Need electronic advice for a scratch build CNC router

[Browellr]

I'm building a 24x48" CNC wood router. I've got the mechanical movements on lockdown. Solid gantry, sliding table with covered/sealed screws and guideways, and a very thick frame (gantry is static, so she's big). I have been programming and running CNCs as a career for a couple years, so I know what a good machine is capable of.

I don't want to run mach3 and geek out over missed steps and rely on a computer, so right off the bat I know I'll need a standalone motion controller vs PCI card. I'm looking at a SMC4-4-16A16B (on amazon), and I really like the idea of popping a card in with a program on it (written in Fusion 360) and running it right off the panel.

NEED TO KNOW:
- what power supply to buy to run three 2.8A 269oz/in. steppers with this system, with the option of upgrading to bigger steppers in the future
- what drivers to buy to match (how do I match a driver to a motor?)
- what gauge of wire I'll need to hook this ****e up

BOTTOM LINE
- I need a system that doesn't rely on a computer because reasons, and the easier it is to hook up the better.

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[Tkamsker]

Which force do you need at the spindle how fast should it move so you can calc the needed motor


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[Browellr]

I want to be able to run it up to 80 inches/minute or more if possible but will probably run it slower depending on how the build goes. I don't really care about rapid speed, just want enough torque for hardwood and the occasional aluminum.

[ger21]

What is the pitch of your screws, and the inductance of your motors?

I have a similar size machine, and get get 150-175ipm with 250oz motors on 24V, with 1/2-8 2 start acme. But I'd generally recommend a higher voltage.

A Gecko G540 or Leadshine MX4660 are tow of the better options.

I don't want to run mach3 and geek out over missed steps and rely on a computer

You'll be just as likely to lose steps with a standalone controller as you will with Mach3.
Lost steps are caused by an improper setup.

[LeeWay]

Right.
Mach 3 doesn't really cause lost steps. That can be caused by many things. Improper Mach 3 setup. Computer issues. Poor electrical connections. Improper wiring or grounding. Bad CAM output. Yes even a real mechanical issue can cause lost steps.
I understand your wanting to use a flash drive or something to run the Gcode. This is basically what I do for all the machines we have. We just load the code off the FD to the computer. Most of the time, we use the same code over and over, so that does save us some time in the long run.
I can't tell you when the last time was that I saw any lost steps that was not a result of calibrating a machine. It has been at least several years ago. We use our machines daily too, so that is what you can expect as well with a properly setup machine.



Last year there was a piece of dross on our plasma cutter that was perfectly shaped like a wheel chock. That did stall one side of our gantry and it skewed out and was very obvious when it happened. Certainly not the machines fault but a lazy operator that did not blow off the rails. Me!

[hanermo]

Many options..
Standalone controllers from china are cheap.

Wont run *all* code, but will run almost all code.
If You are doing to programming in cam, should be fine.

Mach3/4 with a good controller is bulletproof.
Some of my machines are on for days.

Likewise, a well-done controller on linuxcnc is bulletproof.

Commercial use of any kind.
Use servos. Use step/dir. Use high-res encoders.
Cannot lose steps, and vastly better performance/accuracy vs steppers.

Cheap and great.
Pokeys CNC/ethernet,
Best.
CSMSIO-IP-S from polabs.

[Browellr]

Right.
Mach 3 doesn't really cause lost steps. That can be caused by many things. Improper Mach 3 setup. Computer issues. Poor electrical connections. Improper wiring or grounding. Bad CAM output. Yes even a real mechanical issue can cause lost steps.
I understand your wanting to use a flash drive or something to run the Gcode. This is basically what I do for all the machines we have. We just load the code off the FD to the computer. Most of the time, we use the same code over and over, so that does save us some time in the long run.
I can't tell you when the last time was that I saw any lost steps that was not a result of calibrating a machine. It has been at least several years ago. We use our machines daily too, so that is what you can expect as well with a properly setup machine.



Last year there was a piece of dross on our plasma cutter that was perfectly shaped like a wheel chock. That did stall one side of our gantry and it skewed out and was very obvious when it happened. Certainly not the machines fault but a lazy operator that did not blow off the rails. Me!

Good to know, thanks! I'll be sure to take my time with calibration and working out the acceleration features built into the controller. My plan is to write a program to mill out a bunch of squares and circles of a known size to test repeat-ability right away and dial in the accuracy.

The controller can run on 24V or 12V. The motors I'm looking at now are 3amps, 425oz/in, nema23, 1.8 step angle, bipolar. Does the voltage rating of the controller limit the voltage I can send to the motors or limit the power of the machine as a whole, or Is that something that the power supply will take care of independently of the signal processing? From what I gather, and this may be wrong, but the controller sends the signal and the power supply and driver give it the gain staging and power?

[LeeWay]

you would want a dedicated PS for the controller and then another supply to run the motors. It's rating would be consistent with the motor and drive requirements. The controller gets power from the PS of course and then it tells the drives how and when to apply power from it's PS.

