All items were measured with calipers to 0.001", thickness taken at multiple locations to check for variation. Cardboard, while it looks creased, laid perfectly flat. Made sure to check all 4 corners for any warp. I can use some draftboard, but doubt it will fix the 0.250" offset.
As to the squareness of the blue blocks, I just threw them in for about right, they were scrap parts. Regardless they were place directly under the camera, with the exact height entered. So the fact the engraving in not lining up with placement is very disappointing.
Also do you what the point of auto focus is then? I guess I am confused with the point of it…
At the moment the auto focus is used for that and that alone. placement is handled completely by the lid camera at the moment. What the future holds? Your guess is as good as mine.
I’m not calling your ability to use calipers in into question it’s just that customer service is going to ask you to do some on some proof grade anyway so you might as well go ahead and do it.
The “after” bed images are supposedly less accurate than the “before”. So if you’re trying to retrospectively see how accurate your glowforge was by looking at the post bed image, you can’t.
Why would they be at all different? Same camera, same position. I guess I will take a snapshot of the before, and super impose it on the after to see if that is the case.
I’m honestly not sure why they would be different - its one of those things I’ve seen mentioned several times, but I’ve yet to stumble across the original discussion or comment where it was learned, which might explain the reasoning.
I know @Jules reads pretty much everything and has talked about it before - she might know the reasoning behind it or the extent of off-ness or something useful.
A couple of weeks ago they told us “surprise, new camera software which uses that calibration data we collected is now available for everyone!” But, as far as I can tell, they have not promised additional work beyond what they just delivered. I have seen Support messages which include things like “as the camera improves” but that is not the same as a confirmation from @dan that we can expect more camera improvements.
Such a promise may have been made. I do try to read every post, but I am sure I have missed some good ones.
If your material height is entered correctly, and the material is flat, does non-Proofgrade material really have worse camera accuracy than identical material with the Proofgrade certification? It seems like they’d actually have to to out of their way to make the non-PG results worse since the math should be the same for each.
To clarify, the lid camera is fixed focus - it has no motors etc. With that wide of an angle, the depth of field is very large and everything in the range is in the plane of focus. The autofocus is to focus the actual beam. Right now, it takes that measurement when it scans just before a job starts. Presumably, they could take a pre-measurement and determine thickness, but that’s just speculation.
I never said or implied that non was worse. Yes, the math is the same. The difference is that often non items are not perfectly flat and we (or perhaps it is just me) make errors measuring thickness. Scraps and smaller pieces of also benefit from being placed directly under the camera. It is just how placment works.
My understanding is that the recently released work is just a first level of using that data. “As the camera improves” is exactly saying they are working on more improvements. How else is the camera going to improve?
In my opinion, they will be able to achieve sub-pixel accuracy at the edges.
Perhaps a little de-mystification might help.
The camera takes an image of the inside of the Glowforge. Support released an example of the raw image a while back, clearly showing that it sees a wider angle than is being displayed.
Take the simple case if a perfectly-aligned, perfectly-manufactured, machine.
When the Glowforge calibrates, it is taking a picture of the top of the head, very close to the camera. Thus, the logo is huge in the picture. This allows them to very accurately associate the position of the head with what the camera sees.
The image processing software transforms the picture this perfect machine takes of the bed into a flat image to be displayed on your computer. The pixel data from the raw fisheye image has its highest density directly under the camera and gets somewhat course as it gets to the edges of the bed. Most of what you see on your computer screen is interpolated data. Almost none of it is the exact pixels recorded by the camera.
When the software is deciding what value to show in the tiny rectangle (destination pixel) of any given pixel on your screen, it mathematically maps that rectangle, along with your current zoom level, to a precise rectangle on the source image after that image has been dewarped (source rectangle). This source rectangle might map exactly to a single pixel, or it may enclose multiple pixels, or a tiny area enclosing the corners of four pixels.
Once the software determines the source rectangle, it applies a mathematical function, called a filter, to the colors of the enclosed and surrounding pixels to compute the color to show in that destination pixel on your screen. Repeat for every pixel on your screen.
The GFUI knows the exact source rectangles for every destination pixel on your screen. At .001” per step the bed is over 20,000 steps across, but the source image has fewer than 1900 raw pixels horizontally (full sensor is likely 1920 pixels wide, but some of those are overscan). So the GFUI can accurately direct it to cut between pixels.
All of that is fairly easy. The hard part is determining the dewarped image and mapping each raw pixel to the exact location in the physical machine taking into account that the machine is not perfect. Imperfections in the lens, minute shifts in the angle the lid closes, warping of the case because it’s not on a perfectly flat surface and many other imperfections make the dewarping process very complicated.
But given that they have very carefully recorded calibration information, they can solve that.
But it will take time, and each iteration will fine tune it further taking smaller variations into account.
The camera certainly isn’t perfect but I have found that doing what others have said and positioning it directly under the camera helps a lot.
Here are two “beads” from Michael’s Craft Store. the stone is flat and the turquoise one is slightly rounded. That being said, both of them engraved VERY close to where I placed them with the aid of the camera.
Overall I was impressed. I look forward to seeing future improvement though… especially when it comes to the TRACE feature.
I’m not sure why you would do this, the idea behind draft board is that the barcode has that information, not just for the material, but that particular batch of material. The measurement used is Glowforges gold standard for calibration. If the calibration is off with proofgrade, and their settings, then that’s on them.
