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Problems with multiple passes

I am having some trouble with multiple passes on my maslow. I am cutting a 5" square using a 1/8" bit going 20ipm. The machine will cut one pass but then when it cuts the second the cut seems to have moved up in y about .050". It will do this for each cut. I see a little movement in X but nothing like in Y. I am running GD .84 and firmware .84. I calibrated right before the cut. Any ideas?

Just some ideas,

  • before cutting, send the sled 4” or so away from home and use the Home button to re-position the sled.
  • are the gcodes for both passes identical?
  • is one of the chains riding up on the teeth of the sprocket due to an alignment issue? Try a different hole on the sled chain bracket to get the chain more nearly parallel the sheet with your cutting stock under it.
  • is the sled well supported throughout the path?
  • are the arms flexing? Tie a piece of dental floss between them ,’just barely taught’, and watch for droop as the sled moves.
  • is the material moving beneath the sled?
  • is the sled dragging due to friction? Watch the bricks. Try moving them in toward the router. Think of ways to reduce the friction.
  • Try a slower cutting speed, 15ipm maybe.
  • think about the router rpm setting, is that causing drag?
  • how deep is that first pass? Try shallower passes.

I have read the code and it is identical on each pass. The sled is completely supported. With our frame design there is no possible way for the flex between the motors to happen. the material is not moving as it is clamped in place. It is not an alignment issue or drag. I am only cutting .050" per pass.

Just to add to the list,

  • how about twisting of the motor mount?

You might want to set up to pre-flight cuts with a pen on a piece of butcher paper. It’s not exactly the same as dragging a routher around, but it’s cheaper than wood :slight_smile: and separates one set of variables - the router and bit.

I haven’t seen that behavior before, would you be willing to post the gcode that is causing the issue so I can try to replicate it?

Since I am a new user it will not let me attach files but here is the code. It came out Easel. Could it be an issue with the arduino not reading all the encoder pulses? We built this machine ourselves and not from the kit. The motors are an exact match to yours and we had boards printed using your files.

