New DIY Router Cutting Issues

[charlie1126]

So I built a cnc router with a 1.5kw spindle and 3 Nema24 steppers. I previously built a cnc laser engraver which works great.

I am just trying to get this new one to cut what i tell it to. RIght now I am trying basic things like cutting out a basic design outline from wood.

I am creating my design in Inksape then converting to gcode with MakerCam. Everything looks good and the path looks good in MakerCam but its not cutting anything properly.

See attached. Not sure how this design and G Code gives me the design on the wood. I am using TB6600 drivers as well.

I have the moving distances perfect. I measure and adjust the GRBL settings until its dead on.

Any help is appreciated.

THanks,

Charlie

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[charlie1126]

A little more info about the setup. I am using an Arduino Uno. 8 microsteps. Universal GCode sender.

[charlie1126]

Here are my GRBL Settings

[ger21]

Looks like your motors are stalling.

[charlie1126]

I have been having issues with the set screws coming out but I used some loctite and it seems like they are staying out. I can move the machine around with the commands in Universal Gcode sender with no problems. In the piece that I posted I can see that it is making all those duplicate cuts as if it is stepping down. No clue why its doing this.

[awerby]

Hopefully you meant to say your set screws are staying in. Loose screws on a coupler could certainly cause the problems evident in your photos. Try running the pattern again, and see if it works better now. Just because it works when you're cutting air, it may not work when confronted with the resistance of plywood. If your program is trying to cut the plywood in small increments, then it would make duplicate cuts at progressively lower Z levels; they are supposed to stay in the same place, though.

[charlie1126]

Yeah I meant staying in. I'll double check them now though. Thanks.

Hopefully you meant to say your set screws are staying in. Loose screws on a coupler could certainly cause the problems evident in your photos. Try running the pattern again, and see if it works better now. Just because it works when you're cutting air, it may not work when confronted with the resistance of plywood. If your program is trying to cut the plywood in small increments, then it would make duplicate cuts at progressively lower Z levels; they are supposed to stay in the same place, though.

[charlie1126]

OK so I checked and everything was tight and the motors and couplers are moving fine. I took the set screw out and put more loctite on and tightened them as tight as I could on the flat part of the shaft. I attempted that same design and it did the exact same thing. I feel like if it was missing steps or it was slipping on the motor shaft that it wouldnt have been absolutely identical. I am going to try a basic circle right now and see how it does. I wonder if its my arduino or the grbl thats flashed on it.

[charlie1126]

Just made a perfect 8" circle. Trying to compare Gcode to see if there are any major differences.

[SteveWill]

Did you rezero after each run? If not it looks like you losts steps in the x direction. with the pattern repeating I thinking the stepper are doing what they are told. I would slow down feed speed and see if it make any different, don't think it will. With doing the basic circle I would do a 3" square also

[charlie1126]

Thanks. I think I figured out a common gcode issue with all the ones that are screwing up. I just tried another 5" NY Yankees symbol and about 30 seconds in it just started taking off way off the work area. So I saw what line it was up to and checked it out. I am getting some crazy I and J values in certain spots. They are way off from where they should be. See the 4th and 5th line below.

G2 X1.8747 Y3.4753 I2.7488 J2.5807
G2 X1.7421 Y3.6434 I2.8076 J2.3507
G2 X1.5687 Y3.8877 I5.6852 J4.2202
G2 X1.5676 Y3.8893 I1699.5044 J1153.376
G2 X1.5655 Y3.8925 I6688.6722 J4539.2871
G3 X1.4792 Y4.0194 I-103.296 J-70.1021
G3 X1.4512 Y4.0604 I-10.7418 J-7.3092
G3 X1.4084 Y4.122 I-5.3227 J-3.6517
G3 X1.3888 Y4.1491 I-0.9772 J-0.6873
G3 X1.3655 Y4.1781 I-0.4203 J-0.3135
G3 X1.3439 Y4.1985 I-0.1103 J-0.0952
G3 X1.3073 Y4.2171 I-0.0681 J-0.0888
G3 X1.2712 Y4.2219 I-0.0339 J-0.1155
G3 X1.2268 Y4.2103 I0.0017 J-0.0972
G3 X1.212 Y4.2012 I0.0748 J-0.1388
G3 X1.2028 Y4.1945 I0.1375 J-0.1989
G3 X1.1912 Y4.1855 I0.3328 J-0.4363
G3 X1.1706 Y4.1683 I0.5686 J-0.7052
G3 X1.1382 Y4.14 I1.6226 J-1.8948

[SteveWill]

I know you not using Mach 3 but there is a config setting in there that is I J mode, I have a chose between Absolute or Inc. So I would look for something like that.

[charlie1126]

Ok. I just used meshcam to convert the gcode and for like a minute it looked like it was doing everything right. Then it had a mind of its own. X and y motors were really hot. Not sure if that's normal. Maybe the drivers

I know you not using Mach 3 but there is a config setting in there that is I J mode, I have a chose between Absolute or Inc. So I would look for something like that.

[LeeWay]

Your drivers are not the most reliable and many many have had severe issues with them. Just an FYI.

[charlie1126]

Yeah I have heard the TB6600 werent that reliable. Any suggestions on drivers? Can the drivers cause this issue? Thanks

[LeeWay]

I think almost any driver would be better than what you have.
Not quite true, but close. Budget is usually a big consideration, but Geckodrives and Leadshine digital drives will get my vote and support when I need a drive

[charlie1126]

Yeah I think I am going to get those Leadshine digital ones.

I was just wondering could it also be the vfd is close to the drivers and the Arduino? Its literally sitting right next to it and sometimes when I dont have the arduino connected to the laptop the motors will move on their own. Is it noise from the spindle?

[awerby]

I was just wondering could it also be the vfd is close to the drivers and the Arduino? Its literally sitting right next to it and sometimes when I dont have the arduino connected to the laptop the motors will move on their own. Is it noise from the spindle?[/COLOR]

It's possible. Have you tried running the code without running the spindle? Zero Z well above the lowest point its supposed to reach and try that. If the successive passes all seem to line up, and the tool returns to your established XY zero points afterwards, that would indicate RF interference from your spindle. Spindles are supposed to have a braided conductive shield over their cables, grounded to the motor but not to the VFD.

[charlie1126]

Ok so I have just regular shielded wire going from vfd to spindle. Grounded on both ends.

I got home from work and moved the vfd. Separated wires from axis motor wires. I then used same code as last night but slowed down the feed rate and lowered the acceleration and it's working perfectly. See attachment

It's possible. Have you tried running the code without running the spindle? Zero Z well above the lowest point its supposed to reach and try that. If the successive passes all seem to line up, and the tool returns to your established XY zero points afterwards, that would indicate RF interference from your spindle. Spindles are supposed to have a braided conductive shield over their cables, grounded to the motor but not to the VFD.

[Biggs427]

I used TB6600 for one year without any problems. I was able to take 3/8 DOC cute using a crappy flat cutter withour any missed step. Yes it's not a stellar drive but for such a light cut it should do the job.

Seems like missed step for me. Especially if it worked at lower feed / accel.

What's the inductance of your motor? Power supply voltage to the drive? How have you configured your amperage dip switch on the TBs?