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17967RE: [z_scale] Re: STEP/CNC for Creating Low-Demand, High-Quality Z Gauge Items

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  • Robert Allbritton
    Dec 1, 2003
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      Hi Jim & Group,

      Just a comment or two:

      I don't want to dampen ANYONES enthusiasm, but when it comes to machine
      tools, you really do get what you pay for. I have owned 3 lathes:

      A Unimat One - $150 This thing is a toy, I can make parts with it, if I have
      about a day per part of free time on my hands.

      A Harbor Freight Lathe (forgot the model number) - ~$600 Nice Lathe and mill
      combo machine, but it was a pain to switch back and forth between Mill and
      Lathe. It also needed to be readjusted regularly to keep it in tolerances.
      Probably OK for prototyping, but forget production.

      A Sherline Lathe with Milling attachment - ~$1500 with all the attachments.
      This thing is *GREAT* right out of the box, works like a champ. VERY easy to
      go from Lathe to Mill and back. Could you do production runs with it?
      Probably, but even then, it is going to get tedious awful fast. A small
      production run of say 20 units (assuming we are talking about a locomotive
      frame) could be done.

      But in the big picture, you are still talking about Locomotives that will
      cost in the AZL price range when you get done - unless you are willing to
      donate quite a few man hours to our hobby, and I thank you if you are
      willing!

      People forget that it takes more than just time and materials to produce a
      product. There is a TON of your own time spent on design, marketing,
      distribution, support, repair, and a hundred other little things. You really
      need to sell a product for at least 50% more than your production cost just
      to break even with all of the other cost built in.

      Again, I'm not trying to rain on anybody's parade, but consider just making
      models for yourself - did you see the pictures of the Big Boy? - and how
      many man hours did that take? Its a lot easier to rationalize big purchases
      on machine tools when you say: I'm going to make things that will pay for
      this "investment." But it is a lot more realistic say that you are doing it
      because you enjoy the hobby - oh, and if you do make any money, use them to
      buy more trains (grin)

      Best,
      -Rob

      -----Original Message-----
      From: jim_manley_alpha_six [mailto:jim_manley@...]
      Sent: Monday, December 01, 2003 1:12 AM
      To: z_scale@yahoogroups.com
      Subject: [z_scale] Re: STEP/CNC for Creating Low-Demand, High-Quality Z
      Gauge Items


      Hi Steve,

      I'm going to continue with this in public on the list until a poll of
      the list members indicates we need to go private, but I think it's
      important for the future of our scale in all its glorious gauges
      (thanks for the clarification, Jeffrey - I should have known better!
      :) Besides, there's a handy "Next" button at the top of every message
      that allows non-interested parties to ignore my babbling. Those who
      are interested could very well determine our future - or not, our
      mileage may vary.

      Anyway, your wish is the manufacturer's command. The lowest-cost RTR
      (Ready-To-Run, for our newbies :) "desktop CNC milling machine" (yep,
      like desktop publishing) that I've found so far is the MaxNC 5 for -
      are you sitting down? - $895, which has 8" X-axis by 5" Y-axis by 6"
      Z-axis travel and a claimed resolution of 0.00012" (yes, that's 120
      microns - the next level of machines can supposedly get you down to a
      micron or less), which is plenty for Z scale). Here's a link to the
      product description:

      http://www.maxnc.com/page12.html

      Now, it's designed to have a hand motor tool (e.g., Dremel Moto-Tool,
      etc.) clamped into the Z-axis frame, so it doesn't come with a true
      milling machine spindle, or even a spindle motor, but it looks like
      those could be retrofitted, if you decided to get into this seriously.
      The purists are going to immediately jump on this and say, "You fool!
      Those hand tools aren't able to withstand very much side-force on the
      cutting heads because of their puny bearings, so accuracy and speed
      will suffer!". This is absolutely true, but we are more likely to be
      working plastic, wood, and soft metals like brass and non-alloy
      aluminum (aluminium for our UK friends :) and not making titanium
      airframe parts for the F-22 Stealth Fighter (the cockpit/fuselage
      interface is CNC milled from a single roughly 6 x 8 x 1 foot block of
      titanium over several days!). If you run the cutting tool at a low
      enough feed transit speed (measured in inches per minute, so we're not
      talking about something all that fast anyway), you can still do some
      pretty neat stuff. Besides, we're not trying to pump out hundreds of
      thousands of identical parts, and it certainly would have to be faster
      than what it takes dealers to get stuff from most manufacturers
      (measured in products per month ;)

