Advice cutting Y-plate for lowrider

I have recently become interested in CNC routers and have decided to try building a LowRider. I have printed all of the 3D plastic parts successfully and am now moving on to the flat plates.

I have access to a CNC router machine and Vectric Vcarve Pro. I imported the 611 plate file and created toolpaths and was able to cut it successfully.

 

I then tried to cut the Yplate and ran into problems. I had 3 toolpaths. The first one cut the screw holes. The second toolpath cutout the hole for the motor. The final toolpath cut the outside diameter. (I had done the same with the 611 plate).

The CNC cut the screw holes with no prolem. But, when it cut the hole for the motor, it shifted a nit in the X direction so that it wasn’t central between the screw holes. Then, when it cut the outside perimeter, with each of the 11 passes, it moved slightly further in the X dirextion. Everything looked fine in the toolpath preview.

 

Any ideas on what might have caused this, or how to correct it?

 

 

How did you set up between the jobs? Can you just run them all in one job?

I only know about the v1engineering machines, maybe someone out there would know more about the specific machine you are using?

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Jeffeb3, thank you for your reply. I had intended including the machine name and model in the original post but couldn’t find it. I now have it; it is a General iCarver 40-915X CNC.

 

Another person was operating the controls, but I believe that between cutting the 611 and the Y, he sent the machine to the home position, then entered the new coordinates for the centre of the new project. I am wondering if there was something from the first job’s gcode that remained in memory?

 

I have made another observation, the bevelling effect only seems to have happened when the machine was cutting in the -Y direction, and not when moving in the +Y direction.

 

Vern

 

 

Do you have a photo? Sometimes there are clues there.

There are a lot of ways this could have moved a nit. My guess is that the coordinates weren’t the same between the two runs. If he actually homed the machine, then the homing could have returned a slightly different result. I can’t think of a good reason to do that in between the tool paths.

Did you split it into three files to change the bits? Maybe it skipped a step when you were changing bits? I would have just done the whole thing in one toolpath with a 1/8" bit.

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I set the cuts on both plates as separate toolpaths because the screw holes and centre cutouts needed to be cut on the inside whereas the perimeter had to be cut on the outside. Originally, I did the holes separately from the centre piece because I thought I might have to change bits. In fact, the entire plate, all three toolpaths, were cut with the same 1/8 in bit. The three toolpaths were set up individually but were run as a continuous job. There was no resetting home, or changing bits between one set toolpath and the next.

 

I realize now that the shifting was happening on al Y direction cts, but on the one side were it was undercutting, it was trimming off the top to make a nice vertical cut but shifted over, as you can see by the holes in the photo.

 

I am attaching a photo of the 611 plate (modified for makita) and two of the Y plate, one being a close up to show the steppimg effect.