Update to the update: We'll sell replacement tubes (discussion)

I was thinking the same thing. I graduated in the 80’s and a calculator was not an option. We were always told we wouldn’t learn how to do it in real life if we used one.


Times are constantly changing. Heck, I don’t even have to know conversions anymore when cooking. “Alexa, how many tablespoons an a gallon?” Boom… answer.

In the end though, even with the calculators, you still had to show your work to prove that you knew the process. The calculator just takes the tediousness out of multiplying out multi-digit numbers longhand. The basics for that stuff is learned in grade school and junior high, and no, we couldn’t use calculators in grade school or junior high (that I recall… but that was a long time ago).

I think that the principles of math are really about solving problems, not about the resulting numbers. If I can break down my real-world problems into mathematical components, then it becomes easier to solve them… or rather to determine ways to solve them.



That’s what I missed in algebra and calculus: understanding what it was I was supposed to be doing.
“Solve the problem.”

  • but what does it mean?
    “Use the calculator.”
  • but what does it mean?
    “Put these numbers into the formula, then solve.”
  • but what does it mean?

I got geometry. I can balance checkbooks. I designed a deck that is structurally sound when the [Hardware Chain] pro desk gave me “plans” that were not structurally sound. I factor the numbers on license plates and shipping cartons because that’s what my brain does when there’s nothing else to do. I can do math; but only if it is logical, first.

But algebra II and calculus didn’t compute.


Have always said that an Engineering degree has nothing to do with what you memorize. You can get equations out of books later. It teaches you how to think a certain way. (and of course the ability to understand the equations and concepts.)

Where I worked, Electrical, Mechanical, Aeronautical were all interchangeable.


TIL that there’s exactly 256 tablespoons in a US gallon. Thanks, Internet! :relaxed:


Cool, my first computer was a PDP 4. You loaded the boot sequence with bit switches


177753 or something like that. It’s been almost 40 years.

Edit: Actually now that I think about it the PDP 4 even predated my lab work, I was thinking about the PDP 11/45 and 11/70. The PDP-4 was a 1960s machine. Didn’t get to touch my first computer until 1970.


When ‘booting up’ had real meaning, not just the time between when you press the power button and when you can actually use the machine.


Has the packaging been decided yet and is that what the pre-release folks have been getting?

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I always tell people that Calculus classes are there to make you learn how to think.

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Maybe they should make the box out of non-laserable material, so we are not inclined to cut them up?


My boys complain incessantly about that and it seems to have turned them negative regarding math. As my older one says, “I’m never going to pick up a pizza and say, 'I wonder what the area is in centimeters of this piece of pizza? I’m just going to eat the pizza.” I think if they had better scenarios for the problems they give it might help the enthusiasm of the students. Not always possible, I know, but there could be a little more effort.


I learned more about math in Physics than I ever did in the math classes themselves, real world practical use for the win. Plus, my Physics teacher in high school built demonstrations for almost every lesson plan where we could plug in different numbers in the formulas and test them out in real life.


This is really bad.
First; @Dan has already reported a life expectancy of 2years for these laser tubes. I can tell you with certainty that tubes have a finite shelf life… and that life should be >5years. So either these Chinese tubes are of unacceptable quality; or @dan is not being clear how he measures the tube life… IE 2years of constant use… is a lot different the 2years of life - period.

Second, Having the tube non-user serviceable is a problem. It’s clear from their $500-we’ll-do-it fee that the swap isn’t trivial. Again; comparing to real laser machines… the swap is as simple as two - four screws and disconnecting a “molex” connector. The fact that glowforge isn’t doing this should send alarm bells to all users.

Third; There is more than the tubeswap itself. You have to recalibrate the entire system to ensure the beam path is accurate so that the new tube will lase properly. Not doing this will be dangerous to the operator and not having laser safety glasses to do this step is a problem.

I’m more than a little concerned now given @dan 's trivial dismissal of this. a 2year lifespan with will require me to recalibrate the system after a full teardown of the system should really scare the crap out of everyone. At $5grand for the production units without discount… that’s really not a good use of money.

IMHO; Glowforge needs to show a video of the tube swaps as it stands today… and they need to do it asap. Having customers spend this kind of money without a real clear picture of what’s involved is not good.


I’m trying to figure out why you’re trying so hard to convince other people that this is a bad deal.

Or are you trying to convince yourself?

All lasers have to have tubes replaced, and all lasers need to be re-calibrated afterwards. I think it’s great that Glowforge is giving people who are terrified of doing it an option to have it done for them. And the $500 is not much more than the tube replacement costs - just shipping for the machine, round trip. Might be a couple hundred dollars difference. (The tubes aren’t cheap.)

On the other hand, if we are moderately inclined to do so, we are going to be able to do it ourselves, and save the shipping costs. That sounds like a pretty good deal to me…it gives us a choice. And I can wait until they have time to get the machines out to tell us how to do it…unlike you, I don’t distrust them and think they are out to just screw us over.

You are getting pretty worked up over an extra $200 over a two year period - that’s $8.33 a month. Less than that if the tubes outlast two years.

Buy one less sheet of Proofgrade a month, and you can afford to have the unit shipped to them to do it right.

Glowforge isn’t likely to put out a tube-swap video just now. They’re busy. I’m sure they will before it’s needed, and on the off chance that they don’t - there are people here smart enough to figure out how to do it. :relaxed:


So proofgrade is $8.33 a sheet?:slight_smile:

Depends on the size, and the shipping costs. :wink:


It’s called sharing… IE providing alternate views to the situation.
True - all lasers have to have their tube replaced which is why Glowforge should have baked this into the design from day one.

What is at issue here is @dan has not shared the COST of replaceing the tube. Is it $200… or is it $1000 or is it 2500? We don’t know.

Did I read his update incorrectly? The actual tubecost is unknown. It’s $499 for them to do the swap… but that still doesn’t explain what that cost is.

Combine the quoted time of 2years… and the unknown of the tube cost… and the unknown amount of work needed to do the tube swap. That’s the concern.

In closing; The laser tube “issue” was so trivialized in his update that I actually missed it the first time I read it. As owners we should all be concerned with this turn of events… because the bottom line is this laser we bought may be “disposable” in 2years. Are you prepared for that?

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If sending it in costs 500$ then buying the tube will cost less. There’s your ball park number.

Otherwise here’s this handy link again:


Read it again.

It clearly says that for them to do the swap is $499… I read both of those together and it no so clearly states that the swap “labor2swap+shipping” is $499. The first bullet clearly states that the cost of the tube is not known and won’t be until they are ready to ship.

Did I miss a post by @dan where he said the $499 INCLUDES the cost of the tube?