G20
G90
G1 Z0.30000 F9.0
G0 X3.61966 Y1.06546
G1 Z-0.05000 F5.0
G1 X3.73901 Y1.07428 F20.0
G1 X3.85724 Y1.08884 F20.0
G1 X3.97571 Y1.10938 F20.0
G1 X4.09210 Y1.13553 F20.0
G1 X4.20752 Y1.16745 F20.0
G1 X4.32117 Y1.20499 F20.0
G1 X4.43301 Y1.24817 F20.0
G1 X4.54187 Y1.29642 F20.0
G1 X4.64874 Y1.35019 F20.0
G1 X4.75333 Y1.40942 F20.0
G1 X4.85413 Y1.47327 F20.0
G1 X4.95227 Y1.54239 F20.0
G1 X5.04633 Y1.61581 F20.0
G1 X5.13687 Y1.69394 F20.0
G1 X5.22357 Y1.77643 F20.0
G1 X5.30606 Y1.86313 F20.0
G1 X5.38419 Y1.95367 F20.0
G1 X5.45761 Y2.04773 F20.0
G1 X5.52673 Y2.14587 F20.0
G1 X5.59058 Y2.24667 F20.0
G1 X5.64981 Y2.35126 F20.0
G1 X5.70358 Y2.45813 F20.0
G1 X5.75183 Y2.56699 F20.0
G1 X5.79501 Y2.67883 F20.0
G1 X5.83255 Y2.79248 F20.0
G1 X5.86447 Y2.90790 F20.0
G1 X5.89063 Y3.02429 F20.0
G1 X5.91116 Y3.14276 F20.0
G1 X5.92572 Y3.26099 F20.0
G1 X5.93454 Y3.38034 F20.0
G1 X5.93750 Y3.50000 F20.0
G1 X5.93454 Y3.61966 F20.0
G1 X5.92572 Y3.73901 F20.0
G1 X5.91116 Y3.85724 F20.0
G1 X5.89063 Y3.97571 F20.0
G1 X5.86447 Y4.09210 F20.0
G1 X5.83255 Y4.20752 F20.0
G1 X5.79501 Y4.32117 F20.0
G1 X5.75183 Y4.43301 F20.0
G1 X5.70358 Y4.54187 F20.0
G1 X5.64981 Y4.64874 F20.0
G1 X5.59058 Y4.75333 F20.0
G1 X5.52673 Y4.85413 F20.0
G1 X5.45761 Y4.95227 F20.0
G1 X5.38419 Y5.04633 F20.0
G1 X5.30606 Y5.13687 F20.0
G1 X5.22357 Y5.22357 F20.0
G1 X5.13687 Y5.30606 F20.0
G1 X5.04633 Y5.38419 F20.0
G1 X4.95227 Y5.45761 F20.0
G1 X4.85413 Y5.52673 F20.0
G1 X4.75333 Y5.59058 F20.0
G1 X4.64874 Y5.64981 F20.0
G1 X4.54187 Y5.70358 F20.0
G1 X4.43301 Y5.75183 F20.0
G1 X4.32117 Y5.79501 F20.0
G1 X4.20752 Y5.83255 F20.0
G1 X4.09210 Y5.86447 F20.0
G1 X3.97571 Y5.89063 F20.0
G1 X3.85724 Y5.91116 F20.0
G1 X3.73901 Y5.92572 F20.0
G1 X3.61966 Y5.93454 F20.0
G1 X3.50000 Y5.93750 F20.0
G1 X3.38034 Y5.93454 F20.0
G1 X3.26099 Y5.92572 F20.0
G1 X3.14276 Y5.91116 F20.0
G1 X3.02429 Y5.89063 F20.0
G1 X2.90790 Y5.86447 F20.0
G1 X2.79248 Y5.83255 F20.0
G1 X2.67883 Y5.79501 F20.0
G1 X2.56699 Y5.75183 F20.0
G1 X2.45813 Y5.70358 F20.0
G1 X2.35126 Y5.64981 F20.0
G1 X2.24667 Y5.59058 F20.0
G1 X2.14587 Y5.52673 F20.0
G1 X2.04773 Y5.45761 F20.0
G1 X1.95367 Y5.38419 F20.0
G1 X1.86313 Y5.30606 F20.0
G1 X1.77643 Y5.22357 F20.0
G1 X1.69394 Y5.13687 F20.0
G1 X1.61581 Y5.04633 F20.0
G1 X1.54239 Y4.95227 F20.0
G1 X1.47327 Y4.85413 F20.0
G1 X1.40942 Y4.75333 F20.0
G1 X1.35019 Y4.64874 F20.0
G1 X1.29642 Y4.54187 F20.0
G1 X1.24817 Y4.43301 F20.0
G1 X1.20499 Y4.32117 F20.0
G1 X1.16745 Y4.20752 F20.0
G1 X1.13553 Y4.09210 F20.0
G1 X1.10938 Y3.97571 F20.0
G1 X1.08884 Y3.85724 F20.0
G1 X1.07428 Y3.73901 F20.0
G1 X1.06546 Y3.61966 F20.0
G1 X1.06250 Y3.50000 F20.0
G1 X1.06546 Y3.38034 F20.0
G1 X1.07428 Y3.26099 F20.0
G1 X1.08884 Y3.14276 F20.0
G1 X1.10938 Y3.02429 F20.0
G1 X1.13553 Y2.90790 F20.0
G1 X1.16745 Y2.79248 F20.0
G1 X1.20499 Y2.67883 F20.0
G1 X1.24817 Y2.56699 F20.0
