Working With 3D Printed PLA

[BG John]

Although I haven't built my 3D printer yet, I'm currently learning all the various software needed for it (and my CNC mill). My aim in buying the printer wasn't to produce visible parts of models, but to use it for hidden structural parts, and for mountings, brackets, boxes and other bits and pieces on my layouts. I'll see what results I can get with visible parts too though.

 

My aim is to produce "multi-media" models, using the best material and techniques for each component. This means that I'm going to need to attach PLA to other materials, like plasticard, card/paper, various woods, metal, acrylic etc.. From what I've read so far, everyone seems to have different opinions on which adhesives work, and which don't. What are you using, and does it work?

 

I'm currently learning OpenSCAD to draw up the parts for a small 0-16.5 loco. It's a static model for my Cakebox Challenge entry. I'm aiming to 3D print the boiler, boiler fittings, footplate, frames and wheels. Other parts will be plasticard, either cut on my Silhouette Portrait, or CNC milled. I'd like to experiment with the kirtleypete "Painting Without (much) Paint" method of attaching printed paper overlays. To achieve this I need to:

 

1) Stick the PLA boiler, footplate, frames, axles and wheels together

2) Laminate a thin plasticard footplate to the thicker 3D printed one, to give a fine top surface and overhang at the edges, and also add thin plasticard buffer beams

3) Stick the plasticard cab to the plasticard footplate overlay, and to the PLA boiler

4) Attach various PLA and plasticard details, fittings etc. to the PLA/plasticard body

5) Stick the laser printed paper "paintwork" overlay to the PLA boiler and plasticard cab, and to other parts

 

This is a great exercise to learn OpenSCAD with, but if it will be impossible to assemble because I can stick the parts together, I need to rethink it before I get too far.

 

Any suggestions, experiences, that could help?

 

 

[eldavo]

PLA is awkward stuff unfortunately. In my experience the only things that will stick it to anything are cynoacrylate (superglue) or epoxy adhesives. None of the normal plastic cements or solvents will touch it.

 

Cheers

Dave

[BG John]

I've read a few discussions where lots of different solutions seem to have worked for someone, but other people don't get on with them. It seems like PLA is better for the planet and us than other filaments like ABS, but the ways to stick it are much worse.

 

I suppose ABS is the solution, but it's supposed to be harder to print, and I was hoping to get on and do some successful modelling ASAP, rather than wait until I'm really proficient with the printer. Perhaps I should have a rethink about this loco, and try to avoid sticking stuff to PLA.

[BG John]

Next question? A lot of people seem to make moving parts out of PLA. Is it tough enough to use for wheels and rails? Or will it wear? Not conducting electricity isn't a problem. And what about gears?

[letterspider]

Although I haven't built my 3D printer yet, I'm currently learning all the various software needed for it (and my CNC mill). My aim in buying the printer wasn't to produce visible parts of models, but to use it for hidden structural parts, and for mountings, brackets, boxes and other bits and pieces on my layouts. I'll see what results I can get with visible parts too though.

 

My aim is to produce "multi-media" models, using the best material and techniques for each component. This means that I'm going to need to attach PLA to other materials, like plasticard, card/paper, various woods, metal, acrylic etc.. From what I've read so far, everyone seems to have different opinions on which adhesives work, and which don't. What are you using, and does it work?

 

I'm currently learning OpenSCAD to draw up the parts for a small 0-16.5 loco. It's a static model for my Cakebox Challenge entry. I'm aiming to 3D print the boiler, boiler fittings, footplate, frames and wheels. Other parts will be plasticard, either cut on my Silhouette Portrait, or CNC milled. I'd like to experiment with the kirtleypete "Painting Without (much) Paint" method of attaching printed paper overlays. To achieve this I need to:

 

1) Stick the PLA boiler, footplate, frames, axles and wheels together

2) Laminate a thin plasticard footplate to the thicker 3D printed one, to give a fine top surface and overhang at the edges, and also add thin plasticard buffer beams

3) Stick the plasticard cab to the plasticard footplate overlay, and to the PLA boiler

4) Attach various PLA and plasticard details, fittings etc. to the PLA/plasticard body

5) Stick the laser printed paper "paintwork" overlay to the PLA boiler and plasticard cab, and to other parts

 

This is a great exercise to learn OpenSCAD with, but if it will be impossible to assemble because I can stick the parts together, I need to rethink it before I get too far.

