[Phy6]

Hi, I'm just getting started with CNC, so please assume I don't know what the heck I'm doing. I have a lot of questions, but most of the hobbyist answers out there are geared toward a Mach3 approach.

I just bought a used 2'x4'x3" 3 axis CNC router that uses a Dewalt 611 router, Nema 23s and a 6b 6560 driver/controller with a parallel interface.
The original owner used it for wood cutting.


Usage: My main usage is cutting aluminum and MDF in 2.5D and 3D for car parts and molds for fiberglass parts, as well as parts to make a better CNC machine!
A secondary usage is 3D scanning using a probe (probably a $200 ebay touch probe) to digitize surfaces and bring it back into the CAD software.

I'd like to add a 4th axis in the future and the 6560 board I have supposedly supports it.
For some parts I want to make I think I'll need 2 sided machining using the pin method.


Pics:
CNC - Imgur

Attachment 230438Attachment 230440




The only software I've bought is Rhino 4, and I've been using that for over 10 years now. Autodesk 3dsmax and Inventor are also options for me, through school.


I have a couple issues: The [nice] laptop I want to use is 64bit Windows 8, with no parallel port.
So it seems I have these options:

• Buy an Ethernet smoothstepper and use Mach3
• Or I could buy the kflop and use KmotionCNC and possibly avoid investing in Mach3 at all
• Or I could find a docking station with a parallel port, install a 32bit Windows and use Mach3
• Or ??? (I'd love to hear the wisdom of someone who went down my path!)

I haven't selected a CAM package, but the previous owner said Rhino + MeshCAM worked really well for him.


Is there anything else I'm missing? Should the 6560 work as is with a kflop, or would you recommend that I upgrade (and to what)? I have heard that a breakout board + separate drivers is the preferred setup, in case one driver goes bad. I hear some 6560's have a bad rep, and I'm sure the one I have is a cheap implementation of it.


As a [Java] software engineer, I really don't like the stock look and feel of Mach3. I can't deny its popularity and momentum, but I hear whispers that KmotionCNC might be all I need.

Do I have less choices/more complications in the way of CAM packages when using KmotionCNC over Mach 3? I.e. am I going to need a lot more post processing or C programming to make use of G Code? I'd prefer not to need extra post processing steps if possible, unless you can tell me it's dead simple and free.
Are there popular, low cost CAM packages that 'just work' with KmotionCNC's interpretation of G code?


I hear great things about kflop, and I feel unburdening the computer from realtime responsibilities is the right approach, since this frees up the computer to do other things like CAM and maybe even CAD. If I can eliminate needing another computer in the garage and having to transfer files around, that would be great.

[TomKerekes]

Is Kflop/Kmotion CNC right for me?

Of course!

I think you have provided a good and correct characterization of your situation. I think KFLOP+KMotionCNC can provide some of the best 3D contouring performance.

But KFLOP's Step/Dir Pulses are not compatible with the slower drives like those TB6560 types. KFLOP was designed with high Step rates in mind (up to 2.5MHz) and has a max pulse width setting of 3.78us. Those drives probably require 10us or more. So some type of pulse stretching would be required. See page 10 here:

http://www.toshiba.com/taec/componen...E_EN_27885.pdf

Consider upgrading to a KSTEP or something like Geckos.

HTH
Regards

[spank]

Your instincts about separating realtime responsibilities is right on. In this sense, Kflop is really an excellent solution. I used Mach, and Linux CNC for years before learning of and then buying Kflop. Mach and EMC were way less stable for me, and I ruined far more parts as a result of control gremlins. The only parts I've ever messed up with Kflop were due to my own errors.

As far as the C programming goes, you wouldn't need to much at all with the machine you have, and if you did, the example files that exist should suit your needs just fine. Post processing is not a big issue. I generally use Mastercam, and I don't have a post that works direct with KmotionCNC (which by the way is a great simple control interface... so yeah you can save a few bucks on Mach there), but the way Kmotion CNC works is that it runs through the code and will stop at anything it doesn't understand. In the case of a basic Mastercam post, there are a few items it the beginning and end of the post that I delete (3 lines... 6 total), and then my gcode runs perfectly. With other programs, a basic Gcode post (using Vectric for example) usually will run without any issues. Long story short, even if you don't have a perfect post, it's not a hassle at all to make it run with a few strokes of the delete button.

I think if you read through the various forums about different solutions, there is no doubt that Mach is the king for DIY CNC. Mach 4 certainly looks interesting, but I'm not sure I'll ever switch to it even if Tom writes a plugin. Most people do OK with Mach and a SmoothStepper, but I think you'll find the percentage of people having gremlins with a Smooth Stepper and Mach is far greater than people whop are using Kflop. If you read through the Dynomotion forum, what you'll see is people with questions about set up and certain behaviors that can be resolved with changing settings/C programs rather than fundamental issues that exist between a PC and a card like SS or the obvious and really frustrating problems of using Mach without a control card.

[Phy6]

Thank you for your inputs!