G1 X1.29642 Y2.45813 F20.0
G1 X1.35019 Y2.35126 F20.0
G1 X1.40942 Y2.24667 F20.0
G1 X1.47327 Y2.14587 F20.0
G1 X1.54239 Y2.04773 F20.0
G1 X1.61581 Y1.95367 F20.0
G1 X1.69394 Y1.86313 F20.0
G1 X1.77643 Y1.77643 F20.0
G1 X1.86313 Y1.69394 F20.0
G1 X1.95367 Y1.61581 F20.0
G1 X2.04773 Y1.54239 F20.0
G1 X2.14587 Y1.47327 F20.0
G1 X2.24667 Y1.40942 F20.0
G1 X2.35126 Y1.35019 F20.0
G1 X2.45813 Y1.29642 F20.0
G1 X2.56699 Y1.24817 F20.0
G1 X2.67883 Y1.20499 F20.0
G1 X2.79248 Y1.16745 F20.0
G1 X2.90790 Y1.13553 F20.0
G1 X3.02429 Y1.10938 F20.0
G1 X3.14276 Y1.08884 F20.0
G1 X3.26099 Y1.07428 F20.0
G1 X3.38034 Y1.06546 F20.0
G1 X3.50000 Y1.06250 F20.0
G1 X3.61966 Y1.06546 F20.0
G1 Z-0.10000 F5.0
G1 X3.73901 Y1.07428 F20.0
G1 X3.85724 Y1.08884 F20.0
G1 X3.97571 Y1.10938 F20.0
G1 X4.09210 Y1.13553 F20.0
G1 X4.20752 Y1.16745 F20.0
G1 X4.32117 Y1.20499 F20.0
G1 X4.43301 Y1.24817 F20.0
G1 X4.54187 Y1.29642 F20.0
G1 X4.64874 Y1.35019 F20.0
G1 X4.75333 Y1.40942 F20.0
G1 X4.85413 Y1.47327 F20.0
G1 X4.95227 Y1.54239 F20.0
G1 X5.04633 Y1.61581 F20.0
G1 X5.13687 Y1.69394 F20.0
G1 X5.22357 Y1.77643 F20.0
G1 X5.30606 Y1.86313 F20.0
G1 X5.38419 Y1.95367 F20.0
G1 X5.45761 Y2.04773 F20.0
G1 X5.52673 Y2.14587 F20.0
G1 X5.59058 Y2.24667 F20.0
G1 X5.64981 Y2.35126 F20.0
G1 X5.70358 Y2.45813 F20.0
G1 X5.75183 Y2.56699 F20.0
G1 X5.79501 Y2.67883 F20.0
G1 X5.83255 Y2.79248 F20.0
G1 X5.86447 Y2.90790 F20.0
G1 X5.89063 Y3.02429 F20.0
G1 X5.91116 Y3.14276 F20.0
G1 X5.92572 Y3.26099 F20.0
G1 X5.93454 Y3.38034 F20.0
G1 X5.93750 Y3.50000 F20.0
G1 X5.93454 Y3.61966 F20.0
G1 X5.92572 Y3.73901 F20.0
G1 X5.91116 Y3.85724 F20.0
G1 X5.89063 Y3.97571 F20.0
G1 X5.86447 Y4.09210 F20.0
G1 X5.83255 Y4.20752 F20.0
G1 X5.79501 Y4.32117 F20.0
G1 X5.75183 Y4.43301 F20.0
G1 X5.70358 Y4.54187 F20.0
G1 X5.64981 Y4.64874 F20.0
G1 X5.59058 Y4.75333 F20.0
G1 X5.52673 Y4.85413 F20.0
G1 X5.45761 Y4.95227 F20.0
G1 X5.38419 Y5.04633 F20.0
G1 X5.30606 Y5.13687 F20.0
G1 X5.22357 Y5.22357 F20.0
G1 X5.13687 Y5.30606 F20.0
G1 X5.04633 Y5.38419 F20.0
G1 X4.95227 Y5.45761 F20.0
G1 X4.85413 Y5.52673 F20.0
G1 X4.75333 Y5.59058 F20.0
G1 X4.64874 Y5.64981 F20.0
G1 X4.54187 Y5.70358 F20.0
G1 X4.43301 Y5.75183 F20.0
G1 X4.32117 Y5.79501 F20.0
G1 X4.20752 Y5.83255 F20.0
G1 X4.09210 Y5.86447 F20.0
G1 X3.97571 Y5.89063 F20.0
G1 X3.85724 Y5.91116 F20.0
G1 X3.73901 Y5.92572 F20.0
G1 X3.61966 Y5.93454 F20.0
G1 X3.50000 Y5.93750 F20.0
G1 X3.38034 Y5.93454 F20.0
G1 X3.26099 Y5.92572 F20.0
G1 X3.14276 Y5.91116 F20.0
G1 X3.02429 Y5.89063 F20.0
G1 X2.90790 Y5.86447 F20.0
G1 X2.79248 Y5.83255 F20.0
G1 X2.67883 Y5.79501 F20.0
G1 X2.56699 Y5.75183 F20.0
G1 X2.45813 Y5.70358 F20.0
G1 X2.35126 Y5.64981 F20.0
G1 X2.24667 Y5.59058 F20.0
G1 X2.14587 Y5.52673 F20.0
G1 X2.04773 Y5.45761 F20.0
G1 X1.95367 Y5.38419 F20.0
G1 X1.86313 Y5.30606 F20.0
G1 X1.77643 Y5.22357 F20.0
