PG not cutting though: material height?


#1

My first GF had a “head hits the front door” problem, and was returned.
The replacement GF isn’t cutting all the way through PG material.
I’ve cleaned the lenses and windows, triple-checked to make sure that they are completely dust and print free. The material is flat, crumbtray is clean and sitting flat.

I just tried a test and confirmed that 2 cuts through does cut.

I’m using PG medium maple hardwood (QR “Glowforge:B:AJAAFAk”). And this is where I just noticed something. The PG settings says to use a cut of 189/full with the focus height set to 0.125". However, my calipers say that the material (with tape) is 0.141", and without tape is 0.131".

Would this thickness difference between the actual PG material and PG settings account for it not cutting through?

My first GF (that was returned) did cut through this exact same board when I placed it in the middle of the crumbtray. Did someone change the thickness setting for the material?

I also read about a recent software change by glowforge. Could this impact the ability to cut through PG material?

Meanwhile: If I manually set the correct material thickness, will that be enough to make it cut through? Or should I also slow down the speed (since I can’t increase the power) to something like 165/full?


#2

The lens causes the beam to converge to the focal point (the beam waist) then it diverges. According to those thickness numbers, the focus is just below the surface, which I think would cause a deeper penetration.
My guess is that difference is not the problem, but I don’t know. I would slow it down a little.
Too slow and you will start to see flash-back burning on the bottom.

When in doubt, a good practice would be to hold the material still and see if the cut is complete by trying to lift the cut from the material with a piece of tape. If it isn’t free, and the material hasn’t moved you can run the cut again.


#3

What you said about the focal point totally makes sense. Thanks!

Do you have a gut feeling about how much slower to try? 189/full doesn’t cut through (or might make a “.” cut at corners). Running it twice makes sparks (laser hitting metal) but not any burn marks on the back tape. Is 165/full too slow? Should I try 180? 175?

I don’t have a good feel about speed differences yet…


#4

I would guess if you aren’t getting flash-back burn then your numbers aren’t far off.

Join the club!
When I got the pre-release I got flash burn on everything, so you adjust your numbers and adapt. Then they did power updates and it went away! Then they changed the scales from %power/ inches per minute/ lines per inch to the current standards. Adapt again.
It has been an evolution for both the machine and me. :sunglasses:
Personally I’m glad to ride along on this evolution, I would have hated to wait until everything was dialed in to get delivery of this marvelous machine.

I know they devote a lot of time and effort to getting the settings jus right, so I’m curious what might have changed.


#5

I have found that the PG thickness isn’t always what the thickness really is. So I adjust that number. I have hardly gotten to use mine.


#6

You’re not alone, I have been having repeated issues with PG maple plywood not cutting all the way through. Different designs, different sheets of PG. clean lenses, magnets holding sheet flat. Very frustrating to extract parts with razor and have to sand each piece.


#7

I’m sorry to hear you’ve hit a snag and am very sorry for our slow reply.

No, this wouldn’t cause your print to fail to cut through.

There were no changes to the settings for cuts.

Could you take a look at the troubleshooting guide for cuts failing and let us know if any of the solutions there help?


#8

Hi Rita,

You know when you call IT support and they say “have you tried rebooting it?” even through you’ve already rebooted it a dozen times? That’s how I feel right now each time GF support directs me to instructions that say “Have you tried cleaning the lenses?”

I have followed the cleaning instructions a half dozen times. As far as I can tell, the lenses are dust free, spot free, and completely clean. I put them under a high intensity light and a magnifying glass – no specs or dust. (The only glass that I haven’t done that to is the lens window at the far left of the machine – and that’s only because it’s mounted in a place that I can’t easily reach. Still, I have wiped that lens and I am sure it is clean.)

Attached is a photo of my crumbtray. It is clean. And it is sitting in the dimples and flat.
Attached is a side view of the material – it is flat. It is so flat, that I cannot even slide a piece of paper under it.

The third picture shows that I’m currently just cutting circles with a test image. (And I’m adjusting the mouth on the test cut, so that’s why it looks different in each disc.) With this lastest test, I use PG medium draftboard. The engrave looks great. The cut failed.

The default cut used 168/full and took 3 passes to cut.
I lowered to speed the 150/full and it took 3 passes to cut.
On my first GF that I returned: the head may have kept hitting the front door, but it cut this exact same board on the exact same crumbtray with one pass.

Is there anything else I can take a picture of for you? Would you like a photo of the lenses and windows? A picture showing the clean surface under the crumbtray?


#9

Here’s the gift of good measure that I tried earlier using the default PG settings. Front and back.

The round hole next to it was after 3 cut passes.


#10

I apologize for the frustration. I’ve replied to your email recommending that we replace your Glowforge.


#11