Large build plate ideas please.

Large build plate ideas please. So I'm building a rather large i3. The rough size is three square feet. Needless to say the stock frog plate (i think thats what its called) wont work. So I need some feedback on a good way to mount a build surface to this beast. I need to keep it light weight as I'm still using nema17 motors. I will be printing pla mostly and am not planing on running a heated bed at this point. I'm thinking of using square stock aluminum for the frame and topping with 1/8" plywood or lexan. I guess the only problem I see with that is that the aluminum under frame is whats holding up the flexable plywood or lexan. This would mean that to level the bed I would need to shim the frame where it meets the printed lm8uu holders. Would that work ok? https://reprap.org/forum/read.php?151,269809,269809#msg-269809 Fri, 12 Jun 2026 16:23:07 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?151,269809,274747#msg-274747 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,274747#msg-274747

Quote
hcker2000
So I'm building a rather large i3. The rough size is three square feet. Needless to say the stock frog plate (i think thats what its called) wont work. So I need some feedback on a good way to mount a build surface to this beast. I need to keep it light weight as I'm still using nema17 motors. I will be printing pla mostly and am not planing on running a heated bed at this point. I'm thinking of using square stock aluminum for the frame and topping with 1/8" plywood or lexan. I guess the only problem I see with that is that the aluminum under frame is whats holding up the flexable plywood or lexan. This would mean that to level the bed I would need to shim the frame where it meets the printed lm8uu holders. Would that work ok?

Lexan or polycarbonate will expand greatly when heated. Although you don't intend to use a heated bed, the heat from the object being printed will warp the bed a lot. Why not use 3mm (1/8th") aluminium (Australian spelling), it is strong, light and doesn't warp so much.
To make it even stronger and do away with the frame, you could fold the edge over on two (or more) sides to form a channel or box. The folds don't have to be big, just 10 or 12mm would be plenty.
As for leveling, look at the bed leveling system elsewhere or this forum, it is cheap to make and works a treat. No need to have to level your bed any more and that also does away with your problem.]]> regpye General Mendel Topics Sun, 01 Dec 2013 19:43:00 -0500 https://reprap.org/forum/read.php?151,269809,274270#msg-274270 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,274270#msg-274270 Anonymous User General Mendel Topics Sat, 30 Nov 2013 12:51:48 -0500 https://reprap.org/forum/read.php?151,269809,271786#msg-271786 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,271786#msg-271786
Plywood on top
Plywood on bottom
Plywood cut in strips in between. (or even better - poplar boards)

Brad nail it up (to keep them all in place while clamping), then clamp it to dry.

Alternate approach:

Aluminum sheet on top
Aluminum sheet on bottom
Aluminum rectangular tube sections in the middle

Carefull (as in small) dabs of hot melt glue purely to hold things while clamping. Epoxy it together and clamp it flat while it dries.

In both cases you have a rim around the outside and some sort of grid inside the “box”. The materials don’t have to be terribly heavy duty. The interconnect between the grid elements can be pretty terrible and it all still works amazingly well. You do need to get all of the grid elements (and rim) well glued to the top and bottom sheets. The main trick is keeping it all together while you set it up and glue it.]]> uncle_bob General Mendel Topics Mon, 25 Nov 2013 12:31:44 -0500 https://reprap.org/forum/read.php?151,269809,271706#msg-271706 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,271706#msg-271706 hcker2000 General Mendel Topics Mon, 25 Nov 2013 08:45:35 -0500 https://reprap.org/forum/read.php?151,269809,270769#msg-270769 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270769#msg-270769 uncle_bob General Mendel Topics Fri, 22 Nov 2013 17:51:43 -0500 https://reprap.org/forum/read.php?151,269809,270722#msg-270722 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270722#msg-270722
Another idea that popped to mind would be using some of the thick pink panel foam. The ridged stuff used for houses. You could easily cover that with aluminum and glue the aluminum to it. Would be light and I dont think it should flex over a two foot span.]]> hcker2000 General Mendel Topics Fri, 22 Nov 2013 15:22:40 -0500 https://reprap.org/forum/read.php?151,269809,270664#msg-270664 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270664#msg-270664 uncle_bob General Mendel Topics Fri, 22 Nov 2013 12:38:33 -0500 https://reprap.org/forum/read.php?151,269809,270565#msg-270565 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270565#msg-270565 hcker2000 General Mendel Topics Fri, 22 Nov 2013 08:54:44 -0500 https://reprap.org/forum/read.php?151,269809,270562#msg-270562 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270562#msg-270562
I haven't tried doing this myself (constructing a large, lightweight yet totally flat moveable bed) but it seems you'd want something like an aluminum channel structure supporting the right gauge of aluminum plate. It needs to be thicker than sheet but not too thick so that it makes things heavy. The aluminum stock sold (usually in 12" wide rolls) for use in gutter and roof flashing is almost thick enough.

