Comment by TaylorAlexander | Hacker News Reader

Comment by TaylorAlexander | Hacker News Reader

TaylorAlexander

If anyone is interested I designed a 60 inch by 78 inch large format laser cutter that can be built for a couple hundred bucks, designed for cutting fabrics for sewing. It is an ultra low cost design, and it can be built in a way that essentially takes up no extra space in your apartment, because the gantry is removable and the bed is a thin sheet of plywood which you can cover with a rug when the system is not in use. The concept works but in my case the gantry gets a bit sticky and I lose steps, so it needs to be refined. However I have basically abandoned the project. I would love for people to use it as inspiration for future versions:

https://github.com/tlalexander/large_format_laser_cutter

I never finished making the youtube video for it, but I have a partially completed video that lacks a voiceover or proper edits for the second half. However it shows the operation of the system and offers some additional detail:

https://github.com/tlalexander/large_format_laser_cutter/iss...

Notably the design includes a built in raspberry-pi based pattern scanner which can be used to scan in clothes to make copies (with some manual work in inkscape) and can be used to scan in paper sewing patterns.

Oh that's great, shall I link to your project from the article?

Yes please! Feel free to link to the video too, which is otherwise buried in the issues page. I do really want this project to get more exposure, but I am lead on a pretty important open source farming robot and that has taken up enough of my time that this laser cutter did not get the attention it deserves.

You probably have a bit of a fumes issue with that setup :)

Done. How is the farming robot coming along? I have not kept up the last couple of months.

Hah yes at my old apartment it was easier to leave all the doors open and wait outside until the fumes cleared (with an easy view in to check for issues), but at my new apartment fume extraction is such an issue that I have stopped using the system.

The robot is coming along! We completed a ground up redesign of the robot and it is waking up every day in the field and running test cycles on solar power. I have been refining the electronics. I got back new revs of the motherboard and motor controllers and both work well, though I already see additional changes I want to make. I designed a new steering angle sensor that dramatically simplifies the corner assembly. We are working on moving the shop closer to my house so I can go in to low volume production on prototypes. This will allow us to get long term reliability testing done! Then we would start looking at kit sales and publishing official recommended designs for those that want to make their own.

It has been a hell of a slog, so I have not produced a video in a while. Hope to get one out in 1H 2024.

Since it contains a high power laser: how much thought and money did you put into the safety aspect?

I think the video answers that question decisively!

Not a lot. If the laser module somehow broke off and pointed somewhere it would be bad, though it is not a very coherent beam actually so it wouldn't be horrible if you were watching and shut it off quickly (I did get laser safety glasses but they are cheap ones).

I did have lunch with a laser safety engineer about 20 years ago who scared the shit out of me talking about problems with blue lasers. That deterred me from ever playing with for example those big handheld laser pointers you can buy. But this module is about 30mm square and sits 5mm from the fabric, so not much light really escapes anyway. One important consideration is that there are no metal screws underneath the lasing area, so I'm not going to get dangerous reflections.

Anyway I lived alone and had no pets and I was always present while it operated. For my use I felt the safety was adequate, but obviously for something like university use it would need a full enclosure. This version is a prototype slash proof of concept.

What's scary about this question is the lack of regard to safety in most US manufacturing facilities that employ lasers. Union shops tend to be up to par with safety standards, but if you go to the smaller shops, laser cutting and engraving is often performed by an unsecured machine with broken or missing cabinet parts or optical fencing. I travel to a lot of these shops to perform repairs on a variety of equipment my employer distributes and I can't remember the last time my log didn't include notes to have sales recommend the needed safety measures for the device. This neglect to safety seems to be just accepted by the workers and met with reluctant compliant by management, with everyone pointing to how inconvenient and "unnecessary" some safety measures are.

If anyone things OSHA has a handle on this issue, they are delusional. Without a major accident happening, most of these small shops can play by their own rules simply because the body enforcing them is stretched ridiculously thin.

So, thank you for asking this. It's insane to me how many do not bother to ask.

It's a really cool project, thank you for all the work. Is there a list of fabrics it can cut? I guess no synthetics?

It will cut basically any fabric. I have used it to cut synthetics (polyester) and I've cut heavy cotton with it. The hardest materials to cut are white fabrics as they reflect a lot of light, but you can always go slower. It can take a while to cut a large white thick cotton piece though. If that was desired it would make sense to go for a slightly higher powered laser module if one was available.

How bad is the burned edge? I also imagine it would be quite different for cotton and synthetic fabrics.

Amazing project!

Thanks!

The burned edge for synthetics is itchy. You can either design the garment to hide that edge from skin contact, or design your cuts to be a bit large and then snip off the edge that would be in skin contact (beats manually tracing out the entire pattern). The burned edge for cotton is nicer.

The gantry sticking is likely due to the two motors moving just a little differently at times.

Actually even with the motors disabled and moving the gantry by hand you will find spots that stick, independent of gantry misalignment (which obviously creates extra friction). The issue is that the gap between the side rails is not perfectly consistent, and the super minimal rail riding system doesn’t like this. The side rails, basically, are a little wavy.

The direct drive rack and pinion system is probably limiting your torque too.

Well and they are small steppers, because I took apart a mini delta 3D printer to reuse them. It would be a good idea to upgrade the design to use the more commonly sized 3D printer steppers.

I was thinking using 2 ball screws with one stronger motor and tying them together with timing gears and belts. But that will blow the roof off your budget.

Did you ever think about adding a camera close to the beam so that you could track cuts as registration marks and have a smaller cutting area while still being able to reposition to precisely cut out a larger whole?

Well there is a camera on the drive carriage. But no I did not think of this. It would be hard to precisely reposition the fabric because fabric distorts a lot.

There are industrial cutting tables that have rolls on both side, they leave some tabs so the material stays attached. Another trick of the trade is to cut through a stack of fabric (usually with a waterjet).

this is amazing!!!

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