There is a difference between a laser cutter and engraver outside of the little laser cutters like the epilogs and the chinese units. True engravers are often q-switched yag units that will mark just about any material and use galvos and f-theta lenses to scan the beam over the surface. They engrave at a pretty high rate, much faster than a gantry setup. But they cant cut.
When you get to industrial sized units they usually dont etch/engrave worth a damn. They will mark material but they are really limited. Mostly used for marking the part number of a part. The laser cutter I built uses a ~6watt 355nm UV DPSS laser, it can cut at least up to .010 copper. This is it cutting BeCu sheet to make some jumpers. https://www.youtube.com/watch?v=oaFdA8ix_ws&list=UUs8IM14Fwq2bsLf7X3IoXkg -Jerry On Thu, Aug 28, 2014 at 6:55 AM, Doug Ausmus <[email protected]> wrote: > For those who are curious, here is one table of TEA-mode laser pulse > characteristics. Note the lower average power to get megawatt peak pulses > about 1/6 uS wide: > Pulse Energy (J) 5 4 2 0.4 0.15 > Max. Average Power (W) 60 60 60 60 75 > Max. Repetition Rate (pps) 12 15 30 150 500 > > Beam Size (H x V, mm) at laser 25 x 25, 25 x 25, 12 x 16, 11 x 14, 8 x 9 > > Note: Specifications apply to operation in both the 10 μm and 9 μm > wavelength ranges > > > On Thu, Aug 28, 2014 at 6:46 AM, Doug Ausmus <[email protected]> wrote: > >> UV laser for copper, IR laser for circuit board substrate material. >> >> Some laser machining 101: >> >> When ablating (not cutting), you need short, high-energy pulses.. not >> average watts. This means you can do a lot with low "watts" as long as >> those average watts are concentrated in very short, very high strength >> pulses. Different lasing approaches can create differently-profiled pulse >> energy (time vs. energy) with a given average "wattage". >> >> I've seen very powerful and fast copper ablation with LED excited UV >> lasers running less than 5 watts, generating a pulse train above 50 KHz. >> Similarly, a tea-mode laser pulsing at 500 Hz with a continuous power of >> 75W very effectively "cuts" fiberglass circuit board substrates. >> >> Note that tea-mode lasers typically use a flowing-gas chamber and very >> high voltage capacitive discharge to cause a laser pulse to form, shaped >> with a very high peak energy for a very short time. In other words, the >> pulses "hit very hard". These are usually expensive lasers to buy and >> operate, but they work quite well. I just wish they could cycle faster. >> >> Using an engraving laser can work (maybe), but is sub-optimal. Copper can >> be used in making mirrors for IR lasers, so you can see why IR lasers don't >> even touch copper very well. >> >> To find the proper laser for a given material, you must look at the light >> absorption curve vs light wavelength. As mentioned by others, heat >> dissipation of the material and damage of material by the heat-zone must >> also be considered when looking at choosing a wavelength and power. You >> can't always "go faster" by "going more powerful". >> >> Lenses and mirrors must be carefully chosen to reduce heat build-up and >> keep your beam optimal. Pre-lens beam diameter is critical for lasing tiny >> features (bigger beam entering the lens can allow a smaller final spot >> size, one of several reasons you will find beam-expanders involved) and >> lens focal length is important for depth vs focus vs spot size vs optics >> protection issues. And masking (pre-lens) can help shape and manage beam >> modes at the expense of final power at the substrate. >> >> Hope this was informative, if not actually useful. >> :-) >> >> >> >> On Thu, Aug 28, 2014 at 2:33 AM, Mike Payson <[email protected]> >> wrote: >> >>> There is no inherent difference between a laser cutter and a laser >>> engraver, the main difference is one of setting expectations. If a laser >>> can engrave a given material, it can generally cut that material also-- >>> *provided >>> the piece is thin enough*. Generally with laser cutters that are priced >>> in the range that hobbyists can afford (even well-funded hobbyists) that >>> generally means metal is out. I think you can cut very thin (<1mm or so) >>> stainless on a high-powered (~150W) small CO2, but generally any other >>> metal can't be done on small machines. >>> >>> Copper in particular is hard to laser cut, even on very expensive >>> machines. It is the worst possible combination for laser cutting: It is >>> both highly reflective and it dissipates heat very well (aluminum is also >>> hard to laser cut for the same reasons). Our laser cutter at work can cut >>> 3/8" stainless steel and plain steel, but it can barely make a mark on >>> 1/32" copper (I haven't tried anything thinner than that yet). >>> >>> >>> On Thu, Aug 28, 2014 at 3:36 AM, Kenny <[email protected]> wrote: >>> >>>> My understanding is that an engraver is like a cutter with less output >>>> power. Enough power to leave a mark, but not much more. The level of >>>> precision probably isn't implied in either case. >>>> >>>> If you are looking at engravers on Ebay, they are probably low power CO2 >>>> which can't engrave copper. There are IR and UV lasers designed for >>>> prototyping PCBs, but they cost somewhere in the $60k range to get >>>> started. >>>> >>>> There are other options for using a CO2 engraver, I suppose. Like >>>> painting on a chemical resist layer that can be engraved off, leaving >>>> exposed copper to be consumed by your favorite acid. >>>> >>>> http://www.instructables.com/id/Double-sided-PCBs-with-a-laser-cutter/ >>>> >>>> >>>> -- >>>> Kenny >>>> >>>> -+---+++-++-++++--+------+-+-++--++--+-+-++--+++-++----+-++-+++---+----+--+----+ >>>> >>>> >>>> >>>> On Wed, 2014-08-27 at 22:15 -0700, benjamin barber wrote: >>>> > Question: is a laser engraver a smaller and more precise version of a >>>> > laser cutter? >>>> > >>>> > Question: can a laser engraver be used to manufacture PCBs? >>>> >>>> _______________________________________________ >>>> dorkbotpdx-blabber mailing list >>>> [email protected] >>>> http://music.columbia.edu/mailman/listinfo/dorkbotpdx-blabber >>>> >>> >>> >>> >>> -- >>> www.MakersToolWorks.com - Tools for Makers >>> >>> _______________________________________________ >>> dorkbotpdx-blabber mailing list >>> [email protected] >>> http://music.columbia.edu/mailman/listinfo/dorkbotpdx-blabber >>> >> >> > > _______________________________________________ > dorkbotpdx-blabber mailing list > [email protected] > http://music.columbia.edu/mailman/listinfo/dorkbotpdx-blabber >
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