Build Volume - perceived limitation?

First post here.
I had the pleasure of meeting Tantillus and Sublime at maker faire this weekend. Now I can't get the Tantillus out of my head
Anyway, I'm quite impressed with the printer, and some of its output is jaw-droppingly good.

I'm teetering on the fence about jumping in making this my first 3D printer. My main concern is build volume. Probably 20-40% of the objects I'll be printing will be larger than the 100x100x100 (potentially 120 with a different hot-end, I understand - is that available, or custom?). I intend to use PLA, primarily.

So - my main question is regarding PLA bondability and post production performance. I intend to use the printer as a prototyping machine, not so much for decorative pieces.

I suppose that durability can be increased/decreased by modifying the infill - correct?

I've read that crazy glue doesn't cut the mustard in bonding PLA. I've also read that possibly the best approach is via welding with soldering gun and PLA filament as filler. Is this the case that others have found here? I'd imagine that I would just modify the parts so that they have welding grooves/tabs built in that could be subsequently welded when joined. Beyond that, does it machine/sand well enough to hide welds and such?

Sorry for the long (entry) post, but I feel I need to know this before I can make a decision.

Thanks for any help you can give.

Cheers!

Gorilla glue works great for PLA-PLA bonding and PLA-to-most anything else. Among other parts I've glued with Gorilla Glue, my Prusa y-carriage is stuck to the bearing holders with it and has survived numerous crashes against the rail ends and other sorts of abuse.

The soldering gun welding sounds interesting, mind posting a link to the page where you read about it?

There's a product called Plastruct Plastic Weld that's worked really well for me on ABS parts. It's a solvent cement (so it melts the material, unlike super glue, which is more like an acrylic resin if I remember correctly) and I've been wanting to test it with PLA. I need to get my hands on some PLA parts and was going to wait till my Tantillus machine arrived, but if you're decision is riding on it you may want to give it a go yourself. Or I'll do it if someone wants to send me some PLA parts or tell me where I can buy PLA locally. You can buy the plastic weld at hobby stores for a few bucks.

If the solvent cement does work, you'll want to cut the parts you'll be bonding such that there's a large amount of surface area in contact at the joint (and you coat each surface with the cement when bonding). I've had luck with mortise joints, dovetail joints etc. It really depends on the part geometry/wall thicknesses etc when deciding which type of joint to use.

ernchesto Wrote:
-------------------------------------------------------
> First post here.
> I had the pleasure of meeting Tantillus and
> Sublime at maker faire this weekend. Now I can't
> get the Tantillus out of my head
> Anyway, I'm quite impressed with the printer, and
> some of its output is jaw-droppingly good.

Thanks

> I'm teetering on the fence about jumping in making
> this my first 3D printer. My main concern is build
> volume. Probably 20-40% of the objects I'll be
> printing will be larger than the 100x100x100
> (potentially 120 with a different hot-end, I
> understand - is that available, or custom?). I
> intend to use PLA, primarily.

The reason I say 120 is possible is because that is how far the Z-axis can actually move up and down. To print that tall it would require a short hotend and moving the Z-limit switch. It would also require having the upper bed really close to the lower bed. So until someone actually does it I would say it is not easy just yet.

I also have an idea to add legs to the bottom of the case that would allow you to increase the Z height.

>
> So - my main question is regarding PLA bondability
> and post production performance. I intend to use
> the printer as a prototyping machine, not so much
> for decorative pieces.
>
> I suppose that durability can be
> increased/decreased by modifying the infill -
> correct?

PLA is durable for most applications as it is harder than ABS but in the case of applications that require stability at temperatures above 60c ABS is the better material.

>
> I've read that crazy glue doesn't cut the mustard
> in bonding PLA. I've also read that possibly the
> best approach is via welding with soldering gun
> and PLA filament as filler. Is this the case that
> others have found here? I'd imagine that I would
> just modify the parts so that they have welding
> grooves/tabs built in that could be subsequently
> welded when joined. Beyond that, does it
> machine/sand well enough to hide welds and such?

I designed a plastic welder for just such occasions [www.thingiverse.com] It does need a better control circuit but the hardware is complete.