[Browellr]

How much better is a gecko driver vs. a $30-40 driver? Where would I see the improvements on a part?

[Browellr]

you would want a dedicated PS for the controller and then another supply to run the motors. It's rating would be consistent with the motor and drive requirements. The controller gets power from the PS of course and then it tells the drives how and when to apply power from it's PS.

I found a stepper kit at my kind of price! If I buy this kit all I will need is a power supply for the controller?

https://cnc4pc.com/motion-control/st...z-in-4030.html

[LeeWay]

Yes. You said your controller needs 12 or 24 VDC. That is the voltage your power supply must provide. 36 VDC is pretty low voltage itself and that kit will be fairly low performance wise. 36 VDC is too much for the controller. With such low voltage for the drives and motors, you are more likely to see missed steps even at meager speeds. I do not have experience with such low voltage motors, but the Zone is full of stories about upgrades due to lack of performance due to low power, low cost drive packages. There are better systems for not much more money. Look for at least 48 VDC systems.
That is a good low voltage starting point.

Those drives are not great either.

If you want my recommendation for a drive package that you can count on being happy with that has excellent support, then check out CNC Router Parts. It would be worth the extra money to me. I actually use this kit in 4 axis versions on my plasma cutter and my 4824 Pro CRP router.
Both work very well. Zero complaints.
3-Axis Digital DIY NEMA 23 Electronics Kit | CNCRouterParts

[Browellr]

ok you sold me on the driver package. Do you know of any standalone controllers that would work well with it, or should I just go ahead and get the ethernet smoothstepper package?

[LeeWay]

I can say that Smooth Stepper works very well with Mach 3. I use smooth stepper and Mach 3 on my router. My mill came with it too, but I have since upgraded it with a Mesa card and Path Pilot instead. I think that might be a good option for you. Something to check out anyway. My plasma cutter uses CandCNC electronics with Mach 3 because it uses THC. They have very nice machine controls for plasma, but might be on the expensive side for just a router. Especially a small one.

[hanermo]

Use pokeys ethernet for a controller.
Dont use usb anything for many reasons.

1. Ethernet is electrically isolated, for free.
2. USB has hw to cut the connection if any other USB devices is plugged or unplugged.
3. Most USB stuff is poorly supported. (Pokeys is an exception.)
4. Most USB stuff has poor drivers. (Pokeys is an exception.)

I myself mostly use a very expensive high end CSMIO-IP-S, from CSLabs.
The Pokeys is the best cheap device I know of.

I have not used my smoothstepper for 4+ years.

48V DC, 2M542 series drivers (cheap), + Nema 23 steppers are the best cheap combo I know of.
If you want speed, go to servos.

[helpmeout]

If you have built the cnc,and its ready for electronics, you need to dive in completely and build your power supply also you can use two transformers wired in series, (secondary side only) to increase the voltage output. Go to radio shack and get a full-wave bridge rectifer to convert to dc voltage add some capicitors to the dc output to help with ac ripple, the add a gecko stepper drive to each axis, they are tough and very cost effecient, ive got a gecko 202 on each axis, and have not had any trouble with them from day one. the reason you should build this is when you have any trouble, you will have a better understanding where to find the problem,believe me you will be glad you did.and you will save a lot of money by doing it this way.Use a good breakout board with a computer ,that uses linuxcnc for your stepper motor program,Very easy to set up and above all Its free.use the internet for your search tool to help (youtube)and watch any thing about DIY cnc building.

Go to all thrift stores and find, Small ga. wire for limit,home switchs,pick up db 25 cable for just a dollar or less, salvage micro-switches from old junk micro-waves, rewind the micro-wave secondary transformer for a free power-supply transformer make it any voltage you want,saved 80-100 bucks.

when you do that you can truely say you diyed a cnc machine.again watch every thing you can on each phase of your build,and it will help you a lot...

[Browellr]

Here`s where I`m at so far...

I have the CNC Router Parts` 3 axis Nema23 kit and am waiting on a smoothstepper. Probably gonna run it just with the parallel port on the weekend to get the axis orientated and adjusted correctly. On a leadshine MX3660, do I reverse the motor direction by switching the two dir wires? Just one coil needs to be reversed right?

[ger21]

You can just check the "Reverse" box in Mach3, Config > Homing/Limits.

[Browellr]

ok I got everything dialed in, movement is within .0004. One problem though. I tried to use a USB gamepad (an NES controller,... I know, I'm a hipster) to move the machine around. It was awesome at first, but The x axis just locked into a continuous movement when i wasn't hitting any buttons. After re-setting, it was still locked in that movement.

I think I chose the wrong controller and should've went for something with joysticks, but is it possible that this is a timing issue with a usb input? It might be trying to 'catch up' due to some kind of lag, not sure. I've got an MPG on the way anyways, just wondering if anyone else ever had this issue.