Grand Unified Theories of CNC/MakerSlide devices

General Forum Stuff...Introduce yourself

Re: Grand Unified Theories of CNC/MakerSlide devices

Postby TLHarrell » Wed Sep 12, 2012 5:28 pm

I think what he's trying to do here is to build multiple machines which are properly suited to their tasks, but to have all the common drivers and controllers swappable so as to buy only one set to power and operate all the machines. So, for a 3D printer, laser and small CNC mill, he'd be purchasing one controller and set of stepper drivers. The rest of the stuff which is specific to each machine would remain with the machine.

The questions here are:

1. Is there a controller which is suitable for running all types of machines?

2. What stepper driver(s) would you use for best interoperability to share between the machines? Is there any problem with using a driver for a NEMA32 motor on a machine with NEMA17's?

3. How much of an issue is it swapping config files and software stacks to move the controller/driver combo to a different machine?

4. Would you also include the power supply with the unit which is swapped from machine to machine? Or would a dedicated power supply for each machine be preferable as each have differing power needs? Obviously, a laser power supply differs greatly from one for a small CNC.


I think an actual swappable drive bay would physically be way too small. But the concept is solid. You may be able to repurpose the connectors from one, or look up a larger format connector. I think as far as a removable system, there should be a power interlock as part of the mechanical latching system for the swappable hardware. When you unlock the controller to move it to another machine, it will cut power completely before you pull the unit out of the connector.
40w Full Spectrum Engineering 5th Gen Hobby 20"x12" w/ Rotary Engraver
South San Francisco Bay Area - Sales and Support Representative for Full Spectrum Engineering
408-47-LASER - Skype: whitelightlaser-thomas - Facebook: White Light Laser
TLHarrell
 
Posts: 419
Joined: Thu Jul 28, 2011 11:30 pm
Location: Morgan Hill, CA

Re: Grand Unified Theories of CNC/MakerSlide devices

Postby mikegrundvig » Wed Sep 12, 2012 9:57 pm

I've very seriously looked into this and still don't want to kill the idea outright. Space is a bit of an issue for me and I hate the idea of having to put all this equipment in the garage. The hassle of using my big mill absolutely effects how much I use it. Desktop or at least office-accessible equipment is very attractive to me and that limits size a lot. I firmly believe it's possible to make a router + laser cutter in a single machine. I also believe it will be expensive and require some good machining. I don't think adding a 3d printer in there is worth bothering. They use specialized electronics (g-code interpretation on the device rather than the computer in most cases) and a heated bed. I do believe you could get it on the same machine but I don't see a lot of value in it.

The first issue, as has been called out, is the differences in speed vs. rigidity. The more rigid a router or mill is, the better it can cut metals. Both faster cutting as well as more aggressive. I'm not interested in cutting steel and the like on a desktop machine, I do that in the garage. But cutting sheet aluminum and such would be VERY useful as it's a pain to cut on my big mill do to lower cutter RPM (small endmills have to spin faster for efficient cutting). That means it needs to be a lot more rigid then something like a ShapeOko. Generally this means using heavy support structures and such. Weight means bigger steppers and that means slower speeds. You also need torque to accelerate quickly. Toothed belt is great stuff but not meant for that.

So with those requirements (speed AND torque AND rigid), I think you need to use servos rather than steppers. Servos can produce lots more power and speed then steppers in general though you need to gear em down for sure. I also think Makerslide is a too light by itself. Bart's clever trick of bolting it to larger extrusion might be enough but I suggest instead using linear rails and dodge the issue. Then you need to transfer the power - on a small router (as opposed to a mill) you can use ACME screws with nylon anti-backlash nuts just fine. When you add all that together, you are easily doubling the cost of the machine: far more then if you just made two machines and shared a computer.

-Mike
mikegrundvig
 
Posts: 166
Joined: Sat Oct 15, 2011 5:25 pm

Re: Grand Unified Theories of CNC/MakerSlide devices

Postby Enraged » Wed Sep 12, 2012 11:11 pm

One thought I had awhile ago was building a laser cutter into a desk, and then have a slide-out drawer/platform to hold my ORDbot and Shapeoko. The whole thing would need to fit through a door, or be able to be disassembled easily into transportable sections.
Enraged
 
Posts: 439
Joined: Fri May 06, 2011 3:13 pm

Re: Grand Unified Theories of CNC/MakerSlide devices

Postby neocalm » Thu Sep 13, 2012 7:59 am

Love the idea of having unified mechanicals but my expertise is more in electronics/software, so it's not going to be me. I'd love to use those inexpensive 5/8" McMaster Carr ball screws everywhere but am guessing the speed might be underwhelming for the Hadron build I'm doing. Except maybe the z-axis.

So far those questions TLHarrell posted are the ones I'm chasing down.

1. Is there a controller which is suitable for running all types of machines?

I cannot see a lower cost alternative to the LinuxCNC/EMC2 host with $199 Mesa 5i25+7i76 PCI Card. It provides 5-axis + Spindle, with hardware PWM up to 12.5 MHz. That assumes a PCI-based PC close at hand (there's also a PCIe solution with similar price) but includes the software cost ($0) and a RTOS kernel to boot.

There is a 6-axis + Spindle version but I haven't found a hobby machine that would require the sixth axis.

There is the minor (cough) matter of using LinuxCNC with something specialized like the 3d printer/rep rap but it looks like there are some basic solutions there. I'm not against writing some software to make it happen.

2. What stepper driver(s) would you use for best interoperability to share between the machines? Is there any problem with using a driver for a NEMA32 motor on a machine with NEMA17's?