I’d also check it with the Acrylic, I think it lays a bit flatter than draft board YMMV.
It shouldn’t matter if it is entered manually or if the “proofgrade” barcode is taking care of it. However, I have no idea how accurate their barcodes even are. So lets remove one possible source of error.
Any idiot can use calipers to get the actually thickness of a material. The medium 1/8" draft board measures out to 0.133" on average.
As I was told above, apparently placement is very sensitive to thickness. As to how much? I have no idea.
But was I wrong to assume we were going to be able to place an image using the software/camera and have its reliably print where it was placed? Did I read these specs wrong?
CAMERAS
Wide Angle Camera — View of the entire laser bed
Macro Camera — Able to view one square inch with resolution of 0.002” (0.05mm)
Camera can record stills and video for documentation and sharing of projects
Optical Thickness Measurement — Optical system measures the height at various points across the material to 0.005” (0.13mm)
AUTOFOCUS
Completely Internal — Lens moves internally up and down inside the head by 0.5” (13mm)
Continuous Autofocus — Laser focal point can be changed as the head travels, following complex curves during cuts and engraves
Multipass — Focus can be shifted between engrave passes, allowing detailed depth engraves.
Focus Override — the laser can be defocused to experiment with a range of techniques that require less intense heat including acrylic bending and cooking
MISCELLANEOUS
WIFI Connectivity
110/220 VAC
50/60 HZ
Basic model is a CDRH Class I Laser Device
Pro model is a CDRH Class IV Laser Device
Positioning precision to 0.001” (0.025mm)
Engraving at 1000 DPI with 256 power levels
You didn’t, but you also agreed to receiving a unit with software in beta, and agreed to accepting it with only certain things working, some partly working, and a whole lot not at all working.
There is understandable confusion with the images. I don’t know how or why but they are different. When you open a file initially and place it according to the bed image, the laser will burn it right there.
The camera image post op is slightly displaced from the actual engrave, and is easily assumed the laser didn’t engrave where it was supposed to by looking at the post op image.
I learned this on a job where tokens had to be engraved on both sides. After 2-1/2 hours to do the first side, with the sheet of material held in place by magnets, I flipped them all to do the back.
The post op camera image showed a displacement of about 1/4", and I was freaking out that it wasn’t going to register correctly. I knew nothing had moved, so I hit print and it engraved them all perfectly despite the offset image on the screen.
Across 8 months, every file printed right where I had initially placed them, and every post op image showed the displacement from where the actual engrave was.
Well I guess i’m crazy for thinking a 2 year delay would have allowed them to deliver units with less issues and get their software more refined. I get that delays happen, I am a mechanical engineer and have had to delay projects myself, but 2 years… lol.
I am also guessing I missed this announcement stating that alignment doesn’t work yet. All I saw was that agreement box saying that our unit might be scuffed and somethings were being fine tuned still.
I just didn’t know it was that one of the key selling points doesn’t really work. I don’t think this is a ridiculous expectation, but to each their own. We will see what happens over time.
The software on your Glowforge is responsible for ensuring that the print lands on the material in the same place as the preview. When you’re done with a print, let a new image load. If the print appears on screen far from where it was supposed to go, you may have an alignment problem.
Most alignment problems come from the material being closer or farther from the camera than expected. While the software is still improving, you can take these steps for the most accurate alignment results:
Use Proofgrade™ materials.
If you don’t use Proofgrade materials, use a precision set of calipers to measure your material, and enter the thickness in the “uncertified materials” dialog.
Use material that is not warped or tilted.
Place your design near the center of the bed.
Clean the area underneath your crumb tray, particularly the four indentations on the floor.
Reboot the machine. Alignment can drift over time, particularly if you bump the head of your Glowforge while removing material.
Should you finish all of these steps, and find that you have an alignment error of more than 1/4", please try the following troubleshooting steps:
Turn off your Glowforge.
Check for small pieces of debris or dust.
Check the lower door to make sure it closes all the way. It may require some force to open, but open it, wipe any dust off the edges, and close it all the way.
Remove the tray and clean any dust or debris from the surface underneath. Pay careful attention to remove all debris from the four dimples where the tray rests.
Check the lid to make sure it closes all the way. Small particles of material, such as dust or debris, can prevent it from closing completely.
Check the surface your Glowforge is on to make sure it’s flat. Ensure it is not twisted slightly and that there is no debris propping up one side of the machine.
Turn your Glowforge back on.
We included an extra piece of Proofgrade Draftboard with your materials shipment for troubleshooting. Place Proofgrade Draftboard in the center of the bed and print the Gift of Good Measure using the default settings.
When the print finishes, without moving your artwork or your material, take a screenshot of the workspace to show us the difference between the artwork placement and the actual print placement. Make sure to include the rulers in your screenshot and show as much of the bed as possible.
Mac: Press Shift-Command-4 and click and drag a box around your image. You’ll find the screenshot file saved on your desktop.
Windows: Click on the Start Menu and search for the Snipping Tool. Open the Snipping Tool > New then click and drag a box around your image. Click the Save icon and name and save your file.
Send us the screenshot along with the date and time of the print, and we’ll investigate.
and has talked about it before - she might know the reasoning behind it or the extent of off-ness or something useful.
was worse. Yes, the math is the same. The difference is that often non 