 

Any suggestions, experiences, that could help?

 

 

https://ultimaker.com/en/community/5562-gluing-pla-plastic

 

I tend to use two part epoxy as I have a lot of it lying about. For a stronger joint, which can be sanded and painted, I mix in talcum powder.

[Robin2]

Next question? A lot of people seem to make moving parts out of PLA. Is it tough enough to use for wheels and rails?

I am trying to make Loco driving wheels - but have not got to the stage of knowing anything about wear rates yet.

 

First thing that I noticed when I put my wheels onto a chassis in place of regular wheels is how very much lighter the plastic wheels are. Yes, I know that should have been obvious. I don't know whether the lightness of the wheels will matter if the total vehicle weight is the same.

 

And assuming I do get a good set of wheels they won't get a lot of use by me - I prefer building and experimenting to running trains.

 

...R

[BG John]

https://ultimaker.com/en/community/5562-gluing-pla-plastic

 

I tend to use two part epoxy as I have a lot of it lying about. For a stronger joint, which can be sanded and painted, I mix in talcum powder.

That's one of the discussions I've read.

 

Epoxy would be OK for joints, but surely not practical for adding printed paper overlays. Talcum powder is an interesting addition.

Edited November 25, 2017 by BG John

[BG John]

I am trying to make Loco driving wheels - but have not got to the stage of knowing anything about wear rates yet.

 

First thing that I noticed when I put my wheels onto a chassis in place of regular wheels is how very much lighter the plastic wheels are. Yes, I know that should have been obvious. I don't know whether the lightness of the wheels will matter if the total vehicle weight is the same.

 

And assuming I do get a good set of wheels they won't get a lot of use by me - I prefer building and experimenting to running trains.

 

...R

I've got as far as drawing a basic tyre! I'm trying to make everything parametric, so I can gradually build up modules I can use everywhere, rather than keep on having to rewrite code. Tyres are fairly straightforward to start with, doing it with spokes, crankpin positions etc. will take time. I want to print the wheels for the loco I'm designing at the moment, as it will be a static model, and it's a good opportunity to learn without having to make them work. At least I can stick four tyres in position in OpenSCAD, letting the loco float in mid air, get on with more straightforward stuff, and add the spokes later when I've got some sort of idea how to do it!

 

When it comes to O gauge locos, wheels are eyewateringly expensive, and the printer could almost pay for itself if I could print the wheels for a couple of locos. That seems like a good incentive to try it!

 

I'm only building small layouts, so my wheels won't get a lot of wear either. People do seem to make moving parts like gears though, so it must have some sort of reasonable life.

 

If PLA turns out not to be good enough, my printer will handle half a dozen types of filament.

[rdr]

i've bonded pla to pla using acetone with good results. Be careful though use it sparingly

[Robin2]

I just tried a couple of quick experiments - gluing a couple of test wheels together back-to-back (i.e. the shiny sides that were on the printer bed) and half overlapped.

 

Bostik Glu & Fix which I use for a lot of my card stuff actually seems to work very well.

 

The other test was with Evo-Stik Impact adhesive. It is holding also, though not as strong. But it may improve with time.

 

And a third test - cellulose thinners does not work

 

...R

Edited November 25, 2017 by Robin2

[eldavo]

Very few chemicals (at least those available to ordinary folk) will act as a solvent to PLA. The stuff is pretty hard even though it melts at fairly low temperatures. I suspect you will struggle to get a reasonably smooth tyre or even a nicely concentric one using an extruder filament printer. You could machine it after printing but be very careful of it melting. I've managed to weld small drills and even my piercing saw to various bits of the stuff.

