# Manual Operation After Cnc Conversion



## grepper

When converting to CNC, can I use dual shaft steppers with a hand wheel on the outside shaft to use the mill manually by simply unplugging the motor before manual operation?

I like the idea of being able to do a quick manual job.


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## JimDawson

Yes......The only question that comes to mind is how do you position the table with no reference?  Leaving the dials intact or a DRO would be needed I would think.


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## grepper

Thanks once again, Jim.  I really appreciate your replies.  I don't want to make any expensive mistakes deciding what to get (been there, done that!).  I've done so many hours of research trying to get up to speed it's actually somewhat exhausting.  Lot to learn!  I want to do it right the first time.


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## Jim_Hbar

Grepper:

The thing you have to get your head around (if you go with the Nema23 steppers that you have referenced in your other thread)  - is the fact that the dual shaft versions only have 1/4" or 6mm shafts coming out the back end...  Not much to hang a hand-wheel on.  

Another thing to remember is that the handwheels should be removed when you are operating in NC - they add significant inertia to the system.


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## grepper

Thanks, Jim H. 

Have you done this?  Is that an actual problem  or just something to be aware of?

I can machine my own handles.  I'm surprised that would add significant inertia!  Hadn't thought of that.  Really?  The motors are moving the whole table, etc.  Why would an aluminum handle add so much inertia?

I haven't thought the whole thing through, but I was thinking I could put a keyway in the shaft and use a set screw.  That would be quick and easy to remove.

I really like the idea of not giving up on manual operation.  It makes me wonder why I never see it done.


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## JimDawson

grepper said:


> Why would an aluminum handle add so much inertia?



Think flywheel attached directly to the motor shaft vs. the table with a screw thread moving it.  



grepper said:


> I really like the idea of not giving up on manual operation. It makes me wonder why I never see it done.



It is done, my machine can convert between manual and 2 0r 3 axis CNC in seconds.  But you are correct, it is not that common.  I don't have to take off my handles, but the cranks fold up.  I also have big DC servos, so the inertia of the handles is not really a factor.


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## grepper

Fold up handles.  Good idea.

Jim, your mill would crush mine. But I can only wish...

I'm doing a LMS HiTorque 3990.  Been looking at 425 oz Nema 23 motors.  Is that enough holding?  What about a Nema 24 400 oz?  I'm a little surprised that the torque of these motors is so close to requirement that that the added inertia of the handles would effect it so much!  This is great information!  Thanks.  Stuff I would not have thought of.

I'm going to use the CNCFusion kit #5 conversion.  Would Nema 24 motors fit their motor mounts?

Do I need to rate the power supply by the combination of all three motors.  Say each motor is 3.5A, would a 10A supply be enough?  I'm guessing that full torque on all three motors at the same time is not likely.

Sorry, so many questions!  The more I learn, the more questions I have.  It seems endless.  It's frustrating!


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## Jim_Hbar

grepper said:


> Have you done this? Is that an actual problem or just something to be aware of?



I'm just a professional engineer (mechanical) with 30+ years of design/manufacturing/commissioning experience with industrial machinery that used hydraulic and AC servos for some applications. 
And I've been crunching the numbers for my own conversion.

So I plugged some numbers into my model.
Suffice to say, a 6mm thick x 100mm OD aluminum disc at motor speed has as almost 8X the inertia as a 100kg mass load driven with a 5mm pitch screw. 
And a little over 3 times the inertia of the Nema23 motor I have in my spreadsheet.  
It effectively doubles the inertia of the whole Nema23 system as I have it modeled.

The reality is, while machining, it will likely never be an issue.  But it will definitely become a limiting factor when you try to go faster with a stepper system, and you don't know when you've lost a step or two.  
It's easy enough to remove the handles, and basically enable double the acceleration potential. 

BTW, Mr. Dawson with his DC servos and direct reading closed loop feed-back has a real industrial control system on his machine, not the hobby grade toy stuff we are playing with here.  To replace his stuff with new industrial gear, you are likely talking north of 10k per axis, and that's without the CNC software.


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## JimDawson

I looked at the drawings for NEMA 24 and NEMA 23 motors.  The mounting holes look the same 47.14mm spacing, and the centering flange is the same size, 38.1mm, the outside dimensions of the frame is slightly larger.  The shaft size might be different so you will have to confirm that.  So yes, it looks like they will interchange.

425 oz motors should be big enough for your mill, but bigger is always better.  You can always cut them back, but it pretty hard to get more power if you need it.

