Laser Engraver/Cutter for Custom Masks

[JeffB]

Robert Ray used his laser to cut what looks like brass. I think what he did was just trace over the same pass again and again until it cut all the way through. The results looked a little bit crispy so I doubt it was ideal.

 Sorry it is a "short"   
https://www.youtube.com/shorts/3MV3dBSsq4M

I asked him a few questions in the comment section of the video...  I'm definitely intrigued by what he's done here.  I stand by what I said in prior comments, but I've not seen every laser out there, so this might be something relatively new.  I know my 50W CO2 laser system can't do this!  Very interested in how a supposedly 20W diode laser can.

Jeff
 

[Chris333]

I think it is .004" thick Phosphor Bronze using a Chinese Fiber Laser.

https://www.trainboard.com/highball/index.php?threads/z-scale-np-style-crossbucks.144961/

[JeffB]

I think it is .004" thick Phosphor Bronze using a Chinese Fiber Laser.

https://www.trainboard.com/highball/index.php?threads/z-scale-np-style-crossbucks.144961/

Ah...  Fiber laser.  Probably more power than 20W? 

Looks pretty darn cool though.  The possibility of being able to laser cut very thin metal on a home machine is enticing.  Though I think for what he's doing, photo etching would be a better solution.

JB

[rray]

This spring I bought a 50W fiber laser to see what I could do with it. I know, you guys think that it's crazy to waste that much hobby money that could be better used buying all kinds of great models "THAT OTHER PEOPLE MADE BECAUSE THEY WANTED THEM", but I model Z.

Modeling Z means either you are at the mercy of Southern Pacific modelers, "AZL" or you learn to make all your own models. So I spend my money on the machines and tools instead of other people's models, because I prefer to model the Northern Pacific Railroad.

I decided I needed some Z Scale road signs that were actually Z Scale, and I wanted them made of metal because the 3D resin ones are both thick, fragile, and out of scale. So I used 0.004" Phosphor Bronze for the signs, and .025" square half hard brass wire for the square posts, which is the finest square wire I could find. I used 0.7mm brass tube for my NP crossbucks, which I recently learned were on round posts, and that scales to about a 5.5" round post. I have to make take some liberties, but the results are signs that are much closer to scale than otherwise available, and they were fun to make:

As you can see, I need more practice on the NP Candy Cane stripes on the crossbucks, but I'll figure it out eventually:

[peteski]

This spring I bought a 50W fiber laser to see what I could do with it. I know, you guys think that it's crazy to waste that much hobby money that could be better used buying all kinds of great models "THAT OTHER PEOPLE MADE BECAUSE THEY WANTED THEM", but I model Z.

Neah, I think you're ok. If you can afford it --why not!  The more hobby tools one has, the better!     After all, you are having fun hobby time using it.

[rray]

So I just finished reading this thread. Yes I use a laser to cut masks all the time. I use my CO2 laser for that. A recent example is I needed 0.1" wide strips of Tamiya masking tape to mask my Z Scale KFC roof.

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I just laid out the 6mm wide tape, and laser cut it to strips for masking, then masked my roof. The trick to a good mask is to paint the roof with clear coat after applying the masking tape, and the paint bleed will be clear instead of the color. Then you can paint your color layer with minimal color bleed.
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I wanted a KFC, but as always, they are not available in Z, so I had to make my own.
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Now as far as tool go, I want to learn 3D drawing for resin printing, but since I already know how to 2D print with a laser, I have been trading my work for other guys work. And I built him a large laser cut dock with structures in trade for this NP W3 Class Mikado Shell:
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[JeffB]

This spring I bought a 50W fiber laser to see what I could do with it. I know, you guys think that it's crazy to waste that much hobby money that could be better used buying all kinds of great models "THAT OTHER PEOPLE MADE BECAUSE THEY WANTED THEM", but I model Z.

Not crazy at all...  Cutting 0.004" thick Phosphor Bronze with 50W is pretty crazy though!  What machine did you buy Ray?  I'd be interested in something like that!

What are you using for a feed rate?  I assume you're using compressed air for a cutting gas?  Or are you using O2?  I still can't get over that you can cut a copper alloy with 50W!  But a Fiber Laser is it a bit different than a Disk or CO2 laser.  I'm currently in the beginning stages of testing a 6kW fiber laser here at work.  The laser kerf/spot size is quite a bit smaller than the disk lasers we usually use.


Jeff

[Chris333]

That W3 is looking good!

[rray]

Not crazy at all...  Cutting 0.004" thick Phosphor Bronze with 50W is pretty crazy though!  What machine did you buy Ray?  I'd be interested in something like that!

What are you using for a feed rate?  I assume you're using compressed air for a cutting gas?  Or are you using O2?  I still can't get over that you can cut a copper alloy with 50W!  But a Fiber Laser is it a bit different than a Disk or CO2 laser.  I'm currently in the beginning stages of testing a 6kW fiber laser here at work.  The laser kerf/spot size is quite a bit smaller than the disk lasers we usually use.


