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Thread: Another "which one?" question

  1. #1
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    Another "which one?" question

    I want to make my own clock dials, using 0.04" sheet brass. These dials are just under 7" diameter.

    The attached image is close to what I want, and was made by etching with ferric chloride on a photo-resist. That method is inconsistent, with almost a 90% failure rate. But I can get fine detail as well as wider etched areas to accept the dark wax that's used to mark the numerals. I'm not going to pass these clocks off as 18th C., but I want buyers to consider them as a competitor for those antiques. In the attachment there is a larger square plate with the numbers and minute ring, as well as a round piece that was etched all the way through. I know that a round CNC bit can't make the sharp joints seen in that overlaid piece, but if I go the CNC route, the machine would have to do well at the main dial. Price point: at $2,000 I'd wonder why I hadn't done this long ago. At $5,000 I'd be satisfied, as long as it does everything I need. Over $6,000 I couldn't justify it...pay somebody else to do it.

    The Nomad 3 (by Carbide 3d) says the right things, but a seller's claims won't really tell me whether I'll get precision equal or greater than what I already have. I like their policy of selling the full software without a 'subscription'.

    So I don't know:
    - Can any CNC give me very sharp, very tiny script (see the name, printed near the center of the overlaid piece, and the stylized "K" symbols between the Roman Numerals).
    - Will a machine that's excellent for these dials still be excellent with a 2' x 2' bed (or greater) for the day when I go to CNC wood projects? I can see a CNC for roughing out floral 'carvings' (etc) in clocks or furniture.

    What would you folks buy to do this work?
    Dial.jpg
    Last edited by David Kenagy; 07-04-2022 at 5:31 PM.

  2. #2
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    Sharp corners are indeed possible to engrave on metal like that with a CNC using V-Carve techniques and appropriate tooling. You can absolutely engrave what you show with CNC. (You mention 3D printing which is a completely different thing...it's additive rather than subtractive)

    The biggest challenge with sheets of non-ferrous metal is workholding...a good vacuum system or use of superglue/tape or double sided tape come into play to keep things flat which is required for the engraving. For production work, vacuum is the way to go, IMHO. Cutting metal does require a bit of housekeeping consideration as you can't use the kind of dust collection that one can use for wood products due to fire hazard. And metal shavings are "not fun" to clean up.

    For working metal like this, you'll get the best results from a machine that's equipped with a spindle that can be directly managed by the CNC machine controller software. Spindles are friendly for tooling as they generally have a lot more options for collets, especially when using very small tooling for the kind of work you want to do. Router motors are screaming loud and often do not provide as much speed control as spindles...and whatever speed control you have with a router motor is manual. Sometimes an incremental change in RPM provides better results in cut quality as well as for chip load which is what keeps the tooling from getting hot and dulling quickly.

    My recommendation would be to shop for your second machine first and make your investment closer to your upper limits. You'll have the best chance of hitting your goal that way. You don't need a "big" machine for the work you propose, but you will be happier if you have a quality, well engineered tool to work with.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
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    Thank you!

    I edited the "3d printer" term...as you recognized, I meant CNC. It will now make more sense to the next reader.

    Before I started thinking about using CNC on brass dials, I'd been thinking about the Shapeoko Pro. I'll use your feedback in re-looking at these tables with bigger beds than the Nomad. Their cost is lower than my limit...which aspect does a more expensive machine overcome?

    I'd enjoy reading what companies folks prefer, especially with features that made them prefer theirs. A web search only bombarded me with advertisements. Videos by users almost all love whatever machine they bought.

  4. #4
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    Yes, I'm one of those folks happy with the machine he bought, a OneFinity Journeyman. 1F even makes a CNC specific for milling metal, though any of their models will mill brass and aluminum. I milled some thin brass on mine last week w/o issue, other than chips everywhere as Jim mentioned. I used the Makita trim router that's on my machine and had no issues, but you can easily add a spindle to any 1F and still stay under your budget. The noise issue everyone talks about with a router is a non-issue once you turn on the dust collection system, unless you are lucky enough to have that located outside your shop. At 10 - 15K rpm the Makita is not very loud and is completely lost when I turn on the dust collection and the bit hits wood. My friend has an Axiom with spindle. In all honesty, it's just as loud when it's running. Get a spindle if you want, but not for the lower noise during actual use.

    You can use most any software you want. I purchased V-Carve Pro with the machine and it does everything I need, and way more than I am yet capable of. Including the software and spindle, should you feel it necessary, you would be under your budget. I was at $4200 all in. The 16 x 16" Machinist model lists at just under $2K, plus software, spindle, etc.

    John

  5. #5
    I have done a small amount of sheet brass on my Avid Standard 2448 machine with a Bosch 1617 router. (I would go for a spindle if I could afford it - especially for metal). It worked ok. I had to go through a learning curve for holding the work, tool, speeds, feeds, etc. I've done some brass hardware and a few odd assorted items like sundial gnomons. Looking at your dial, my concern would be those sharp inside corners. I don't think that would be easy to do. I have tried using "v-carving" with a v shaped tool, but the sides of the cut are sloped. Before you make the investment, I would try and find someone to do some test pieces for you to make sure you are happy with what the machine can do for you. I usually just work around the limitations, but I'm not trying to do work at the level you are. Engraving is a breeze -you can get very sharp lines spinning or dragging. I use cheap engraving bits on brass and aluminum. I have been very pleased with the results. The tool angle is very steep, so you can cut deep enough and the sides not look angled.

