Hi Everyone 
I am running some v-carve tests and have noticed some irregularities. When making circles, it appears that the bit may be losing track of where it is. Also, when making squares, I am getting issues at the outside corners.
And yes I am working on getting my belts to the correct tightness and making sure my wheels are good to go. In the meantime, I was just wondering if anyone has experienced this before and had it end up being something besides belts and wheels?
Modeled the test in Fusion 360, F3D file attached. Carving MDF sheet with Whiteside 1550 60 Degree. Tried 40 in/min settings on first test and then 20/25 in/min it in half for the second test. Similar results.
Thanks for the feedback!
For Inventables Forum.f3d (4.7 MB)
Ouch.
I agree belts/wheels seem likely suspects.
At least something hardware-ish…
Was the cut on the slower pass any better, and if you push it any harder is it worse?
The cut in the circle, where it goes wrong, it almost looks like a depth change too, or is that just shadow?
It gets a little better when I go slower, but still too much to ignore.
I was also wondering if it could be bit defection, though I doubt it, given the cutter profile and it not being hardwood?
Time to get tuning, will report back progress
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I assume you don’t see similar behaviour when using non-vbits?
Good luck with your tuning 
Good Evening
My belts are tight to around 3.6lb at 1inch deflection on center (no change needed).
I tightened all my wheels so that they were difficult but possible to move by hand (many were pretty loose).
It got better, almost there, but not quite perfect yet 
Going to try a standard straight bit next and see if the results are just for v-carving. Also worth noting- the entry paths that Fusion 360 generated were kind of odd. I know 360 isn’t known for its v-carve abilities.
I shall return…
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Nice one.
And going to some easier ground to get some solid steps/results in is a very good call.
Ran another test and the results were near perfect Acceptable for sure.
I set the home for my Z-axis to a micro-fraction higher than I had on previous tests and it definitely helped. I think the remaining difference is likely the MDF being slightly uneven, the workbed being ever so slightly off, etc.
So, to summarize (for myself and for anyone else struggling with v-carve accuracy):
Slow down the feedrate
Z-Axis needs to be perfect
Get your bed flat
Use high quality (flat) MDF
Test, test, test
@PaulKitchener thanks for being along for the ride
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You win!
V carving is worth the effort to get it right!
