Power seems to slowly be dropping off


Wife has been using the glowforge pro for a while now and it is becoming clear that the power levels seem to be dropping off over time. By that I mean that the same materials struggle to cut through with settings that previously worked and need to have the cut slowed down further.

I have always looked after it for her in terms of cleaning lenses etc, so I don’t believe it is due to dirt build up. Inspecting the mirror it appears clean.

I had initially put it down to differing humidity etc but it seems to be a constant downward trend. For example cutting some 4mm oak laminated laser MDF used to work fine at 145 and full power, but we’ve progressively had to reduce speed over the months to make sure it cuts all the way through. Its now just failed to cut through first time at 125 which has prompted my post.

Is there anything that could be causing this other than a dying tube? Material is always held down as flat as possible with some big neodymium magnets and I try to keep all the lenses and windows clean.


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In a Video that Dan did for Amazon showing off the GF, he indicated that the tube should last ~ 2 years if used ~8 hours / day. So unless your wife has been Very Very busy, it’s likely not the tube…

Are you sure you’ve been cleaning all the mirrors and replacing the lens correctly?


I wrote this up a few days ago. So don’t assume it’s directed at you. Just held off posting until I saw a relevant new topic.

My GF suddenly failed to cut through Proofgrade material. I am fairly anal about cleaning, making sure the crumb tray is lying flat, and using material hold-downs. It’s almost unheard of that the machine would develop a power issue in only 8 months of use. So, to check the most likely cause, I re-cleaned the windows, pulled and quickly wiped the head lens.
Nope. Still wouldn’t cut through. Not even close. Went back and checked all the surfaces with a bright flashlight. The windows were crystal clean, the internal mirror was spotless, but when I closely examined the lens with a flashlight it looked pitted and scarred. It would not come clean with a lens wipe. I ordered a new $75 lens.
In the mean time I decided to vigorously wipe the lens with my fingernails through the Zeiss wipes. The lens slowly started to clean up. It took several minutes to get everything off the lens but it’s now perfectly clean. It turns out the pits were probably microscopic balls of re-fused acrylic that had splashed up on the lens. (could have been polyurethane but I think it was the acrylic.) I popped the lens back in and the machine cuts like new.

I always first assume my processes are at fault.


yeah, my first guess would dirty lens/mirror.

Just to be sure, there are 4 that should be cleaned.

Far left hand side on the gantry. This is a lens
left hand side of the head. Lens
bottom of the head. lens
and under the top of the head. Mirror.
There is also a light and laser under the head that should be cleaned, but shouldn’t have anything to do with the cut not going through.


The other thing to do is test the Rules on Proofgrade.
That will rule out material density changes…


I have a sneaking belief (perhaps wrong) that late summer humidity may be part of the issue.

Houdini7 - yes agreed, assuming no manufacturing defect. However defects do occur and it could certainly result in a reduced tube life…

I have been cleaning all mirrors and lenses with zeiss lens wipes. I design and build my own CNC machines so have a fairly decent level of technical ability, I can certainly confirm that I have been cleaning them all and checked and the lens is installed correctly etc.

rpegg - I had a fairly close look at the lens but thank you for posting that, I will take another close look tomorrow to make sure there’s nothing lurking like you describe.

As for proof grade, it has never reliably cut through on proof grade settings even back when we got it in January… again it’s problem that has seemingly got worse (at first it would mostly cut through, more recently not at all. As I am not in the US I wasn’t overly bothered as we weren’t using proof grade materials regularly and use other laser specific supplies.

The humidity is possible, but it is less humid now than it was a few weeks ago and yet the speed at which it will cut through is still lower than before. Also while humidity will vary, the speed required has only ever decreased, not increased.


Actually it could. That’s used by the software to determine the material height and assuming you don’t override the focal point setting it tells the GF where to focus.

A dirty or otherwise compromised setup could potentially cause the head to focus incorrectly.


Amazingly enough I was having similar problems that came down to the larger head fan not pushing enough air and I noticed that there was more smoke floating between the lens and the work getting very lit up in the process. Also the smoke caught fire more often, not keeping the flame after the cut was passed but scorching , and even charring the surface of the wood so it could not be cleaned off but had to be sanded down.

