While doing a prototype of my first project I noticed that my cuts were not where I had put them in the GFUI. After some initial experimentation I decided to simplify everything and just test cut a 1"x1" square at various places around the GF bed. What I found is the cuts are actually shifted up ~.2-.3" and to the right ~.06-.3" depending on where on the bed the cut is done. I’m interested to know if others see such shifting or if there is a way to stop it shifting entirely.
I created a design with 3 rows of 4 1"x1" squares using the same SVG file for each square. I marked the upper right corner of each on the .126" cardboard and aligned the artwork to each one as best I could at 200% magnification. The final setup looks like this:
As you can see, the shift is more pronounced the closer the cut is to the upper right corner of the bed. I did 5 separate tests using the same 1"x1" square and consistently get those same results.
I have only cut 3 small projects before now (e.g. the sample ruler in the Catalog and a couple coasters with minimal artwork) so I did somewhat ruled out (ok, dismissed) the shift being caused by my GF needing cleaning. Looking back now, all my cuts after the first one were not quite aligned to the material which up until now has been the 1/8" proofgrade Walnut. (I admit I was too excited about doing my first cut to notice if there was any skewing or not.)
I will do a close examination of all the belts and internal mechanisms as well as a good cleaning all around. However given every cut has been shifted at least since the 2nd and I am only up to 8 now (including my 5 tests for this post) I am inclined to think the issue is not due to contamination yet.
Does anyone have any other suggestions about the cause or how to get rid of it?
I have more detailed photos of the rows and test squares both before and after if that would be useful in solving this problem.
The current visual placement alignment can be off by up to 0.25" at the outer areas of the bed due to the fisheye effect of the lid camera.
But you didn’t specify…did you set the actual thickness of the material in the Unknown Materials slot? It makes a big difference. (If the height of the material is off, the visual placement error is dramatically increased by the correction calculation algorithm.)
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",we’d like to have you try a few troubleshooting steps for us:
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 the Proofgrade Draftboard in the center of the bed and print the Gift of Good Measure using the default settings.
When the print finishes, leave the lid closed and wait until the fans stop and the picture updates. 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 type “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.
My apologies for not mentioning that in my setup. For the non-proffgrade material (cardboard) I used my digital calipers to measure the thickness in 4 places which I entered into the GFUI manually (.126" - .1265").
The 2nd and 3rd cuts I did were on the proofgrade Medium Maple I got with my GF were also shifted. I switched to cardboard and got the same offsets without consuming any more of the “good stuff”.
I’m willing to use my last small piece of proofgrade Walnut and run the test again after I clean the GF out. That will happen some time this week.
Thanks for the response. I plan on doing a very deep cleaning of my GF this week. Once that is done I will do a new alignment test on my last small proofgrade Medium Maple sheet and report the results. Does it matter if I test on the maple or the Draftboard?
I did a full cleaning as described and got my GF to almost white glove clean (I left some streaks on the inside of the lid). I found no particulate matter in the GF, in or under the honeycomb, and nothing on the belts. There was residue on the honeycomb and on the interior surfaces which I cleaned with a Zeiss wipe (the optics and tube) or a clean paper towel and Windex (sprayed on the towel, never directly on anything). I also carefully vacuumed out the GF to be 110% sure it was clean.
I then put in a sheet of medium draftboard and did 2 test cuts: a series of 1"x1" squares separated by 1" and the Gift of Good Measure. Both cuts were done w/o opening the GF once I put the draftboard in.
The net result is my alignment is off between 1/8" and 1/4" vertically and under a 1/8" horizontally. The horizontal shift does vary by the distance across the bed the the cut is at (or at least it appears to).
Since a shift of up to 1/4" is possible (this was news to me until now) I guess I will just have to factor it into my drawing placement going forward.
Gritty Test Details:
Here is a close up of the topmost 1"x1" cubes along with the placement markers. First the right side cubes:
I am now curious how the varying horizontal shift will affect my project cuts in the future. That is, will my box sides match or will I have to make sure I minimize my horizontal placement in favor of vertical placement.
Here you can see how much the Gift of Good Measure shifted:
Given the left and right edges shifted differently I wondered if my measurements on it would be accurate or not. I measured the 2" on the tool with my calipers and it came out to be 2" so that is some good news.
My 1"x1" squares are 63/64" x 63/64" and the holes are 127/128" x 127/128". That is expected given there is a kerf to factor in. The distance between the cuts on each row and between each row was also 63/64" x 63/64". Yet on the screen I see what appears to be more space. That I will attribute to fisheying of the camera since I am comparing cuts on different sides of the bed centerline.
My next task is to figure out how much to “pre-shift” the artwork before I start the cut so that it ends up exactly where I intended it to be.
Thanks again for the prompt responses @Jules and @pip!
There’s a very easy way to do this with pre-masked Proofgrade material. Just score the outside line very lightly, just enough to mark the paper without burning through it, and then you can easily shift the design a bit for the real cut if you need to…
There is also a method called Kentucky Windage that folks have had very good luck with if precise placement is critical. If it’s not as critical, you can just leave a little extra room at the edges.
Are you asking if your design will cut true to what the design says? If so, yes, it will. The camera has no impact on the path the laser actually takes once it’s going - that is determined by the path coordinates in the file. The camera is just overlaying the visual, like a heads-up display.
By the way, are you using Proofgrade settings on that draftboard? Your Gift of Good Measure looks really toasty.
By the way, are you using Proofgrade settings on that draftboard?
The GFUI said the material was “Medium Draftboard” and I left the default Engrave, Score & Cut settings that came when I loaded the Gift of Good Measure. If that is not how to get the right settings then the answer would be no. Otherwise it is yes.
Thanks again for your help Jules! I will check out that tip and use it to make more efficient use of my dwindling proofgrade stocks. (I’m getting more stock for gifts from the family this year so I just have to curb my projects until then!!)
I’m not looking to get critical placements. I just want to keep my material waste to a minimum so I can get more out of the stock I have.
I hear that! (After a few months you’ll get less obsessive about it, but at first, it feels really critical and you buy a half dozen small bins to store the scraps in. Just try to not save the bits under half an inch square. They really pile up.)
The test with the Gift of Good Measure shows that your Glowforge is performing within the range of accuracy that we expect right now. As we make improvements to the software, I expect you to see further improvements to your alignment.