Inconsistent Cuts

I am experiencing a series of inconsistencies when trying to cut a set of shapes out of thin cardboard.

6x3 Card Weaving Squares

This file is a SVG export from Corel Draw x8 allcut at speed 500 and power of 50.

When cutting the fle some of the holes are cut through and some are close and some are barely marked.

6x3 Card Weaving Squares INK

This is the same Corel SVG re-saved as InkScape SVG and it is doing the same thing.

I have video files I can upload to go along with the cut files and pictures.







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I think this may be pretty typical of the material. It’s even worse with corrugated because of the varying density of the material plus it’s often hard to get it to be perfectly flat. I think folks work around this by over powering it and putting something underneath (masking, for example) to catch the flash back for when the density is low.

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If you’re worried there may be something wrong with the laser, I think support will ask you to print something (probably gift of good measure) in the same spot of the bed using ProofGrade Draftboard.

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Flat isn’t a problem, i have 8 neodymium magnets on a 5x12 piece and the holes that are not cut through are scattered over the work but happen no matter where I put the design on the work piece. It’s seems as if the motion control file is not being created correctly, but it is the same incorrectness each time I load the same SVG file.

Edit: I just reran the InkScape SVG file with the cut speed lowered to 350 to try and “power through” and was able to definitely see the speed of cut change from hole to hole (speeding up and slowing down) and different places in the process. All these elements in this file were originally one square with rounded corners and 4 circles that were copied and pasted repeatedly and then lines cut away from the shapes to prevent double cutting.

Ah, I hadn’t paid attention to the position problem since I thought you were just talking about the laser not cutting all the way through. It does look like you have two problems:

One, it looks like you’re losing registration at some point (you wouldn’t happen to be trying to print something in the front right corner, would you?) This is likely lost steps from: hitting something, binding, or a torque problem with the X stepper (if the picture orientation is as it was on the bed). The most common torque problem is due to a weak connection back to power (wire fatigue, bad solder joint, etc.)

Two, it isn’t cutting all the way through consistently. This was the part I was talking about before. From the info available to me, my first guess would be material variation.

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Quite typical of corrugated cardboard, regardless of “flatness.” The density variations are killer with this sort of cut. In order to verify this, support will almost certainly ask you to try at least part of the file on the draftboard provided for testing…

Oops – I missed that the first time around, too!

Its not corrugated, it just flatted Coke 12 pack that I found used to work really well for prototyping a design shape and cut file. .018" thick

Okay, you have three problems. The third is that there are some problems with the svg:

Some of the lines are doubled up and some are not. The laser will cut some of them twice and some of them once. Also, I think there are some intended lines missing (like across the top. Still checking on the holes…

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Try slowing down the cut and reducing the power somewhat.

You get a certain momentum going with the printer head, and teeny tiny circles, while they can be executed, might not execute consistently. This machine moves very fast, and the speeds have recently been upped.

Small tight curves are problematic for cutters of all kinds, for that reason. If a design contains them, I’ll slow it down. :slightly_smiling_face:

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I pulled the file into Illustrator and drug lines and none of them seemed overlapped…the corners are separate from the lines in some spots… I would try to join all of the lines into a single path and that should cut down on it having to jump around to different parts and things would be completed all at once…

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I think some of them don’t have a stroke so only showed up in outline view in Inkscape. Some of the rectangles were two sided and some were three.

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The pic you added showed the same problem see? The right hand side of one square will overlap with the left hand side of the next one (not all the time, but sometimes).

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No… none of the lines overlap… they are just all separate and in pieces and not all consistent, but not overlapping…

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Sorry, I disagree. Here, i just dragged the upper right corner one a little bit to the right so you can see what I mean:

image

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Right now I am not worrying about possible duplicate line issues on the square cuts, just the inconsistent circle cutting. The arrows in the Comparison Pic are showing the same circles in all 3 cuts having the same issue of not cutting though, even when slowed down from 500 to 350 with the same power. While watching those circles cut I saw the motion of the drastically increase and then slow down as it moved to another hole

Once I can get consistent cuts on the circles I can verify all the blocks have had the duplicate lines removed. The blocks without an edge were supposed to be positioned on the factory edge of the final material so I didn’t need to cut that line.

In your original file, try removing the circles that are not cutting through and replace them with copies of the other ones that do.

Then re-save the SVG and see if there is a difference. :slightly_smiling_face:

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What he said.

I’m no expert here, but the fact that all three resulted in the same holes not being cut means the problem is almost certainly with the file, not the machine. So take a portion that works and put it in place of something that doesn’t. I’d be surprised if that doesn’t fix it…

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I think we need to figure out what part of a design file might be influencing the speed of the laser head if all the lines and curves are the same weight and color and were originally a single set of elements that were digital duplicates of a single set. All the circles were duplicated from a single original circle. The only operation that I performed on the circles was to group, duplicate, ungroup and then reorder them in Corel and then save as SVG.

I sent the SVG to see if anyone else can duplicate the issue, or dig into the SVG better than I can to see if there is a stray artifact or command that could be causing the slowdown.

The speed of the laser head is going to vary based on the motion plan I think - it will need to slow down more for travel along the Y axis due to the need to stop the weight of the gantry as well as the head, so depending on which direction the head is approaching the particular circle it intends to cut, you’re likely to see more slowing.

Don’ think you’re going to be able to do anything about that aspect of it. You might just need to slow it down some more to power through the ones that it isn’t cutting through. :slightly_smiling_face:

Okay, I just ran that print - a bit smaller to fit on the chip - no changes to it except for changing the cut order on the circles to make them cut first, and I used my standard settings for that chip of 380/58.

All the circles cut out fine. What might have happened is - if you let the outsides of the squares cut first, the pieces might have shifted, and that might have caused some of the circles to not cut all the way through. You want to anchor it down as flat as possible for the little circles.

So you might want to try moving those to the top if you haven’t already done it. :slightly_smiling_face:

Having said that - running that file caused one of the most frightening displays of travel speed on the part of the head movement that I’ve seen. It was shaking the table from the vibrations it caused. There is something wonky with the file - maybe because of the various conversions it went through, or maybe something in how it was created, I don’t know. If I could interpret the code for it I’d look for some kind of acceleration code in there…but not my bailiwick. Never seen it before. But that wasn’t normal movement.

I’d re-create the file from scratch rather than let that continue. But if you want to use that one, moving the holes to the top of the thumbnail column will let it cut through. :slightly_smiling_face:

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