@Bryant
Good luck. Just so long as you get the power hooked up correctly, rest seems pretty forgiving based on my experience

 

Good to hear. I'm using the 12V 30A power supply I bought from the parts store. Should I be adjusting that down in Amperage at all? As near as I can tell that is the only adjustment available.

 

IF you are using the gShield .... you need to follow the procedure to set the small pots on each x, y, and z driver .... turn them gently all the way CCW then slowly CW until motors begin to run steadily, then a bit more CW. Warm motors are OK, hot ones are not, they will stop working. Did you read the WIKI on the shield and on the TinyG ... I think the motor adjustment procedure is actually in the TinyG WIKI.

 

I'm using the Protoneer shield. I've got GRBL installed and the Universal G-Code Sender is communicating with the board. However, I am not getting any movement when I send commands. The protoneer shield doesn't appear to have a whole lot of documentation so I'm working through it.

 

Wasn't the shields fault at all. Evidently I should look at the correct driver board when orienting them on the shield The Pololu DRV8825 has the pot on the opposite side. Once I lined up the enable pin on the driver board and shield I have movement. Now to tune them in.

 

Lucky you didn't fry it

 

@Robert Hummel

OK ... thanks. I will try a bit of wax ... when I try again.

 

@Bryant

Docs on the Protoneer shield seem pretty good actually ... I assume you have looked here?
http://blog.protoneer.co.nz/arduino-cnc-shield-v3-00-assembly-guide/#FirstRun

 

Forrest,

You are quite correct. Once I figured out that it was my positioning of the Pololu drivers that was the problem the shield's documentation was just fine. And to be honest, if I would have stopped and read the part about lining up the enabling pin on the shield and the board I would have saved an hour of head scratching

Chris, I do feel lucky that I didn't either kill the shield or the drivers. I did just find out that pololu is here in Las Vegas so I guess I have quick access if I do blow one of these boards.

On another note, can anyone explain how to test the current your stepper is pulling. I'm a bit of a electronics newbie (computers fine, electronics - not so much).

Bryant

 

I'm no expert, but the pololu website suggests putting a multimeter on one of the pins going to your motor (i.e. measure the current across one coil) with the stepping set to single step (no microsteps) and the motor stationary. This will then be 0.7x the max current the driver will draw. The max current value should be just less than the max current specified for the motor.

 

I finally got my machine built guys. Its a bit of a black sheep though because the parts list was (as expected) wrong and had to just make it work. 20x80 on the side for the gantry supports and 20x60 for the Z and Y axis. A bit of a hack but it should work just fine.

I got to the electronics portion thinking this would be the easy step. lol. Has anyone flashed an arduino with the grbl shield hex file using an arduino? Is such a thing even possible or must I buy an Amtel programmer for this. Basically I need to get this .hex file on the chip but everything I have tried in avrdude has not worked. The arduino i'm using is a ATmega328P on an uno board. Connected via USB on com5. Each attempt has ended in "avrdude: stk500_getsync(): not in sync: resp=0x00 avrdude done. Thank you."

I love how it thanks me for the fail

 

Don't use arduino for loading the hex
Use Xloader
Go to the files section of my Laser v build and download my hex/Xloader and upload your hex with the Xloader program, just del my hex so you don't mix them up

 

Select your port and don't change anything, direct to your hex and hit upload

 

Thank you. I will give a shot as soon as I'm back from a business trip. Glad someone has done this before

 

Just got back from the trip and thought I would post my results. I tried to upload my hex file but I'm not sure it is working or if it even worked. I'm guessing no because XLoader still has "Uploading..." down in the status bar for about 5 mins now. 5 mins for 74 k tells me that something is wrong. I followed your instructions and didn't change anything, I only selected the port my arduino is connected to and pointed it to the .hex file.

I just tried to click the application and it doesn't seem like its responding at all.

Dis-regard that.... stupid me choose the wrong chip. In my defense its late and I've been flying all night. Say's upload complete. I'm going to power it up and see if I can get it to respond to grbl controller now.

 

Its ALIVE!!!! ALIVE!!!!

Such a sweet sound steppers spinning. Thank you very much Robert you totally unstuck me on that one. Most appreciated. This solution works using Xloader to flash latest release of grbl hex file on to an Arduino Uno with a ATMEGA328P (Duemilanove).

