GRBL shield alternative

Came across this item again today. It has been awhile since I have been looking at GRBL shields and this one has been greatly improved. The price has decreased too. You can also slave a second drive to the Y axis. Would make a great spare.

Arduino CNC Shield http://blog.protoneer.co.nz/arduino-cnc-shield/

A pi shield is also available.

Not much advantage to this unit. Once you add the stepper motor controllers the price is higher than the gShield and the stepper drivers do not handle as much current per phase as the gShield.

You can add a psuedo-fourth axis, but I haven’t had any trouble with using the two Y motors on the X-carve in parallel. Grbl only supports three axes.

Interesting, I will keep an eye on this. I like the fact that the Stepper drivers are on separate boards. As someone who has smoked a few driver chips in his 3D printer being able to replace just the bad driver chip is very nice.
Plus you have the option of upgrading to the better pololu driver chip.

Having the filter capacitor and jumpers directly under the driver chip may be a problem though. As the pololu drives boards have a built in heat sink on the bottom of the circuit board and work best when they have airflow underneath.

Having a 4th chip so each Y stepper can be on its own driver is nice.
It is one of the main features that is making me consider the X controller. As it is my Y axis chip that runs hottest. I figure if I can get each motor on its own chip I will reduce my chances of losing steps to over heating.
And $20 is not a bad price for an upgrade ($60 if you get the higher quality stepper drives as well)

Of course I would not be able to use the stock enclosure anymore. Thankfully I have the means to make a new one :wink:

I actual would be a lot more excited about trying this out ($20 in not bad to risk and I can always go back to the original gshiled) except that I am contemplating switching to a TinyG.
(I noticed that my XC really shudders and shimmies sometimes as it cuts and I am thinking I need to read up on the TinyG’s S Curve acceleration as see if that will help with that.)

Look again. $20 does not include any stepper drivers.

Also, quote from Pololu (not enough current) ($7.45 each)

This breakout board for Allegro’s A4988 microstepping bipolar stepper motor driver features adjustable current limiting, over-current and over-temperature protection, and five different microstep resolutions (down to 1/16-step). It operates from 8 V to 35 V and can deliver up to approximately 1 A per phase without a heat sink or forced air flow (it is rated for 2 A per coil with sufficient additional cooling).

Substituting the DRV8825 ($10.45 each) (still not enough current for the NEMA 23s, ok for NEMA 17s)

This breakout board for TI’s DRV8825 microstepping bipolar stepper motor driver features adjustable current limiting, over-current and over-temperature protection, and six microstep resolutions (down to 1/32-step). It operates from 8.2 V to 45 V and can deliver up to approximately 1.5 A per phase without a heat sink or forced air flow (rated for up to 2.2 A per coil with sufficient additional cooling). The driver has a pinout and interface that are nearly identical to those of our A4988 stepper motor driver carriers, so it can be used as a higher-performance drop-in replacement for those boards in many applications.

Would be nice to replace one motor chip at a time.

Oh well, if I went with one I was planing od doing high current drivers anyway (hence my $60 figure)

Hmm, I didn’t realize that the DVR8825 would have a problem with NEMA 23’s
I assumed that being “high current” was for the 23’s

Oddly I can’t find / figure out the info on the current max for the DVR8818’s in the gshield

Just the note on invetables stepper page:
“The larger 262oz-in NEMA 23 stepper motors are not recommended to be used with the X-Carve due to the capabilities of the stock electronics…”

But it is a good point that if someone goes with this board they need to purchase driver chips that will work with their motors. And factoring in that additional purchase it is no cheaper than the gshield.

It’s 2.5 amps per phase with adequate cooling. Adequate cooling is very nebulas. Right now I’m running mine (NEMA 23s) with 1.6 amps per phase without a problem. The NEMA 23s can take up to 2.8 amps per phase.

I got it off Amazon with 4 DRV8825 stepper drivers, heat sinks, jumpers, and Arduino clone board for $35. I’d say that was a good deal.

My longest carve so far was about 20 minutes, but running the drivers at about 1.6 amps they seem to do fine. The heat sinks get hot, but I can still touch them for a second or two before it becomes uncomfortable. They are rated to 1.5 without any cooling, so I’m thinking they will be ok with a heat sink at my settings. I’ll keep an eye on it as I start doing longer carves.

I am running a 500mm X-Carve.

Can you share the link?

Sounds like it is working well for you. I would install a fan for good measure. It will keep the drivers running longer.

I’m going to do some longer carves today or tomorrow, so I’ll see how it goes. Once I get an encloseure built for the electronics I will be installing a fan.

This is the one I ordered. The first one I got was a little iffy, but the vendor sent out a replacement no questions asked.

http://www.amazon.com/3D-CAM-Arduino-Compatible-StepStick/dp/B010MZ8UE0

They are showing unavailable at the moment, but when I asked for the replacement, the vendor mentioned that he was in the process of changing out who does the fabrication on the CNC Shields. This may just be temporary. I don’t know. You could shoot them a message and see.

EDIT: This board will not work properly with versions of Easel Local higher than 0.2.2. Presumably due to the USB to serial chip it uses. It works fine with older versions, and with UGS and other software.

Looks like here is another source for a few dollars less.

http://www.amazon.com/dp/B016O7TD6O?psc=1

That has the A4988 Stepper driver, so you would need to replace those with the DRV8825(about $15 for 5 on Amazon). They are just not powerful enough. Still not a bad deal.

That uno appears to have the standard USB to Serial chip, so it should work with Easel.

Thanks for pointing out the difference in the stepper drivers. Missed it!

I Have been using a Protoneer clone board and DVR8825 boards for several months now. I got a Uno r3 clone, protoneer board with 4 driver board for 32$. Current at 2.2 amps. (1.1 vref). I have a 90mm fan blowing on the boards. Heat is not a problem. This allows all steppers to get max power from each board. I load a sheet of Al in and let it run for hours. Works fine. One problem, Easel can not find the usb chip. I use UGCS. Gave up on Easel.

Be careful of the Asian clones of protoneer’s CNC SHIELD. You want v3.51 from Protoneer, because it is compatible with GRBL v.9’s changes to z-limit pin swap. “Arduino CNC Shield V3.51 – GRBL v0.9 compatible (PWM Spindle + Soft limits)”
the Amazon link you provided is a CLONE of the older 3.0 ( grbl .8 and before only card ).
Also beware ANY Arduino CLONE card with a CH340 USB to Serial chip. the CH240’s have a u-code bug causing data
corruption of the serial traffic at speeds of 115k & above. This is a KNOWN issue on the GRBL Forums.

Honestly I’d order the two separately from the manufacturers. I have a few of Protoneers cards & love them.

Ty Hoeffer
Palmyra, VA

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