Can someone help me out? This is a 1.5x8” 3D engrave WITH the grain using a 0.5mm tapered ball nose bit from sienci labs, stock is black walnut.
(Fine detail pass was after a roughing with 0.25” end mill.)
Why is it warping? I did a test on MDF earlier and the same thing happened, but I assumed it was because the cutout happened first and it lacked supports… making me think it was shifting during the engrave… but that’s certainly not the case this time.
I don’t believe it’s a software issue, but I’m using VCarve Desktop and LongMill MK2 with the Makita router at speed 5. Turns out just fine in the vcarve playback.
… I’ve done a second test cut and the warping changes. The first test (left) was raster engrave (skews up ans the engrave progresses to the right side) and the second (right) was climb offset (both sides are skewing up). So now I’m thinking it’s a hardware issue on the X-axis gantry.
I’ve had a few oopsie moments, so I’m assuming something needs to be readjusted? What do I need to do and how do I test it?
What was the orientation of the wood during the carve? Was it like in the picture or rotated 90 degrees? I ask because you mention maybe a problem with the X axis but if it was milled the way it is pictured my guess would be a problem with the Y axis.
You used raster on the left. I assume it started at the left side moving up and down the image and progressing to the right with each pass. And the image, focusing on the face, is skewed up as it progresses to the right. The lips are more level in the reference carve, I assume.
Then on the right carve it started in the middle and spiraled out from there but the long axis is still the Y. The result is the image skews up the farther you get left or right of center. This gives the really pointy chin compared to the right.
So my thinking is that for some reason you are losing some steps when moving in the negative Y direction. It’s like the machine moves 100mm in positive Y and then only 99.9mm in negative Y and then repeats. Those are just made up numbers but you can see how missing some travel in the negative Y leads to the image skewing up over time.
So I would look for anything overly tight that may be making the negative Y move too hard. I don’t think it’s backlash because backlash doesn’t accumulate, but missed motor steps do. I also might try backing off the feed rate or pass depth but that would depend on how aggressive you are being. My thinking is that missed steps are more likely when cutting aggressively due to the increased cutting resistance.
That’s my two cents. Hope it helps. If you did mill it rotated 90 then everything I said about the Y would be about the X instead.
Yeah, this was cut sideways (90 degrees CCW from what’s pictured). I’ll try easing up on the speeds/plunge rate. I was going with sienci lab’s PDF chart, but 143 feed rate for the 0.5mm does seem fast. I’m also gonna try doing a “Finish” roughing stage with my 1/16" TBN and try using the 0.5mm TBN to just sharpen things up.
Ok, I’m still getting misalignment issues. I’m running two “finish” passes… using a 1/16” TBN for first finish pass and then the 0.5mm TBN… which ends up going wrong.
I’m assuming the nose is because the stock is likely thicker at one end…
The 0.5mm starts fine, not pulling any extra material off… but I guess I start losing lines in the tiny areas it does. This is really aggravating since I wanna do more detailed (and small) engraves.
One thing occurred to me… the 0.5mm TBN is a 1/8”shank using the collet adapter… could that be the issue? I’ve read somewhere that not using a proper ¼” shank bit can cause problems?
I’ve never had a problem with using 1/4" and 1/8" bits. It shouldn’t matter because the center is the same. Are you losing position between finish passes? If so are you resetting X and Y zero with a bit change? You should only redo the Z0 for bit changes and the X and Y stay where they were. That’s assuming all the tool paths start from the same location, which is usually a good idea IMHO.
@gwilki The flat nose is probably just from the wood not having uniform thickness… my concern is the misalignment of the 0.5mm TBN. Look at the mouth and chin…
@_Michael I’m leaving zero material from the “roughing” pass. I did a full finishing pass with a 1/16” TBN as my “roughing” so the 0.5mm would have minimal material to remove and just “sharpen” the engrave details.
As for zeroing, just to be completely sure, I did a full re-zero with the 0.5mm TBN using my auto touch plate. I also watched as the 0.5mm didn’t remove any new material over open areas (as planned) and made tighter details more defined… I even reduced feeds/speeds to 96in/min (sienci labs says 143in/min for finishing pass). But it seems even just that still has me losing lines.
For the record, this is the only bit causing me these issues… my 1/16 TBN “roughing” pass is at pretty aggressive speeds (within recommendations) with no issues… that’s why I asked about the adapter being the problem…?
@pauljima You can’t leave zero material after the roughing pass and expect to get good carves.
You are introducing more room for error by resetting XY0.
How far into material did you place the model in VCarve?
@gwilki Oh, no, I think you’re misunderstanding… I didn’t actually do any “roughing” passes. I went straight to finish pass using 1/16" TBN and then did another finishing pass with the 0.5mm TBN. The idea is for the 0.5mm to only have to carve tighter details. In the most recent pic above, the bottom half is 0.5mm TBN and the top half is 1/16" TBN.
But even with that minimal amount of material for the 0.5mm to remove, it started losing alignment, as you can see by the mouth and chin.
And I’ve set the model to be 0.25" thick and sits flush with the surface.
@pauljima With respect, I don’t believe that I am misunderstanding. In your first post, you said, “(Fine detail pass was after a roughing with 0.25” end mill.)”
@gwilki Oh, sorry about that, that’s on me. That’s how I first started (original pic), but the latest test (pic above with clipped nose tip) was going directly to 1/16" TBN finish pass and then 0.5mm TBN… and still getting misalignment despite having virtually no material to remove.
@pauljima No worries. Your issue may be that, without a roughing pass, you are trying to take off too much material with a 1/16" bit. On the finish pass, VCarve will take off all the material in one pass. That toolpath overrides the pass depth setting in your tool database. It’s hard to see from the pic, but it’s conceivable that you are getting bit flex with your 1/16" end mill.
As I’ve said, I would not do this project as you are doing it, so I don’t believe that I can be of further help. Others here no doubt can advise you better.
Good luck. I’m sure that you will be able to get this done.
@gwilki No problem. Well, I’m not having any problems with the 1/16" going straight to finish pass. Everything stays aligned and the results pretty much match VCarve’s previews. My issue is solely with the 0.5mm TBN. If you look at the original results, the entire carve gets WARPED… and even with a full finish pass done before using the 0.5mm, it still starts to skew and would result in a warped result again… my thought was that with almost no material to remove for the 0.5mm, it’d assuage the warping problem… but it doesn’t seem to have had much of an effect ('cause I also slowed speeds).
I was having a similar issue with a 3d carve I have been working on. It was definitely a x motor missing steps/shaft slippage problem. I have replaced my v wheels, anti-backlash nuts (swapped for new version) and went gorilla on the coupler. I also set the max feed in the firmware to 3000 from the 4000 default. My Y axis can jog faster than 4000 on the dual motors but my x motor starts locking up at around 3500. This and adjusting down stock to leave between my roughing and finishing passes (I use Fusion) seem to have mostly alleviated the issue.
