Hello everyone,

I´m planning to build a 3D printer (probably like everyone else here). I´ve been looking into different DIY kits for the Prusa i3 and read a lot about the advantages and disadvantages for those kits. I´m planning to print a certain product, which needs a bigger printing size than 200x200x230 and I´ve seen a video where someone bought 4 of those kits and built a big Prusa i3 out of them. As I´m new and just planning to get started I have no idea of how complicated the increasement of the printing size is. Actually I would "just" need the size 200x200x400. I´m planning to print shoes so the height and the width aren't the problems, but the length is. Any ideas or suggestions how I could "simply" double the length from a Prusa i3 DIY kit or are there any other DIY kits which you could suggest?
As I´m a student, my budget is limited and I should have started the day before yesterday, because I´m doing this whole project for a course at University ^^.
Many thanks for your help!

Patrick

My best bet would be a tall delta printer. They are easy to scale up.
But sourcing parts,building and calibration might take a few weeks for a newbie.

What material do want to print the shoes off? It's important for the built ( enclosure, extruder, heatbed ?)
-Olaf

An important question is if the object to be printed can be built with the height or vertical axis as the long 400mm axis.

Things to consider are:

1. are there gaps or holes in the print that mean it must be, or should be, printed with one side of the object at the bottom? It is very hard to print an object accurately if it has a large gap with a "roof." Or, holes that are round and must be used for connectors print better if the holes are printed vertically.

2. Does the object need to be stronger in one direction? Layers in a 3D print are not as strongly held together as each layer is held to itself. So printed objects are stronger in the X and Y axis' than they are in the Z axis. If an object needs to be stronger in one or two directions those directions should be X, Y or both. Also, holes with connectors in them that are horizontal split easier for the same reason - they delaminate between layers.

If you determine that the 400mm axis of your object CAN be vertical, then a Delta printer is likely to be the easiest printer for you to build. If the 400mm axis must be horizontal, you will probably be better off building an H-bot or CoreXY printer.

Actually it might be REALLY easy to build a Prusa i3 style printer and just lengthen the movement of the Y axis Flat Bed so it moves 400mm

Another point would be support material.
If a lot of support material is needed in hidden places, a dual extruder with soluble filament would help.

@patrickrio
Do you know a heated bed with 400mm length?
Would it be enough to look for longer smooth rods or would they have to be thicker too?
-Olaf

For a heated bed in that strange size, it would be a custom job. Probably from that company that will build a Mains voltage silicone mat to desired size....

Based on seeing the Prusa i3 style x axis in action, It is my hunch that you could double the length of the rods in the same size and it would work without much vibration. have not seen someone do it yet though.

Edited 1 time(s). Last edit at 11/06/2015 03:48AM by patrickrio.

Thanks for the quick answers!

I´m planning to print the shoes soles only! Well obviously I´m just getting started, but from my point of view it might be easier to print the sole horizontal, because it wouldn't need as much support material. So far I've just tried a material called `ninja flex`at University and i think for a sole of a shoe this might be a good idea. But I´m open to any of your professional suggestions!
@patrickrio: thats what I thought too! But what about the adjustment in the software? I´d have to "tell" the printer that he is able to print 400mm instead of 200, no?!
I was planning to get the prusia i3 kit and just get some 400mm heated bed as well as replace the rods with 400mm - but that can't be it, can it?

2x 200x200 heatbeds placed end to end with a 200x400 piece of glass/aluminum placed over them would work. Your going to need to think about powering them. The 400mm Y axis, you might think about some supported linear rails.

What do you mean by "think about powering" ? The supported linear rails would just be a "stabilizer" for the Y-axis ?

Many thanks

Power to heat them up was meant.
A Ramps board with common 12V 350W powersupply wouldn't be enough.
-Olaf

My advice is to use an aluminium tool plate for the bed to ensure it is flat, optionally with glass on top, heated by a silicone heater underneath. You can get a silicone heater made to your size, voltage and power specifications from [www.aliexpress.com]. Use a bed a little larger than the heater to leave a 15mm margin around the edge for bed clips and fixings.

I suggest you choose a 24W/10A/240W heater and use modern 24V-capable electronics such as Duet or Smoothieboard, because you can drive the heater directly from those. If it doesn't heat up fast enough you can turn the power supply voltage up a little e.g. the Duet 0.8.5 would easily handle 28V and 12A. You can get a 24V 400W power supply on eBay and these can usually be adjusted up to about 28V if necessary.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi guys !

To me it's a nosense to get a big PSU to power a big heatbed. It's money and energy wasted.
If your heatbed needs power or is a large one, you should consider a AC heatbed with a SSR.
The aliexpress provider dc42 talked about can build any AC heatbed.
Unless you want to use your printer in a car somewhere...

++JM

Edited 1 time(s). Last edit at 11/11/2015 11:41AM by J-Max.

Quote
J-Max
Hi guys !

To me it's a nosense to get a big PSU to power a big heatbed. It's money and energy wasted.
If your heatbed needs power or is a large one, you should consider a AC heatbed with a SSR.
The aliexpress provider dc42 talked about can build any AC heatbed.
Unless you want to use your printer in a car somewhere...

++JM

The choice of whether to use an AC mains or low voltage heated bed depends on a number of factors, including the size of the bed, the understanding that the person building it has of electrical safety requirements, and whether or not the bed is moving.

I do use an AC mains heated bed on my delta printer. It was an easy decision, because I am knowledgeable about electrical safety requirements, the heater power (350W) is too high to be easily handled at low voltage, and the bed is fixed which makes it easier to comply with safety requirements.

For the printer being discussed here, the decision is less clear cut. The bed area to be heated is within the range that printer electronics can switch directly using 24V, and also within the power range of low-cost 24V power supplies. A moving bed presents additional safety hazards with regards to connection safeguarding, protective grounding, and cable stress relief. The OP says he/she is a student, and unless he is an electrical engineering student then it is unlikely that he has the necessary electrical safety knowledge. So although in these circumstances I might choose an AC mains heated bed if I were building it myself (and take the opportunity to increase the power to get a faster heating time), I thought it better to suggest a 24V heated bed.

Edited 1 time(s). Last edit at 11/11/2015 12:18PM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi again,

Well, I don't know how it is abroad, here we learn electrical basics at 12.
I appreciate it might be different somewhere.

Anyways, AC power can kill someone easily. You're right.
But a wrong wiring of DC power can cause severe injuries, or cause a fire and kill people too.
A 24V machine is probably not so safe if you do things the wrong way.
Whatever the power, you want to do it right.

BTW, if you don't have any electrical/electronic skills, get some help or buy an Ultimaker.

++JM

Quote
J-Max
Well, I don't know how it is abroad, here we learn electrical basics at 12.

Which country is "here"?

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi,

France my friend.

++JM