PLA is a little difficult to file or sand because the processes always generate heat above 60c which softens the material a little and it is more like trying to sand rubber at that point. Wet sanding would avoid this.

I do dremel small bumps some times and as long as it is a small amount it works well and does not get hot and gummy.

>
> Sorry for the long (entry) post, but I feel I need
> to know this before I can make a decision.

Ask away that is what this is here for.

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Here's where I read about the welding - [www.thingiverse.com]

Yes, I've used Gorilla glue, and can attest to its strength - it just requires time and careful jigging, so as to not have parts drift (in my experience - but that was mostly with wood/metal).

I'll have a look at the Plastruct stuff you mentioned Eric.

It would be really nice to find a solution that is quick, bomber, and biodegradable

I'd imagine that folks using larger machines also have found the need to bond parts to create larger overall parts - say, like airplanes and the like. So I'm sure there's folks about who've overcome the fact that most all printers have a size limitation to them. Maybe I should post a question on a less specialized forum...Or just practice patience

Ooops - I see the full link didn't go through - [www.thingiverse.com]
If it still doesn't it's /thing:23606

Ah- -greetings Sublime - OK - I just found your welder on thingiverse - that's NUTS! I'm guessing you see the world layed out in printed layers

So - I'm leaning toward thinking that build volume stuff can be overcome through one of the above techniques, and more.

Question about the > Z height with legs: If I got a laser-cut kit - and then printed up some sexy legs for it, would it just require longer Z-axis rods?, I mean, is the kit going to be set up so that wiring, filament tube (not sure what you call it) such are ready to 'grow', or would they require new parts? I realize that this is a delicate balance to not make it messy in the Tantillus build..

ernchesto Wrote:
-------------------------------------------------------
> Ooops - I see the full link didn't go through -
> [www.thingiverse.com]
> If it still doesn't it's /thing:23606

It works for me!

>
> Ah- -greetings Sublime - OK - I just found your
> welder on thingiverse - that's NUTS! I'm guessing
> you see the world layed out in printed layers

I sure do.

> So - I'm leaning toward thinking that build volume
> stuff can be overcome through one of the above
> techniques, and more.

I am not sure if I mentioned to you at maker faire about the size limitations brought on by the plastic itself. But over 100mm on x and y directions is when warping gets harder to control. This is when a heated bed is required.

So making things that bolt or snap together is usually a good solution.

Also the larger a single item is the longer it takes to print and the more risk you take in something going wrong and having a failed print. So if you can cut things up in a way that each part takes less then 8hrs you will not loss much if something goes wrong (power failure, dog unplugs the machine, run out of filament, etc).

> Question about the > Z height with legs: If I got
> a laser-cut kit - and then printed up some sexy
> legs for it, would it just require longer Z-axis
> rods?, I mean, is the kit going to be set up so
> that wiring, filament tube (not sure what you call
> it) such are ready to 'grow', or would they
> require new parts? I realize that this is a
> delicate balance to not make it messy in the
> Tantillus build..

If you have access to a laser cutter it would just require stretching the case out longer ( the back and left sides need the bottom 100mm of the case extended to whatever height you would like and the front and right would need the bottom 40mm of the case extended the same amount) and and using longer Z smooth rods.

If it is just legs I would make them printed and replace the corner brackets on the bottom with them. It would also need a small extension to mount the Z motor and lower bracket but those too could be printed (or longer version of what is already there and then use the same bolt holes).

The wiring is long enough that it would not need extending and the bowden part would not move at all.

Edited 1 time(s). Last edit at 06/25/2012 04:28PM by Sublime.

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Ah Geeze! The barriers are falling faster than my bank account is growing!
But the more I look around at all the things I need to fix/make, etc., it seems to pretty much be a no brainer!

Thanks for your answers and insight folks. Much appreciated.

I'm going to go outside and let my serotonin levels get back to normal..

Another solvent cement called Sigment was mentioned as working well with PLA in the comments of the Thingiverse entry on PLA welding. Not biodegradable though I'd imagine.

The Sublime welder looks awesome! Will have to try making one of those at some point.

