5 ms·

I don't know if the idea is unique (edit: no, they mention it's based on a known concept of "hanging plotter"), but that's a neat way to utilize gravity to brin

by Yaggo 10y ago

I don't know if the idea is unique (edit: no, they mention it's based on a known concept of "hanging plotter"), but that's a neat way to utilize gravity to bring down costs. It's much more accurate (.4mm) than I would expect, enough for most hobby work with big sheets. (Off topic, but a hanging plotter (for drawing) would be rewarding project to build with a kid!)

DannyBee 10y ago
Errr, .4mm is not very accurate. It's about 5-15x less accurate than basic wood cnc machines, which do 0.001-0.005 (they could easily do better, it's just not necessary for wood). If each part was off by 1/64th, you can't even form a 4 sided box that is guaranteed less than +-1/16, which is a lot. I'm pretty sure they are also not including the router runout (since it uses a router and not a spindle, add about 0.005-0.010, or, rather, halve their precision again) Now, don't get me wrong, it's a neat idea. It may be really cool for construction (though drywall/etc guys are a lot faster than this machine is), but ... But you actually could not likely use this for real cabinet parts, etc. To give you some idea: Their specs: Encoder Resolution: 8148 steps/rev Real World Precision: +- 1/64th inch (.4 mm) or better Max feed rate 48 inches/minute Specs on my pretty basic 36x36 wood CNC router: Encoder Resolution: 4 million steps/rev (22bit). Electronically gearable to whatever (they are servo motors) Real world precision: +-0.001 (1/1000) inch Max feed rate 1200 inches/minute Now, obviously, there is a range of costs and other machines between these two machines :) But building precision CNC routers, even with good closed loop servo motors and ball screws, is not anywhere near as expensive as it used to be.
- joshu 10y ago
  Can you talk about where to get the cheaper closed loop stuff? I am using usdigital encoders and geckodrive controllers currently...
  - DannyBee 10y ago
    ebay most of the time :) You just have to know what to look for. So, for example, mitsubishi EOL'd the mr-j2-* series, and released the mr-j4 series. If you look on ebay, you can usually find mr-j2's and mr-j3's , as new old stock, for about 300-400 for drive + motor (I'm going by the 400 watt ones, so mr-j2-40 and hc-kfs43). If you are really good at it, you can find the mr-j4's for good prices occasionally. There really isn't much of a resale market because in the automation world, people don't buy used or eol'd stuff (you aren't going to shove used motor into critical factory machine) I ended up getting 3 new mr-j4-40a's and associated motors for about 1000 bucks. You can play the same game with yaskawa, etc motors.
    - joshu 10y ago
      How do I learn which mfgs I should look for?
      - DannyBee 10y ago
        The easiest way is to see what gets used in wood routers by typical manufacturers. The short list is pretty much: Mitsubishi Yaskawa Sanyo Panasonic It is hard to go wrong with any of these. Unless you are doing something nutso, you won't need more than 400 watt motors (which, being brushless dc servo motors, have enough power to pretty much destroy every other part of your machine)
- swimfar 10y ago
  He said, "It's much more accurate than I would expect." He's referring to how accurate it is based on how it is designed. And I disagree that it's not very accurate, given the use case. 0.4mm or 1/64" is way more accurate than almost anyone can do with traditional power tools. Sure, other more expensive machines have better precision. But how many people actually need that much? Even plywood is going to experience changes in length due to temperature/humidity greater than 0.001" (0.025mm). Solid wood (which I guess this machine isn't really designed to cut) is going to be even more.
  - DannyBee 10y ago
    "And I disagree that it's not very accurate, given the use case. " What use case? "construction" is mentioned, but plywood guys and drywall guys can make cutouts and curves far faster and more accurately than this machine can cut. So seriously, what is the real use case other than "fun toy"? " 0.4mm or 1/64" is way more accurate than almost anyone can do with traditional power tools." This is just flat out false. With a simple track saw, i can easily get within 1/128th without even trying. Hell, i can do that with a circular saw and a straight edge without a track. You can get to within 0.005 pretty easily if you have bothered to tune your tools at all and don't beat them up. You can definitely get 0.005 if "traditional power tools" includes routers. Of course, if you go to hand tools, getting within 0.001 is utterly trivial with good hand planes. "But how many people actually need that much? " Wood certainly moves, but 0.005 is about being able to make nice fitting joinery repeatably. https://woodgears.ca/mortise/accuracy.html https://woodgears.ca/mortise/accuracy.html "With a mortise of 0.503", here's how the tenons fit: ... Realistically, the total range of latitude is about 0.005" for a good fit. And this is using spruce, which is a very forgiving soft wood. For mortise and tenon joints in hardwoods, accuracy is even more critical. "
    - Yaggo 10y ago
      For a wood-cutting system supported by two chains and gravity, .4mm is surprisingly good tolerance. Sure, it is possible to get far more stricter tolerance with tradiotional power tools (for skilled person) but first you need to somehow draw a line to follow, a challenging task in itself for complex shapes. This tool can do CAD, a big benefit.