There seems to be a relationship like the squared / cubed law for supporting a flat surface area and the weight needed for the support structure. The larger the area the heavier it gets, geometrically, and this is compounded by needing to have it moveable. All of the large-bed CNC machines I've seen use a moveable gantry with a fixed bed for really large areas, and if you're doing that it opens up another set of possibilities and challenges.

It's an interesting project!]]> papergeek General Mendel Topics Fri, 22 Nov 2013 08:39:56 -0500 https://reprap.org/forum/read.php?151,269809,270218#msg-270218 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270218#msg-270218 uncle_bob General Mendel Topics Thu, 21 Nov 2013 12:46:45 -0500 https://reprap.org/forum/read.php?151,269809,270198#msg-270198 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270198#msg-270198 Kirschner3D General Mendel Topics Thu, 21 Nov 2013 12:19:37 -0500 https://reprap.org/forum/read.php?151,269809,270136#msg-270136 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270136#msg-270136 Kirschner3D General Mendel Topics Thu, 21 Nov 2013 08:58:23 -0500 https://reprap.org/forum/read.php?151,269809,270132#msg-270132 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270132#msg-270132
Here is a picture for scale.

]]> hcker2000 General Mendel Topics Thu, 21 Nov 2013 08:47:21 -0500 https://reprap.org/forum/read.php?151,269809,270123#msg-270123 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,270123#msg-270123 and have this design atm.

prusa i3 expansion]]> Kirschner3D General Mendel Topics Thu, 21 Nov 2013 08:11:22 -0500 https://reprap.org/forum/read.php?151,269809,269972#msg-269972 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,269972#msg-269972
Length of the smooth rods is three feet. So build area will be about 2 foot by 1 1/2 feet.

Not really related to my question but my z smooth rod is also 3 feet long. As for stabillity on the z I'm bolting it to my wall or very large 2x4 frame.]]> hcker2000 General Mendel Topics Wed, 20 Nov 2013 22:08:04 -0500 https://reprap.org/forum/read.php?151,269809,269933#msg-269933 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,269933#msg-269933
If you are going anywhere near this long, dump the round smooth rod. Go with supported linear motion rod. It will droop a lot less than any round rod you can reasonably manage to get.

As you take your belt out to that sort of length it will be "interesting" to keep it from being an accuracy issue. There are a lot of ways to address that, I can't think of any that are cheap.]]> uncle_bob General Mendel Topics Wed, 20 Nov 2013 19:19:34 -0500 https://reprap.org/forum/read.php?151,269809,269882#msg-269882 Re: Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,269882#msg-269882
1) This sounds really, really cool.
2) This guy/gal is going to have to go with something beefier than 8mm smooth rods to ensure that axis travel isn't bowed under the weight of those rods, particularly on X.
3) Regardless, that is going to be one heavy bed. I wonder if nema 17s can handle it.
4) Any print that takes advantage of all that build volume is going to take a very, very long time with typical nozzle sizes. Weeks, maybe.
5) If I were to try to build a printer this big, I'd probably use that as an excuse to explore a corexy or delta implementation to move the nozzle around, and let the bed move in Z, if at all.
6) Should this project advance, I want to see videos.

Good luck.]]> Karmavore General Mendel Topics Wed, 20 Nov 2013 17:05:14 -0500 https://reprap.org/forum/read.php?151,269809,269809#msg-269809 Large build plate ideas please. https://reprap.org/forum/read.php?151,269809,269809#msg-269809 hcker2000 General Mendel Topics Wed, 20 Nov 2013 14:51:34 -0500