      As John pointed out, Sherline (http://www.sherline.com) also has a
      line of desktop CNC milling machines, but they start at a couple
      thousand dollars and go up rapidly from there. You can find other
      manufacturers if you look long and hard enough via Google (and believe
      me, I have), but their lowest-priced models also start in the
      mid-thousands. However, their focus is on small professional shops
      (there are an estimated 500,000 of them out there) and so their
      machines have spindles with motors, larger beds, better mechanical
      resolution, more capable (but also much more complex) software, etc.
      Our good friend here on the list, Yuji Kuwabara, used a Taig
      (http://www.taig.com) desktop lathe to create some of the parts for
      his wonderful Big Boy, and there is a CNC option for that lathe and
      their desktop milling machine, but the prices are close to the range
      of the Sherline units. A useful source of info on lower-end
      commercial products is at:

      http://www.super-tech.com/default.asp

      You can get a quick feel for the range of CNC machines that have been
      manufactured over the years by monitoring the CNC milling machine
      section of your favorite four-letter WWW auction site (which shall not
      be mentioned by name here - Ah-ah-mennnn! ;) You can find some pretty
      interesting older models that are definitely in the industrial
      category (they are measured in cubic yards and weigh tons!), but good
      luck getting them into your garage/basement without laying a new
      concrete slab and putting in a dedicated exterior door, much less
      figuring out how the software works (many are proprietary and no
      longer supported, but some have been retrofitted with PC interfaces
      very similar to what the MaxNC and Sherline models use).

      If you're a real glutton for punishment, you can even Do It Yourself,
      i.e., build your own CNC milling machine (or lathe). MaxNC sells
      their PC interface board (with their basic software package) with
      three stepper motors (very low-torque - only 70 ounce-inches, but
      again, probably more than adequate for our needs) for $295, and you
      can build the milling bed from all sorts of interesting materials
      (some people have used Medium Density Fiberboard - MDF, or particle
      board, all the way up to machined aluminum and steel). Since the
      stepper motors don't care how long the feed screws are (they move the
      feed table around under a fixed spindle, or the spindle over a fixed
      table), you can build a much larger table - some DIYers have machines
      the size of a 4 x 8 sheet of particle board, and even larger, where
      the spindle moves over the work. Some good WWW sites for DIY CNC are:

      http://213.10.73.60/majosoft/index.html (lots of examples of DIY machines)

      http://www.hobbycnc.com/ (3-axis controller kit + three 85 oz-in
      motors $219)

      http://www.stepperworld.com/ (3-axis controller kit $50, kit + three
      33 oz-in motors $119, kit + three 125 oz-in motors $219)

      http://www.mendonet.com/cnclinks/index.html (links to all sorts of CNC
      stuff - hardware, software, controllers, motors, kits, assembled, etc.)

      There are links from some of these sites to DIY efforts all over the
      world, if you follow enough of them. Stepper motors can be had on the
      aforementioned four-letter auction site starting at a few dollars for
      used ones, less than $30 for new, and going up pretty much linearly
      with their torque and speed capacity. So, the minimum cost of entry
      for a bare-bones DIY CNC machine is probably a few hundred dollars and
      a few dozen hours of work. A lot of sites sell plans, but if you're
      willing to peruse Google for several evenings, you can find info
      similar to what I've listed above.

      The free and shareware CNC software is fairly basic (and some is even
      written in BASIC!) that allows you to manually control the tool and
      process G&M code files, but there is a lot of it out there, and I
      haven't even scratched the surface, yet. Most of the commercial stuff
      has 30 day trial versions that can be downloaded, so you can get an
      idea of what's possible, especially if you can afford to spend a few
      hundred dollars. TurboCAD is a good lower-end choice, and I happen to
      know the guy who is the master machinist and mechanical engineer in
      the aerospace industry who led the development of AutoCAD (he's quite
      a character, and has no limit in his animosity for what the executives
      at AutoDesk did in ignoring their own technical experts, in addition
      to buying out better upcoming competing products just so they could
      bury them, one of which he also directed the development).

      Analysis continues, as we say in the intelligence business.

      All the BeZt,
      Jim


      --- In z_scale@yahoogroups.com, STEVDEL@p... wrote:
      > I've been wondering when equipment like the CNC
      > would be widespread and economical enough to start to
      > show up in the model railroad supply chain.
      > What's the order-of-magnitude of the cost of this
      > kind of equipment now?







      "Z" WARNING! HANDLE WITH CARE! Highly addictive in Small DoseZ!


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