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Rough Edge on Angled Cuts

When cutting an ‘A’ for example, the angled portion of the ‘A’ produces a bumpy edge and I was wondering if there is anything magical that I can do to rectify the situation? See image.

Thanks,
Bruce Hyslop

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Welcome!
What CAD/CAM workflow do you use?
Wondering if a large number of ‘line-segments’ instead of a straight line is causing this.
If you post the .nc file i could tell.

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Gero, thanks for jumping in. I have used MakerCam.com so far and that is what produced this file. I don’t have access to the .nc file where I’m currently at but will send it tonight when I get home.

What is your depth of cut per pass?

1/4 inch per pass. I am suspicious of that and let me know if I’m going to deep per pass.

It might be too deep. Rule of thumb (and that’s all it is… a rule of thumb) is depth per pass equal to 1/2 the router bit diameter… so 1/4 inch router bit would mean 1/8-inch per pass (0.125 inch). I normally do around 0.14 inch per pass for plywood. I’ve not cut MDF on my Maslow, but I suspect it would be harder than plywood and therefore, would drop it down to maybe 0.1 inch? Others likely have more experience with MDF and could provide better input.

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I have actually experienced the MDF cutting really well without such hitches. I go quarter-inch all the time on the depth. that doesn’t mean that I didn’t just happen to get exceptionally sharp bits or something. 1 experiment doesn’t give us proof.
My first thought was angled cuts being what appear to be pixelated could have come from the source of the SVG. For instance, when I am changing a .png image into an .svg I use inkscape to trace the bitmap image. Initially when loading my picture into inkscape it asks me if I want it to be smooth or not. Because I haven’t been doing Minecraft images or something I have chosen smooth every time. This may not be what it’s talking about at all but based on my experience this is why I have chosen smooth and I just wondered if it may contribute to your issues.

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I will try that. Your reply outlines how I produced the image and that may very well be my issue. Thanks!

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I will try this as I was suspicious of how deep I was going each pass. Thanks!

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One thing I will add to this is that when I have an image that also contains regular text I usually delete the text after tracing the whole image and then use Inkscape to write the text back in. I find that this gives me very regular text rather than the slightly warped text from tracing an image. If it turns out that the source of the ripples is from the image tracing, this method will alleviate that artifact. Do note, though, that you have to add text using a vector drawing program like Inkscape to get the benefit.

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That looks like the bearings are not moving smoothly on the ring. While you are cutting, I’d bet that the rollers move in jerks.

smooth the inner surface of the ring and see if that helps.

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A good point that was overlooked although present in the Forum.
Edit: The horizontal and vertical cuts look smooth. Wouldn’t a crater infested inner ring show the same, no mater of the angle?

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Another possibility is the sled weight or friction. - Fww

Thank you

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that pattern seems too even for weight/friction, but exactly matches ring
smoothness

however, I would expect to see that on most cuts, not only the angled ones.

David Lang

I initially thought ring/roller jerks might be the culprit but after looking closer at the picture I’m second guessing myself. Ring/roller jerking is usually less “predictable”, assuming he did several passes I would expect to see ripples in each pass that don’t line up with each other. There is possibly the chance that subsequent passes “smooth” the ripples of previous passes but I’d still expect to see something…

The verticals look good and the horizontal that I can see has only a minor blip. Checking the file should be easy but if it appears to check out and you still can’t figure it out a simple test would be to rotate the design so that one leg of the A is horizontal and run the cut like that. If the horizontal line is smooth and angled lines are bumpy then that points to a problem with the physics of the machine instead of the file (the ring and rollers can have a tendency to make bumpy cuts but usually that is seen on long horizontal cuts.). Another easy test would be to cut the same letter at a different scale. If you get the same number of ridges simply scaled up or down then you know it’s coming from the file/software and not the ring/rollers.

Keep us posted!!

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I’ve noticed the same thing, but less prominent, and I think it has to do with feedrates on the angled parts. The machine slows down a bit sometimes and the bit digs in, creating a scalloped appearance. I think that the spindle speed is too fast for the rate that the router is moving, but unfortunately, that’s the minimum speed that the rigid is capable of running. I just ended up running the edges past a belt sander to smooth them up, because the size wasn’t critical in my cut.

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