Jeff

So the fiber laser is a Chinese JPT 50W. It don't have a nozzle and air assist gas because it is a galvo laser instead of a plotter laser. It takes about 7-15 passes at 250 speed. I don't know what that unit of measure is, maybe mm/sec. It is pretty fast. The video Chris linked shows me cutting the .004"Phosphor Bronze in a few seconds. It was cutting out 25 stop sign heads in that video. The kerf is about 45 microns wide with the 175mm lens I have, but I can concentrate it to 20 microns if I use a 70mm field lens.

I have cut .030" half hard 260 brass sheet, but it takes about 600-700 passes. I was making a steam tender underframe, and it takes about 2 minutes to cut one out.

Surprisingly Copper based metals cut much better than Iron based because it expands from heat less. I can cut stainless steel sheet but it expands and warps really fast. Aluminum engraves and cuts well too, but I have little use for it so far. I have not tried making PC boards yet, but I know I can do it.

[Chris333]

You say Chinese, but the price tag sure looks American 

Interesting that they look like a milling machine. What does that vertical arm adjustment do?

[JeffB]

So the fiber laser is a Chinese JPT 50W. It don't have a nozzle and air assist gas because it is a galvo laser instead of a plotter laser. It takes about 7-15 passes at 250 speed. I don't know what that unit of measure is, maybe mm/sec. It is pretty fast. The video Chris linked shows me cutting the .004"Phosphor Bronze in a few seconds. It was cutting out 25 stop sign heads in that video. The kerf is about 45 microns wide with the 175mm lens I have, but I can concentrate it to 20 microns if I use a 70mm field lens.

I have cut .030" half hard 260 brass sheet, but it takes about 600-700 passes. I was making a steam tender underframe, and it takes about 2 minutes to cut one out.

Surprisingly Copper based metals cut much better than Iron based because it expands from heat less. I can cut stainless steel sheet but it expands and warps really fast. Aluminum engraves and cuts well too, but I have little use for it so far. I have not tried making PC boards yet, but I know I can do it.

Got it...  Thanks for the info.  Yeah, lasers that use galvo's are really fast.  20 to 45 micron kerf/spot size is pretty damn small!  Between the wavelength and the kerf size, it makes sense that you can cut thin PB, though it takes multiple passes to do it.  Same with 0.030" brass, 600 to 700 passes is a lot, but if that's what it takes, at least with the galvo setup, it's relatively quick. 

FWIW...  Shorter focal length lenses have a smaller spot size.  So do compound lenses for that matter. 

Interesting stuff Ray...  Will have to look into this machine.  Sorry for the double inquiry (here and the YouTube video). 

Jeff

[Jesse6669]

Modeling Z means either you are at the mercy of Southern Pacific modelers, "AZL" or you learn to make all your own models.

Great stuff.  I'm the same with T gauge (I'm including 1:450 and 1:300 scale), and frankly that's one of the main sources of appeal.  I really enjoy doing the research, drafting a model from scratch, designing the decoration, and inventing things like better couplers, mechanisms, etc.  My approach has been mostly to 3D print, which has improved a hundredfold with the home 8K resin printer.  I also do a lot of 2D drafting for etching handrails, some road signs, and decals.

In other news... I bought a 250g bottle of "rubber"resin, with the idea of printing a very thin layer to create a mask.  Tests will show how thin I can go on the build plate and still remove it successfully, if at all... Maybe I could put a layer of frisket on the build plate to hold the mask?  Even if it's a giant failure, at least I have rubber resin to play with for other stuff like plaster molds or to make wee little tires..
 
Jesse
 

[rray]

You say Chinese, but the price tag sure looks American 

Interesting that they look like a milling machine. What does that vertical arm adjustment do?

The Galvo head sits on top, and steers the beam. It is composed of X and Y mirrors connected to a voice coil like a speaker, so the mirrors can move very fast, and steer the beam to the pattern you draw. There is a Field Lens under the Galvo, that both expands and focuses the beam. Mine is 175 mm, meaning my effective engraving window is 175 mm square. You can screw on several different Field Lenses, with the smallest being 70 mm. When you do this, you have to adjust the Z Height quite a bit, which is what that vertical column does. Focus is as simple as moving the Galvo head up or down till the laser throws the most sparks and makes the loudest buzzing sound.

[Chris333]

Wow very cool how the lenses work.

Some 3D printers use lasers, maybe that would get you into it 

[TrainCat2]

I was thinking of ways to do an SP bloody nose or other masking jobs in T scale (bloody small, if you pardon the pun) and thought about all the custom-made masks available to aircraft modelers.

I have a great deal of experience in cutting paint masks using a professional cutter purchased for my giant scale planes. If you have an artwork in Adobe Illustrator, I can cut you a piece and drop it in the mail. I actually would like to see how the cutter does on something as small as an Ngine (pun for a pun). It's possible to do come quite complicated masks with multiple colors. Not sure how it would do over details, but that is why I am curious.