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Mar 2015
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Cinter
Mar '15

Hello Community,

So we have you a little challenge and/or a polite question! How do you make big things with a standard size desktop printer e.g. Makerbot Replicator 2 or an Ultimaker 2?

Like us, you may chop it up like quartered Marvin below but then how do you stick it back together? What would you do if each quarter was dimensioned to fill the maximum bed size? Do you feel sometimes constrained and/or limited to your build envelope when printing and making designs?

Marvin_1.png
Marvin_1.png842×562 185 KB

We have often wondered if there is a solution that could make the task of joining simple, harmless, easy to do and provide a clean and barely distinguishable seam. Let us know your stories and your challenges as we in-turn want to make this easier for everyone.

Look forward to hearing all of your views and maker stories.

Kindest regards,

The London Mayor’s office

Cinter

  • created

    Mar '15

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    Mar '15
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Steve_35
Mar '15

For parts made in sections, I often add a positive and negative feature (like a bump and cavity) on the mating parts. Great for alignment. Or, add 2 cavities and then insert a dowel pin for alignment.

Seams can be made cleaner be assuring the edges are sharp and maybe even a little longer so they can be sanded once assembled.

Joseph_1
Mar '15

A little while back I documented how I divide models into different parts in Blender. The advantage to using blender is I can create holes for pegs that I use to peg them together which I’ve done at times, but mostly I don’t worry about it because with a little glue things tend to line up well enough.

Priit
Mar '15

I have printed parts over 80 cm long with my Makerbot 2X (works only with ABS I think). I print them in many little pieces, sand them properly and make a thick mix of ABS and acetone. Then I add the pieces with some Loctite and cover the cracks with the ABS-acetone mix. I let it dry and then sand of the excess plastic and cover a light layer of ABS-acetone mix on the whole model. Then I use acetone vaporing and after that I colour the model. Good and strong solution in my opinion.
A good example of one of the prints (sunglasses for comparison): http://postimg.org/image/hsol7qwrj/ 1

Alex3DHubs
Mar '15

I think what you are looking for are ‘keys’. Essentially, they allow you to easily reconnect parts after a plane cut or something similar. Bold Machines 1 has a pretty solid tutorial for printing their movie characters, although they dont go over much detail for the software process. Hot glue is apparantly useful also :slight_smile:

DaveDelay
Mar '15

With ABS part I use “same stuff” or Ambroid “ProWeld” to fuse surfaces together. Keying if necessary. I got that tip from a tour of Stratasys back in the mid 90’s

Gary
Mar '15

The software 3D-COAT has a feature that will split an .stl, and automatically add in alignment pegs and holes.

Pot8oSH3D
Mar '15

Yup. That’s more-or-less the process I use. I wet the mating surfaces with Acetone before I stick em together with ABS/Acetone slurry though, just to soften the surface and ensure the dry surface doesn’t absorb the Acetone out of the slurry to quickly. A good sanding afterwards finishes the job. Spot the joint…

Cheers!

AndyL

Pot8oSh3D

IMG_0594.jpg
IMG_0594.jpg2448×3264 2.44 MB

Cinter
Mar '15

Fantastic responses, keep them coming!! :slight_smile: ‘Keys’ seem like a great idea particularly for alignment. Some of the techniques still sound a bit messy and dare I say it not very user friendly. Is anyone out there trying chemical free solutions?

Cinter
Mar '15

@Gary we will definitely be trying out this software, thank you and it’s free (seems too good to be true).

Cinter
Mar '15

@ST3P_GLASGOW This project is great! A really useful and helpful post too. Are you able to tack the parts together before fully attaching and would this be of benefit to the process if you don’t?

LA_3D_Print
Mar '15

I have built around 6 large scale models that have been larger than my build plate. One project had 212 parts!

Many different ways to do this.
Pegs are awesome
Allow holes to run through center of parts to insert metal rod or PVC pipe. Make it like a shish kebab

Weld edges together with soldering iron
Friction welding with dremil and old filament.

Bondo
or xtc 3d

STEP_GLASGOW
Mar '15

we’d definitely be interested in keys, but skeptical about the fit due to shrinkage. If there’s some way of adding keys with consideration for shrinkage, we’d love to find out more about it!

Voltl_Design
Mar '15

I bought the 3D Doodler pen for just this reason, when i have curling at the edge surfaces, I will glue the pieces together and where I have gaps, I will plastic weld the two pieces together to create a smooth surface.

Voltl_Design
Mar '15

Does this software account for FDM printers hole shrinkage because if I have models that need connector? As a way to combat this issue without an automatic solution I will model the part and offset the hole by .0125" to adjust for printer tolerance.

Joerg_4
Mar '15

“…, thank you and it’s free (seems too good to be true)”

it really is? I just find a limited trial for free, did I miss something?

MetaCAD
Mar '15

IF YOU HAVE AUTODESK INVENTOR, LIKE WE DO. THERE IS AN APP TO DOWNLOAD.

OR

CHEERS

BARRY

METACAD ENGINEERING SOLUTIONS LTD

www.metacad.co.uk

Cinter
Mar '15

Great to see so many fantastic pieces of software that are making this easier. @MetaCAD do you have any experience of how they cope with thin-walled large builds?

Dwayne
Mar '15

Solvent welding is the best solution I have found. Despite what community trends may lead you to believe, acetone is not ideal for dissolving ABS. MEK (butanone) works far better and is commonly used when assembling plastic model kits. If you don’t have a perfect fit between pieces solvent welding will not produce a strong void-free seam, you need to dissolve some ABS in the solvent to create a glue that can fill the gap. I have also experimented with friction welding (ABS filament in a handheld rotary tool) but I don’t think it’s ideal for most parts as the weld is only on the surface. It has applications, but is more limited than solvent welding.

8 days later
Cinter
Mar '15

Thank you @stephan_5 I think this project is really great and shows that innovation can be achieved by questioning, adapting and experimenting with what we already have available.

Cinter