That power supply should be good.  You are correct, the motors don't all run at anywhere near full torque at the same time.  I'm running two NEMA 23 steppers (coolant pump and 4th axis), one NEMA 34 stepper(Z-axis), and two DC servos (X & Y axis) on my 70V, 5 amp supply.  No problems so far.

I took a look at the  pictures on the CNCFusion site, I can't tell what motors most people are using.  It almost looked like people were using NEMA 34 motors and mounting them diagonally on the mount.  I'm surprised there is no motor size recommendation on the site.  You might read through the CNCFusion forums, there might be some information there on motor sizing.


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## Jim_Hbar

Grepper:

You posted while I was typing the above.

The "holding torque" number the vendors all publish for the stepper motors do not mean squat - What really matters is the torque curve (or "lack of torque" curve, more correctly)
These are the most believable NEMA23 stepper curves that I've found - just go to the link and download the PDF, and scroll down.
See how the torque drops off at speed?  That's what I'm talking about.

Reality is, just copy what others have done on similar machines, and you should get similar performance!  

Doing the math, those 425 oz-inch motors should be adequate to power the knee on my Clausing, if I gear them for 100 ipm at 1000 rpm.  At 40%  of the published torque value, it should result in about 400lbf being available to lift the table and accelerate it, ignoring friction.


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## JimDawson

JimH

I have to agree with what you said above.  My machine is not a normal hobby machine.  But if my DC servos ever fail, I have a set of 1280 oz/in NEMA 34 steppers on the shelf that are going on the mill.  The DC servos are ~425 oz/in, but the torque curve is nearly flat on them.


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## grepper

Jim and Jim H. - Thank you so much!  Exactly what I wanted to know.  Nothing like truly informed information.  Thank you for taking the time to share your knowledge.

I really try to do my research before asking questions.  Getting started gets pretty complicated and overwhelming quite quickly.  So many options and options within options.  My background is computer programming and I know a little bit about electronics, but even with research I constantly come up with electrical and engineering questions that I don't know enough about to answer myself.  Very frustrating!

Jim H.,  That inertia and torque info is amazing and eye opening.  Very cool.  I'll remove the handles!  Thanks for the motor info too.  Most helpful.

Again, thanks.  You wouldn't believe how helpful it is to have such informed assistance when getting started.  It makes a world of difference!

Mark


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## Jim_Hbar

The link works for me, but here is the URL again.
www.leadshine.com/productdetail.aspx?type=products&category=stepper-products&producttype=2-phase-stepper-motors&series=57HS&model=57HS22

And here's the graph.


The curve is for a Leadshine 57HS22, with a rated holding torque of 311 Oz-in. (2.2 Nm) - most importantly, the body of the motor is 81mm long.  
For any frame size stepper, in general, the longer the motor the greater the holding torque, and the higher the inductance - so the torque drops off sooner as speed increases

In my case, 1000RPM is close to 200ipm if the motor is direct coupled. 
But the curve shows the *maximum* torque that the motor can put out. And generally with steppers, you want to design/calculate at 40% of that value.  This motor produces about .66 Nm max at 1000 rpm (for the blue line - series connection) so about 27 watts of useful power.   And the blue line is darn near hyperbolic from 250 rpm out, so basically "constant power".

Jim D. - I've never used a brushed DC servo, but with AC servos the rated torque is what they can pull to rated rpm with 100% duty cycle, then are close to constant hp to maximum speed.  Below rated rpm, they have between 2 and 3 times rated torque available for accelerations and other transients - and then being closed loop, it really doesn't matter if they lag a little bit.


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## Jim_Hbar

Jim - this is is the curve for Leadshine's 1200 oz-in Nema38.  
Are your spare motors 8 lead?  If so, the parallel graph could apply.


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## JimDawson

Here is the curve on the NEMA 34 motors I have.  4 wire motors


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## grepper

Those graphs are interesting.  I hadn't thought about what rpm the motors are running at.  That is helpful in understanding why Jim H. says use 40% for calculations.

What sort of RPM do motors run at for low, medium and fast movement?  Do they ever get maxed out or do the drives keep them more or less mid range RPM?  Torque is pretty much in the dumper at high RPM.  At the end of a fast move, that is right when high torque would be needed to overcome the inertia of those apparently freakishly heavy handle flywheels if they were not removed! 

Let me guess...  Jim H. said, "if I gear them for 100 ipm at 1000 rpm", so it would depend on the screw, or if you had geared motors, and what you set ipm at?  Forgive me, I'm just getting started.


