I had a short look at the gcode created by the spiralize feature of Cura, I think it’s broken. Here is a sniplet of what it is doing:

```
G1 X207.024 Y172.236 Z17.665 E5514.06029
G1 X205.781 Y174.851 Z17.666 E5514.13974
G1 X204.468 Y177.383 Z17.667 E5514.21801
G1 X203.064 Y179.875 Z17.668 E5514.29650
G1 X201.569 Y182.323 Z17.670 E5514.37521
;LAYER:97
G0 F10500 X201.606 Y182.315
;TYPE:WALL-OUTER
G1 F1500 X200.044 Y184.688 Z17.671 E5514.45316
G1 X198.398 Y187.005 Z17.672 E5514.53115
G1 X197.424 Y188.336 E5514.57641
G1 X197.021 Y188.802 Z17.673 E5514.59331
G1 X197.004 Y188.832 E5514.59426
G1 X196.706 Y189.167 E5514.60656
G1 X196.485 Y189.375 E5514.61489
G1 X195.923 Y189.851 E5514.63510
G1 X194.948 Y190.570 Z17.674 E5514.66834
G1 X193.036 Y191.957 Z17.675 E5514.73316
G1 X191.118 Y193.265 Z17.676 E5514.79686
G1 X189.145 Y194.528 Z17.677 E5514.86114
```

As you can see, there are G0 (travel) moves at layer shifts that shouldn’t happen in spiralize mode as there are no layers in the original definition. There are also G1 print moves without Z, which means it is printing in one plane at this steps. This may be due to the Z increment being so small that Z is constant for some mm, but it also looks strange…

Here is a sniplet of code generated by spliralize function from Slic3r for comparison:

```
G1 Z77.409 X93.748 Y199.428 E4996.44220
G1 Z77.411 X91.166 Y198.714 E4996.53880
G1 Z77.411 X90.640 Y198.545 E4996.55874
G1 Z77.411 X90.204 Y198.355 E4996.57588
G1 Z77.411 X89.875 Y198.181 E4996.58931
G1 Z77.412 X89.564 Y197.980 E4996.60268
G1 Z77.412 X89.273 Y197.755 E4996.61594
G1 Z77.412 X88.955 Y197.456 E4996.63167
G1 Z77.412 X88.694 Y197.166 E4996.64575
G1 Z77.412 X88.402 Y196.761 E4996.66375
G1 Z77.413 X88.185 Y196.384 E4996.67942
G1 Z77.413 X87.979 Y195.922 E4996.69770
G1 Z77.414 X87.340 Y193.717 E4996.78050
G1 Z77.415 X87.098 Y192.973 E4996.80870
G1 Z77.416 X86.430 Y190.529 E4996.90007
G1 Z77.417 X85.786 Y188.056 E4996.99225
G1 Z77.418 X85.171 Y185.561 E4997.08493
G1 Z77.420 X84.584 Y183.046 E4997.17807
G1 Z77.421 X84.026 Y180.512 E4997.27164
G1 Z77.422 X83.480 Y177.876 E4997.36876
G1 Z77.424 X82.881 Y174.754 E4997.48340
```

No travel moves here, just continous printing moves until the top of the model.