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Ideas for 1000mm^2 bed

Posted by L4nce0 
Ideas for 1000mm^2 bed
March 13, 2016 12:29AM
Hi everyone. I have been working on a large format 3d printer. I had designed it originally for 500mm size, had a custom high precision casted metal plate made (very expensive).

I happened to get 2 1000mm^2 heaterbeds as overstock from [3dplatform.com] for a good price. Now a 500mm bed I can figure out how to make. a 1000mm bed, thats is a whole other beast. I have No Clue how I am going to create a perfectly flat bed for this to rest on. I am a bit obsessed with 3d printer so why not go big?

The printer is mostly going to be an open rails design. Still working on the linear motion. The only option that comes to mind is getting 4 of those cast plates as a surface. Though even then, as they are separate bits, might be uneven. Also that will probably cost me a grand or more to do. The other option is to get cheap sheeting and screw it onto a system of extruded aluminum. Though I do not believe they will be within tollerances.

My ideal solution will be cheap. I have spent a lot on this project and want to keep it low. I am hoping I am overthinking it. Maybe my solution is to take the above mentioned metal + screws and top it with glass? Glass should be perfectly flat and I should be able to get them thick. Though likely I would need panels as 1000mm^2 of tempered glass seems like a hard order. Not to mention I will likely move cross county move.
Re: Ideas for 1000mm^2 bed
March 13, 2016 08:17AM
I don't think you're going to do a m2 printer cheap. Glass is smooth, but surprisingly flexible at those sizes. You could go thick, but the weight would be high and you'd be fighting the poor thermal conductivity. I doubt if there is a better solution than aluminum tooling plate. I'd guess you'd need at least 3/8" thickness, which at 1m2 comes out about $544 USD from online metals.

Hmm, looks like tempered glass of the same size in 3/8" is only about $100, and still only $120 in 1/2". That does make you wonder if it might be possible to do something with it, but I don't know how you'd get it sufficiently flat over that size. I wonder just how much 1/2" glass actually bends - maybe it's worth finding out!
Re: Ideas for 1000mm^2 bed
March 14, 2016 09:59PM
I'm looking at [www.onlinemetals.com] I can order a MIC 6 plate 46inches ^2 (bed is just under 40 inches) at a quarter inch thickness, with shipping for like 600. These are casted plates with high precision! Maybe that's the solution? I was surprised I could order them so large and have delivery for just 60. (I mean I just paid UPS 100 to ship a broken b9 across country)

Thoughts? I mean, those are some BIG plates. I don't know what I'd do if I ever had to move. Also as I am living with family, I am pretty sure I am going to be murdered the day this arrives..
Re: Ideas for 1000mm^2 bed
March 14, 2016 10:37PM
Yes, things get serious when you start going to those sorts of sizes. You've seen the pictures in the large scale printer thread right?
Re: Ideas for 1000mm^2 bed
March 14, 2016 10:39PM
Quote
L4nce0
I'm looking at [www.onlinemetals.com] I can order a MIC 6 plate 46inches ^2 (bed is just under 40 inches) at a quarter inch thickness, with shipping for like 600. These are casted plates with high precision! Maybe that's the solution? I was surprised I could order them so large and have delivery for just 60. (I mean I just paid UPS 100 to ship a broken b9 across country)

Thoughts? I mean, those are some BIG plates. I don't know what I'd do if I ever had to move. Also as I am living with family, I am pretty sure I am going to be murdered the day this arrives..

The plate will likely be flat and parallel as manufactured. It will almost certainly not remain that way on it's own without some support structure of some significance. It will sag under it's own weight if not supported, and although cast aluminum has a lower coe, it's not insignificant in a plate that size. You need to work out how to support the plate and allow for thermal growth, then it will work just fine. If you want the plate to span the meter on it's own unsupported you would need to go with somewhat thicker plate.
Re: Ideas for 1000mm^2 bed
March 15, 2016 01:29AM
What layer thickness do you intend to print? If you're trying to print on 100 um layers, even MIC6 plate will need help to stay flat enough to print. If you're going to print in 1 mm layers, it may not require too much special effort.
What are the voltage/current ratings of the heaters?

What sort of printer architecture do you plan to use= bed moving or stationary? If moving, which axis?


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Ideas for 1000mm^2 bed
March 15, 2016 09:37AM
Correct me if I'm wrong, but my gut tells me you could mill/drill holes throughout the plate to help counter the thermal expansion. You would need to do some thermal analysis to keep the holes as small as possible and figure out the best pattern, but it would give the the aluminum some "room to grow".