It doesn't seem like it can be a truly universal solution because drivers for a NEMA 14 hardly would be a good fit for a NEMA 34. But here's what I found with, e.g. the Keling drives:

KL-4042D - 200 kHz Pulse / DC 18-36V / 0.5-4.2 Amps / NEMA 14/17/23 - $70 ==> x 5 = $350
KL-5056D - 200 kHz Pulse / DC 18-45V / 0.5-5.6 Amps / NEMA 14/17/23 - $90 ==> x 5 = $450
KL-8056D - 200 kHz Pulse / DC 18-70V / 0.5-5.6 Amps / NEMA 14/17/23 - $110 ==> x 5 = $550
KL-8070D - 200 kHz Pulse / DC 18-70V / 0.5-7.0 Amps / NEMA 17/23/34 - $120 ==> x 5 = $600

These by most accounts are absolutely smooth stepper digital DSP drivers that give 'servo-like performance' out of the steppers. That falls in line with the philosophy of the project - use inexpensive motors in each of 3x machines but then put 3x the cost in the drivers/controller.

You can see the cost adds up quick so it's sure to spur me to build CNC #2 and CNC #3 pretty quickly!

Don't get me wrong, servos would be great on the universal mechanical project.

3. How much of an issue is it swapping config files and software stacks to move the controller/driver combo to a different machine?


Ah, now that's my expertise. Even starting out with a bash script would make this simple. Those Keling drivers can even be tuned in software - probably THAT wouldn't be easy to switch out and around, but I'm not sure yet.

4. Would you also include the power supply with the unit which is swapped from machine to machine? Or would a dedicated power supply for each machine be preferable as each have differing power needs? Obviously, a laser power supply differs greatly from one for a small CNC.


Not including the "spindle" (laser power supply included in that) I think the power supply for the host/controller/drivers would be a common high quality set of power supplies. Again, the budget is 3x normal because it will be shared amongst the three machines, so no point cheaping out on the supply - we can afford to keep it isolated and ripple free.

So at $550 minimum (for the smaller drivers, using a spare PC, not including the set of power supplies) in comparison to $176 for the Azteeg X3. So basically if one were to build three machines that could be handled by the same drivers, one would be nearly ahead of the game - but with some pretty fantastic DSP drivers and a 12.5 MHz PWM step generator on the controller side. Sounds less hobby and more craftsman to me!
neocalm
 
Posts: 10
Joined: Sun Sep 09, 2012 3:12 pm

Re: Grand Unified Theories of CNC/MakerSlide devices

Postby macona » Fri Sep 14, 2012 2:55 am

There are combo laser and routers out there. But you have to have sealed optics pathways and preferably positive pressure to keep dust out. Dust get everywhere even with a dust collector.

Even for aluminum you need a very rigid machine. Cutters tend to dig in and if your machine is not stiff enough it will pull into the work and destroy either the work or the cutter and maybe both. Coolant of some sort is almost a necessity when it comes to cutting aluminum, mostly to keep it from building up

Dont take machine design lightly. There is a lot to consider including rigidity, resonance, and the dampening properties of the material the machine is made out of. There is a reason machine tools are still almost 100% made out of cast iron. Cast Iron is one of the best dampeners for vibration.

If you are having problems cutting sheet aluminum on your mill do what I have done and use a spindle speeder. This fits in my spindle and multiplies the spindle speed time 5 for a max of 20000 rpm at the cutter. I use a Nikken NX5, found it used on ebay for about $300. You can also make a sub spindle to hold a smaller high speed spindle to your machine. Tormach makes a clamp just for this that clamps around the typical 3-3/8" quill of a bridgeport style milling machine. It is actually pretty well made for the price.

You can run into problems running small steppers on big power supplies. Big motors tend to run at higher voltage and even with current limiting small motors will get hot.

"servo like performance" will never happen out of a open loop stepper driver. And the issue with steppers, their torque dropping off at high speeds, is inherent to the design. Even a closed loop stepper driver can be stalled.

Build your machines with dedicated drives and power supplies. I also build each of my machines with it's own dedicated computers. Computers are cheap. Especially older P4s. It is just not worth it to swap cables around and stuff. Mach3 makes it pretty easy to run multiple machines off one computer though with separate config files.
macona
 
Posts: 363
Joined: Tue Aug 17, 2010 10:30 pm

Re: Grand Unified Theories of CNC/MakerSlide devices

Postby mikegrundvig » Fri Sep 14, 2012 4:03 am

If you are having problems cutting sheet aluminum on your mill do what I have done and use a spindle speeder. This fits in my spindle and multiplies the spindle speed time 5 for a max of 20000 rpm at the cutter. I use a Nikken NX5, found it used on ebay for about $300. You can also make a sub spindle to hold a smaller high speed spindle to your machine. Tormach makes a clamp just for this that clamps around the typical 3-3/8" quill of a bridgeport style milling machine. It is actually pretty well made for the price.
I've looked into the speeders and very seriously considered it. I finished the job with thin plate before I got around to sinking the money. I'd still rather a kick butt desktop router with auto-tool-height touch-off so I can just toss something on there and let it rip in my office.

-Mike
mikegrundvig
 
Posts: 166
Joined: Sat Oct 15, 2011 5:25 pm

Re: Grand Unified Theories of CNC/MakerSlide devices

Postby cncmadness » Fri Dec 07, 2012 6:41 pm

maybe thinking along the lines of a mill/CNC Router, Plasma Cutter would be a better option. have a double sided gantry or as with some 3d printers quick release heads.

*just a thought*
cncmadness
 
Posts: 5
Joined: Fri May 18, 2012 3:05 pm

Previous

Return to General Discussion

Who is online

Users browsing this forum: No registered users and 12 guests

cron