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## JimDawson

Assuming a normal 0.200 pitch lead screw = one inch per 5 revolutions.  So 5 revolutions per second * 60 seconds  = 300 rpm = 60 inches per minute.  Normal cutting speeds would put you into the 20 to 100 RPM range, so almost full torque available for cutting.  A normal rapid on your machine might be 100 IPM, so about 500 RPM max


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## grepper

That was fast!  Got it.  Thanks.


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## grepper

Wow!  That was an extremely informative bunch of posts.  Thanks guys!


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## Jim_Hbar

The critical thing to remember is that steppers are open-loop control.  The command goes out, and the controller assumes that the move is made...  End of story.
The controller must be configured to stay within the limits of the electro/mechanical system. It must command moves that are well below the threshold where it loses steps.
To determine those limits, all you can do is test the actual installation, and determine what the system can do.

Closed loop control is an entirely different animal... 

With steppers, the rapids are where the limits will be touched.  The sophistication of the motion control also enters into it.


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## grepper

Looking at motor specs, most just say 2 phase and give a torque rating.  Some however, such as this
http://www.omc-stepperonline.com/ne...per-motor-31nm439-ozin-24hs343008d-p-275.html have 8 wires and can be configured however you want.

I take it most motors are bipolar parallel?  I understand the difference, just don't know what is standard when it is not stated.

Rated Current(Bipolar Serial) 2.1A
Rated Current(Bipolar Parallel) 4.2A


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## JimDawson

The bi-polar parallel is the most common.  Normally it is clearly stated if a motor is an 8 wire.


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## grepper

.
I thought I was good to go and had run out of questions!  But if you can stand it, I have a couple more.  (I'm almost there). 

Stepper Online has this 3.5A, 425 oz, dual shaft motor.  Just what I want:

http://us.stepperonline.com/3pcs-of...motor-35a-31nm439-ozin-24hs343504d-p-398.html

But it has an ~8 mm shaft?   3/8" = ~9.5 mm.  I thought in general shaft sizes were either 1/4” or 3/8".  Are this slightly smaller size shaft going to be an issue?  Am I going to run into mounting issues?

Also, how much real world difference will a 3.0A motor be compared to a 3.5A draw motor?  Both have about the same OZ holding torque, but I’m not seeing curve charts.


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## JimDawson

The shaft sizes seem to be a moving target and each manufacturer seems to have their own ideas about it.  They don't all use the NEMA standard regarding shaft sizes.  The good news is that couplings come in a range of shaft sizes to adapt almost any shaft size to your leadscrew size.






grepper said:


> Also, how much real world difference will a 3.0A motor be compared to a 3.5A draw motor? Both have about the same OZ holding torque, but I’m not seeing curve charts.



I'm not sure why the same holding torque rating would have two different current ratings.  I going to guess that the motor performance is going to be slightly less at the higher RPM ranges on the lower current motor.  Without realistic performance curves, it's hard to tell.


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## Jim_Hbar

4 Lead  Bipolar connection  = 8 Lead Bipolar Series Connection.

8 Leads gives you the option to wire the coils parallel - so you can achieve higher speeds than you will ever need on your small mill.

I admit it is a totally personal bias, but I don't like the beam couplings that Jim has shown above.  When a $10 part puts down a multi-million dollar production line for an hour or so, you do something different next time!  They do seem to work in this hobby application however.  Make sure to buy a spare.
Couplings that clamp onto the shafts are what you want - the ones that just use grub screws are to be avoided.

PS. - Do you realize that that 439 oz-in motor produces about a 1000 lbs of thrust when it stalls out driving a .2" pitch ball screw???


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## JimDawson

Jim_Hbar said:


> Couplings that clamp onto the shafts are what you want - the ones that just use grub screws are to be avoided.



:+1:


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## grepper

Thanks.  I’m finally getting close to finalizing my setup! This has been a real trip.  I'm so glad to see the endless research and having to ask questions coming to an end! 

The higher amp motor did have more torque. (My bad)

I guess my motor choice is #1:

Nema 24 Dual Shaft 3.5A 3.1Nm(439 oz.in) 24HS34-3504D, inductance 5.6 mH
http://us.stepperonline.com/3pcs-of...motor-35a-31nm439-ozin-24hs343504d-p-398.html

I was also looking at:

Longs Motor 23HS9430B, 3A, Nema23, 425oz.in, 3A, inductance 6.8 mH
http://tinyurl.com/hm9vtoh


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## grepper

Jim H.- You responded while I was typing.
"PS. - Do you realize that that 439 oz-in motor produces about a 1000 lbs of thrust when it stalls out driving a .2" pitch ball screw???"

