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Routy CNC Router (V-Slot Belt & Pinion)

Discussion in 'CNC Mills/Routers' started by Mark Carew, Nov 11, 2013.

  1. Forrest DIetrich

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

    Bryant New
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    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.
     
  3. Forrest DIetrich

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    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.
     
  4. Bryant

    Bryant New
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    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.
     
  5. Bryant

    Bryant New
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    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.
     
    Robert Hummel likes this.
  6. Chris Allen

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    Lucky you didn't fry it :)
     
  7. David the swarfer

    David the swarfer OpenBuilds Team
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    no NOT OIL!!, especially 3in1. 3in1 is not a cutting oil, it is just too good at lubricating to allow cutting.
    on aluminum use kerosene, just a few drops, I just brush it on.
    you can also use bee or candle wax, rub it on before every cut.

    btw people, WD40 is not a lubricant, it is a Water Displacer, for rust proofing. <-:
     
  8. Forrest DIetrich

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    @Robert Hummel

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

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  10. Bryant

    Bryant New
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    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
     
  11. Chris Allen

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    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.
     
  12. Mark Carew

    Mark Carew OpenBuilds Team
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    I just run some code and slowly turn up the current pot until I hear clicking (over-draw protection cut off) then back it off a just a bit. This works well for me in getting the most out of these little drivers.
     
  13. Ceiling Cat

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    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 :p
     
  14. Robert Hummel

    Robert Hummel Custom Builder
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    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
     
  15. Robert Hummel

    Robert Hummel Custom Builder
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    Select your port and don't change anything, direct to your hex and hit upload
     
  16. Ceiling Cat

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

    Mark Carew OpenBuilds Team
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    Looking forward to how you make out with this @Ceiling Cat as I have not had to do it this way. Seems pretty straight forward though.
     
  18. Ceiling Cat

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    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.
     
    #288 Ceiling Cat, Feb 28, 2014
    Last edited: Feb 28, 2014
  19. Ceiling Cat

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    Its ALIVE!!!! ALIVE!!!!

    Such a sweet sound steppers spinning. Thank you very much Robert :thumbsup::thumbsup: 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.
     
    Mark Carew likes this.
  20. Robert Hummel

    Robert Hummel Custom Builder
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    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 :D
     
  21. Bryant

    Bryant New
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    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.

     
  22. Forrest DIetrich

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    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 ...
     
  23. Bryant

    Bryant New
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    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.
     
  24. The Dude

    The Dude Well-Known
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    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
     
    #294 The Dude, Mar 2, 2014
    Last edited: Mar 2, 2014
  25. Bryant

    Bryant New
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    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.
     
  26. Bryant

    Bryant New
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    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...
     
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  27. Ceiling Cat

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    I still have yet to cut anything as well. I keep tuning my machine and since baby is asleep at night :sleepy: 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.
     
  28. Chris Allen

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    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).
     
  29. David the swarfer

    David the swarfer OpenBuilds Team
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    I think the first thing to do is draw a 100x100mm square with the bottom left corner 10mm up and 10mm right of the origin (in Sketchup). now select the 'Centerline' tool and mark the square as a centerline cut (should turn green).
    now generate the Gcode and step through it line by line, making sure that each movement is 100mm in both X and Y directions.
    alternately you could use just a 100m vertical line and a 100mm horizontal line, but doing a square will factor in backlash.

    Having established that the X and Y do in fact move 100mm when commanded to do so, you can then try a circle. if that is not round, or does not start and end at the same point, you are losing steps or grbl has a bug.

    On calibration.... I'm not fantastic at mathematics but I'm sure it can help us here (-:
    if you set grbl(or whatever cnc controller you have) to do a mm per step, then tell an axis to move 100 mm and measure how far it actually moves, surely then you can calculate the actual mm/step from
    distancemoved/distancecommanded

    for example (using a leadscrew for simplicity)
    if I have a 2mm pitch leadscrew and a 200 step per rev motor with no microstepping.
    I set it up as 1mm per step
    I command it to move 100mm (and it does 100steps, half a turn, so half of 2mm pitch)
    I measure this movement to be 1mm to confirm the above
    mm/step is therefore actual/command = 1/100 = 0.01mm per step

    as a crosscheck, 2mm pitch divided by 200 steps per rev also gives 0.01mm per step.

    if you have microstepping, just multiply the motor steps per rev by the microstep number and that is then your actual steps per rev, but the above method will work regardless, for high microstep levels you will just have to command a longer movement to get a decently measureable travel distance.
     
    Mark Carew likes this.
  30. Ceiling Cat

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    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.
     

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