 

ABS is not that hard to print with as long as you have a heated bed on your printer (capable of about 100C) and the parts are not too big. Warping of large flat parts is the biggest problem. Using a large skirt or raft may help.

 

Cheers

Dave

[Robin2]

I suspect you will struggle to get a reasonably smooth tyre or even a nicely concentric one using an extruder filament printer.

My tyres are smooth and concentric. I needed to adjust the X steps per mm a little to get them properly circular. I printed a 20x20mm square which allowed me to check for the error in the X and Y movements (idea I found on the web).

 

...R

[BG John]

i've bonded pla to pla using acetone with good results. Be careful though use it sparingly

I've read that acetone is no good for PLA, although it's the right stuff for ABS.

 

No wonder I'm confused .

[rdr]

acetone definitely melts pla, i've joined printed pieces at high stress points, which have stayed firmly stuck together.

 

i've not printed with abs yet

Edited November 25, 2017 by rdr

[BG John]

Very few chemicals (at least those available to ordinary folk) will act as a solvent to PLA. The stuff is pretty hard even though it melts at fairly low temperatures. I suspect you will struggle to get a reasonably smooth tyre or even a nicely concentric one using an extruder filament printer. You could machine it after printing but be very careful of it melting. I've managed to weld small drills and even my piercing saw to various bits of the stuff.

 

ABS is not that hard to print with as long as you have a heated bed on your printer (capable of about 100C) and the parts are not too big. Warping of large flat parts is the biggest problem. Using a large skirt or raft may help.

 

Cheers

Dave

 

 

My tyres are smooth and concentric. I needed to adjust the X steps per mm a little to get them properly circular. I printed a 20x20mm square which allowed me to check for the error in the X and Y movements (idea I found on the web).

 

...R

 

There are so many different experiences reported, often ones that totally contradict other people's experiences.

 

I've been thinking that a way to approach getting a good finish is to treat 3D printing like casting, where parts are designed to be finished off by machining. But then I read stuff about problems with PLA melting. Is it any worse in this respect than styrene? I'm hoping to be able to CNC mill plasticard, so if I can do that, can I also mill PLA?

 

I'm sure the only real answer to my questions is to try it and see what works, and doesn't, for me, but it doesn't help when there's so much conflicting information.

 

I suppose the answer may be to move on to ABS sooner than I'd planning. Again there is conflicting information. Some people say it's difficult, while others seem to think it's easy.

[BG John]

I've ordered some ABS. I can try it once I've got the printer working, but if it I need more experience to get decent results it will be useful later.

 

This is an interesting item on building locos in ABS, and similar to what I was thinking of doing, apart from using a variety of techniques rather than just 3D printing.

http://www.madge00n3.co.uk/3DPrinting/3d01.htm

[Robin2]

I've ordered some ABS. I can try it once I've got the printer working,

IMHO you are running too far ahead of yourself and you will find yourself with a confusing array of options.

 

My approach (like to computer programming) is to evolve in small steps - at the moment I can't see anything wrong with PLA.

 

...R

[BG John]

IMHO you are running too far ahead of yourself and you will find yourself with a confusing array of options.

 

My approach (like to computer programming) is to evolve in small steps - at the moment I can't see anything wrong with PLA.

 

...R

I was planning to try ABS later anyway, so am just buying it a bit sooner than planned, so I have it available if needed.

 

I'm certainly aiming to work in small steps, which is why I'm impressed with OpenSCAD (thanks for suggesting it Robin). It makes it easy to concentrate on small parts of a bigger drawing, draw them to whatever level I've got the ability to do, and go back to them later when I can do a better job. My efforts to do things in small steps sometimes get foiled by the non arrival of eBay purchases though, as happened today with a tool I'm waiting for to help with building the 3D printer, so it's as well to be prepared!

