So I left a 3D printed matchbox under water for 3 months...

[spandit]

Although I generally like to design the things I print, it's also possible to download stuff that other people have designed, often for free. I downloaded a screwtop bottle from thingiverse.com and printed it in bright orange PETG (same plastic they make drinks bottles from). With a cheap O-ring I filled it with matches and dropped it into a watering can that was full of water. Can't remember exactly when I did so but it was over 3 months ago.

It floated but was mostly under the water. I was surprised to discover that the matches inside were still perfectly dry. Would make a useful geocache container too.

http://creffield.com/pics/bushcraft/matchbox.jpg

Fun little project although looking on eBay you can buy aluminium ones pretty cheaply and medical specimen pots are pretty cheap too! This cost about £1.50 to print and took 8 hours...

 

[Mesquite]

That's a good test, nice to know it works as designed

 

[Fadcode]

After you make something on the 3d machine, does the plastic have to be cured, or is that part of the process, I was wondering if there was a limit on the strength of the item made.

 

[Alan De Enfield]

After you make something on the 3d machine, does the plastic have to be cured, or is that part of the process, I was wondering if there was a limit on the strength of the item made.

Firearm components can be made (and have been) using 3D printing such that the Home Office guidelines to Police forces now includes sections relating to 3D-Guns.

Example :

1.12. What is the government doing to prevent 3D printed guns being used?
If someone were to possess, purchase, manufacture or sell a firearm or its component parts
otherwise than in accordance with the requirements of sections 1, 3 and 5 of the Firearms Act
1968, they would be liable to prosecution. We are working closely with our partners, including the
police and firearms experts, to assess other implications.
See Chapter 3 for more details.

 

[Stew]

After you make something on the 3d machine, does the plastic have to be cured, or is that part of the process, I was wondering if there was a limit on the strength of the item made.

On another forum I go on, a chap has been exploring the printing of surfboard fins with whale tubercle shapes. Lots of strength testing and surprisingly reduction of strength after soaking. Quite a journey.

 

[C_Claycomb]

Plastics, like metals, come in different compositions, can be alloyed or mixed to increase strength, and can be processed in different ways which can have significant impact on strength. Just because someone made a strong part using a particular plastic material and method of additive manufacture does not mean that all plastic parts created by all additive manufacture (3D printing) will be equally strong.

Over the last few years I have done a fair bit of work with Fused Deposition Modelling (FDM = plastic filament fed into a heated print head and extruded as a bead to build up a part layer by layer) and Selective Laser Sintering (SLS = powder bed heated to near melt temperature, then a laser traces the outline of the part on the surface, sintering the grains together, built layer by layer). I have also had parts made using titanium powder in a similar powder bed process.

The DFM and SLS materials that I have used have not required any post process curing, but parts made using liquid bed and stereolithography (SLA) can benefit from a post cure to increase strength and stability.

Most domestic 3D printers are FDM, but there are some fluid types out there. We use PLA plastic, which can be brittle, has a very low softening temperature and does not machine well, but can exhibit surprisingly high strength to a steady load. I have seen testing that suggests it is not suitable for long term immersion. The same printer could use ABS, which would be a more durable choice, less brittle, but in our case the printer's location and fumes given off by ABS made it a non-starter.

Like anything, there will be limits on strength. Even titanium parts have limits on strength There are however plenty of people doing stuff with FDM where the parts have enough strength. You do need to understand something about design, modelling, loads and the method to get the most from it. I have overseen a couple of groups of A-Level students using FDM for a 6-month extra curricular engineering challenge and there is a definite learning curve if you are starting from scratch.



For fun, here are some links that show some interesting developments.
https://markforged.com/materials/onyx/
https://markforged.com/materials/carbon-fiber/

Chris

 

[Hammock_man]

As the software can be downloaded to make the "Create" file away from the machine..... would you be open to taking orders? Say some thing that you would charge a tenner for?

 

[Trig]

I got an fdm printer a few months ago. No real need for it, but its only a click away on the internet so...
What a twisted little bugger it is though...takes a bit of fiddling with sometimes to get it printing correctly.

Printed various usefull things on it that i couldnt really buy though, so they are handy for that, as long as you know how to work the 3d modelling software.

Be interesting to see how it all develops,and all the potential applications.
https://www.nasa.gov/mission_pages/station/research/news/3Dratchet_wrench

 

[Janne]

Nothing to do with this thread, but please, please, PLEASE! do not attempt to 3D print a handgun. Not only illegal, but very, very dangerous to the person trying to shoot it.

