Author Topic: Laser cutter for stainless steel stencils  (Read 17461 times)

0 Members and 1 Guest are viewing this topic.

Offline janekm

  • Supporter
  • ****
  • Posts: 515
  • Country: gb
Re: Laser cutter for stainless steel stencils
« Reply #25 on: May 14, 2017, 04:33:25 am »
BTW just the laser isn't enough to get good stainless steel stencils, there are post-processing steps too to remove the burr from the laser (otherwise the solderpaste won't release well). Usually electropolishing is used. You won't have much luck using an unpolished stencil for 0402 or QFNs (or smaller).
LPKF are probably the best-known brand for the CNC laser setups for cutting the stainless steel stencils, and the better Chinese factories use their machines (there are also some good Japanese ones).

So much like for making PCBs, it's a messy and expensive enough process that it's best left to a factory that do it day in day out and can reduce the costs to a minimum. You can just order the stencil at the same time as the PCB...
 

Offline DigitalDeath

  • Regular Contributor
  • *
  • Posts: 62
  • Country: us
Re: Laser cutter for stainless steel stencils
« Reply #26 on: May 18, 2017, 07:26:29 am »
I use a LPKF mill to mill 5 mil brass. They have 10 mil and 4 mill diameter end mill bits so you can make any size. Here's an example with several different footprints.
You can get used LPKF mills pretty cheap on ebay and on top of that it allows you to make pcb prototypes.
I would assume you can use pretty much any cheap chinese router engraver with these bits and make a similar one.

 
The following users thanked this post: Kean

Online mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 13695
  • Country: gb
    • Mike's Electric Stuff
Re: Laser cutter for stainless steel stencils
« Reply #27 on: May 18, 2017, 08:21:57 am »
I use a LPKF mill to mill 5 mil brass. They have 10 mil and 4 mill diameter end mill bits so you can make any size. Here's an example with several different footprints.
You can get used LPKF mills pretty cheap on ebay and on top of that it allows you to make pcb prototypes.
I would assume you can use pretty much any cheap chinese router engraver with these bits and make a similar one.
How do you keep the material flat while milling?
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Offline DigitalDeath

  • Regular Contributor
  • *
  • Posts: 62
  • Country: us
Re: Laser cutter for stainless steel stencils
« Reply #28 on: May 18, 2017, 08:26:57 am »
LPKF mills have a "ring" around the mill that rests on the PCB while they mill. The depth of the cut is adjusted by how much the end mill protrudes from this ring. This head and ring are held down by a solenoid while the head is down.
 

Offline IconicPCB

  • Super Contributor
  • ***
  • Posts: 1527
  • Country: au
Re: Laser cutter for stainless steel stencils
« Reply #29 on: May 18, 2017, 01:31:46 pm »
What spindle speed and lineal feed rate do you cut at?
 

Offline rx8pilot

  • Super Contributor
  • ***
  • Posts: 3634
  • Country: us
  • If you want more money, be more valuable.
Re: Laser cutter for stainless steel stencils
« Reply #30 on: May 18, 2017, 05:15:28 pm »
LPKF mills have a "ring" around the mill that rests on the PCB while they mill. The depth of the cut is adjusted by how much the end mill protrudes from this ring. This head and ring are held down by a solenoid while the head is down.

That is the only practical way to do the job with any hope of accuracy.
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Offline janekm

  • Supporter
  • ****
  • Posts: 515
  • Country: gb
Re: Laser cutter for stainless steel stencils
« Reply #31 on: May 19, 2017, 05:29:13 am »
LPKF mills have a "ring" around the mill that rests on the PCB while they mill. The depth of the cut is adjusted by how much the end mill protrudes from this ring. This head and ring are held down by a solenoid while the head is down.

That is the only practical way to do the job with any hope of accuracy.

Auto-levelling using a contact probe is also pretty effective, and arguably has some advantages: (and can be done on a much cheaper machine...)
 

Offline DigitalDeath

  • Regular Contributor
  • *
  • Posts: 62
  • Country: us
Re: Laser cutter for stainless steel stencils
« Reply #32 on: May 19, 2017, 07:37:45 am »
@IconicPCB
For the 10 mil (0.25mm) end mil I'm using 52000 rpm and 5 mm/s speed.
For the 4 mil (0.1mm) I'm using 60000 and 4 mm/s speed.
BTW the end mills are shaped for PCB milling so they have pretty short flutes and transition into 1/8 inch shank pretty quickly as shown in the picture below.

