Questions from GF Skeptics on FB

HT and LT were in common use in the era of thermionic valves (vacuum tubes in north America) when I was a child. Above 10kV would actually be EHT (extra high tension). Capacitors were called condensers. You also have LF, HF, VHF and UHF frequencies from those days.

If you use liquid as analogy for electronics then voltage is pressure, current is flow rate, charge is volume. I think tension can also mean pressure in French, so it is probably a bad translation that stuck. A voltage between two plates does cause a force, so capacitors are literally in tension when charged.


I’ve always called a motor vehicle’s spark plug leads HT leads same as high voltage transmission lines. While many people will not have worked in power distribution grids most people will have come across spark plug leads. It’s a very old term.


Dan has said it will be UL listed and CE marked. They have to pass safety testing for this. Does that mean you can half disassemble the machine, lick your fingers and stick them anywhere? No, not without taking your chances, but if you use it as intended you’ll be fine.


I am confident that to achieve the UL and CE listings that;
The tube will perform well.
The duty cycle will be sufficent to allow reasonable functionality.
The filter will function within reasonable parameters.
The case will meet requirements for fire safety. (Ever see an injection molded ashtray?) and once a tube fails, glowforge will be happy to sell me a replacement.
That there will be ample replacement mirrors available (what?) - that it can be cleaned like any other machine, and that requirements for emergency stop will be satisfied. (Lid switch?)
That it will conform to electrical grounding standards (duh).
That user serviceability will be far above many things, like an iPhone for example.

If the Glowforge attains a UL listing, I will be even more confident than I was when I threw money at it before it even existed.


Cool little history lesson with the Tension bit. Nice to know the source on things that bug me :smiley:

Agreed. I’ve learned so much on this whole forum.

I’m in the group where these questions originated. They seem like a bunch of angry children hung up on marketing terms and tearing GF down. Honestly, I don’t know/understand enough to feel comfortable saying much in response to them. But, isn’t that part of what GF is for…people that don’t want to have to (basically) build their own machine? Seems like many people have had serious problems with their Chinese laser machines…so much configuring, replacing, complaining, etc.

Also, as for the ship date changing…I always estimated summer 2016, so I am not sure what has changed. As far as I can tell nothing.

They seem like a bunch of gripers that are waiting gleefully for someone else’s failure. :(. I hope in 10 months I am gloating! :slight_smile:


They actually droop under load more, as they heat up and stretch (they actually worry about a windy day under heavy load that since the loops are longer the fields can start interacting). My father worked on engineering “real” high-tension transmission lines (768kv to ground) which would stretch massive amounts under full load.


There’s people that find a certain amount of pride in getting the Chinese machines to actually work and you’re dumb to spend more, and then the ones that can afford the $15-20k units feel like anything less is crap. And the vocal people are just trolling and no facts will be good enough for them.

I figure it’s easiest just to sit back while they whine and hope that GF will prove them wrong once they hit our doorsteps.


Nice to get to the original use of the words. Thanks so much for the lesson. It much more sense now as to how the usage survives.

That sounds a lot like on-line comments regarding DIY, hobby turnkey, and professional CNC equipment in machining fora around the web. There must be some sort of fundamental truth involved here.

@kim1032 , I joined after the link was put up here and must concur with your observation.

The web has created a degree of anonymity where people feel safe in acting like jerks without repercussion, and on that forum experts when they aren’t and a sounding board for elitists who think you are unworthy because you either A. Bought or didn’t buy a 25k do it all system, or B. Bought, or didn’t buy a cheap Chinese laser and mod it, waste money on it and calibrate it before every use.

Every true expert in their field that I have known, and I’ve known a few, enjoy and encourage others in joining their field and help willingly. That’s just an easy litmus test to weed out the wannabes who think they know more than they really do.

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I understand where the skeptics are coming from, and don’t fault them a bit for waiting until we’ve shipped to decide. Early adopters like us get the fun stuff first, but as the proud backer of 115 Kickstarters (!) I can attest that we early adopters have also been known to receive the short end of the stick from time to time. This won’t be one of those times, but they don’t know that. Glowforge is going to get you all something wonderful. We’ll get them something wonderful too, later, if they want it… they just will have to do without for a while. :slightly_smiling:

I also don’t fault them for asking us to “show our work” and reveal our sources, designs, and so on. If I was skeptical of someone but really wanted to believe, I’d ask too. For practical competitive reasons, we won’t answer those questions, but it doesn’t hurt to ask.

There are a few questions in here that I can answer though, which I’ll do my best to do here:

  • The Basic model is water-cooled and has radiators that shed excess heat. The Pro model uses that, plus a second thermoelectric cooler and radiator.
  • There’s no agreed upon standard for expressing filter life - at least, we haven’t found any of the other laser filter manufacturers’ answers to this question. (If they have, please do point me to where so we can compare!). We’ve said that we expect to have replacement cartridges available for <$250.
  • We will sell and ship tubes guaranteed against DOA. They are user replaceable.
  • The lens is protected by purge air, easy to clean, and easy to replace. When you get yours you’ll be pleasantly surprised by just how easy, in fact, it’s a pretty cool mechanism.
  • Ditto the two windows that protect the mirrors, the output coupler, and the back side of the lens.




Thanks for the additional (or repeated) info. It’s good to see this every once in a while.

That group is a pretty phenomenal resource. My facebook feed is now flooded with all things laser.


yes, other than the occasional glowforge bashing by a few members theres a lot of good stuff in there. It also makes you see how much troubleshooting and maintenance you have to do on the other lasers that are out there. i cant wait til people start getting glowforges to see how the dynamic of the group changes.



This is a big question for me. I purchased the Pro and am wondering how long it can run at full power before needing to take a break. I’m sure things like ambient temperature come into play but I want to make sure it is going to fit my needs. If it wasn’t a closed system then I wouldn’t be so concerned. But with no additional cooling add-on in sight, I would like to know how long it can run please.

The last info we received was many months ago. They had little info on real H/W at that point. The plan seemed to be a Pro that would operate almost continuously at 70 degree room temp. The Basic would have to stop frequently to cool down on long jobs. But they might have better info now.

danStaff Oct '15

Oddly the deciding factor here would be air conditioning. If he’s running in an 80 degree garage, the Basic is going to need to stop frequently to cool down. It will likely be frustrating and slow. The Pro model would be able to run for a much longer period before needing to cool off, if at all.

If you’re at 70 degrees or lower, the Pro will be faster, but the difference will be less stark.

Note that this is back of the envelope right now; we’re still early in our thermal testing - just trying to give you our best sense of where they come in.

Thanks @rpegg,

This is why I’m looking for an update. Our last information to base it off of was so long ago and this was before the new tube or power supply were even available.

I really want to make sure I’m not going to be throwing ice packs in there like some people do with the 40w Chinese ones.

I feel that we are far enough along that this information should be available and on the FAQ.

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