Hackspace Owners Manual - Laser Cutter


#1

Hi Folks,

For those who don’t know I’ve been working on a side project on and off called the Hackspace Owners Manual targeted at providing hackspaces and indeed hobby users with the information they need when making purchases or organisational decisions. The focus is very much on providing information with recommendations and case studies on what has worked for some organisations versus others without boldly declaring that there is One True Way:tm:

More information can be found at https://github.com/UKHackspaceFoundation/resources/tree/master/Hackspace%20Owners%20Manual/About%20this%20manual giving a slightly more in depth explanation of the above.

The pre-amble out of the way, I’ve been working on a document for laser cutters on and off for some time now and frankly I’m a bit stuck on some of the optical stuff. The physics is beyond me and I suspect that someone will tell me “Yeah, you don’t need to care, this is the thing you need to look for” on choosing things like mirrors and lenses.

So, here’s a link to the work in progress document which has already been a useful resource to refer a few people to - https://github.com/UKHackspaceFoundation/resources/tree/feature/laser-cutter/Hackspace%20Owners%20Manual/Workshop/CNC/Laser%20Cutter

What I’m really hoping for is for some help to fill in some of the blanks, and also work out what to say about mirrors and lenses. I think I’ve managed to confuse myself substantially with that part and it’s stopped me from moving on to the next things.

As long as you don’t mind the contribution agreement - https://github.com/UKHackspaceFoundation/resources/blob/master/Hackspace%20Owners%20Manual/About%20this%20manual/contributing.md :wink:

Please help, this has been languishing for several months now and I’d really like to see it finished and published for the wider community to use.

Thanks in advance for any input :slight_smile:

Ian.


#2

Oh, and yes, I need to add something about fibre lasers too which are starting to come into the realms of affordability.

Shiny things!


#3

I’ve seen this Ian. Thank you for posting. I’ll get to it. You should link me to these affordable fibre lasers… I know very little about them myself.

Dominic


#4

I’ve had a read of your mirrors section. What you’ve written, to the best of my knowledge, is correct and more than adequate. It’s a better description of the differences than I’ve seen anywhere else.

What do you feel you are missing? When you say “the physics is beyond me” what specific information are you after?


#5

I’ve had a read of your mirrors section. What you’ve written, to the best of my knowledge, is correct and more than adequate. It’s a better description of the differences than I’ve seen anywhere else.

Awesome, thanks for that, that’s actually really encouraging :slight_smile:

What do you feel you are missing? When you say “the physics is beyond me” what specific information are you after?

So my problem is based on the info in the document so far, I’d be looking to get a Mo mirror for my machine, say 20mm and I’m shopping around for the best deal. Obviously if I need it this week, my first place to hit up is Smoke and Mirrors :wink: but if I’ve got time and don’t mind waiting or perceive that my cash pressed hackspace can’t afford to buy mirrors in the UK and I want to source them directly from China, what figures am I looking at in order to compare one mirror against another?

Buying from Smoke and Mirrors gets me customer service and support along with a warm glow of supporting a UK company and having some reassurance that you’d be around next time if I need another or indeed have issues so I acknowledge that one gets far more than just the mirror there :slight_smile:

But if I were to compare within the Smoke and Mirrors site itself, there are two Mo mirrors, one at £12 ( https://smokeandmirrors.store/products/economy-20mm-od-mo-mirror) and one at £25 (https://smokeandmirrors.store/products/ii-vi-infrared-20mm-si-silicon-based-mirror). Looks like the URL is a bit confused on that one… :wink:

So quantifiably, what’s the difference? Does one have a higher reflective index than the other? What’s the physics that makes the Pro version better than the Economy version? Could be that the QA on the economy version is less with the manufacturer. But that’s my stumbling block. I’m more than happy to pay £25 over £12 for something that’s quantifiably better, but that’s what I can’t work out :slight_smile:

Does that explain the question? Also: Cool, the Pro mirrors are down in price from last time I looked :wink:

Thanks, Ian.


#6

The prices reflect (no pun intended) the price I paid for the items. The URL is not confused, the URL is just a URL and was duplicated from another product. I’ll look at tweaking it.

The more expensive mirror is a branded and high quality product (like getting branded biscuits say) which I’ve paid more money for. They are the same quality as the mirrors were in the machines I sold. They come vacuum sealed with desiccant and are made by II-VI who are a high standard optics company.

The economy mirrors come in tissue or plastic and tissue seal, are unbranded and cost me a lot less to buy (somewhat like an off brand or own brand biscuit). They may perform as well as the pro quality mirror. But they are not the same mirror from the same people.

As to physics, you’re going too deeply in. The physics is the same for both mirrors as far as it’s possible to tell. The difference is the packing and the reputation of the manufacturing company.

What you are afraid of is paying too much for something. In which case only buy the cheap ones. Obviously I can’t speak for other suppliers.


#7

The prices reflect (no pun intended) the price I paid for the items.

Makes sense. And you totally missed a worthy pun there…

The URL is not confused, the URL is just a URL and was duplicated from another product. I’ll look at tweaking it.

:slight_smile:

As to physics, you’re going too deeply in. The physics is the same for both mirrors as far as it’s possible to tell. The difference is the packing and the reputation of the manufacturing company.

This is what I was starting to think that perhaps I was going too deep in trying to understand the details. Pretty much everywhere I looked I wasn’t finding figures to support my earlier comments about reflectivity, flatness and quality. The only places I was finding that information was in scientific suppliers which as you can imagine have much higher prices as a result. Perhaps that information whilst technically correct isn’t helpful to include.

I might have to give up on trying to quantify it and explain it in terms similar to your comments above if that’s okay for me to use similar wording.

Thanks for the help Dominic :slight_smile:


#8

I mean, it’s a project for someone and might be fun if they have the equipment, but it’s not information that’s being made available on $15 mirrors for hobbyists.


#9

…by the way, I just want to add that I think writing this sort of thing is valuable work and want to encourage you to do more. Would love to see this sort of information for other tools.