@janekm
That software seems pretty cool. The only disadvantage that seems to me it would have is that you would need to secure the brass sheet to the base with double-sided tape or some other means such as vacuum. In the case of the LPKF that's not really an issue but then again you would need to get a used LPKF mill. I wonder if there is some gadget out there that does this same ring thing with a regular milling spindle. I bet it could be designed and made into a practical thing.

 

Offline janekm

  • Supporter
  • ****
  • Posts: 515
  • Country: gb
Re: Laser cutter for stainless steel stencils
« Reply #33 on: May 19, 2017, 08:54:57 am »

@janekm
That software seems pretty cool. The only disadvantage that seems to me it would have is that you would need to secure the brass sheet to the base with double-sided tape or some other means such as vacuum. In the case of the LPKF that's not really an issue but then again you would need to get a used LPKF mill. I wonder if there is some gadget out there that does this same ring thing with a regular milling spindle. I bet it could be designed and made into a practical thing.

Yes that's right, normally one would use double-sided tape but it's a bit of a pain to peel off if one was doing this every day. It's fine as an emergency method (which is what I think PCB milling is good for anyway  ;D).
 

Offline IconicPCB

  • Super Contributor
  • ***
  • Posts: 1527
  • Country: au
Re: Laser cutter for stainless steel stencils
« Reply #34 on: May 19, 2017, 11:54:30 am »
Digital,

I am familiar with LPKF tools. Excelent tools albeit pricey.

Tools from precise bits are much less expensive and equal to the LPKF.
I run the 10 thou ( 0.010" ) cutter for PCB work at 30KRPM and 1900mm/min on 1ounce copper ( 35 micron ). Another very interesting product Precise Bits have is cutting compound for copper.
I guess Your LPKF has the 60KRPM spindle. Very nice ...but try to find the mechanically sweet spot of he spindle where run-out of the spindle will not provide excessive resonance and "smear" of the tool tip path.

I run an Alfred Jaeger 100KRPM spindle but rarely push it above 50KRPM. Typically only when drilling 0.3mm holes .
 

Offline DigitalDeath

  • Regular Contributor
  • *
  • Posts: 62
  • Country: us
Re: Laser cutter for stainless steel stencils
« Reply #35 on: May 20, 2017, 08:02:04 am »
Thanks for the tip on precisebits.com it's part of Think & Tinker from which I purchased a plating line. I had not realized they had end mills. I'll keep them in mind for future purchases.
 

Offline CopperCone

  • Super Contributor
  • ***
  • Posts: 1415
  • Country: us
  • *knock knock*
Re: Laser cutter for stainless steel stencils
« Reply #36 on: July 04, 2018, 01:09:06 am »
what kind of laser would you need to cut the brass stencil?
 

Offline rx8pilot

  • Super Contributor
  • ***
  • Posts: 3634
  • Country: us
  • If you want more money, be more valuable.
Re: Laser cutter for stainless steel stencils
« Reply #37 on: July 04, 2018, 05:37:22 am »
100mW cuts metal?
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Online mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 13695
  • Country: gb
    • Mike's Electric Stuff
Re: Laser cutter for stainless steel stencils
« Reply #38 on: July 04, 2018, 05:55:45 am »
100mW cuts metal?
Avarage power of very short pulses - peak power is many kilowatts
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Offline CopperCone

  • Super Contributor
  • ***
  • Posts: 1415
  • Country: us
  • *knock knock*
Re: Laser cutter for stainless steel stencils
« Reply #39 on: July 08, 2018, 10:43:03 pm »
How about carbon fiber?
 

Offline rx8pilot

  • Super Contributor
  • ***
  • Posts: 3634
  • Country: us
  • If you want more money, be more valuable.
Re: Laser cutter for stainless steel stencils
« Reply #40 on: July 08, 2018, 11:19:22 pm »
How about carbon fiber?

Interesting thought.....
In CF you have various forms, each with different cutting approaches available.

I have only seen raw CF and pre-preg cut with mechanical cutters. For cured CF, waterjet and mechanical works well.
I have never seen anyone cutting with laser. My guess is that the huge temp tolerance differential between the CF and the epoxy binders would make it difficult to do well.

Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Offline mrpackethead

  • Super Contributor
  • ***
  • Posts: 2845
  • Country: nz
  • D Size Cell
Re: Laser cutter for stainless steel stencils
« Reply #41 on: July 11, 2018, 06:14:02 am »
 I just bought a 300x400mm framed laser cut and electropolished stencil ex JLCPCB for $22.    They make them really nicely and the job is just fine.   They ship with my pcbs, and if you use LCSC.com for parts ( recommended ) they will ship them at the same time.    Not something to even contemplate making.
On a quest to find increasingly complicated ways to blink things
 

Offline CopperCone

  • Super Contributor
  • ***
  • Posts: 1415
  • Country: us
  • *knock knock*
Re: Laser cutter for stainless steel stencils
« Reply #42 on: July 11, 2018, 04:46:22 pm »
Is there any kind of metal that is a step up from plastic but still possible to cut with a cheap laser?
 

Offline rx8pilot

  • Super Contributor
  • ***
  • Posts: 3634
  • Country: us
  • If you want more money, be more valuable.
Re: Laser cutter for stainless steel stencils
« Reply #43 on: July 11, 2018, 04:50:34 pm »
Is there any kind of metal that is a step up from plastic but still possible to cut with a cheap laser?

I think physics rules the world on this......it takes money to cut metal with coherent light. I have never seen a 'cheap' laser create the wavelength and power necessary to cut metal.
Factory400 - the worlds smallest factory. https://www.youtube.com/c/Factory400
 

Online mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 13695
  • Country: gb
    • Mike's Electric Stuff
Re: Laser cutter for stainless steel stencils
« Reply #44 on: July 11, 2018, 07:56:30 pm »
If you really want to make your own metal stencils, photochemical etch is probably the only option.
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Offline IconicPCB

  • Super Contributor
  • ***
  • Posts: 1527
  • Country: au
Re: Laser cutter for stainless steel stencils
« Reply #45 on: July 11, 2018, 10:31:30 pm »
Copper Cone,

Under ordinary conditions a cheap CO2 laser will not touch stainless steel shim.

There is a spray on treatment for stainless steel which will allow a CW  co2 laser to mark the surface. I suppose repetitive ablation will eventually cut through, probably 20th pass.
I can not recall the name of the product but have seen it in use, a friend was making tattoo machines out of stainlees steel and used to decorate the machine frames by laser engraving the polished surfaces.

 

Offline 1276-2449-1-ND

  • Regular Contributor
  • *
  • Posts: 63
  • Country: ca
Re: Laser cutter for stainless steel stencils
« Reply #46 on: July 22, 2018, 12:18:00 am »
Chinese fiber lasers that can cut thin stainless sheets are around $5K now.

I've been making stencils from mylar sheets on a CO2 laser cutter -- the trick is to ablate (etch), not cut away the mylar to get crisp edges with no bumps or burning.

When the laser was down and I needed some quick stencils I got a cheap craft vinyl cutter and it also made surprisingly useful stencils (the trick here is to overcut the corners so nothing dangles or leaves a little nub).
 
The following users thanked this post: beanflying

Offline mrpackethead

  • Super Contributor
  • ***
  • Posts: 2845
  • Country: nz
  • D Size Cell
Re: Laser cutter for stainless steel stencils
« Reply #47 on: July 22, 2018, 02:16:48 am »
got a link.
On a quest to find increasingly complicated ways to blink things
 

Offline mrpackethead

  • Super Contributor
  • ***
  • Posts: 2845
  • Country: nz
  • D Size Cell
Re: Laser cutter for stainless steel stencils
« Reply #48 on: July 22, 2018, 02:18:24 am »
I've been making stencils from mylar sheets on a CO2 laser cutter -- the trick is to ablate (etch), not cut away the mylar to get crisp edges with no bumps or burning.

I'm not familar with that technique?  How does it work? Is it like a raster scan or something?
On a quest to find increasingly complicated ways to blink things
 

Online mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 13695
  • Country: gb
    • Mike's Electric Stuff
Re: Laser cutter for stainless steel stencils
« Reply #49 on: July 22, 2018, 09:57:31 am »
I've been making stencils from mylar sheets on a CO2 laser cutter -- the trick is to ablate (etch), not cut away the mylar to get crisp edges with no bumps or burning.

I'm not familar with that technique?  How does it work? Is it like a raster scan or something?
Yes - you laser the whole area of the aperture rather than cutting round the edges.
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf