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  1. #1
    Join Date
    Mar 2013
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    0

    recommended machine for PCB stencils?

    Hello. We are looking for a CNC for making stencils for PCB solder paste. These are generally made of thin plastic or thin stainless steel (<0.3mm).

    We plan on importing from China since we do it all the time anyway, will save a bundle, and most machines are made there anyway.

    It is my understanding that there is no chance of doing metal, no matter how thin, with a small laser CNC, so I guess that is out of the question. Of course, we can go with a regular CNC instead of laser if it can give us the precision we need (see below)

    The most important feature is the ability to cut very fine features. For those unfamiliar, 0402 parts are about 1mm x 0.5mm, and QFN leads can be as close as 0.4mm. So basically we need to be able to cut with 0.1mm precision or better with repeatable accuracy. We don't need a very large work area, maybe 300mm square at most, but don't have a problem with a larger machine if it makes more sense. We don't have any other plans for the machine right now, but any added capabilities would obviously be a bonus. For example, the ability to route simple PCBs. But accuracy is really the most important thing here.

    Here are a couple of stencil examples to get an idea of what I'm talking about here.
    http://www.circuitsathome.com/wp/wp-...SO_stencil.jpg
    http://www.smtnet.com/media/images/accuframe1.jpg

    So, can anyone give me an idea of a model we should be looking at? We are hoping to spend <$5k, but are willing to spend more if we can get a better return on investment by spending more. We have been talking with Gweike and Jcut, but it is hard to get straight answers and I'd like to get some from people not interested in selling us stuff* *If not a specific model, what laser power? We are thinking 60w or 80w would be ideal, but aren't 100% sure even after scouring these forums. Thanks in advance!

  2. #2
    Join Date
    May 2012
    Posts
    38
    Pretty much any CO2 laser on the market will be able to cut the mylar stencils you require, even the 40w models. If that's all you're doing, I don't think you really have a big worry on power. That said, I imagine that once you have a laser, you'll quickly find more to do with it than simply cutting stencils! -- I'd say that the anywhere up to 60w would be fine for what y'all need. CO2 lasers have a minimum level that they'll actually fire at, and thus, the higher the wattage, the higher the power of the minimum setting. Cutting thin mylar paste stencils like you intend to, you want to have the flexibility to get your laser power dialed right where you need it, to get the finest accuracy for small pitch components.

    Nice-to-have would be a motorized Z axis to help you get your focus dialed in just right to minimize the kerf.

    Most machines in your price range would be rigged for air assist, which although not entirely necessary for your application, is nice to have. If nothing else, it helps keep the lens clean by keeping cutting smoke from fouling it.

    As for precision, I believe that pretty much any machine on the market from a reputable manufacturer would be able to give you consistent and repeatable results at that resolution. I've seen people with el-cheapo ebay K40 machines which, after some minimal fiddling, can reliably cut stencils for .5mm components. Given that the K40 (from ebay anyway) is pretty much the Yugo of chinese laser machines, I think you'll find you have good luck with pretty much anything from Redsail or G.Weike.

    One thing that'll eat into your budget as well will be customs brokerage, import duties, and shipping to where you are. I'm not familiar with shipping from China, and ports of entry for the east coast/great lakes (if your machine is big enough to need to be shipped by ocean freight) but you may need to arrange shipping from the port of entry to your location.

    Did you have your eye on any particular model from G.Weike?

    Cheers!

    -C

  3. #3
    Join Date
    Nov 2009
    Posts
    314
    Hi,
    If S.S less what you said <0.3mm, it is ok for a CNC Router, but better with mist sprayer to make cooling of the cutting tool(Special bit for metal cutting which we can supply you), you can see attached 2 pictures which our Australia client use to cut 3mm aluminium using our regular CNC 1325 and 1530 model, you can check our website(CNC Router Laser Cutting Machine CNC Engraving Machine-XYZ Machinery LLC) for any model of CNC, all can do your job, only add the mist sprayer and using special cutting bit for metal.If you have interest, please contact [email protected]

    Best regards,
    XYZ Machinery
    Attachment 181186
    Attachment 181187

  4. #4
    Join Date
    Mar 2013
    Posts
    0
    Thank you kindly for your response. I forgot about this post and remembered once we resumed searching for our CNC.

    Quote Originally Posted by wontpontificate View Post
    I don't think you really have a big worry on power. That said, I imagine that once you have a laser, you'll quickly find more to do with it than simply cutting stencils!
    Indeed, I'm sure we would. That is why we are looking for a reasonably-sized work area, even though we really don't need it at this time.

    Quote Originally Posted by wontpontificate View Post
    CO2 lasers have a minimum level that they'll actually fire at...Nice-to-have would be a motorized Z axis to help you get your focus dialed in just right to minimize the kerf.
    That's great advice, thank you.

