and a 3 phase motor, they can be controlled from Mach 3, I have not done it,but have seen it done.Not the cheapest way to spin a shaft, but does give you very good rpm control of the motor, and will allow for reverse spindle direction if required.
Advantages of servo motors is the ability to time it's position so threading like on a cnc lathe become possible.But more money though.
You might find that the axis you have spins fast enough to do some trials and may not be so bad. If it does only 100 rpm, then slow down the rest of the process to the feed rate and cut per tooth rate work out for you. If it is an automatic operation and time per part is not critical, just let it run. Your time in measuring and getting the right taper won't change if it takes 1 min to pass or takes 30 min to pass. Sometimes when you have an auto operation going that takes a while to process, that will give you time to be doing something else meaningful instead of watching the spindle run.
Neil

I am a slow typer.
Click to expand...

My suggestion as well... 2 setups.
 
JoeyInCali said:
How about if you attach a pulley on the X axis leadscrew ?
Click to expand...

That could work and in fact it is how Unique Products did their Taper / Shaper machine.
Works great.
However I would rather have some control over the speed of spin to control vibration and turn it for a very smooth cut surface.
Spin it to fast and you get he dreaded "barberpole" cuts.

Willee
 
A axis

That's what the ex-Porper AllignRight I recently bought has: a stepper-driven A axis for inlays and right next to it, a Dayton worm gear gear motor driving, by means of a v-belt, a small headstock with a center in it's chuck for turning.
All this seems to work great but the gear motor makes more noise than the none-too-quiet spindle.

Robin Snyder
 
A axis

That's what the ex-Porper AlignRite I recently bought has: a stepper-driven A axis for inlays and right next to it, a Dayton worm gear gear motor driving, by means of a v-belt, a small headstock with a center in it's chuck for turning.
All this seems to work great but the gear motor makes more noise than the none-too-quiet spindle.

Robin Snyder
 
We make close to 5000 taper passes every week, all done with steppers spinning the parts.

We have some fast, some slow. Some take big cuts, some tiny, but all work fine with steppers to spin the stock.

Regular AC or DC motors are great too, but with steppers I get complete control of the rotational speed of the stock. Playing around with that and the feed speed allows us to home in on the right combination.


Setting it up to do both is very easy as well. There's a few steps that you have to take, no special programming or anything. As long as you don't have to do both turning and indexing in the same program, it's all easy to do.

I can elaborate a little more on the setup later tonight.


Royce
 
RBC said:
We make close to 5000 taper passes every week, all done with steppers spinning the parts.



We have some fast, some slow. Some take big cuts, some tiny, but all work fine with steppers to spin the stock.



Regular AC or DC motors are great too, but with steppers I get complete control of the rotational speed of the stock. Playing around with that and the feed speed allows us to home in on the right combination.





Setting it up to do both is very easy as well. There's a few steps that you have to take, no special programming or anything. As long as you don't have to do both turning and indexing in the same program, it's all easy to do.



I can elaborate a little more on the setup later tonight.





Royce
Click to expand...


I would love to hear how you do it,
I just made the plunge into cnc and this is exactly the topic floating in my mind :)
 
Ok, I have a little time so I can put out the general idea of what to do.

For anyone who uses Mach3 and doesn't already have the installation and configuration manual, here's a link. This is a must, and I suggest you read it many times over. This is for the Mach3 Mill software.

http://www.machsupport.com/help-learning/product-manuals/


Now, to run the same headstock as both a spindle and as an indexer, first you will need to have 2 different Mach3 profiles. One for turning and one for indexing. If you don't know how to use or setup these profiles, check the link. It's all in there.

To setup the headstock as a spindle, you need to do a few things.
Go to Config>Ports and Pins>Motor Outputs, and set the step and direction port numbers under the "spindle" axis to match your controller.
Go to Config>Ports and Pins>Spindle Setup, and under Motor Control check the boxes for "use spindle motor output" and "Step/Dir Motor".
Go to Config>Motor Tuning, and click on the "spindle" button. Set the Steps per unit to match how many steps your motor will need to rotate the spindle one revolution. You'll need to know the ratio if you're using a belt drive. Set the Velocity to the max RPM you want to run or think you can run. I recommend an easy number and use 1000. I can't run that fast, but it's an easy number to remember and you'll see later that you will need to know it. Set the Acceleration slider to somewhere just below the mid point. You can play with this later, but don't change the RPM's! You must click the "Save" button or it won't keep the info.
Go to Config>Spindle Pulleys and set all pulleys to 0 to 1000 rpm, and a ratio of 0. It's extremely important that the max rpm here be exactly the same as your max velocity in the motor tuning. If they're different, your spindle won't go 100 rpm when you command 100 rpm.

That should do it. The S command in your G code will set the rpm, and M3 and M4 will rotate CW and CCW. M5 will stop. If your spindle rotates the wrong direction, then toggle the active high or low in the motor outputs section to reverse the motor.


For the index profile it's a little easier.
Go to the same Motor Outputs screen and setup the "A" axis step and direction pins to match your controller. They'll be the same ones you setup for the "spindle" in the other profile.
In Motor Tuning, you'll need to set the "steps per" to be the number of steps for 1 degree of rotation. The Velocity will greatly depend on what your setup is. Remember, it's in Degrees of rotation per minute! Start off easy on the acceleration too. Remember to click the Save Button!
Go to Config>General Config, and check the box for "A Axis is Angular". Make sure "Rot 360" is not checked.
That's pretty much it. When you command an A move, you'll need to give it an appropriate feedrate, and program the move in degrees.


The manual won't tell you all these settings, but it will tell you how to make all these changes. READ IT! More than once!

Royce
 
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