by Yaggo 10y ago

DannyBee 10y ago

Errr, .4mm is not very accurate. It's about 5-15x less accurate than basic wood cnc machines, which do 0.001-0.005 (they could easily do better, it's just not necessary for wood). If each part was off by 1/64th, you can't even form a 4 sided box that is guaranteed less than +-1/16, which is a lot. I'm pretty sure they are also not including the router runout (since it uses a router and not a spindle, add about 0.005-0.010, or, rather, halve their precision again) Now, don't get me wrong, it's a neat idea. It may be really cool for construction (though drywall/etc guys are a lot faster than this machine is), but ... But you actually could not likely use this for real cabinet parts, etc. To give you some idea: Their specs: Encoder Resolution: 8148 steps/rev Real World Precision: +- 1/64th inch (.4 mm) or better Max feed rate 48 inches/minute Specs on my pretty basic 36x36 wood CNC router: Encoder Resolution: 4 million steps/rev (22bit). Electronically gearable to whatever (they are servo motors) Real world precision: +-0.001 (1/1000) inch Max feed rate 1200 inches/minute Now, obviously, there is a range of costs and other machines between these two machines :) But building precision CNC routers, even with good closed loop servo motors and ball screws, is not anywhere near as expensive as it used to be.

joshu 10y ago
Can you talk about where to get the cheaper closed loop stuff? I am using usdigital encoders and geckodrive controllers currently...
- DannyBee 10y ago
  ebay most of the time :) You just have to know what to look for. So, for example, mitsubishi EOL'd the mr-j2-* series, and released the mr-j4 series. If you look on ebay, you can usually find mr-j2's and mr-j3's , as new old stock, for about 300-400 for drive + motor (I'm going by the 400 watt ones, so mr-j2-40 and hc-kfs43). If you are really good at it, you can find the mr-j4's for good prices occasionally. There really isn't much of a resale market because in the automation world, people don't buy used or eol'd stuff (you aren't going to shove used motor into critical factory machine) I ended up getting 3 new mr-j4-40a's and associated motors for about 1000 bucks. You can play the same game with yaskawa, etc motors.
  - joshu 10y ago
    How do I learn which mfgs I should look for?
    - DannyBee 10y ago
      The easiest way is to see what gets used in wood routers by typical manufacturers. The short list is pretty much: Mitsubishi Yaskawa Sanyo Panasonic It is hard to go wrong with any of these. Unless you are doing something nutso, you won't need more than 400 watt motors (which, being brushless dc servo motors, have enough power to pretty much destroy every other part of your machine)
swimfar 10y ago
He said, "It's much more accurate than I would expect." He's referring to how accurate it is based on how it is designed. And I disagree that it's not very accurate, given the use case. 0.4mm or 1/64" is way more accurate than almost anyone can do with traditional power tools. Sure, other more expensive machines have better precision. But how many people actually need that much? Even plywood is going to experience changes in length due to temperature/humidity greater than 0.001" (0.025mm). Solid wood (which I guess this machine isn't really designed to cut) is going to be even more.
- DannyBee 10y ago
  "And I disagree that it's not very accurate, given the use case. " What use case? "construction" is mentioned, but plywood guys and drywall guys can make cutouts and curves far faster and more accurately than this machine can cut. So seriously, what is the real use case other than "fun toy"? " 0.4mm or 1/64" is way more accurate than almost anyone can do with traditional power tools." This is just flat out false. With a simple track saw, i can easily get within 1/128th without even trying. Hell, i can do that with a circular saw and a straight edge without a track. You can get to within 0.005 pretty easily if you have bothered to tune your tools at all and don't beat them up. You can definitely get 0.005 if "traditional power tools" includes routers. Of course, if you go to hand tools, getting within 0.001 is utterly trivial with good hand planes. "But how many people actually need that much? " Wood certainly moves, but 0.005 is about being able to make nice fitting joinery repeatably. https://woodgears.ca/mortise/accuracy.html https://woodgears.ca/mortise/accuracy.html "With a mortise of 0.503", here's how the tenons fit: ... Realistically, the total range of latitude is about 0.005" for a good fit. And this is using spruce, which is a very forgiving soft wood. For mortise and tenon joints in hardwoods, accuracy is even more critical. "
  - Yaggo 10y ago
    For a wood-cutting system supported by two chains and gravity, .4mm is surprisingly good tolerance. Sure, it is possible to get far more stricter tolerance with tradiotional power tools (for skilled person) but first you need to somehow draw a line to follow, a challenging task in itself for complex shapes. This tool can do CAD, a big benefit.