glass bed vs. e.g. BuildTak flex plate

Discussion in 'Getting Started' started by zil0g, Dec 17, 2019.

  1. Greg Holloway

    Greg Holloway Administrator
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    Don't need a chamber for the PEEK i was printing :cool:
     
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  2. garethky

    garethky Well-Known Member

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    I want a thick, milled flat, magnetic bed with thermistor ports on both sides. I'm going to explore getting one from https://713maker.com/. Either custom for the E3D Tool Changer or cutting one of their Rail Core beds to size. I have a track saw that cuts aluminum and a router so I could "make it work".

    There are a lot of parts of this printer that are projects and I was 100% on board for that when I bought it (just like Sanjay said). But the bed is not a thing I can turn into a project. Ultimately, you need a mill with a fly cutter or a surface grinder and I have neither of those tools so I have to sub this out.
     
  3. Ben Kay

    Ben Kay Well-Known Member

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    If it helps, and ordering more than 1 impacts price per unit, I'd be potentially interested too. I'm running a sticky back magnetic sheet on top of the standard bed at the moment, but it's far from satisfactory.
     
  4. blarbles

    blarbles Well-Known Member

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    I am interested as well if a group order is put together.
     
  5. garethky

    garethky Well-Known Member

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    I will ask them if quantity makes a difference.

    I am also making the design open so they can offer a bed for sale through their store, if they want to do that. alternately any of you can submit the design tot hem or any other job shop. The CAD only took a couple of hours to do.

    Design: https://cad.onshape.com/documents/8d39fa86f828e9049e311f0a/w/1b143dfc829362336d52c230/e/cc90854da771fc50efdb384d
    • 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.

    Top: Screen Shot 2020-02-26 at 11.44.52 AM.png

    Bottom: Screen Shot 2020-02-26 at 11.47.15 AM.png
     
  6. Digi2life

    Digi2life Active Member

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    @garethky Did you ever hear back from them? I'm interested as well, though I would want the rectangular magnets.
     
  7. garethky

    garethky Well-Known Member

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    They are being impacted by the covid-19 situation I think. So I bid the job out through Xometry. It was expensive. By the time I have a bed it will probably be 2x what 713 sells them for. But I will have a bed. It will be here later on this month and I will let you know how it works out.
     
  8. garethky

    garethky Well-Known Member

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    P1000527.jpg P1000525.jpg

    I got my prototype. It was about 2x the cost of one of the 713 Maker beds to have this cut as a 1-off through Xometry. It is MIC-6 tooling plate (same as 713 Maker uses) which is a more expensive material than standard T6 Aluminum, but not THAT much more. Choosing MIC-6 caused the job not to be auto-quotable and the price jumped 4x over the same .step file in T6. When I asked why and offered to alter the design to help bring costs down, Xometry cut the price of the job in half. I chose the cheapest grade of machining with tolerances of +/- 0.005" (0.13mm). The magnets I was able to source had a similar tolerance so I opted to increase all of the magnet pocket dimensions by 0.015" (0.39mm). I didn't want to get a part with the holes too small and have to re-work it by hand.

    So hats off to 713 Maker, their product looks great and the price is very reasonable from what I can see. Honestly I could have done this cheaper by buying one of their beds and cutting it down to fit the Toolchanger.

    Magnets: I could not find a cheap supplier of high temp magnets so I opted to get them from McMaster. Those come from China and I have no idea on the supplier but clearly there is a huge markup. Going direct to the source would be a massive cost savings.

    Initial assessment is that it could use more magnetic force. I can slide the bed around without too much effort. Its stronger than the flat magnetic sheets I was using, but maybe only 1/2 as strong as the Prusa beds. It should work fine in practice.

    Weight wise this is ~450g heavier than the stock plate + glass bed. Hopefully that's not an issue as the machine should be able to handle a print that involves at least a couple Kg of filament being dropped on the bed.

    The heater pad adhesive and the magnets max temp is 150C. Realistically this get us all the common filaments, PLA, PETG, ASA/ABS, Nylon and maybe PC. If you want to print ULTEM etc the glass bed is probably right for you.

    This was expensive and it was something of a learning experience for me using Xometry. If you have a home shop with a mill, you can make your own for a reasonable price using MIC-6 plate. But for most owners that want a magnetic bed I think using a company like 713 Maker that has the supply chain, jigs, fixtures and machines dialed in for this work would be way cheaper.
     

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