What are you trying to tell me?  Is there a problem choosing that motor?


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## Jim_Hbar

Pick one, you'll be fine..

The service qualities of the Vendor is the most important thing - not a 3% difference in a theoretical torque number.


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## grepper

Last question before I finalize my order.  

Because I want to add handles for manual operation, (and be able to quickly remove them), I was thinking of ordering the motor shafts D cut to facilitate a set screw in the handle.

Any problems with that as far as ball screw mounting?  I'm guessing not, but I thought I'd ask.


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## JimDawson

Jim_Hbar said:


> PS. - Do you realize that that 439 oz-in motor produces about a 1000 lbs of thrust when it stalls out driving a .2" pitch ball screw???



That is true.  That would be the virtually instant torque just before the stepper motor decouples and the torque drops to about zero.  Stepper motor are friendly to machines in that regard.  AC and DC servos are not so friendly and you have to plan for max torque at 0 RPM by torque limiting or throwing an excess lag error that shuts the system down.  With servos on a CNC mill, it normally just breaks the tool bit and continues on.  Yeah, I've done that a time or two


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## JimDawson

grepper said:


> Last question before I finalize my order.
> 
> Because I want to add handles for manual operation, (and be able to quickly remove them), I was thinking of ordering the motor shafts D cut to facilitate a set screw in the handle.
> 
> Any problems with that as far as ball screw mounting?  I'm guessing not, but I thought I'd ask.



That should work fine.  That's pretty common.


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## Jim_Hbar

grepper said:


> What are you trying to tell me?



You are in "analysis paralysis", picking a motor based on a number that you are never going to use.  
I'm being a bit of a "devils advocate", getting you to think about things that you haven't, but maybe should.
It's a habit I picked up mentoring young engineers.

You should make sure to limit the current to the motor(s) so that they can't break your machine if/when it jams, particularly when doing the initial start-up.
First you crawl, then you walk, then you run!



grepper said:


> I was thinking of ordering the motor shafts D cut to facilitate a set screw in the handle.


It's easy enough to file a bit of a flat, or dimple the shaft for the set screw.  It would be PITA for the vendor to do it, if they even would.


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## Jim_Hbar

Jim D posted while I was typing... 

Mark's mill is 125lbs total - there can't be a lot of meat where the steppers mount.


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## grepper

Jim_Hbar said:


> You are in "analysis paralysis", picking a motor based on a number that you are never going to use.



"analysis paralysis"   No kidding.  I've been at this research 8 hours/day for days now.  Brain = toast.  But... Five days ago I knew nothing, and now thanks to yourself, Jim W. and a couple others, I think I am up to speed enough to make at least somewhat educated selections.

While grueling, I can't help but do the research.  I just can't make equipment decisions without at least some understanding of what I'm doing! 



Jim_Hbar said:


> I'm being a bit of a "devils advocate", getting you to think about things that you haven't, but maybe should.
> It's a habit I picked up mentoring young engineers.



Please don't stop!  I love a devil's advocate!  It's exactly how I think and why I keep asking all these pesky questions!



Jim_Hbar said:


> You should make sure to limit the current to the motor(s) so that they can't break your machine if/when it jams, particularly when doing the initial start-up.



I don't know enough about this yet to know how to limit the motor current.  I thought the drive took care of that.


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## Jim_Hbar

grepper said:


> I don't know enough about this yet to know how to limit the motor current. I thought the drive took care of that.


Read up on the drives - it's one of the things you set when you are configuring the drives.



JimDawson said:


> and you have to plan for max torque at 0 RPM


Actually, 3 or 4 times full load torque, plus the impulse from the load back driving the screw 
Then have a good "safety factor" so the controls guy doesn't break anything when he does it all over again..


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## grepper

Jim_Hbar said:


> It's easy enough to file a bit of a flat, or dimple the shaft for the set screw. It would be PITA for the vendor to do it, if they even would.



Correct.  Filing a flat spot, etc., would be easy enough.  FWIW, it says:

http://us.stepperonline.com/3pcs-of...motor-35a-31nm439-ozin-24hs343504d-p-398.html

*Custom Options*
[/QUOTE]
*   Connectors*: Molex, Harwin, Tyco/AMP, JST etc.
*   Lead wires & cables*: Special lengths, Protective hose
*   Shaft*: Round, D-Cut, Cross drilled, Key-Way, Thread or Hollow

I don't know if they are already manufactured that way and ready to ship or is truly a PITA custom thing.  I want simple, no hassle, no additional cost ordering.  I'll probably end up just filing a flat spot.


