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Build Plate Design

Posted by forreason 
Build Plate Design
December 29, 2018 03:57AM
Hey Folks,

I am currently designing a 3D printer and would like to know what you think about what I've come up with for the buildplate.

- the print Surface will be 304x304 (buildtak on springsteel)
- the sheet of spring steel will be held to the 8mm thick aluminium core with temperature resistant ferrite magnets
- the aluminium core is heated from the bottom with a Silicone heater
- below the silicone heater will be an insulation sheet
- the whole buildplate will be mounted to the Z axis with 4 M5 screws. I am not entirely sure yet how I want to do the leveling. I am thinkting about 4 springs or with spacers.





Edited 1 time(s). Last edit at 12/29/2018 04:04AM by forreason.
Re: Build Plate Design
December 29, 2018 11:06AM
How about reading all the previous discussions on how to build a bed ?
You will see the mistakes you already made.

Edited 1 time(s). Last edit at 12/29/2018 11:06AM by MKSA.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Build Plate Design
December 29, 2018 12:29PM
4 leveling screws doesn't make much sense if you recall from high school geometry that 3 points define a plane. See: [drmrehorst.blogspot.com]

When you heat the plate it will expand (about 0.5mm if you heat it to 100C to print ABS). That will push the leveling screws sideways and something will have to bend/move. Will your plate stay level or at least return to level every time it heats up? That potential problem can be mitigated by using a kinematic mount.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Build Plate Design
December 30, 2018 02:49AM
Other people have used magnetic foil or sheet instead of seperate magnets.
Re: Build Plate Design
December 31, 2018 04:46AM
Quote
the_digital_dentist
4 leveling screws doesn't make much sense if you recall from high school geometry that 3 points define a plane. See: [drmrehorst.blogspot.com]

When you heat the plate it will expand (about 0.5mm if you heat it to 100C to print ABS). That will push the leveling screws sideways and something will have to bend/move. Will your plate stay level or at least return to level every time it heats up? That potential problem can be mitigated by using a kinematic mount.

To be honest, I don't really bother about a 3 Point Leveling design. While it might be faster and more convenient, I don't plan to do bedleveling before each and every print. The Printer should be rigid enough to withstand some prints without further bedleveling required. With a 3 Screw design, I am a little worried about lost stability and more give. Not even that much on a level perspective but more on X/Y movement. Mark Rehorst from your post also outlines this:
Quote
Mark Rehorst
All are flat enough for edge to edge printing in 200 um layers. I can't say how big the bed can get and still be rigid enough to stay flat enough to print on with only 3 screws supporting it. That will depend on the thicknesses of the bed plate and the first print layer. Larger printers are typically used to print larger objects in thicker layers, and thicker layers are more tolerant of variations in flatness, so I suspect that 3 point leveling can be used to go quite a bit larger than 300 mm square, unless you're trying to print a 50 um first layer.

From my point of view, a 4 screw level design is just the same as a 3 screw design if treated correctly. Of course you are not supposed to pinch in two opposing screws like hulk and even then I believe the spring will have more give than outright bending the 8mm aluminium. The only difference is that the jaw and pitch axis are differently mapped and a screw is missing:


The kinematic mount might be a thing that I have to consider. While I had no issues there in the past, with a wider, thicker bed issues might occur. I do not want to add unneccessary complex solutions that might bring other issues with them so I will just test it out practically.

Quote
o_lampe
Other people have used magnetic foil or sheet instead of seperate magnets

That's true. The BuildTak kit that I ordered comes with a sticky magnetic foil. The inserted magnets might as well cause issues. I will have a look out what works best for me.

Edited 7 time(s). Last edit at 12/31/2018 05:34AM by forreason.
Re: Build Plate Design
December 31, 2018 06:12AM
foreason, did you complete this one ? [reprap.org]
How did you build the bed ?

Edited 1 time(s). Last edit at 12/31/2018 08:11AM by MKSA.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Build Plate Design
December 31, 2018 08:41AM
Hello MKSA,

unfortunately I had to move to a smaller apartment temporary (1 room with my Girlfriend) and had to stomp the entire project due to insufficient space, planning and funding. This time I'm trying to utilise everything I've learnt to use different and easier approaches such as the now available Titan Aqua instead of a self built water cooled hot end (which worked like a charm but I was not Happy with the Bowden Setup in this size of a printer)

I think I will continue the development of my Printer in my old thread as soon as i'm on the building process again. Currently I'm mainly testing all sub-components (such as the build plate) to be able to make optimisations and add them to the final design.

Edited 4 time(s). Last edit at 12/31/2018 09:06AM by forreason.
Re: Build Plate Design
December 31, 2018 04:28PM
I think you miss the point of using three leveling screws. It isn't just to make the bed quick and easy to level, which it does, but to make it stable so you don't have to keep releveling it. You say you don't intend to keep releveling your bed, but using 4 screws almost guarantees that you will have to because a flat plate isn't stable on 4 screws.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Build Plate Design
January 01, 2019 01:48AM
With 4 "feet" you can always level using these [www.ebay.it] as in your favorite bar !


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
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