Edited 1 time(s). Last edit at 03/15/2016 09:38AM by gmh39.


greghoge.com

HUGE 3D PRINTER PARTS SALE!!!
Re: Ideas for 1000mm^2 bed
March 15, 2016 10:30AM
Quote
gmh39
Correct me if I'm wrong, but my gut tells me you could mill/drill holes throughout the plate to help counter the thermal expansion. You would need to do some thermal analysis to keep the holes as small as possible and figure out the best pattern, but it would give the the aluminum some "room to grow".
Not going to help that issue. Pocketing the plate will cause more issue than help, even in cast. Plus you don't want to pay what it would cost to machine smiling smiley
Re: Ideas for 1000mm^2 bed
March 16, 2016 08:10AM
Hey Lance,

I was just looking in the large scale printer thread, and the builder has just installed a big glass bed. I couldn't see any obvious levelling mechanism, and it occurred to me that you could sidestep the issue. If you mount the glass solidly to the carriage you can support it at more points (minor issue about where the heater goes to be worked out) so there would be less issues with non-flatness due to bending. Then use auto bed levelling to deal with any non-levelness. With this approach you could probably use thinner glass and get a workable printing surface that's much more affordable at large sizes.
Re: Ideas for 1000mm^2 bed
March 18, 2016 04:57AM
Sorry for the delay in replying. It's been an eventful week. Also thank you for all the high content replies! They really help.

jamesK Thanks for that thread, its a great one. Also I will admit I am now a bit intimidated because his design is so much more complicated than mine. Especially as I am also using openrails parts. I can at least take comfort that I made a good cheaper choice in linear motion. Right now, I have 3 E3d hot ends, I have a duet board. Some nema 17 motors, As the plan was to build a medium size printer before I came across these giant heat beds. I knew I needed to upgrade the motors, but that power set up is concerning to me.
[forums.reprap.org]
I am guessing those allow him or her to drive the larger motors while still using a standard 3d printer board? Can you identify those parts. Thankfully my dad is a EE so is a friend. The whole point of this project is to take on a challenge.

Very interesting things he's done. That X axis is just so over complicated. [forums.reprap.org] Though I am sure there is a reason. I would not have used direct drive extruders, or more than one 2040 extrusion.

For the frame
My plan is a simple square frame made out of 2040. The bed being so heavy will be static. The hotend will move in ZYX. With the Y driving the X. The XY will be similar to the Ultimaker, but much thicker 2040 rails instead of rods. The XY will be in its own self contained square, which will be mounted to the Z axis (And supports). Over time I plan to add 1 then 2 then 3+ hot ends, so the lighter the better, thus bowden hotends. (3mm)
Far as extrusion size I am looking at a 0.8mm head, just to make life easier.

For the Bed
I was thinking of putting 4 -5 2040 extrusions as slats. will have to think move about the thermal expansion. I can safely say I have no experience with that.
this image looks interesting. Though I don't see a need for the plate in between.
[forums.reprap.org]

I was thinking the flat plate, the silicone heater attached at the bottom. However if I am going to need to drill holes, the only option is going to be 2040, metal sheet mounted with screws, the heater on top, and some sort of stand off lip for attaching the bed. If I add a simple adjustment screw to each side of the lip (2 per side, 8 total) to account for heat warping of the metal place. (so that the glass stays in place)

It occurs to me that if I am using a glass sheet for flatness, and putting the heater on top I do not want a metal bed. I want a thermal barrier that rests on top the the 2040 slats. Maybe some sort of store or granite tile ( I have to look into what qualifies as a thermal barrier). So that would be something like 2040 slats, thermal barrier, a static lip, glass, done. What do you all think of that? Not to mention the power savings will be tremendous. Especially if I reflect the radiation back up.
Re: Ideas for 1000mm^2 bed
March 18, 2016 05:38AM
Your Duet can probably drive Nema 23 motors if you choose them carefully, with a rated current no more than 2A, and use 24V power - although the maximum travel speed may be limited. But the safer option is probably to use external stepper drivers, connected to the expansion connector of the Duet, and use the M569 command in config.g to map the XYZ motors to the external drivers. You can use the built-in drivers for driving Nema 17 motors for the extruders.

Although I am usually in favour of glass beds, for a bed as large as that I doubt it makes sense. I don't claim expertise in this area, but if I were building it then I think I would consider a cast aluminium tooling plate, supporting bars around the edges and across the middle of the underside, and two or four silicone heaters mounted between the supporting bars.

As DD said, you can't expect too get the bed flat enough to print a 0.1mm first layer. So you will need to use either a large nozzle (which is the only way you will get large prints completed in a reasonable time anyway), or grid-based bed compensation.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Ideas for 1000mm^2 bed
March 18, 2016 06:19AM
Hmm. Yeah suspending just wont work..