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## grepper

JimDawson said:


> That is true.  That would be the virtually instant torque just before the stepper motor decouples and the torque drops to about zero.  Stepper motor are friendly to machines in that regard.  AC and DC servos are not so friendly and you have to plan for max torque at 0 RPM by torque limiting or throwing an excess lag error that shuts the system down.  With servos on a CNC mill, it normally just breaks the tool bit and continues on.  Yeah, I've done that a time or two



With steppers, are the drives/motors intelligent enough to bail if a full torque stall occurs?  You said, "before the stepper motor decouples and the torque drops to about zero."  I take it that [decouple] is electrical rather than mechanical?


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## Jim_Hbar

grepper said:


> With steppers, are the drives/motors intelligent enough to bail if a full torque stall occurs?


Nope.  You need to "close the loop" to get that functionality.  And that's a huge jump in cost and complexity.

The shaft option question can only be answered by the supplier - my previous comment was based on the assumption that the rear shaft would be stocked unkeyed and round - I could very well be wrong.


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## grepper

Thanks to all of the amazing assistance I've received here, this is what I've come up with.  I believe all components are well matched.  If any of you gurus see anything you think won't pan out, please let me know!

LMS HiTorque 3990 Mini Mill
http://littlemachineshop.com/products/product_view.php?ProductID=3990&category=1387807683

CNCFusion Kit #5
http://www.cncfusion.com/minimill1.html

Gecko G540
http://www.geckodrive.com/geckodrive-step-motor-drives/g540.html

Ethernet SmoothStepper:
http://warp9td.com/index.php/products/#details

3Pcs of Nema 24 Dual Shaft CNC Stepper Motor 3.5A 3.1Nm(439 oz.in) 24HS34-3504D:
http://us.stepperonline.com/3pcs-of...motor-35a-31nm439-ozin-24hs343504d-p-398.html

Switching Power Supply 500W 48V 10.4A for CNC Router 115V/230V S-500-48:
http://us.stepperonline.com/switchi...04a-for-cnc-router-115v230v-s50048-p-168.html

Motor cables:
http://www.cncrouterparts.com/cnc-motor-cable-p-45.html

Mach4 software:
http://www.machsupport.com/software/mach4/


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## JimDawson

grepper said:


> I take it that [decouple] is electrical rather than mechanical?



It's more magnetic,  the motor tries to keep stepping, but can't.  It just sits there and growls.  Under some conditions, like trying to run faster than the motor wants to go, a stepper will do that even with nothing attached to the shaft.


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## JimDawson

Jim_Hbar said:


> Read up on the drives - it's one of the things you set when you are configuring the drives.
> 
> 
> Actually, 3 or 4 times full load torque, plus the impulse from the load back driving the screw
> Then have a good "safety factor" so the controls guy doesn't break anything when he does it all over again..



Jim, I see you have been there and done that!     A controls guy wouldn't do that


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## Jim_Hbar

JimDawson said:


> A controls guy wouldn't do that





I strongly suspect that we know a few of the same people...


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## hmwhitehead

Here is what I did for my conversion.  I am using NEMA 23's with 430 in oz torque with at 4.5:1 belt drive reduction.  By using a belt drive I am able to keep the handles on the lead screws.  (I have just upgraded to ball screws).  Maximum speed is around 15 in/min. on the X and Y axis at 24 volts.  I am currently working on changing that to 36 volts so should get a few more inches/minute once that is done. 
In order to eliminate the voltage feedback when operating the mill manually, I have installed DPDT relays between the amplifiers and the motors which breaks the circuit when the CNC is not being used.  Otherwise, if you do not do this, you will blow the driver transistor in the amplifier (learned that the hard way) when using the mill manually.
Hope that helps,   Harry
	

		
			
		

		
	


View attachment 123256
View attachment 123256


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## wjstape

grepper said:


> When converting to CNC, can I use dual shaft steppers with a hand wheel on the outside shaft to use the mill manually by simply unplugging the motor before manual operation?
> 
> I like the idea of being able to do a quick manual job.


