3d Printing

Discussion in 'DIY' started by Dustin B, Apr 19, 2015.

  1. Dustin B

    Dustin B Well-Known Member

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    I'm sold on Fusion 360 now too. The frustrations it causes are less than the frustrations sketchup causes trying to make the model a true solid. The main two issues I've been running into with Fusion both occur after changing a parameter that is used in a sketch causing down stream errors. One is a dimension constraint will move a line to the opposite side of the line it's being dimensioned to. The other is this causing a line that was projected into another sketch to be lost. IMO neither of these should be happening and the combination of the two make it so the parameter changing doesn't work the way it should in any moderately complex model.

    You've hit on a definite secret. The first layer is the most important thing to get right. If you have a perfectly flat print bed, getting it nicely leveled will solve all your problems. But more than likely your bed isn't perfectly flat. In that case the next step up is to get mesh bed leveling enabled to compensate for any unevenness in your build plate. It's much easier with a probe, but Marlin supports doing it manually. Well worth the effort if you're doing any printing of larger parts with big flat surfaces against the build plate.

    I just got a BuildTak system I'll be installing on my printer this weekend. I'm hoping that along with 7x7 mesh bed leveling using my BL Touch will solve my bed adhesion problem with the x gantry parts I've been trying to print. Evidence from the case printing at work on the Prusa MK3 printers indicates it will. If it does I'll get the rest of my parts printed out and installed including a new X-Carriage that will be using a Bondtech extruder instead of the Wade's extruder. Then I'll only have a small issue with some Z banding and my part height being off by 50-100% of a layer height on a finished part. That one is really perplexing me.
     
  2. Chris Slade

    Chris Slade Well-Known Member Top Poster

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    Today I ordered a Shapeoko XXL. Not 3d printing but similar and similar design process. Should be fun... or frustrating as hell.
     
  3. Dustin B

    Dustin B Well-Known Member

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    This for your garage or your business Chris?

    Now I know where I can get a custom build plate made when I design and built a coreXY machine :)
     
  4. Chris Slade

    Chris Slade Well-Known Member Top Poster

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    This is for my garage. There is a pretty decent user community, and I have some idea what I am doing from my experience with my cnc plasma table. It should hopefully be fun. If I get into it I will add a laser to the machine too. I hope that once I get decent with this that I can get my son interested, but we'll see. Once step at a time. I bought a router for it today, placed the order today, I would expect the machine to arrive next week. And I have installed enough software to get started. I bought a laptop specifically for design and running the Shapeoko. I need to build a permanent home for the machine. I have a large enough work bench to build the Shapeoko on. Then I'll build some to hold it that will be designed specifically for the Shapeoko.
     
  5. Chris Slade

    Chris Slade Well-Known Member Top Poster

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    Hopefully machine and some end mills arrive before the weekend. I'll put it together, then build a basically fire proof enclosure for it, find it a home in the garage and get going. That will take longer than it sounds.
     
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  6. Dustin B

    Dustin B Well-Known Member

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    That sounds like a mid summer update goal ;)
     
  7. Chris Slade

    Chris Slade Well-Known Member Top Poster

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    Dustin a CoreXY moves the workpiece (I don't know 3d printer speak) in two dimensions correct? Then the print head would only handle the z plane? Is that correct? Is there a benefit to this? Shapeoko makes a small hobby mill called a Nomad that moves the material instead of the spindle.... this is the same thing for 3d printing?
     
  8. Dustin B

    Dustin B Well-Known Member

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    In 3d printing the hotend is the equivalent of the spindle but it adds material instead of removing it. There are roughly 4 main types of movement for them. The most popular right now and cheapest for hobbiest is one of the 2 Cartesian styles. It's called an i3. This one moves the work piece in the y axis. Has a gantry that moves the hotend in the z and a carriage on the gantry that moves in the x. H bot designs move the work piece in the z and then have a gantry that moves in the y and a carriage that moves on the x. Then there is a core xy which is same mechanical structure as an h bot but isn't a Cartesian because the xy movement isn't controlled by individual motors. If one of the xy motors is running the hotend will move on an angle. Both motors have to run for it to move straight on one axis. The final type is delta. In a delta the bed stays stationary and the hotend is attached to 3 arms that are attached to 3 vertical rails. 3 motors move the far end of the arms up and down the rails to position the print head in x y and z. So this type has a circular build volume.

    I'm not aware of any 3d printer designs that move the same way a cnc usually does. I think 3d printers usually have significantly more z axis range than a cnc usually does.

    Moving mass is an enemy of accurracy with speed. So any design that moves the work piece bed is considered inferior to one that doesn't. But the i3 design is cheaper and easier to design. The others the gantry moving in y is way heavier than the carriage in x and z doesn't ever have to move more than a layer height at a time. Delta can print the fastest as the mass is the same in all directions and if you design a light carriage it can have a big advantage. It's problem is it loses accuracy as it gets to the edges of its build volume because of how it's movement is achieved.
     
    Last edited: Mar 13, 2019
  9. Chris Slade

    Chris Slade Well-Known Member Top Poster

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    Yeah similar but different. I don't have to move mass..... I have resistance between the cutter and the material. Depth of cut, spindle speed, and linear speed would be how we deal with the equivalent of mass.
     
  10. Dustin B

    Dustin B Well-Known Member

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    Yep. And the limitations on movement speed dictated by how fast the cutter can remove material dictates much lower movement speeds than you can see in 3d printing. But 3d printers are also laying down 0.45mm wide beads of plastic that are 0.2mm tall. While a CNC can remove a lost more material than that in a single pass making them effectively a lot faster.
     
  11. Chris Slade

    Chris Slade Well-Known Member Top Poster

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    The UPS guy just delivered my machine. If I can wait I won't start assembly until the weekend when I can likely do it in one sitting.
     
  12. Chris Slade

    Chris Slade Well-Known Member Top Poster

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    Had to pick up 250 t nuts, ended up buying 300. They were 28 cent each. That adds up, he gave me 30% off. Jesus hardware and fasteners are expensive now.
     

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