Inventables Community Forum

Divots on every corner!

I have a case open with Inventables and a couple people are trying to help me on the Facegroup group, but I thought I would post here in case someone has other ideas.

I have…
Trammed using a tramming gauge (twice!)
Resurfaced
Run the calibration test carve and everything comes out perfect
Done the X Y and Z calibrations. I even did the Z using a gauge and adjusting $102 until perfect distances.
Checked every V wheel using the two finger test.
Tried 60 and 90 V bits.

Every test I run gives me perfect results.

Yet, every time I use a V bit I get divots (oversized) corners and gouges in corners of anything raised.

Everything I do with any other kind of bit comes out perfect. Flat pockets, nice edges, etc.

With the V everything looks great until the very last pass when in comes down and ruins every corner on the piece.

I’d really like to be able to do detail carve with a V but I have never been able to in the two months I have been trying this.

How are you setting your Z-zero?

I am using the Inventables Z Probe.

Try using a piece of paper instead. It sounds like you’re cutting too deep.
It could be your zeroing or it could be the bit.

Try on a scrap piece difference height offsets with the V-bit.
No V-bit have a true, infinite fine point but some degree of flat spot. This cause the Z-zero routine to have the bit lower than calculated.

Running a few samples with incrementally higher Z-zero might find you a good offset value to use, reducing/eliminating the dimples (dogbones)

Well that and I’ve found for really sharp v-bits, they actually cut into the brass surface a smidge. I once had the probe puck actually get stuck on the v-bit point like a thumbtack and it lifted off when the z-axis retracted from probing…

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I will certainly run some tests with varying offsets and manual Z zeroing. What doesn’t make sense with that, though, is that the rest of the V bit detail carve is fine. The edges of the letters taper to the pocket at the correct depth, and the entire carve looks perfect except for the corners. I feel like raising the Z will interfere with the rest of the carve. I will give it a try though!

Alright, so I back it off in small increments and also try the paper zero method. All I get is a slightly shallower pocket with the same round marks in the corners. If I greatly decrease the Depth per Pass (to .01) I can get it to look better, but it runs way and it still is not great - nothing like the results I see others post.

Inventables said it is a physics issue having to do with deflection, but we still haven’t landed on a solid reason why this impacts me and not many others.

I am not sure its 100% relevant to your issues but its related to V-bits and how angles not 100% true to stated dimensions may affect the outcome:

I picked up another 60 V bit from a different manufacturer and I get the exact same results. I also went through a bunch of troubleshooting with Inventables, adjusting depth per pass, V wheels and length of shank in the collet. I ended up with this ridiculousness. The last suggestion Inventables has is using a 1/8 shank V bit, which I am going to try. They keep saying it is deflection, but the deflection adjustments don’t seem to make a difference. Reducing depth per pass to .01 is marginally better.

It really shouldn’t be this hard.

That doesn’t make sense.
What bit are you using?
Are you using Easel?

I was using an Amana 60 V bit with 1/4 inch shank.

I tried today with the Whiteside 1541 60 V bit with 1/4 shank.

I will have an Inventables 1/8 shank 60 V bit tomorrow to try.

Note that, as a test, I also tried an Amana 90 V Bit and got similar results (although wider).

I also want to point out that with “dog bone” examples I have seen it is usually caused as the bit is moving along X and Y and trying to turn a corner. That is NOT what is happening here. These holes are causing by the bit coming straight down the Z to make corners at the end of the carve.

I am using Easel Pro, yes.

Can you also share the Easel-project?
This allows us to dive deep into the gcode + run samples too with the exact same origin.

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I’ve changed it a few times. Currently set to a two-stage carve with a 1/8 straight and then a 1/8 60 V bit. I’ve tried with a variety of combinations. When I started this thread it was just with a 1/4 60 V bit (no detail carve).

Your 60 degree bit is only .25" wide? What 60 degree bit are you using? The shank and the width of the bit are 2 different things.
Edit: If you’re using the bit in the picture then you need to select the 60 degree bit because that bit is 1/2" wide
image
Russell

Yes, the bit in the picture is a 1/4 inch shank and a 1/2 diameter. It’s the Amana 60 V bit. I also have tried a 1/4 shank, 1/4 diameter bit from Whiteside, and the Inventables 1/8 shank, 1/4 diameter. For all of these, I selected 60.

In that photo I was confirming that it is a 60 and the angle is true.

Ok because in the Easel file you had the 60 degree bit selected but you had .25 as the width.

That would have been my Whiteside bit (60 .25 width). It’s hard to tell because you don’t have the same bits installed that I have. I’ve been trying this with all three bits and different settings, so it probably depends what I had in there at the time you accessed it.

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Here is a few things that you can look into. Since the issue is happening in the corners it makes me think that the issue could be in the gcode created from the design. If you are creating a v carve it is possible that there are two layers a top and bottom layer one represents the upper diameter of the cutter the other represents the tip of the cutter. If the dimensions of the cutter are not entered correctly, say smaller than what it should be then this could cause this issue. Another possibility is that you are either gaining steps or losing steps in the z axis from too high of settings or too low of settings