G1 X1.69394 Y5.13687 F20.0
G1 X1.61581 Y5.04633 F20.0
G1 X1.54239 Y4.95227 F20.0
G1 X1.47327 Y4.85413 F20.0
G1 X1.40942 Y4.75333 F20.0
G1 X1.35019 Y4.64874 F20.0
G1 X1.29642 Y4.54187 F20.0
G1 X1.24817 Y4.43301 F20.0
G1 X1.20499 Y4.32117 F20.0
G1 X1.16745 Y4.20752 F20.0
G1 X1.13553 Y4.09210 F20.0
G1 X1.10938 Y3.97571 F20.0
G1 X1.08884 Y3.85724 F20.0
G1 X1.07428 Y3.73901 F20.0
G1 X1.06546 Y3.61966 F20.0
G1 X1.06250 Y3.50000 F20.0
G1 X1.06546 Y3.38034 F20.0
G1 X1.07428 Y3.26099 F20.0
G1 X1.08884 Y3.14276 F20.0
G1 X1.10938 Y3.02429 F20.0
G1 X1.13553 Y2.90790 F20.0
G1 X1.16745 Y2.79248 F20.0
G1 X1.20499 Y2.67883 F20.0
G1 X1.24817 Y2.56699 F20.0
G1 X1.29642 Y2.45813 F20.0
G1 X1.35019 Y2.35126 F20.0
G1 X1.40942 Y2.24667 F20.0
G1 X1.47327 Y2.14587 F20.0
G1 X1.54239 Y2.04773 F20.0
G1 X1.61581 Y1.95367 F20.0
G1 X1.69394 Y1.86313 F20.0
G1 X1.77643 Y1.77643 F20.0
G1 X1.86313 Y1.69394 F20.0
G1 X1.95367 Y1.61581 F20.0
G1 X2.04773 Y1.54239 F20.0
G1 X2.14587 Y1.47327 F20.0
G1 X2.24667 Y1.40942 F20.0
G1 X2.35126 Y1.35019 F20.0
G1 X2.45813 Y1.29642 F20.0
G1 X2.56699 Y1.24817 F20.0
G1 X2.67883 Y1.20499 F20.0
G1 X2.79248 Y1.16745 F20.0
G1 X2.90790 Y1.13553 F20.0
G1 X3.02429 Y1.10938 F20.0
G1 X3.14276 Y1.08884 F20.0
G1 X3.26099 Y1.07428 F20.0
G1 X3.38034 Y1.06546 F20.0
G1 X3.50000 Y1.06250 F20.0
G1 X3.61966 Y1.06546 F20.0
G1 Z0.30000 F5.0
G0 X6.00195 Y0.93753
G1 Z-0.05000 F5.0
G1 X6.03168 Y0.94611 F20.0
G1 X6.05362 Y0.96790 F20.0
G1 X6.05991 Y0.98215 F20.0
G1 X6.06244 Y0.99753 F20.0
G1 X6.06140 Y6.01166 F20.0
G1 X6.04831 Y6.03967 F20.0
G1 X6.02338 Y6.05795 F20.0
G1 X6.00830 Y6.06195 F20.0
G1 X0.99414 Y6.06223 F20.0
G1 X0.96503 Y6.05179 F20.0
G1 X0.94449 Y6.02869 F20.0
G1 X0.93912 Y6.01407 F20.0
G1 X0.93945 Y0.98453 F20.0
G1 X0.95428 Y0.95740 F20.0
G1 X0.98029 Y0.94067 F20.0
G1 X0.99557 Y0.93765 F20.0
G1 X6.00195 Y0.93753 F20.0
G1 Z-0.10000 F5.0
G1 X6.03168 Y0.94611 F20.0
G1 X6.05362 Y0.96790 F20.0
G1 X6.05991 Y0.98215 F20.0
G1 X6.06244 Y0.99753 F20.0
G1 X6.06140 Y6.01166 F20.0
G1 X6.04831 Y6.03967 F20.0
G1 X6.02338 Y6.05795 F20.0
G1 X6.00830 Y6.06195 F20.0
G1 X0.99414 Y6.06223 F20.0
G1 X0.96503 Y6.05179 F20.0
G1 X0.94449 Y6.02869 F20.0
G1 X0.93912 Y6.01407 F20.0
G1 X0.93945 Y0.98453 F20.0
G1 X0.95428 Y0.95740 F20.0
G1 X0.98029 Y0.94067 F20.0
G1 X0.99557 Y0.93765 F20.0
G1 X6.00195 Y0.93753 F20.0
G1 Z-0.12500 F5.0
G1 X6.03168 Y0.94611 F20.0
G1 X6.05362 Y0.96790 F20.0
G1 X6.05991 Y0.98215 F20.0
G1 X6.06244 Y0.99753 F20.0
G1 X6.06140 Y6.01166 F20.0
G1 X6.04831 Y6.03967 F20.0
G1 X6.02338 Y6.05795 F20.0
G1 X6.00830 Y6.06195 F20.0
G1 X0.99414 Y6.06223 F20.0
G1 X0.96503 Y6.05179 F20.0
G1 X0.94449 Y6.02869 F20.0
G1 X0.93912 Y6.01407 F20.0
G1 X0.93945 Y0.98453 F20.0
G1 X0.95428 Y0.95740 F20.0
G1 X0.98029 Y0.94067 F20.0
G1 X0.99557 Y0.93765 F20.0
G1 X6.00195 Y0.93753 F20.0
G20
G90
G1 Z0.30000 F5.0
G0 X0.00000 Y0.00000
G4 P0.1

