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Buyer's Remorse?

Discussion in 'General Talk' started by Wrenchforhire, Mar 1, 2019.

  1. Wrenchforhire

    Builder

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    I've been wanting a cnc router for years, and this is the year. I can't decide if it would be better to make a bigger machine with belts, or stick with my gut feeling to stay with lead screws.

    Right now my "dream machine" would have a 48"x24" working area, can't say exactly why, but that size sounds right to me. I'm budget minded, but understand the value of quality. I work in robotics, so the nuts & bolts part does not intimidate me.

    Why did you start with the machine that you did, and what would you have done differently?

    Any comments about belt vs screw, or practical size would be appreciated.

    J
     
  2. Giarc

    Giarc Master
    Moderator Builder

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    I have a self designed machine that can cut 26.5" by 49". The total extrusion lengths are 1500 mm y axis by about 835 mm x axis. It was supposed to be 1500 x 850, but I messed up a cut and had to shorten it. At the time I built mine, there were no kits. Now I would probably go with a kit, or copy a kit with some substitutions. Like a 1500x1000, but cut the x axis cbeam at 840 mm giving me a leftover piece to make a small vise.

    I chose this size to be able to cut 26 inch wide cabinet sides. I did not need the full 1000 mm width and I wanted the x axis to be stiffer. I routinely cut aluminium, plastics, and wood. I used 6 foot long 1/2 - 10 5 start high speed precision lead screws for the 1500 mm y axis. So screws at that length are readily available.

    The funny part about my large build is that most if my cutting occurs in the same 12 by 12 inch area. :rolleyes:
     
  3. Rob Taylor

    Rob Taylor Master
    Builder

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    I started with a machine lathe, because I knew I could make essentially any part of any machine with it and it would help me internalize the fundamentals of machining. I added a mill, because milling with a lathe is miserable and I wanted the higher throughput speed of parts. Also milling has a somewhat distinct set of rules to keep in mind.

    I used those to make a V-Slot-based, but otherwise custom-designed and scratch-built, 12x15" diode laser cutter (belt, NEMA17). Nice and convenient sized to get started with. Less expensive, too- never underestimate how much wire you're gonna need to buy.

    I'm now in the process of CNC converting the mill with closed-loop NEMA 34s- which was intended from the initial purchase.

    Short-medium term future machines, according to my current thinking:
    1. "Large format" linear rail/ballscrew gantry router/bridge mill (1200x800x300mm-ish working area, 1500x1100x600-ish general dimensions). This would be a workhorse for banging out large pieces and palletized smaller ones.
    2. Plasma cutter- probably 2x4, but definitely subject to change, whenever I get a plasma cutter and a compressor/air drying setup capable of running it. Possibly rack and pinion, not sure yet.
    3. Small PCB cutter, probably 100x200x50, 400-500W, fairly cheap but still linear rail and ballscrew- I don't think I'd bother building a milling machine without those at this point, they're so inexpensive now.
    I may also do a 3D printer at some point; ultra-rigid, high-speed, heated enclosure, something that can produce highly detailed and/or functional parts. Commercial ones are pretty decent though, so DIY might not really be necessary.

    All will be custom-designed, most will be to some extent extrusion-based. I suspect by the point I can jump into a big steel'n'epoxy build, I'd have the money and work to jump on a lower-end Haas, so I'm not sure that one will ever happen at this point. Maybe a mini one just for fun- ultra-rigid benchtop 5-axis for sub-2" parts? Why not!

    I don't really do kits... They're generally designed to appeal to the most possible people for the widest variety of use cases, and my needs are basically guaranteed to fall outside of that, I can set my watch by it at this point. Plus the whole point of the DIY/maker movement, to my mind, is to eschew the pre-formed in favour of personal taste and on-demand customisation, so I sort of have a philosophical opposition to it too. Obviously for these things to go mainstream, they have to be streamlined for the slightly less obsessive, self-starting, or obnoxiously technical, so businesses do what they do, including OpenBuilds! Just makes business sense, though I occasionally ponder if the (must be significantly?) increased rate of issues and help requests is worth it.

    Most parts most people make are human-scale, which in this context generally translates to fitting into a roughly 12x24" area. The smaller a machine, the more rigid it is and easier to dial in (and easier to build). I went about that size for my first build for that reason. I knew there'd be a lot of learning along the way! (Spoiler: main lesson, always completely draft out your entire machine, not just parts of it!)
     
  4. Gary Caruso

    Gary Caruso OpenBuilds Team
    Staff Member Moderator Builder

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    Same!

    upload_2019-3-1_17-40-24.png
     
    GrayUK and Giarc like this.

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