Hey all, I have an Openbuilds Lead 1010 machine and am using Fusion 360 for this - I’m working on a guitar neck/body and need to be able to flip the piece and have it cut exactly the same on the other side. I’ve done everything I can think of and can’t get it to line up 100% or even 99%. I get about .005 difference every time and not sure how else to proceed. I did a test piece today using a different alignment method. Instead of ¼ holes/pins straight up and down from each other, I did offset holes like this: On the necks, I was going dead center above and below in the stock so that when I flipped the piece, it should line up perfectly when flipped. But every time, it’s still just slightly off. I know there can be a lot of variables, but I’ve calibrated the machine, made sure it’s square and all I can think of. So to test, I just did this rectangular piece to see if it would line up -- it does the same with the .005 difference. Almost exactly the same on both Y-axis. X-axis seems good at the very bottom -- but not at the top of the piece. The cut seems perfectly straight so that’s all good, just slight off. And I’m not leaving any stock to leave in the job either. Just a basic contour on each side just over half way so I can see where it meets up and what the difference is. I’m also zeroing off of the “fixture” the same way every time. This is what it looks like when I pull it over afterwards. See how the top cut and bottom are off from each other? Any help would be greatly appreciated! Thanks again! I have the Fusion file as well if you need to check it and see if I'm doing something wrong.
What are you calling the fixture? Are you zeroing X & Y, or just Z? Chance are that there is a (small) discrepancy in the position of your locating dowels between CAM and reality. ETA: Feel free to post the F360 file and I'll take a look.
You can see the zero in the first pic on the fixture. when I do the other side, I'm flipping the fixture, but keeping the same X and Y since the fixture is perfectly centered as far as the dowels go. I also had the CNC re-bore the holes before started just to make sure that they are lining up to the same spot. I know I can probably just contour all the way through and resolve the issue, but wanted to make sure things were centered since as you know on a guitar neck of all things, the carve on the back really needs to be centered. I'm attaching the Fusion file to help -- I pulled most of the guitar related stuff out of the file, and left this test piece that I was doing a similar thing on -- but I did move the alignment pins to offset each other to try a different approach. I can also add the original one as well if need be.
That will only work if your fixture is also *exactly* 7.000 inches wide in real life - any error between what you tell F360 that it measures and what it really is will get doubled when you flip it over. I've looked at your F360 file, and while it it is a little bit 'busy*' ( ) it looks like it should do what you want, but is critically dependent on the actual dimensions of the fixture matching the CAD/CAM dimensions (since the edge of the fixture determines the origin). I'd suggest putting the locating dowels on the centre line and using one of them as the CAM origin - that way, the fixture dimensions get taken out of the equation. (*I notice a lot of 'moves' in your design - strongly recommend learning about & using 'joints' to position things accurately and reliably - 'moves' have a habit of coming back to bite you eventually! )
Ok thanks for the info -- yea, this file is actually much larger since it's a whole guitar and all the parts for it. I did cut the fixture from Fusion on the 1010 so it should be tight, but when I flip the piece I'm not actually re-zeroing the X and Y, just the Z since theoretically it's the exact same size both ways. And I would assume that would take that factor out of being not exact. So I would assume since Fusion thinks it's exactly 7 inches and the flip is theoretical, it would be good? So when you say center the dowels and use one of them as the origin, you mean setting the X and Y to that dowel center? As far as moves, I assume you mean the fixture? Yea, I'll have to read up about joints. Most of this is definitely all new to me, so I'm still learning for sure. Just ran the test again after re-homing in between flips and the X- axis part looks pretty decent but the Y-axis runs are still off by the .05 or so. Weird.
That's the way to do it. Good in theory, but not necessarily in practice - F360 is putting the centre of the part at 3.5" from the origin (being the centre of your theoretical 7" fixture). If your zero point on the machine isn't exactly 3.5" from the dowels (if the fixture isn't exactly 7"), you'll get a mismatch when you flip. Yep. I didn't drill down to see what they were, but in general, they are a bad idea. Model each part, then align them with joints. You're flipping the part about one axis. If there's any centring error it will show in the other axis.
Ok - so in fusion, when I do side 2 (the flipped part) I should re-zero off of the center of the bottom dowel hole? Or should I do that on both sides? In other words, if I used 2 dowels, top and bottom of the extra stock above and below the actual piece that's being cut out - centered, I should find the dead center of those and set the zero x and y to that part? Like this?
But if I don't change anything about the zero - and it bores the hole at the 3.5" mark, then when I flip it, if I don't touch the zero, it should be exactly the same since the zero wasn't ever altered and the piece should contour exactly perfectly along the Y-axis unless it's something with the machine possibly?
You're setting your zero off the fixture at the moment, aren't you? Exaggerating: Suppose your fixture is actually 6" wide, rather than the 7" that the CAM is working to. You set your workspace origin on one edge of the fixture. The holes will get bored at 3.5" from that edge, which is 0.5" off the centre line of the fixture. When you flip the fixture and locate it on those same holes, the part will be 0.5" on the opposite side of centre, leading to a 1" mismatch between the first side and second side operations.
On two-sided parts, if the alignment holes are drawn as part of the model then copied to the other side, you are correct in that you do not re zero x and y. You cut side A, remove the part, load side B file, drill holes that were copied from side A into your spoilboard, insert alignment pins, flip and align part, re-zero Z then cut side B. I use at least 3 pins when I do this process. Broken endmills work great. Especially if they are the same diameter as the endmill you are drilling the alignment holes with. I believe what we are both describing is essentially this process where no fixture is needed. That eliminates any alignment error or measurement errors on the fixture.
Thanks again for all the info - yea on this piece at the top of the post, that's exactly what I did. Didn't use the fixture at all - drew the holes into the piece of stock that I used as the "stock". Drilled the holes half way thru the top side, cut the contour about half way thru, took the piece off, never re-zeroed anything. Drilled the holes into the spoil board directly, flipped the piece and put it in the holes on the spoil board, ran the back side contour and was off the above. So it would seem the process is ok?
That wasn't the setup in the F360 file that you posted. Again, if you're setting your machine zero using the edge of the stock for this sort of operation, the stock needs to be *exactly* the same size as what you have assumed it is in CAM. If not, you will get double the error as a mismatch when you flip it.
Is your machine accurately calibrated? If it is off and cuts slightly too big, then it will be off by that much just like you showed if zeroing on a corner. If you zero in the center, it should not be off. And that center can be anywhere you say as long as the stock is big enough. Check calibration, or do the same process, but flip end for end rather than side to side, or zero in the center.
Yes I did check the calibration and it's pretty good - pretty much dead on. I did check it over a 600mm span. Yea I guess I could try centering it based on the piece - guess it only needs to be centered on the x-axis plane since it's going to be flipped?
