Metall FFF for printing a wood building screw

[toemmes 0]

Hello everyone! I´m new to this channel because I´m searching for someone with experience in metall FFF and its capabilities. I read a few things about it, but I´m not sure if it is possible to print a metall wood building screw. The steer angles and the point tip seem a little bit tricky to debind and sinter. The screw should be M8 x 80 mm.

 

[gr5 2,265]

So my understanding is that there is a special support material that goes with FFF metal printing. So you can do overhangs (the threads) just fine.  The point obviously can only be as sharp as the nozzle radius (typically 0.2 or .3mm) if you print on it's side or vertically.  So either way the point will be like 0.4mm in diameter but it will be sharper if you print the screw on it's side and flat 0.4mm if you print it vertically.

 

@SteveCox3D is an expert (well at least he knows MUCH more than I do).  Maybe he can respond.  I believe Steve has customers who save both money and time using FFF metal.  Significant amounts of both (even companies with their own metal shop can have a multi month backlog).

 

I think some customers make pretty boring things like brackets to replace a broken part in a factory and others print really amazing things like generative design (think computer AI designed) parts that can't be made any other way.

 

If Steve doesn't reply, PM him with more questions and if he still doesn't reply, PM me and I'll give him a nudge as we are in the same chat group.

[SteveCox3D 87]

21 hours ago, toemmes said:

Hello everyone! I´m new to this channel because I´m searching for someone with experience in metall FFF and its capabilities. I read a few things about it, but I´m not sure if it is possible to print a metall wood building screw. The steer angles and the point tip seem a little bit tricky to debind and sinter. The screw should be M8 x 80 mm.

 

Hi there @toemmes, as @gr5 says I've hot lots of experience with Metal FFF.  As far as printing threads go, it can work really well as I showed in this post on LinkedIn 

 

The key thing here is whether the thread is large enough size and has enough definition when sliced to print out nicely. The part gets scaled up automatically in Cura 5.1 when you select the metal materials to account for the shrinkage that occurs when the printed part goes through debind and sintering.  That means that the part grows by 19% in X/Y and 25% in Z, so you can only get an impression of how the part will turn out by looking at the Preview of the slice where these scaling factors are applied,  

 

The thread angle on the picture suggests that no support would be required for this part and maybe at an M8 size the thread definition would be ok.

 

It's not just about the 3D printing though, you have to consider the post-processing and the stability of the part when it goes through the final stages of sintering at around 1300-1400°C. The stability of the part and ability to support it's own weight is crucial here.  This is a part that you would normally print upright but it is quite tall in relation to it's footprint, so may be unstable and fail at that point. There are stress analysis tests that you can run to carry out a virtual simulation of whether the part will survive which is something I covered here.  The screw is also quite tall, and that also affects the costs associated with debind and sintering because of the way the cost is calculated for that processing.

 

As a general rule of thumb Metal FFF works best with parts that can fit in the palm of your hand and have a Z height up to 50mm with a good size footprint for stability (25mm or less in Z is even better).

 

There is lots to know to be effective in taking advantage of this process of making metal parts, which is why I shared some of my insights in a series on LinkedIn which you can find by searching on #MetalThursdays

 

Let me know if you have further questions, I'm happy to help.     

Edited November 29, 2022 by SteveCox3D

[toemmes 0]

@gr5 & @SteveCox3D thank you for your time and your answers.

 

In my experience it is better to print wood building screws in horizontal position. (I only have experience with non metall filaments) Then the flanks of the thread are better and the overall quality is better. When I want to print it horizontally I need BASF Forward AM Ultrafuse® Support Layer right? When I print it in that position I can make it in a the size of a palm and only a z-hight of 20 mm. Could this be a solution for the problems in the sintering process?

 

For the size I chose M8 because I thought it would be easier to print. What do you think is the smallest thread size which could be printed accurate? 

 

Another topic is the air manager – I read different opinions on this: Some say it is necessary, because of the heat control – other say it is good without it. I´m just not sure if it is smart to buy it before I know that it is possible to print the parts I need with metal FFF.  

 

Thank you in advance for your time and expertise.

[SteveCox3D 87]

No problem @toemmes, we're here to help.

 

I too have 3D printed polymer bolts in the horizontal orientation to achieve better strength.  One thing that I have tested with that orientation is flattening the thread where it contacts the support to provide a better first layer on top of the support material, rather than just lots of small extrusion at the tip of the threads.  With a threaded bolt I had a good result with this, it gave a more efficient print with no significant loss of performance of the threadform.

 

I'm not sure how applicable this would be to a woodscrew though, so I have experimented to show you what I mean and the difference it creates when slicing.  In the image where the screw is normal you can see the small areas of red extrusion in the first layer of the thread printed on the support structure. There is also a lot of small areas of support layer material also being printed.  In the other sliced image where the thread has been flattened you can see a much better first layer being put on top of the support layer material, and the support layer on top of the support structure is also much better because it is a continuous layer, rather than a lot of small individual areas.

 

I'd be happy to share the slice files for these if it helps......

 

I think that threads around the 6-8mm area are the smallest that would work successfully using a 0.4mm nozzle, I think it could go smaller with a smaller nozzle but the CC0.4 is currently the smallest nozzle that you can use with the metal filaments.      

 

I would always recommend the Air Manager for use when printing with these materials. It does keep the print area more stable and the added air filtration that you get is a good thing too.  

 

Edited November 30, 2022 by SteveCox3D
Air Manager comment added..

[gr5 2,265]

Steve it looks like you modified that screw before slicing it?  To have a flattened side.  Very interesting!  Or is that just a cut-away view?

[SteveCox3D 87]

31 minutes ago, gr5 said:

Steve it looks like you modified that screw before slicing it?  To have a flattened side.  Very interesting!  Or is that just a cut-away view?

@gr5 I flattened it in CAD to provide the flat face to interface with the support when it's sliced. 

[geert_2 558]

If you print them for real use, and not for demo-purposes: aren't they too brittle to screw into wood?

 

I even occasionally snapped standard bolts and screws, before I began to use copper grease on metals, or a drop of oil on woods for lubrication and thread cooling.

 

[SteveCox3D 87]

@geert_2 The parts end up at 96-98% dense after sintering (providing there's no defect in the printing). 

 

I've not found these parts to be brittle, they seem to me to behave the same as if they've been made in any other way.  That's not to say they won't break if they're over-stressed, in the same way that you can snap a standard fixing if it sees too much torque through it.

[geert_2 558]

7 hours ago, SteveCox3D said:

@geert_2 The parts end up at 96-98% dense after sintering (providing there's no defect in the printing). 

 

I've not found these parts to be brittle, they seem to me to behave the same as if they've been made in any other way.  That's not to say they won't break if they're over-stressed, in the same way that you can snap a standard fixing if it sees too much torque through it.

Wow, 96-98% is pretty good. Thanks for the info. You know, in the back of my head, I still had the idea that 3D-printed metal parts were rather like sugar cubes for the coffee, sort of, but then in metal...  🙂