After cleaning that fan by means noted elsewhere there was a large increase in volume from it and the cuts were much c;leaner as well as deeper…


Thank you all for your suggestions.


I’m sorry you’ve had this problem for a while, and I’m glad you let us know about it.

To cut successfully, there are three important things to check. First, your material must lie flat. This requires a clean, properly installed crumb tray and flat materials. Second, there must be no obstructions, dirt, or damage preventing the laser light from reaching your material. Third, your design must be set up properly - for example, with lines that are fully on the material and that are set to cut.

It sounds like you are well informed of this, so let’s try a controlled test print. To start, please follow all the instructions listed in our cut-through troubleshooter. If you’ve done any of the steps recently and have not printed since, you can go ahead and skip that step.

Once you’ve inspected and cleaned, please try another print. We included an extra piece of Proofgrade Draftboard with your materials shipment for troubleshooting. Please print the Gift of Good Measure on that Proofgrade Draftboard and let me know the result. If it doesn’t print well, please let me know the date and time of your print and send photos of the front and back of the print.

Thanks in advance!

Rbtdanforth - thanks for the input. Today I took a look at both the assist fan and the purge fan, made sure both were nice and clean and also gave the contacts a good clean with a wipe. Certainly seems to have spruced up the assist air, but alas still fails to cut through on older settings.

As well as the above, I also cleaned the lens/ both windows/mirror/focus sensor windows yet again, had a very close inspection of the lens (couldn’t see anything at all) and needed to cut out a piece of acrylic for a picture frame. I used a piece of proof grade and it didn’t cut through until I ran a second pass - I guess that largely rules out moisture content of the wood being a potential issue.

Something I forgot to mention but feel that I should - There is a very light scuff off-centre on the laser head window but there always has been, glowforge credited me some store credit for the damage for a replacement piece. Sadly as they (still!) do not yet ship internationally from the store, I have been unable to actually order one despite the credit.

That said, the scuff is very small and completely unchanged from when I received the unit. Very first ruler I cut out worked but proof grade has always been slightly dodgy in terms of reliably cutting out, usually requiring some clean up on the back. As you will see from the pics now, proof grade performance has become substantially worse in addition to speed continually having to be reduced for our normal materials. Given the scuff hasn’t changed at all in appearance, I find it unlikely to be the issue for a continual power drop off but as glowforge stores shipping policy remains US only it is currently difficult for me to acquire a replacement it’s hard to rule it out.

Printed the gift of good measure as requested on medium draft board. As always, crumb tray is sitting flat with no dirt in the alignment divots, the surface is clean and the wood held down extremely flat in this area by several strong neodymium magnets. Proofgrade settings were used (as of the time of this post it is the most recent print for glowforge tech support if you want to look at it, 30/08/18 at approximately 11:58 UTC ).

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Unfortunately, I have no suggestions for you, but I want to commend you for your even tone despite how frustrating this must be. It’s starting to feel like a warranty call.

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Hoping to avoid a full on return given the international problem… so here’s to praying it’s something we can solve remotely. I’m more than happy getting my hands dirty trying out any support suggestions so hopefully we can rule out everything else first. It still works for now, we just have to adjust the settings to compensate for the apparent drop off and things take a little longer make. For the cost of 2 way shipping the thing again I could build the wife a laser myself (Lord only knows I’ve got enough linear motion components lying around the man cave!) and just put up with the headache of teaching her to use a less intuitive interface and no fancy camera.

Just a thought by the way jaz - given that I can’t easily get a replacement window, would support be happy for me to run a single gift of good measure with the laser head window removed to rule out the scuff as a culprit? Given it’s not in the airflow direction it shouldn’t get much, if any, muck in from a short cut and I can clean out the head/mirror/lens again afterwards. Obviously I don’t want to do this if it will cause warranty concerns for you.

Might need to 3D print myself a little removal tool though given I don’t appear to have a 3 prong socket :slight_smile:

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Have you asked about having them send you the part? I would think there would be some kind of arrangement for international customers to get machine parts other than via the store, even if materials can’t be ordered yet!

Thank you so much for completing the test and posting the photos.

I’m so sorry about the printer head window. We can send you one directly, and I apologize that we didn’t the first time.

I’m going to close this topic and reach out to you via email to sort out the shipping details.