Thanks again sir. I can't stop playing with the jog now.

 

No problem, that's what we're here for to help and share
You sound like me the first time I got it working lol.
Have fun

 

So, I have my X and Y moving fairly smoothly but my z axis is causing me trouble. I went out and replaced the cheaper Pololu DRV8825's that I bought from China with the real thing from Pololu. The major difference is that the real thing has stops in the potentiometers while the cheap ones just keep spinning. With that fixed things have worked much smoother and the adjustment has been significantly easier.

My problem now is that my z-axis makes a short grinding noise upon starting to move and at the end of the movement. Additionally, it sometimes moves in the wrong direction. Adjusting the potentiometer doesn't make much in the way of difference. I adjusted the acceleration setting in GRBL but counterintuitively it gets worse the lower number I put for the acceleration. I've played with the step rate and that also doesn't seem to make too much difference.

Any advice? From googling I've discovered that I might need to loosen things up to try to reduce the initial load so I'll give that I try while I see if any other advice surfaces.

 

Can't watch your video ... says it is "private".
What are you using for screw and nut? making sure they are in line and that nothing is rubbing sounds like good first step. I used a nut made for the screw I used and they work well together, no grinding problems ...

 

Sorry about the privacy setting. It should be visible now. I bought the delrin nut and screw from the same guy. I haven't tried adjusting the nut yet. Perhaps that is the next step.

 

Dude, I have the same motors and mine can produce enough force to bend the gantry, strip the belts, etc. I had a nightmare cutting aluminum because my spindle mount was weak and there was play in my v-wheels. Once that was fixed it does just fine. I'd be looking at your dremel for runout, a dull bit, play in the wheels, etc. Maybe your mount is weak too.

My motors run at about 0.85 A on 12V

 

I should note that I have also tried various feed rates and there doesn't appear to be much difference between the default feed/seek rate of 200 and 500 mm/min on the z-axis issue. I've checked the backlash nut and it doesn't seem to be binding.

Turning the leadscrew by hand take a bit more effort than turning the pulleys on the other axis. I've largely run out of ideas. I may solder together my extra driver to see if that will make a difference.

 

Ok, so upon further review, I'll blame this one on my shoddy soldering Upon closer inspection on of the header pins wasn't well soldered. Once that was remedied the z-axis moves smoothly in the correct direction. How to put a spoiler board in place, strap my dremel on and cut something...

 

I still have yet to cut anything as well. I keep tuning my machine and since baby is asleep at night I don't want to stand the chance of waking her up.

I have started doing some dry runs with my machine, I too do not even have a spoiler down yet and I noticed that circles do not trace well. With the stock settings in sketchup you will end up with a circle with 24 segments. Indeed if you try and cut it SketchUCam will segment your circle (this was discussed earlier). I found a nice way to generate circles without all the segments and that is by increasing the segments from 24 to say 64 using Window->Entity Info under sketchup.

The resulting gcode looks good enough, seems like it would make a nice circle but when I run it the machine does not do anything smoothly at all. It is very jerky when it starts preforming the tool path. It is like it is starting and stopping a lot for some reason. Anyone have any suggestions on how to smooth this out to make a nice smooth circular cut without all the starting / stopping?

Also this starting / stopping only seems to happen when I start cutting anything with a radius to it. Linear stuff works nice and smooth. Its almost as if its just doing segments and the look ahead that the grbl shield is supposed to have doesn't seem like its doing its job.

 

I would suggest downloading a free trial of a 'real' CAM program such as CamBam. Draw a simple circle in that and generate the GCode. If that does the same thing, then it's probably just the best you can do with your setup. If it is different, you can inspect the GCode to see what is different, or consider shelling out for the program (I hear it is really good).

 

David, Thanks for the tip. First thing I did after getting my spoiler in place today was to draw some text. Then I read your post and followed your suggestion. Looks like my machine is not quite calibrated correctly (see attached image). The Y length is spot on but the X is all outta whack by a little under half. Actual line on the x measured 47mm. I'll go over the settings and see if I can figure out where I went wrong but thanks for the help guys most appreciated, I'll let you all know how it turns out and what the deal was.