Papercraft and Pepakura

I’ve been making papercraft models on my laser cutter at home. It’s a bit of an awkward 2 part process where I have to split the raster images from the vectors and then realign the two inside the machine. I’ve written an instructable about how to do it.

I would love to see the camera in the glowforge used to align the images and do the cutting for me. Pepakura already has plugins for doing similar things with paper cutters but a laser would do it so much faster and awesomer.


I give you +20 for using “awesomer” correctly in a sentence. What laser do you currently use?

Ability to detect standard printed alignment marks would be really useful!

It might be a little cheat because we own a company that imports Chinese lasers to the UK. I usually have a choice of lasers to play at work with but my personal laser in the garage is this one.

We can’t wait for the Glowforge because of the features like the cameras, I’m excited to see what we can do with some fancy hardware. I have a blog of laser cut things here


That is a great blog. A great resource that will keep me busy for quite some time. Thanks for sharing it.

Funny, I posted an idea about this over in the Ask Glowforge area as a response to tracing options:


The trouble is scanning and identifying the cut lines is extremely hard to do, there are probably programs already out there to do it but if the paper model is black and the cut lines are black most things are going to struggle.
It’s much easier to tell the machine what the registration mark looks like and where the cut lines are, not to mention it’ll be significantly faster and you already have that data calculated anyway.

@m_raynsford: I posted your blog to our internal “project inspiration” channel and boy, did it get a lot of love from the team at Glowforge. (Good to see you on the board btw; really enjoyed our conversations at Maker Faire!)

@fablab_elpaso: We already do fiducial detection, so it’s definitely workable. Fun fact: the Glowforge logo on the head isn’t just decorative. The camera sees it and uses it to align the head with the lid image. You wouldn’t believe the custom lens needed to focus 20x12 from 6" away, and also stay in focus 1" away…


If the model is black, and the cutlines are black, then I’m guessing a person would have nearly as much difficulty figuring it out too – detection would only streamline what already takes eyeballing.

If you happened to have a file that already included separate layers for graphics (appearance) and cutlines (form), then would make sense to just go ahead and print a registration mark ahead of time; but a lot of the files to be found on the net are flat PDFs without cutline information, so etching a registration mark would be a convenience bonus if a multi-page “scan > cutline markup > cut” workflow were done.

So the lid camera used for homing too. Does the 1" focal length enable any other functionality?

I ask because it sounds like the custom lens might have been expensive (in cost, time, or both) and I am hoping it isn’t just for homing when it seems like a traditional approach (limit switches, I guess) would have been both simple and cheap.

The lid camera is used for scanning, positioning, homing, and many other tricks we’re still working on.

1 Like

I was trying to ask specifically about the (difficult to obtain) 1" focal length capability.


The projects I’ve worked on where there is a camera as part of an embedded system you need a custom lens - there is no way around it. Unless you happen to have an engineer with a lot of lens design experience you contract it out. The additional cost of a somewhat more complex lens is relatively trivial compared to the minimum NRE of a custom lens. And the time of course is not borne by your engineers so it really isn’t relevant. We were always able to have our lenses molded (as opposed to ground glass), so the per lens cost was pretty small. Considering the cameras are key to what they want to do now and in the future it would seem a wise investment.

I can’t comment on what they paid, but if I remember correctly, the last lens we did cost $15k in NRE, plus a mold of 5-10k and a dollar or two for each production lens. You may also need a second mold for a lens holder, but while the mold will be roughly the same amount, the cost of the part should be cheap and the engineering not that much. Double those numbers, divide by 10,000 glowforges and it’s $5-10 per unit and they’re probably well past the 10,000 unit mark.


Thanks for the detailed response!

If it’s basically a wash, I don’t understand why Dan said it was difficult.

Using a camera with a custom lens attached to the center of a hinged door only to be forced to write machine-vision software to visually “watch” for a logo which might get scratched or covered in soot or dust on the top of the laser head only to avoid using the tried and true practice of using limit switches seems like an odd choice to me, especially if there is no other reason for the camera to need to focus on objects 1" away.

My Nexus 6 doesn’t have the best camera in the world, but at 6" its field of view is 7", the Glowforge lens needs to be nearly three times wider. The closest it can focus is about 2.5", the Glowforge needs to be about 2.5 times better. Obviously, the Glowforge camera doesn’t have to fit inside a cell phone case, but it seems like it might have been a bit of a challenge to satisfy either of these criteria by themselves, much less both with the same optics. … and JUST to avoid limit switches?

When engineers speak of difficult they can often times mean, “that was a challenge, but we overcame it and we’re feeling great about it.” That is how I took it.

Generally, I consider avoiding switches a good thing. They’re mechanical, their contacts degrade and wear out, if you’re counting on them for some sort of precision application you have to make sure the mechanical housing cannot somehow leave alignment and their throw length can’t change over time. Not only does a dirty glowforge logo only need a quick wipe to fix, but you can detect the error condition and inform the user to take action.

When designing a new system you make a lot of choices for a lot of varied reasons. Different teams come to different conclusions. My personal biases are pretty much running with their choices, but I can understand where others might have gone a different route.


Watch out for them worn out limit switches! A couple million clicks after they’re new and BAM! you gotta spend another $4 on a new one. Why, they’re only going to last 5000 years at that rate.

This begs the question: do cameras work forever?

Limit switches do not have to be mechanical. They do have solid states ones i.e. inductive sensors. Which I use on all my CNC’s. They tend to be more accurate than the mechanical ones (over time) and extremely repeatable.


I know that there are photographers on one of my flickr groups still using cameras manufactured as far back as the 1890s (1896 Rochester Empire 8X10, 1898 Western Cyclone No. 5 ) and many of the kodak brownies have survived, even though they are made essentially of cardboard. There are certainly a decent number of 100+ year-old cameras that still work.
Also, there are 12 beautiful Hasselblad cameras just sitting up there on the moon for the taking. Doesn’t get too wet up there, they probably still work just fine!
My oldest digital camera still takes pictures, actually. a whopping 1.3 megs. Viewfinder is shot and they don’t make the battery anymore, and it takes a second or two from when you press the shutter button to when the thing actually fires, but… works!

I don’t have any CNC machines but I am trying to learn as much as I can, especially trying to understand how the Glowforge will function out of the box. You refer to limit switches. As I understand it, they ensure that the business end of the tool doesn’t go too far in any one axis. Makes sense. But then there is the whole homing function routine to establish 0,0,0, or however you designate the coordinate. It seems to me that the two cameras eliminate the need to have six homing switches (again, just assuming as I don’t have any practical experience in CNC design.). The cameras also allow you to establish a starting point wherever the beam is in relation to whatever is in the tray set to be engraved or cut.

1 Like