Has anyone tried making a larger version of the Core?

Hi All

I'm thinking about building a larger 3d printer, I have had a few different models but nothing larger than 200 x 200 x 200mm build volume. Has anyone tried to make a larger version of the Core? It seems like the box offers a very simple, cheap and sturdy construction and any weakness in a larger box could be addressed with struts to brace the front.

Would it be easier to expand X+Y rather than Z or the other way around? Or would it not matter? I guess I'm more interested in building something that has a larger X+Y than Z.

Would the belts be a problem? I can see from their website the Gigabot doesn't use GT2 belts but not sure what it uses instead.

Thanks

John

Edited 1 time(s). Last edit at 05/14/2015 08:29PM by John Cummings.

I don't see any issues with it. I went with a 200x200x300 design for the sake of cheapness. When you get into the larger heated beds, you have to start looking into bigger or separate power supplies with relays which adds more to the cost. I don't see any issue with having a 300x300x300 Smartrap Core. I think the bigger you go though, the thicker the wood you should use and you should probably add a brace across the top front to help keep it's rigidity.

My current build (not finished) has a 304mm x 304mm x 255 print capacity. The box is 457mm x 457mm.

Jose

Thanks very much

I'd be happy to make one without a heated bed, I'm only interested in printing with PLA for now. What size do you think I could get up to? I'd be very happy with something 400mm or 500mm square.

What would I need to do in terms of software to make it understand that it is larger? Would it simply be changing the sizes in Cura etc?

Cheers

John

I am slowly designing a larger printer, about 450mm cubed build volume. You should consider the stiffness of the rods as you increase length - it's not a linear relationship between beam (rod) length and vertical deflection (sag) under the weight of the machine parts it carries. I calculated that I would need very heavy rods to make the x axis stiff enough to avoid a significant difference in height between the edge and centre of the build plate. This primarily affects the first layer and a multi probe point bed tilt compensation (all included in smartcore version of marlin) might mitigate it totally. The problem with using steel rods for the long spans is that their own weight becomes a more significant part of the deflection force. I switched to using v-slot aluminium profile and wheels to minimise self-weight and maximise stiffness. By the time you find large enough steel rods, the cost is cheaper if you go for aluminium profile IIRC.

The other consideration that you should make is whether your motors produce enough torque at the speeds you want to accelerate, drive at constant speed and decelerate the moving parts. I stuck with nema 17 motors for my larger printer design (remember I haven't made it yet) but don't know what your goals are.

Once I'm done with my current build I'm planning on building a large Core. Idk what the build dimension will be but the MDF I have laying around is 500++mm on each side, so it'll probably be massive.

Kinda wish I had found the Smart Core before I started my current build. Would have saved me lots of $$. Oh well.

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Thanks

If there's a few of us interested in making a bigger Core perhaps we could agree on a size and make ours at the same time so we can help each other get over the lumps and bumps.

Cheers

John

Hi.

I'm interested i make a big Smartrap Core. I plan to use a 220V heatbed, because 12 or 24 v needs a wide wiring to carriage the amps, the better way i thing is go to use a relay.

About the size, for the moment, i only find one shop here in Spain that sells 220V heatbeds, and the bigger size is 200x300mm (heatbed + aluminium base), have to search more. Maybe someone can help me in the search

Instead of and inductive sensor i will use a capacitive sensor, conected to 12V, and have two alternavites, use a volt divider with 2 resistors, or use a litle circuit with and optocoupler to isolate 12V from power the sensor to the in of ramps, that will be 5V. Like this one Ebay_Link, this way can use interchangable glass or mirrors.

My target is a print volume of at least 300x300x300 or 400x400x400 (if i found a heatbed), with dual extruder, and maybe, with enougth room to make a triple extruder...
My actual Prusa I3 Box Frame have a footprint about 500x500x500 and wanna change it by a Core that fits this foot print maybe the printing volume will be larger still analyzing it...

Wanna use M8 leadscrew for Z, with 2 motors, thing that for this size is the better way. I see some coment on the facebook group about put a z-max endstop, i think it's a good idea. And put some adjust screws in the plate.

It's a long term project, because i have problems with financing

@John Cummings, the size of mine was based on needing 2 rails for the Y axis and 1 for the x axis. V slot profile is sold in a 2m length and my supplier in UK was prepared to cut it into 3 pieces for me. Not only did I get better edges but also think there was less chance of getting the pieces bent in transit (imagine 2m in the mail system!).

Thanks, so is there an accepted maximum size that the standard rails in the Core kit can be used with?

Cheers

John

"maximum" is dependent on your appetite to accept or ability to mitigate the deflection in the rods across the build area. Different sizes, materials and cross sectional profiles of beam (rod) will have varying resultant deflection. The other factor is the time length of prints you want and how much extra volume the larger prints will be. Extruders don't scale up as easily as linear motion parts of the machine (feed rate, heating rate, printer head acceleration and velocity). If you are planning low volume but high bulk (e.g long and spindly) or can accept a long print times and can handle filament spool changes, this isn't going to be your limiting factor.

I haven't looked at the new version, but 8mm XY rods looked like the maximum size with the previous JSCAD files. That's what your limitation will be. Besides rod deflection, I'm not sure if the printed Y parts could support the extra weight of lengthened rods to well. I think 300mm is about the limit without a lot of extra work.

I don't get the need for large machines anyways. I feel it would be better to design smaller parts that assemble into larger parts well. Could you imaging the loss of a failed print at the 2 or 3 day Mark of a large part instead of 6-12 hours?

Ok, thanks, I'll try building one under 300mm for now then

This is a nice example of a large printer making big parts quickly using a larger nozzle
https://plus.google.com/+BrookDrummpb/posts/jmM7bwShYLw