[raymw]

In the many tests I tried with sticking pla, I found this by far to be the best solvent - http://www.chemicalsuppliesuk.co.uk/products/product.php?categoryID=1812&productID=8200 I obtained it from a local plastic sign maker. It evaporates quickly, make sure you keep the container well sealed. It's, best to use a syringe when applying (don't stab yourself), and allow a drop to wick in between the bits of pla you want to join. Very rapid in use, and gives a strong joint, even on 0.5mm strands. I much prefer pla to abs,at least for the things I was using it for.

[BG John]

In the many tests I tried with sticking pla, I found this by far to be the best solvent - http://www.chemicalsuppliesuk.co.uk/products/product.php?categoryID=1812&productID=8200 I obtained it from a local plastic sign maker. It evaporates quickly, make sure you keep the container well sealed. It's, best to use a syringe when applying (don't stab yourself), and allow a drop to wick in between the bits of pla you want to join. Very rapid in use, and gives a strong joint, even on 0.5mm strands. I much prefer pla to abs,at least for the things I was using it for.

Does it work with styrene? I'm wondering about joining PLA and plasticard, and also laminating thin plasticard overlays to PLA.

[dhjgreen]

In the many tests I tried with sticking pla, I found this by far to be the best solvent - http://www.chemicalsuppliesuk.co.uk/products/product.php?categoryID=1812&productID=8200 I obtained it from a local plastic sign maker. It evaporates quickly, make sure you keep the container well sealed. It's, best to use a syringe when applying (don't stab yourself), and allow a drop to wick in between the bits of pla you want to join. Very rapid in use, and gives a strong joint, even on 0.5mm strands. I much prefer pla to abs,at least for the things I was using it for.

The bottle of Plasticweld I have says it is dichloromethane, had a while though, might have changed.

http://modelshop.co.uk/Shop/Adhesives/Item/Plastic-Weld-Solvent-57ml/ITM5060

[Robin2]

The bottle of Plasticweld I have

That prompted me to try  Deluxe Materials "Plastic Magic" which seems to work nicely. I now have 3 pairs of PLA loco wheels stuck together.

 

I think the "magic" part of that stuff is its ability to escape out of the bottle even when the lid is on

 

...R

[BG John]

The bottle of Plasticweld I have says it is dichloromethane, had a while though, might have changed.

http://modelshop.co.uk/Shop/Adhesives/Item/Plastic-Weld-Solvent-57ml/ITM5060

Also available in larger containers from the same source

http://modelshop.co.uk/Shop/Adhesives/Methane-Based-Adhesives/Item/Liquid-solvent-cement-500ml/ITM5061

 

Dichloromethane on eBay. These are the sizes from one supplier, so it seems the postage has a bigger effect on the price than the contents.

https://www.ebay.co.uk/sch/m.html?_odkw=&_ssn=proton-scientific&hash=item4d4d4efd5c%3Ag%3AjVgAAOSwI7tZ2jCg&item=332009504092&_osacat=0&_from=R40&_trksid=p2046732.m570.l1311.R4.TR12.TRC2.A0.H0.Xdich.TRS0&_nkw=dichloromethane&_sacat=0

 

This gets more confusing! It seems that Plastic Weld works with ABS, styrene and acrylic too, so should stick everything I need. Presumably Dichloromethane will do the same.

 

It's not one of the worst solvents

http://www.wikidoc.org/index.php/Dichloromethane

[BG John]

Syringes are usually plastic. How do you make sure whatever you buy won't dissolve?

Edited November 26, 2017 by BG John

[raymw]

The syringes and needles I bought for a few pennies, from a local agricultural merchant, are these https://www.kruuse.com/ecommerce/userfiles/kru/11748_KRUUSE_Injection_brochure_INT_2017.pdf .Fwiw, the solvent is supplied in plastic containers - not all plastics are equal, as you know...

 

edit to add - as I said, I tried all the common model solvents, Carrs plastic weld was hopeless, useless for abs, too. I expect any of the usual model supplied stuff is 'let down', and over priced, the same as their solder fluxes.

Edited November 26, 2017 by raymw