My guess is that this is the 1st place to focus on identifying any possible inconsistencies. Even to the point of double checking that the currently published schematics are accurate to the shipping Maslow Shield.

Then moving on to locating other potential differences like “is the expected voltage (and PWM) being delivered to the motors?” It could be something as simple as cable gauge/length.

good luck!

Are you free to reveal the source? A lot of folks would like to be able to buy a pair :slight_smile:!

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I know that I saw similar issues when the encoder resolution was higher because the pulse length was short enough that capacitance in the wires was making the pulses that arrived at the Arduino too small to detect sometimes. If the encoder resolution on your motors is identical to the ones we use, I would start by checking the wires. An oscilloscope can help a lot to see what’s going on if you have one

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Count me in on finding the motor source as well…the ones I wound up with are not working with total ppr at 14000. So, it you are able to give out your motor source I would greatly appreciate it.

Try slowing down your feed rate, you are getting about twice as many pulses per
rotation as stock, which is going to cause more load on the arduino, and the
shorter pulses will be significantly more sensitive to wiring issues.

I want to thank you for your responses. We went back and shortened our cables running to all the motors and that seems to have solved our problems. I guess just because we can make a cable 10 feet or 20 feet long doesn’t mean we should.

3 Likes

I recently ran into a very similar issue, but was seemingly inconsistent. I have now traced it to what I believe is electrical noise from my Makita router, when the speed control isn’t quite at full speed. I have since grounded the sled and router and frame and power supply to earth ground. Seems to have done the trick.

3 Likes