3D Printed Parts

Hi,

With the prices of 3D printers dropping price over the years I decided to get one. Of the many items you can make with these I was hoping to make replacement plastic parts for models.

I've been using my Hudson MK2 Sten as a testbead to see the durability of printed ABS plastic compared to injection moulded ABS.

The first step was to attach a bolt face to the original metal one and dry fire some carts, which stood up to 50 cycles without noticeable damage.

Test two was a fully printed bolt.... this one suffered from damage to the feed lips which is possibly down to poor layer adhesion.

I'm still learning how to use this new toy and I'll post updates as the project progresses.

Plastic frontend

Which 3D printer did you get ?

its looking promising this, even if they break you just print off another, which sounds good to me, nice work on that bolt by the way

I got a "flying bear" from aliexpress. It's a kit which you have to assemble and I've made a few modifications, but for £250 shipped to the uk it's a bargain.

8ace

8ace wrote:

I got a "flying bear" from aliexpress. It's a kit which you have to assemble and I've made a few modifications, but for £250 shipped to the uk it's a bargain.

8ace

Thanks I will have a look !

That printed bolt looks amazing - just like a factory replacement part!!!

How exciting to think of the possibilities for parts.

how long to print a bolt though ?

The print times are slow and depending on your settings they can take many hours, one thing to consider when making large parts. I'm working on a non-modelgun part which I've had to split into x6 sections as the overall print time is 50-60 hours.

The bolt took 6 hours to print on a course layer setting which is why I think I've got delamination of the layers. There's a trade off between speed and quality and that's something I'm looking into.

I wasn't sure if the stressed parts can be made this way but the early trials look hopeful and they are developing new plastic filaments with different characteristics so there should be one that works.

8ace

Just a quick update.

I cut the broken bolt face off and reattached the original one I printed which seemed to work for about 30 carts before the feed lips disintegrated all at once

Also looking at the section the cocking handle went through had broken.

I'll be looking to reprint with a few changes to the print setting and also material.

Hello mate!

Thank you for the update. Well, of course this is a setback. But I am sure there may be solutions or improvements in the future.

Merry Christmas to you! Enjoy the holidays.

Well the different printing strategy didn't work, but as they say a negative result is still a result.

Damn! i had real hopes for 3d printing, is it possible to put a metal insert in to strengthen the feed lips, as has been done on marushin mp40 bolts?

Yes it’s disappointing, but it was always going to be an issue. And to be fair I’m asking a lot as the feed lip design is very thin, but if I can get it to work on this then other models will be great.

A metal insert is possible Plan B but I’d like to get to a stage where other members could print out replacement parts without messing around with adding bits, we could even have a design repository section on the forum

The trials continue..........

8ace

Actually its not as bad as it could be, i had a worry that the whole bolt would disintegrate after a few impacts on the chamber. truth is a lot of the original plastic bolts mash the feed lips so its always been a problem.
A design repository sounds great and 3d printing has got to get better and better i would of thought so i still think its the way to go.

I just wanted to say thanks for sharing your ideas and efforts. With a little bit of luck (and lot's of hard work) I think you might be able to provide a solution for the repair or replacement of otherwise impossible to obtain model gun parts. The 3D printing is very neat! The photos serve to indicate how precise the 3D printing process can be.

As an aging boomer, I attempted to employ medieval technology when trying to replace a broken Hudson M1A1 Thompson fire mode selector. Originally, I tried pouring a hot liquified concoction of aluminum washers, lead fishing weights, and soft metal roofing nails into a half dozen plaster molds all taken from the broken piece. It was a bad idea!!!

When I broached the subject of creating a wax impression and perhaps using silver as the casting material, a silversmith suggested that I save my money.

A friend was kind enough to to provide a replacement.

Your efforts are much appreciated! Take care.

Stupid question but do you need to modelize (3D) the part before printing it ?

Sadly yes the design has to be put into a CAD program which can be tricky depending on how complex the part is. Then it's transfered to a "slicer" program which outputs a file the printer can use.

8ace

Yes and no.

Yes, you need a 3D description of the part that a printer can understand and translate to operating instructions. Typically printers use "STL" format for such a description file (see below). This requires 3D modelling:
https://all3dp.com/what-is-stl-file-format-extension-3d-printing/

No, because if you check out a project page in a repository (such as the one below), you can see that projects come with such a file. It can be downloaded and sent to a printer for printing without requiring you to understand anything about 3D modelling, unless you want to modify the design.
https://www.thingiverse.com/

I suspect that in future we might see more use of 3D scanners to create simple models of items where high precision is not required (more artistic than engineering). There is a lot of ideas going around in connection with 3D printing:
http://makezine.com/2015/01/15/5-diy-3d-scanners-to-watch/