    Quote Originally Posted by wontpontificate View Post
    K40 machines which, after some minimal fiddling, can reliably cut stencils for .5mm components.
    This sort of information was tough to find, so I'm glad to hear that. What about standard, non-laser CNCs? We'd love the ability to do PCBs, even if very simple, and to be able to do stainless steel stencils (very thin, usually 0.1-0.3mm)...but as far as I know this is not the domain of low-cost laser machines. This might be the wrong forum to ask this, but should we be looking at a non-laser CNC instead? We were leaning toward laser as we were unsure whether a regular CNC would be able to do the fine details we require with repeated accuracy in our budget range.

    Quote Originally Posted by wontpontificate View Post
    ...customs brokerage, import duties, and shipping
    Thankfully, this is something we do on a weekly basis, so we are OK on that front

    Quote Originally Posted by wontpontificate View Post
    Did you have your eye on any particular model from G.Weike?
    Yes, LG5030, LG500. We were also looking at LC6090, but it might be too powerful based on what you've said. They are recommending an RF tube, and are saying a regular laser might not work for such small features, but from what I've read this does not seem correct.

    Cheers

  5. #5
    Join Date
    May 2012
    Posts
    38
    Quote Originally Posted by nooelec View Post
    This sort of information was tough to find, so I'm glad to hear that. What about standard, non-laser CNCs? We'd love the ability to do PCBs, even if very simple, and to be able to do stainless steel stencils (very thin, usually 0.1-0.3mm)...but as far as I know this is not the domain of low-cost laser machines. This might be the wrong forum to ask this, but should we be looking at a non-laser CNC instead? We were leaning toward laser as we were unsure whether a regular CNC would be able to do the fine details we require with repeated accuracy in our budget range.
    If you're looking to do paste stencils as your primary function, laser is the place to be. I've seen some folks use hobby vinyl cutters to make mylar stencils (really fine pitched ones too) but that's more necessity being the mother of invention than best practice.

    Unfortunately, you'll be limited to mylar stencils with a CO2 laser. Stainless would (to my knowledge) require a fiber laser, and you'd be looking at big bucks there.

    For milling PCBs, you'd probably be looking at a little 2.5d router table. For PCB sizes, I'd look at a fixed bridge machine, and avoid moving gantries. The pros of that style (simplicity of design, and rigidity) outweigh the cons (footprint usually twice as large as effective cutting area) at that size.

    One tool won't do what the other will. I doubt a laser would do you a very good job of making PCBs, and a cnc router wouldn't give you tiny holes with square corners you need for a paste stencil.

    On the plus side though, you get to justify buying more toys! How spiffy is that?

    Quote Originally Posted by nooelec View Post
    Thankfully, this is something we do on a weekly basis, so we are OK on that front
    Awesome! I wish I had skills in that area. I've been finding the idea of importing things daunting at best.


    Quote Originally Posted by nooelec View Post
    Yes, LG5030, LG500. We were also looking at LC6090, but it might be too powerful based on what you've said. They are recommending an RF tube, and are saying a regular laser might not work for such small features, but from what I've read this does not seem correct.
    All three of those look like they're 60w machines, with the LC6090 having an 80w option. I think you'd be fine with a 60w machine for doing stencils.

    Here's some food for thought for you:

    Laser Cutter -- Mike bought himself a K40 for doing solder paste stencils -- focuses more on the shortcomings of the machine, but some useful information there

    microcarve cnc -- John makes some really bang-up mechanical kits for cnc routers. Add motors and electronics, and you've got yourself something capable of machining incredibly fine detail whilst hung from the ceiling by a bungee cord. There's an enormous (and fascinating) thread on the zone somewhere charting the development of his machines. The MV3 would be an excellent PCB mill candidate. Most folks use a Bosch Colt router as a spindle. With a precision collet in place of the factory one, they're said to have very little runout, making them suitable for PCB work. You could probably also use a Proxxon Micromot IBS/E, or even a "real deal" cnc spindle.

    Regarding lasers -- something you may want to consider, given the nature of your setup, is building your own laser. There are a couple of projects out there, like the Bart Dring's Buildlog 2.x laser over at buildlog.net - CNC Laser Buildlogs (very well documented and proven design) and the LaserSaur at Lasersaur by Nortd Labs (I don't know much about this design, just discovered it recently). Could make yourself a really nice machine that does all you want it to and more, since the designs are easily scalable, and customizable.

    Anyway. Hope this helps!

    -C

  6. #6
    Hurricane21 Guest
    No,

    We have sold many lasers for use cutting the stencils you describe. Please check us out at Home page. As you will find on these boards we offer great service and support to our customers.

    You can call me at 855-552-7377 or send me a message.

    Thank you.

    John

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