    This is a gnomon I did. I think the final cut was done with a 1/16 bit. (The marble was engraved with an ebay engraving bit!)
    IMG_4898 (Small).JPG



    I made the brass hardware for this. I had a heck of a time figuring it out. I wanted a beveled edge. Long story, but I finally got there. Material choice is important too. You probably already know that.

    DSC_4896 (Small).JPG

    I have been thrilled with my Avid machine. As mentioned, I have a Bosch 1617 router on it. I have used it for all sorts of materials, brass, wood, marble (engraving), glass (engraving), circuit boards, cardboard, vinyl, stencil material, felt, cork, etc. I use V-Carve for G code and Mach 4 to run the machine. Its one of those things that, once you have it, you figure out tons of uses. I am just finishing up a set of chairs and I used the machine to make half a dozen templates (router templates, shape templates, etc.) Very quick and easy for things like that. Even just making measuring sticks to help layout and such.

    I don't have any good pics of engraving like your dial. If I wasn't in the middle of chair making, I'd do some tests to show you. There is a gentleman on youtube who's name escapes me, but is Winston or Winton Moy - something like that. I believe he has done a bunch of work like this and I think he uses a smaller machine. His videos are very helpful.

    Let us know what you pick. If you are still looking when I finish these chairs (in a few weeks), I'll try a few things. I believe I have some scraps I could play with. Oh, my machine is 24" x 48". I use half of that capacity 75% of the time. I sometimes regret buying a machine so big, but its there if I need it. So, a 2x2 might be plenty for wood parts later. The other thing to consider is accuracy, repeatability, consistency, etc. The smaller machines tend to not be quite as rigid. For roughing, that probably wouldn't matter. I can't really tell you exactly how a good my particular machine is, but it works fine for my work.



    Tony

  6. #6
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    Have you considered laser etching as an option? I think you could get finer detail, but it would be etched and not engraved with a cutter. Just a thought.
    David

  7. #7
    I would second the OneFinity that John mentioned. A friend in the neighborhood has one and it's a lot more rigid than the Shark and others in this category. He's done some very nice work with his.
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  8. #8
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    cheap and cnc dont seem to go together.

  9. #9
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    These suggestions are what I was hoping for. I'll start studying the websites for these makers.

    I spoke with Carbide 3d today (makers of Nomad and Shapeoko). They said the tolerances for Nomad (8" x 8" capacity) are 0.003" and for Shapeoko (24" x 24" and up) are 0.005". The Nomad uses a spindle, and Shapeoko can upgrade to that.
    It appears that blowing or vacuuming chips is important while cutting metals, and Nomad won't allow that (machine stops if the door opens). They also have a video to answer the question about minimum size for lettering (I'm not the first). They did a demo for tiny lettering in graphite, using bits as small as 0.17 mm. That tells me the tolerances are very good, but it's not brass; I can't use bits that small.

    Seeing Tony's brass work is inspiring. I bet any hinge of any size will be possible.

  10. #10
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    Quote Originally Posted by David Kenagy View Post
    It appears that blowing or vacuuming chips is important while cutting metals, and Nomad won't allow that (machine stops if the door opens).
    Perhaps consider using a small dust shoe attached to a shop vac, or simply defeat the door switch.
    David

  11. #11
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    Quote Originally Posted by David Buchhauser View Post
    Perhaps consider using a small dust shoe attached to a shop vac,
    Really not supposed to do that with metal cutting because of fire hazard. Remember, the chips are what takes the heat away from the material and tooling. But there are blower tips commonly used for machines cutting metal (as well as for cutting lubrication/cooling where required) that can keep the chips away from the cut lines. You can vacuum the stuff up after the fact with a shop vac once everything has certainly cooled, however.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  12. #12
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    Quote Originally Posted by Jim Becker View Post
    Really not supposed to do that with metal cutting because of fire hazard. Remember, the chips are what takes the heat away from the material and tooling. But there are blower tips commonly used for machines cutting metal (as well as for cutting lubrication/cooling where required) that can keep the chips away from the cut lines. You can vacuum the stuff up after the fact with a shop vac once everything has certainly cooled, however.
    I agree Jim - a mister could be another possibility. I seriously doubt the small chips from fine cutting brass would be much of an issue though. Opinions may very.
    David

  13. #13
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    I don't disagree that the risk from the brass isn't high...but I'm pretty anal about promoting best practices because there can be "that one time"...
    --

    The most expensive tool is the one you buy "cheaply" and often...

  14. #14
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    If you put a Dust Deputy in front of the shopvac and put some water in the bottom of it, the chips will get captured in that water.

    For the work you are contemplating on thin brass sheet, this seems like a non-issue to me. Just my opinion.

    John

  15. #15
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    The problem with thin materials on any CNC is thin metal is very hard to hold securely. The one time the bit catches will tear it right off the table. Brass won't spark, that's why they use brass hammers in explosive areas.
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller , WorkBee 1000x750 CNC Router - Mach4 - Windows 10

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