Hi,I've converted several manual lathes to CNC and all case I wanted to retain a manual capability.  Here are some things to consider:
 - If you put handles on the stepper motor rear shafts the handles will spin when you are running in CNC mode, so be careful of the flying handles - you could get hurt.
 - All my machines had a lead-screw setup that moved .0005 per revolution so when you wish to hand crank the machine you will do a lot of cranking - not fun.
- most CNC control software proved you with MDI and MPG control modes so you can run your machine in a semi-manual manner.  I use MACH 3 and a Shuttle Pro MPG    which works really well. No need for hand cranking.


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## Billh50

I am thinking of converting my mini-lathe to CNC. I am thinking that if I use dual shafts and put a piece of round stock set screwed onto the shaft with cross slots. I could make a wheel that fits over the piece with dowels in it to fit slots for manual operation and remove it for CNC. Does this sound very feasible?


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## JimDawson

Billh50 said:


> I am thinking of converting my mini-lathe to CNC. I am thinking that if I use dual shafts and put a piece of round stock set screwed onto the shaft with cross slots. I could make a wheel that fits over the piece with dowels in it to fit slots for manual operation and remove it for CNC. Does this sound very feasible?



Completely feasible. Should work great


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## cozmogeek

I thought I'd want to have handles still after converting my mill but I've found that I can just use the USB pendant controller or the computer keyboard to move things around. It's a lot easier to hold down an arrow key than to crank and crank that stupid handle


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## Firebrick43

hmwhitehead said:


> View attachment 123255
> View attachment 123255
> View attachment 123258
> 
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> 
> Here is what I did for my conversion.  I am using NEMA 23's with 430 in oz torque with at 4.5:1 belt drive reduction.  By using a belt drive I am able to keep the handles on the lead screws.  (I have just upgraded to ball screws).  Maximum speed is around 15 in/min. on the X and Y axis at 24 volts.  I am currently working on changing that to 36 volts so should get a few more inches/minute once that is done.
> In order to eliminate the voltage feedback when operating the mill manually, I have installed DPDT relays between the amplifiers and the motors which breaks the circuit when the CNC is not being used.  Otherwise, if you do not do this, you will blow the driver transistor in the amplifier (learned that the hard way) when using the mill manually.
> Hope that helps,   Harry
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> View attachment 123255
> View attachment 123256
> View attachment 123256


 With ball screws how do you keep the cutting loads from back driving the axis????   I work on large cnc machines and without the servo/brake it's very easy to back drive the axis, a single finger on some of the linear way machines, a palm on standard box ways once stiction is broken.  Acme screws have enough friction for the most part. Vibrating/pulsing  loads can sometimes cause an acme to slowly back drive occasionally


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## JimDawson

Firebrick43 said:


> With ball screws how do you keep the cutting loads from back driving the axis????   I work on large cnc machines and without the servo/brake it's very easy to back drive the axis, a single finger on some of the linear way machines, a palm on standard box ways once stiction is broken.  Acme screws have enough friction for the most part. Vibrating/pulsing  loads can sometimes cause an acme to slowly back drive occasionally



You are correct the ball screws present so little friction that it can be an issue even when taking light cuts.  Since I have no table locks on my machine, when operating manual, I have one hand on each wheel to prevent movement.


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## bbutcher

grepper said:


> When converting to CNC, can I use dual shaft steppers with a hand wheel on the outside shaft to use the mill manually by simply unplugging the motor before manual operation?
> 
> I like the idea of being able to do a quick manual job.


I left the handles on my Bridgeport mill when I converted to CNC, and left the 2 axis DRO as well. I am using Mach3, and find that if I just click RESET, I can manually turn the handles just fine. I am running DC stepper motors, which do produce a bit of drag that has to be overcome in manual mode, but as a side benefit, the DRO in Mach3 also changes when turning manually, so I have a second DRO. My Z-axis on the quill does not work as well in manual mode, since there is too much drag produced by the motor/ballscrew combination. I can force it, but it feels wrong to do that. So, I devised a locking mechanism that allows me to disconnect the ball nut from the quill and use the manual handle for drilling, etc.

One problem I have discovered is when making rapid moves in CNC the glass slides and my ancient Accurite DRO cannot keep up with the pulse rate at anything above about 80 in/min, and I get a drift in the DRO reading. The Mach3 DRO saves the day here since I can reset my manual DRO as needed. Be advised though that the handles can really be dangerous if you get tangled up in them while running CNC.

Bob


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## JimDawson

bbutcher said:


> So, I devised a locking mechanism that allows me to disconnect the ball nut from the quill and use the manual handle for drilling, etc.



Can you post some pictures of that.  I'm interested in what others have done with their Z axis.


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