Thought I'd mention one other really handy thing about the solvent cement - if you apply a coat or two in the areas of a printed part that see stress it strengthens the part amazingly well. Works great for keeping the layers from shearing apart.

It can also be used for aesthetics because it can smooth out build lines pretty well. It basically melts a thin layer of plastic wherever applied.

@ Eric

I have tried putting PLA in Acetone and Lacquer thinner and neither do much to the plastic unless it contains a lot of color or additives. The color and additives do seem to melt a little and offer some adhesion at first but once the solvent has washed them away it no longer sticks at all. This was tested with two differnet brands of PLA and both acted the same way.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
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@ Sublime

I've tried Acetone with ABS too and without much luck - like you said with the PLA it gets a little sticky but not nearly enough for a nice bond. I think one needs to really saturate the plastic to get it to work. I've heard of people dunking it, but never tried myself. I hear you can actually make ABS glue by leaving some ABS pellets in Acetone for a day or two. Maybe PLA glue could be made the same way?

Eric Young Wrote:
-------------------------------------------------------
> @ Sublime
>
> I've tried Acetone with ABS too and without much
> luck - like you said with the PLA it gets a little
> sticky but not nearly enough for a nice bond. I
> think one needs to really saturate the plastic to
> get it to work. I've heard of people dunking it,
> but never tried myself. I hear you can actually
> make ABS glue by leaving some ABS pellets in
> Acetone for a day or two. Maybe PLA glue could be
> made the same way?

NopHead did some testing a few months back and his results show that PLA does not dissolve in Acetone.
[hydraraptor.blogspot.ca]
[hydraraptor.blogspot.ca]

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Sublime Wrote:

> NopHead did some testing a few months back and his
> results show that PLA does not dissolve in
> Acetone.
> [hydraraptor.blogspot.ca].
> html
> [hydraraptor.blogspot.ca]
> cated-pla.html


Bummer. And I was wrong about acetone not working for ABS bonding.. apparently I was just doing it wrong because other people have had success with it.


Did some searching for PLA solvents/bonding and found a couple threads with multiple suggestions:
[www.bitsfrombytes.com]
[www.bitsfrombytes.com]

Well, I went for it, and I'm stoked!
I look forward to gaining a bettered appreciation for what the Reprap community had created.
Cheers!

Hmmm, here is my two cents on how I do large prints on our FDM machine (uprint plus) at work.

Background:
Material media = ABS
Support media = PLA (or pretty close to it)

ABS is disolved by MEK (methyl ethyl ketone)
Support media is disolved out by Caustic Soda solution agetated at 70oC. I use industrial drain cleaner now, as it is about 1/8th of the price of the Dimension/Stratsys stuff and basically the same.

Process for glueing ABS:
Get the part in Solidworks, setch a break line(s) on the part (I usually use jigsaw piece style). Split part and body delete parts to form STL's.

Print parts, disolve off support material.
Clip parts together, usually really good fit.
Using syringe or small bottle with nozzle style lid, apply MEK on meeting lines of part.
MEK wicks into gap, dissolves ABS on both sides, MEK evaporates off.
Result is a very strong solvent welded joint.

If you want to make Gap filling glue, mix MEK in a small bottle with some ABS plastic off a spool. Good for Gussits etc.

Other Notes:
I buy pure MEK by the 1L bottle from the local engineering store down around where a whole lot of boat builders are. I think it was about $30NZD a bottle. Hard to get now days in NZ due to the drug makers using, sigh.

As for PLA, interesting enough iFeelBeta, make a PLA dissolving solution for makerbots, A quick look at the MSDS sheet (http://www.2printbeta.de/download/Safetydatasheet-BetaSolution-2printbeta-englisch-v6.pdf) and it seems to be made up off:

<1% Aluminum hydroxide
5-10% Potassium hydroxide
90-95% Propan-2-ol (or IPA)

So possibly a mix of of this maybe a solution, but at a guess it would take a while to set.

Also as a side note, ABS can be bonded with good quality isocyanate glues and the resulting bond is good. Not as good as solvent welding though. I use Loctite 438 heaps at work at the stuff is great.

Sorry no enviromental friendly solutions for you, apart from bolts/nuts and steel dowel pins.

Good info - despite being environmentally terrible