Well lets look at the printer the heat bed I got is from

[www.youtube.com]

That is a giant borosilicate glass, Gravity does a grand job making it flat. The bed in that video is plywood. (they use metal / industrial carts now) Their design is pretty slick, and minimalistic. Though no room for heat chambers etc.

I cannot find anywhere that comes close to selling borosilicate in 1m+ sizes..
Re: Ideas for 1000mm^2 bed
March 18, 2016 06:29AM
[3dplatform.com]

Just look at that.. Some simple compression conrners, some thick glass, and done. Just getting that glass is the problem!
Re: Ideas for 1000mm^2 bed
March 18, 2016 06:37AM
Given the price comparisons between ordinary glass, aluminum tooling plate and what I'd guess borosilicate would cost, I'd be inclined to try something simple with ordinary glass first and see how it goes. One of the problems of printing direct on glass is that large prints will sometimes pull a chunk of glass out of the surface. That would really suck with a very expensive piece of borosilicate. I'm not sure what happens at the size you are looking at, but for the more normal 200x200mm size there doesn't seem to be a need for borosliicate. I've never had a piece crack during heating or cool-down. I suspect a lot depends on how even the temperatures across the heatbed are and how rapidly you heat and cool the bed. I wouldn't recommend whipping the glass off at 110C and throwing it under cold water, but I don't see that as a likely scenario with a 1m2 bed anyway smiling smiley

You could almost certainly avoid the glass chunk problem by covering the surface with tape, either blue painters or kapton. It's a shame though, given how well glue stick on glass works and how much less hassle that is to maintain.
Re: Ideas for 1000mm^2 bed
March 18, 2016 07:18AM
That is a good point. It was not that long ago I pulled off a chunk of borosilicate off my flashforge. I could also add a laminate like the flashforge has, which makes it almost impossible to take parts off and preventing said glass problem. I added it to fore mentioned plate on the reverses side and have had no more issues.

I see I can order a 3/8th tempered plate for 260 +s/h.

The think with normal glass is it will break with a head crash. I have had more than a few head crashes over the years.. If I am running nema 23s, that will easily break normal glass. 600 lbs for thicker normal glass is the max "weight" though single points are different. Tempered is several times stronger, but at a cost.
Re: Ideas for 1000mm^2 bed
March 18, 2016 08:01AM
I don't know if they are any good, but the place I looked at to get an idea of prices was [www.onedayglass.com]
They quote $105 +shipping for 40" square 3/8 tempered, which is what got me thinking it was worth a try.
Re: Ideas for 1000mm^2 bed
March 18, 2016 09:28AM
It looks like an interesting design. The main weakness I see is that as the print gets taller the largest portion of the XZ mass get higher and higher in the air and is going to swing like a pendulum every time it reverses direction. Unless you use very low acceleration which ultimately means printing very slowly, print quality will suffer toward the top of tall prints. If the X axis were supported by 3 or 4 Z "posts" spaced maybe 200-300 mm apart the mechanism would be stiffer (but heavier) and capable of more uniform print quality throughout tall prints.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Ideas for 1000mm^2 bed
March 19, 2016 06:48AM
Quote
the_digital_dentist
It looks like an interesting design. The main weakness I see is that as the print gets taller the largest portion of the XZ mass get higher and higher in the air and is going to swing like a pendulum every time it reverses direction. Unless you use very low acceleration which ultimately means printing very slowly, print quality will suffer toward the top of tall prints. If the X axis were supported by 3 or 4 Z "posts" spaced maybe 200-300 mm apart the mechanism would be stiffer (but heavier) and capable of more uniform print quality throughout tall prints.
That was my thought. however there is a stark advantage when you start thinking about Multiple printing arrays. That said I wont be going that route.
IE
[3dprintingindustry.com]
(OH how I wish!)

I also like the idea of it being open to allow me to tinker for years. For example I am also building an inmoov android. Just the hand for now, but imagine if I could put a 3d doodler and let it work on this heated bed? But that is a tangent.

@JamesK I looked into it. The shipping is pretty nasty! More than the cost of the pane. So now it's 250+ Not the end of the world but not an impulse buy.
Re: Ideas for 1000mm^2 bed
March 19, 2016 08:51AM
Quote
Dentist
The main weakness I see is that as the print gets taller the largest portion of the XZ mass get higher and higher in the air and is going to swing like a pendulum every time it reverses direction.
Yes, and I noticed that all the videos I have seen look to be using very moderate print speeds.

Quote
L4nce0
The shipping is pretty nasty! More than the cost of the pane.

Ugh, I get that wihen ordering metals. I hate it when the shipping is more than the stuff.
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