Plywood or hardwood?
Plywood. I’ve engraved/cut about 20 of these, all from the same large sheet, and they have all come out consistent until now.
Is it the same piece of wood with two different cuts?
Yes
Are you using the same settings?
Yes (a saved preset, not touched between the two jobs - it’s the same file as well)
Have you cleaned the lenses and windows lately?
No. Because the glowforge is fairly new (live in Norway, we didn’t get our preorders until July). It has not been used much yet.
When you set the focus, are you over-riding the value in the individual operations, or are you letting the Auto-focus set it for you?
I did manually input the focus height (it’s set to 3.6 mm), so it should have been identical for both pieces without any auto-focus changing.
…I will try to clean what I can, and see if it return to normal. Will report back asap.
Hmm, I was not aware of the “Set Focus” feature (I had just typed it in manually for this job). I will try it out after I have taken it apart and cleaned all the lenses I can find…
Poplar can be quite variable. Sometimes one part will cut easily and a centimeter away not cut all the way through. Likewise how dark the cut is will vary a lot.
You might mic in various places as well and make sure it is the same everywhere. Unless it is the thickness can vary, and even proofgrade can vary from piece to piece.
Best practice is to reserve the manual focus for special effects that require non-surface focusing.
Your GF will use the small red-dot laser in the head to determine the actual height to focus upon unless you’ve entered a manual focus value. The Set Focus tool allows you to place jobs very accurately with minimal shifting.
The one I have is ideed quite variable. But I have cut an entire settlers of catan board game with this same large sheet of polar, including a box to store it all in, with the same file and same settings. And although it varies from spot to spot exactly how easy it is to cut through, and exactly how clean things turn out, the variation is within a certain range.
This sudden massive change that happened overnight was definitely not normal. After wiping down everything, I am running a new test right now. Will post result in a few minutes.
Focal height setting is actually based on a few rules - since that looks defocused, it’s possible that when the auto-focus was taken, the beam fell off into a cut in the material and you wound up with a wonky setting for material thickness.
I’ll post the rules below, but the safest way to make absolutely sure that the beam is being focused in the same place is to enter the Focus Height value individually into each operation in the left thumbnail column. (Not in the Unknown Material height at the top.) The individual Focus Height will always be respected.
I have just wiped all the lenses, and major surfaces inside the Glowforge, Using the official lens wipe that shipped with the machine (this is the first time I wipe the lenses). Started a new engrave (identical to before), but results have not changed. Still bad, and very different from how I’ve been printing the last few months.
Machine was not all that dirty in my opinion, although I have little reference. The only lens with visible “dirt” was the one on the side, and it looked like this (zoom in to see some specks of dust):
On the main lens on the print head I noticed a small blemish that did not go away with the lens wipe. Not sure if it’s something that can have such a large impact:
I tested with manual focus (like before, set to 3.6 mm - matching the material and what I have used for months, and the setting used when I dialed in the settings for this wood). I also tested with auto-focus, but that just made it look worse (even darker, and lines look even thicker).
Best practice is to reserve the manual focus for special effects that require non-surface focusing.
Got it. Will do that in the future once the machine works again and I have printed this hopefully final piece for my game board.
Any good way to test the focusing of the machine? Perhaps make a test file with some sample lines, and score them with varying focus settings (auto and manual distance up/down) to see ?
Focal height setting is actually based on a few rules - since that looks defocused, it’s possible that when the auto-focus was taken, the beam fell off into a cut in the material and you wound up with a wonky setting for material thickness.
The focus was set manually. And the exact same setting was used for both engraves. Same file, settings, same focus, same piece of wood, same everything. Only thing that changed as far as I’m aware is that 24 hours passed from one to the next.
Almost same as pre-cleaning.
Looking closely I think it is slightly better, but looks nothing like how it has looked for the last couple of months. It appears to cut deeper and perhaps wider. Is it possible that focus has always been off, and I just happened to now randomly fix it, so it doesn’t match what I’ve printed before?
Manual focus on the left, auto-focus on the right (I’m ignoring that one for now - as I need it to match what I have printed earlier).
I think it’s time to switch to proofgrade (it has a finer surface) and make various thin lines to better evaluate the focus… Will try scoring instead of engraving since it’s 1000x faster.
Good idea. At this point I don’t know of anything besides variation of some kind in the wood or wood glue in the plywood that could cause the differences. But if they are on the same sheet, it would be pretty unusual.
Just to clarify… if setting the material thickness (for non-Proofgrade), if you set the focal height to the same value, it will use auto-focus, or, at least that’s always the way that it has worked before. To override the autofocus, the focal height needs to be different than the material height. For example, 3.6mm material height and 3.5mm focal height - where the 3.5 will be respected.
Hmm, that’s interesting. It might have changed then considering it looked even darker when I used auto-focus (material and manual focus were both 3.6 mm). Will have to test that separately tomorrow.
the thickness can vary, and even proofgrade can vary from piece to piece.