From reading some 2013 forum posts, it seems that there is no pre-authored sample code for a simple 3 axis stepper setup. Is that still the case?

How about sample code for a clamp on zeroing probe?

Or sample code to use a probe with kflop and kmotioncnc to digitize objects, using something like this?

Digitizing Probe 4 CNC Sherline Maxnc Taig Plasma Cutter Mill Router ENGRAVER | eBay

Attachment 230454

(I think for Mach3 there is a plugin to do this. The end goal is to get a point cloud (or triangulated surface) back into a CAD program.)

[TomKerekes]

Hi Phy6,

Not sure exactly what you mean by "setup" but we have example programs to configure 3 axes for Step/Dir. Such as for our KSTEP see:

C:\KMotion431\C Programs\KStep\InitKStep3Axis.c

I don't know of a specific Point Cloud measurement example. Here is an example (ProbeDirection.c in the C Code Examples) for a single probe operation that can be called from an M Code in GCode. I would suppose you would need some type of double loop to probe an array of points. Then write the points to a Disk File in some format.

#include "KMotionDef.h"

// For basic KMotionCNC Probing configure KMotionCNC to call this C Program
// with an MCode and 3 parameters P Q R passed in variables 50,51,52 to 
// specify the X Y Z Probe directions speeds
//
// Modify this program for the input bit you are using for your probe.  As
// written the program keeps moving until the bit goes high.  If the polarity
// of your probe is opposit this then remove the NOT Symbol '!' applied to the
// ReadBit result. 
//
// For Example:
//
// M100 = Exec/Wat/Sync  Thread 2 Var 50 <>\C programs\ProbeDirection.c
//
// Then to probe in the X direction at 100 counts/sec use GCode as:
//
// M100 P100 Q0 R0
//
// Then to probe in the Y direction at 50 counts/sec use GCode as:
//
// M100 P0 Q50 R0
//
// 

main()
{
	Jog(0,*(float *)&persist.UserData[50]);	// move in the velocites specified
	Jog(1,*(float *)&persist.UserData[51]);
	Jog(2,*(float *)&persist.UserData[52]);

//	printf("X Y Z Speeds = %f %f %f\n",
//		*(float *)&persist.UserData[50],
//		*(float *)&persist.UserData[51],
//		*(float *)&persist.UserData[52]);

	while (!ReadBit(46)) ;   		// wait for switch to go high

	Jog(0,0); 						//Stop
	Jog(1,0);
	Jog(2,0);
}

Regards

[Phy6]

Thanks Tom! I haven't poked around in the code yet, I apologize. By 'setup' I was thinking some canonical example where I'd plug in some values to get the kflop sending signals for 3 motors. "InitKStep3Axis" sounds like the right place to start! I understand and appreciate that there are too many variations to account for.

I didn't see anything on github for KMotion software, but if I end up going this route, that's likely where I'll post code for other people to use and fork. :-)


This is jumping the gun, but just to help better understand the limits of the Kmotion kflop + kstep combination, let's throw this out there:
Hypothetical H1:

If I was building a new CNC that used Nema 34s over 5 amps, I'd use a kflop + <individual drivers that provide microstepping and safety features> + <individual power supplies appropriate for the drivers>

Does that sound right, and can you drop some names of drivers and power supplies that would suit something like a 7A Nema 34, and have similar or better performance/features as your Kstep? (Or do you offer an individual driver+power supply product?) I'm guessing if I searched on something like 2M982 or other stepper drivers, I have to worry about knockoffs/getting a dud.


Hypothetical H2:

If I was upgrading my Y axis to use two drives (I guess slaved is the term) instead of one, would that use up the 4th axis slot on the Kstep? (Hmm I guess it would have to in order to power the motor)

[TomKerekes]

Hi Phy6,

If I was building a new CNC that used Nema 34s over 5 amps, I'd use a kflop + <individual drivers that provide microstepping and safety features> + <individual power supplies appropriate for the drivers>

Does that sound right, and can you drop some names of drivers and power supplies that would suit something like a 7A Nema 34, and have similar or better performance/features as your Kstep? (Or do you offer an individual driver+power supply product?) I'm guessing if I searched on something like 2M982 or other stepper drivers, I have to worry about knockoffs/getting a dud.

BTW sometimes bigger Stepper Motors don't end up giving much more performance. They have tremendous holding torque but the torque often drops off so fast with speed that the max power is the same as a smaller motor with different gearing.

Geckos are excellent drives and are very commonly used and work well with KFLOP.

I'm not familiar with 2M982 drives. But I Googled and found this:

http://www.hi-end.ro/pdf/motoare/CMP8079.pdf

Unfortunately those spec a 5us Direction setup time which is slightly longer than what KFLOP provides (4us). Actually their spec states 5ms - but I assume they mean microseconds not milliseconds.

If I was upgrading my Y axis to use two drives (I guess slaved is the term) instead of one, would that use up the 4th axis slot on the Kstep? (Hmm I guess it would have to in order to power the motor)

Yes. You could always add a single drive of some type to add a 5th Axis.

Regards