Quick question regarding the SET FOCUS option

Hello there! I recently did a camera alignment and at the end it mentioned something along the lines “for better accuracy do the Set Focus before printing”

I’ve been doing it ever since but today I forgot to do it and I just sent the print and noticed that it actually does it by itself before printing, it goes and shoots the red laser beam to self focus then starts printing.

So my question is what is the difference other than if I do “Set Focus” myself I can pretty much set it wherever I want instead of the machine choosing the area when I don’t.

Thanks

Manually hitting “set focus” measures the thickness of the material and adjusts the lid camera image so that your design placement matches the material as best as possible. It will also use the measured thickness to set focus height for any print steps that do not have that height set.

6 Likes

They do the same thing, but at different times in the overall job. If you’ve ever noticed that your placed print “jumps” a little bit after you hit go, it’s because the autofocus scan registered a different value than what was in the material height field. If you Set Focus at the beginning, at the spot you want to run the job at, that’s the most accurate that you’re going to get.

Set focus will also be more accurate than just typing in a material height and allowing that adjustment to occur because it’s reading the distance from the head to the material surface, rather than adjusting based on material thickness, which has a range of reasons why it could be a bit inaccurate.

7 Likes

Also if your material has holes in it from previous cuts, and the autofocus happens to fall into one of them, it will screw up your print. :slight_smile:

6 Likes

Thank you for such a detail reply.

Since it seems like you are very educated with the machine. What do you think could be the cause for sometimes the cut not being 100% accurate.

Let me explain. I made a coin about 1.5" (circle) and it has an outline probably about 1/8" from the edge where it will cut out the shape. Sometimes the machine is dead on and it looks beautiful, but sometimes the cut is of but like idk lets say 0.01" to the left or right side and even tho it seems like not much it makes the coin look off centered if that makes sense. I just don’t understand why it wouldn’t be 100% centered when the cut line and the design are in the same file and they are actually CENTERED ( I am a graphic designer and I’ve been using illustrator and photo shop fro over 20 years so I am sure my design is good, plus sometimes it looks perfect and sometimes it doesn’t - same artwork)

Is this something that has to do with autofocus? I am always cleaning the lenses and cleaning the machine, I am very OCD so it shouldn’t be anything related to that plus it can happen in the same job I send. Let’s say 6 coins, 4 would be PERFECT and 2 a little off centered

If you are engraving and cutting with the same run this should not happen. however if you are flipping the coins in the hole and doing the other side it can happen. If you use the precision numbers in that popup on the bottom it will print in exactly the same place no matter what it looks like. Then you only need to make sure your base material does not shift,

When I am working however I choose to set focus just to the side of my work as it will not be different after the engraving, often having to do so two or more times till it stops jumping. that way I am sure that I have not moved the base material.

Engraving and cutting with the same run. Not flipping. I use the entire material and dont touch it until its 100% done

See. That’s why I don’t know what could be wrong. Also, I asked glowforge to check out my machine because before it would engrave the same run deeper in some areas (center of bed) and not as deep as it moved away from center (one job, one run). Then they said my machine had a “Bad tuning” at the warehouse and they were going to fix it and upload the fix online or something like that. Now it doesnt engrave different depth of engraving but why is it off centered? It should be 100% precise. You think my machine is broken???

And I forgot to mention. Even tho 3 out of 5 or sometimes like 8 out of 10 are centered. I still have to “trick” my designs and move the circle 2 “clicks” to the left (0.002 in) to make it centered because if my design/artwork is 100% centered it will ALWAYS be off centered when the glowforge cuts out the shape after the engraving.

Maybe its the file format?? I am sending my stuff vectorized PDF. But again, sometimes it works like a charm and sometimes doesnt. Even in the same rub/job

1 Like

If you want to try SVG instead of PDF, it might make a difference. Settings to use is here:

There can be another cause, but one I have not seen since the early days, that sudden stops and starts move the head very slightly from where it thinks it is.
At one time this was a very major issue, but if there is any give (say from a not tight enough belt that can slip slightly) it is still possible I guess,

This was supposed to be three passes in the same cut :roll_eyes:

I will give it a try thanks

Oh wow, mine is not that bad… it is very minimal but it is also because I “trick” mi design moving it a couple notches to the left.

I have noticed too (since I have to 2 two passes cuts) sometimes it goes around twice without “stopping” the first pass but sometimes it stops and starts the second pass (it is like 1/10 of a second) and that created a little knick in the cutout where you can see where it started and where it stopped. Again, this kind of things shouldn’t happen

1 Like

Again this was a big problem as the laser has to start before it moves, They have made what was a huge issue all but go away, As you could guess this is some very tricky math, and different in different situations but usually is less power rather than more than required, Thus a very intricate curly piece like those rainbows that went so wrong will now not cut as deep as a long straight away with the same settings.

I wonder if the belt tension is off and that could be contributing…there’s a section on the support site that tells how to check and adjust it.

I would think that if that was the problem it would happen always, not randomly??? I mean I don’t even know what to do anymore because I always manage to find a trick to make it look good , even tho sometimes it just randomly doesn’t. Because last time glowforge messed with my machine/tuning I had to re adjust all my designs and instead of having them moved to the left side by 0.004 inches I had to modify it to 0.002, so that tells me they do something that screws up my stuff instead of fixing it and I rather them not touch it anymore but, again, it should be DEAD ON SPOT ON cuts and I shouldn’t have to adjust my designs to the machines flaws

The machine specs are for 1/4" design placement accuracy.

CAMERAS

  • Wide Angle Camera — Mounted on the lid, provides a view of the entire printable area, accurate within 0.25" (6mm)

If I understand correctly the differences are happening within the same job, which would point to something mechanical, I think.

No, a loose belt could cause inconsistent results. The circle not ending up in the same spot particularly points to something like that.

Yes, same job, and not always in the same area of the bed, Sometimes could be just 1 out of 10 and it would happen lets say in the center and the next day could be 2 out of 10 and could be on the corner area… random

Is there a way to tighten the belt or it has to be replaced? My machine is just like a month old