Media worldwide has been very quiet about it, but quite a few people have suffered irreparable damage to their hand. That plus facial damage, and lost eyes.


Now a question: Is it possible to 'print' a handle on a knife, one with a tick yang, for example, but so the plastic sticks to the metal?

( as you can read I know absolutely zero about this tech)

 

[Stew]

As the software can be downloaded to make the "Create" file away from the machine..... would you be open to taking orders? Say some thing that you would charge a tenner for?

You read my mind! I have a few bits I would consider getting made.

 

[C_Claycomb]

I am pretty sure that folk are asking Spandit (and maybe Trig) about getting stuff printed. In case you were asking me, sadly, no. The printer and all the material belongs to work and you would not believe the IT hoops I have to jump through annually to be able to use it.

I believe there are places that offer a build to model commercial service that isn't as steep as the people my company has used (AARK, 3DSystems and 3DRPD)

Janne,
Technology; providing new opportunities for idiots to prove themselves!
but...yeah, nothing to do with the thread, so lets call it a day.

As for printing a knife handle directly on the knife? Not in my experience, and while I can imagine that with enough effort the right sort of machine could be put together that could do it, I don't see that it would be a desirable technique compared to the alternatives. Far more practical would be to print handle scales, or a hollow shape, without the blade, then use a suitable adhesive to bond the handle to the steel, as per conventional making, but without the post-bond shaping. I have done a fair bit of reading about adhesives for PLA, but have not tried many or found one that I like. A lot of people say that Superglue works, but that has not been my experience. The solvent based acrylic glues and possibly methacrylate 2 part resins seem good candidates, but not so good for bonding to metal.

A word of warning regarding sending people models to build. My experience has been that it is preferable to send STEP files and have the person who will do the print produce the STL file, and then the G-Code from that. STL files are a pain to manipulate so if there is a problem with the print, there isn't much that the printer can do, whereas if they have the STEP and a Direct Modelling program they can make adjustments as required and output the STL themselves.

I am curious what Stew wants making

Chris

 

[Fadcode]

Thanks very much for your replies and detailed explanations, very interesting stuff

 

[Hammock_man]

Ditto on the thanks

 

[SiWhite]

Hammock Man and Stew - I’ve just stumbled across this thread. I have a 3D Printer at home which I really love using - it’s a budget machine but I’ve upgraded it fairly comprehensively and the quality is good. I regularly take orders from friends and family in exchange for contributions to my filament fund!

Feel free to post up a pic / link to what you’d like and I’ll see if it’s within the scope of the machine and / or operator.

Have a look on Thingiverse.com as a huge number of parts have already been modelled and uploaded for open source use.

 

[Hammock_man]

I am thinking of a small box to hold a magnesium rod, a ferro rod and a small blade ( with tinder in the voids). 12cm square maybe 3cm deep. Have made 3D models for games so should be able to knock one up.

 

[spandit]

I can potentially make stuff to order although I'd have to make sure I've paid to do so on this site. I print in PETG because it's stronger than PLA and doesn't suffer from the fumes and warping that ABS does (ABS does have an advantage where you can polish the surface by leaving it in a jar with some acetone vapour). As others have said, bung up a sketch of what you're after to see how feasible it is.

 

[Stew]

Thanks chaps. I may be in touch.

Chris, it's nothing exciting, just the usual adjustable spanner, eggcup, drink cup, cuff links, etc - not!
It's actually other surfboard bits and jigs but I've done some looking since and think some may actually be available at a sensible cost without needing to do any design work. I need to pin down what will work for what I need.

 

[Hammock_man]

Please see below my idea for a 12cm tall stand for a fire steel. The idea being the steel rests on the back stand, the tinder is in the bowl area and it can be lit without it being knocked all over the place. Could be made more complex to use less material i.e. cut out holes



the 3 other "IMG" links dont work as I had problems !!

 

[spandit]

Think I understand - you hold it with the firesteel in place and it stops the tinder from blowing away? You are aware plastic is flammable?

I've had a go at modelling this - normally I'd dial the setting up that makes for smooth curves but having it faceted looks quite cool, actually.

 

[Hammock_man]

You are aware plastic is flammable?

Was thinking the device would be removed some 5 sec's after the tinder has caught, or even that the pile of magnesium would be big enough to have a spark dropped on from height.