Magnetic heated bed - 713maker style

Discussion in 'Motion System' started by Digi2life, Nov 18, 2020.

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Would you be interested in a group buy?

  1. yes

    1 vote(s)
    100.0%
  2. no

    0 vote(s)
    0.0%
  1. Digi2life

    Digi2life Active Member

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    Hey all, I reached out to 713maker to see if it would be possible to create a magnetic bed for the e3d toolchanger. This was done before and discussed in a different thread (https://forum.e3d-online.com/threads/glass-bed-vs-e-g-buildtak-flex-plate.3490/page-2) by @garethky , who provided a design but ended up having xometry make it.

    The design by @garethky is viewable at https://cad.onshape.com/documents/8...fc829362336d52c230/e/cc90854da771fc50efdb384d
    And a quote from the thread linked above:
    • Extending the lip on the front of the heat bed from ~8mm to 25mm. This should give a slight increase in printable area or just more space for purge/wipers.
    • Front corners of the bed are inset and notched (like the Prusa bed) to allow the build plate to be lifted up easily.
    • Mounting slots are shortened to 1mm inwards from the nominal mounting hole locations. The bed will expand slightly corner to corner (my layman's math say ~0.7mm from 25C to 150C), so 2mm should be enough play. The oversized 4mm holes are retained and there is a countersink so you can use a 3mm socket head cap screw and washer for mounting and that will all fit below the print surface.
    • Thermistor slot in the top of the plate so it is closer to the print surface and therefor more accurate.
    The nominal build plate dimensions would be: 318 x 233. I don't actually know of any commercial ones that size. I'm using 300x300 plates.

    713maker got back to me a day or two ago and is ready to make a prototype but we need to quickly decide a few things. The number of magnets and spacing will be determined by 713maker to create a similar pull force to the railcore design. But I want to hear opinions on the following and whether you'd be interested in buying one.
    1. footprint - I'd like to see if there's a flex plate already available.
    2. mounting solution
      • I don't see any issues with the design but am interested in your thoughts.
    3. thermistor channel - top or bottom?
      • It seems like cutting a channel in the top would impact the temperature distribution in the flex plate. Maybe someone could run a simulation... would depend on the thickness and thermal conductivity of the flex plate.
    And one last thing... we'll need to stick a silicone heater on this thing. I have a keenovo heater on a different printer that smells sooooo bad. Is that typical with the adhesive applied heaters? How are these bonded on the e3d bed?
     
    garethky likes this.
  2. blarbles

    blarbles Well-Known Member

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    I am very interested in this as well. I am using both the aliexpress flex plate (which is ok but not great) and ULTISTIK Premium Powder Coated Ultem (PEI) Build Plate 300 x 300 which is nice but the wrong size (but still works).

    Someone smarter than me should comment on magnet placement and thermistor location. Maybe look at other magnetic bed designs like Jubilee and use that as a starting point? https://713maker.com/jubilee/jubilee-magnetic-heated-bed
     
  3. Rene

    Rene Active Member

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    I did put a simple magnetic sheet onto the e3d-heated bed and done. Think of something like wambam or such. You can get stuff like this for <20€.
     
  4. Akiross

    Akiross Member

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    You put directly to the heated bed or stick it on the glass?
    If I do this directly on bed, I can't warm up the bed to 200 degrees. (I'm not sure if I need 200 degrees on my printer...)
     
  5. Rene

    Rene Active Member

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    Not 200°C, but you can do 120°C.
     
  6. Nicholasav

    Nicholasav Member

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    Is there any reason 713maker won't be using the new rectangular magnets? I'm very interested in this -- I like the extra size.
     
  7. garethky

    garethky Well-Known Member

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    My bed didn't have as much hold down force as I would like so I full endorse having 713maker design the magnet system! Whatever size/shape/placement is easy for them to produce.

    The PEI spring steel sheet I'm using is this one: https://www.filamentone.com/products/ultistik-premium-powder-coated-ultem-pei-build-plate-300-x-300 0
    It's still a little thinner than the Prusa sheets but its the best one I have tried so far. You can cut it down but I'm using it as-is. Eventually Prusa will make their big printer and we can just buy from them :D
     

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