Jump to content
Saito2

Where is 3D printing at strength-wise?

Recommended Posts

I'll be honest, I never bothered looking into 3D printing because of its apparent lack of strength and the crudeness I saw from some the earliest/cheapest "prints". It sounded like at dream when I first heard about it but didn't seem to live up to my needs as an RC enthusiast. I kept tabs on the technology for awhile, asking about how it was coming along. The home printers were getting better and more affordable. When it came to questions about durability, the answer was always: "its not quite there yet". I honestly stopped asking and looked into getting mill and lathe since I was familiar with them from work and there wouldn't be a learning curve with the design software as I am an idiot with computers. Will 3D printing ever reach a point where it is suitable for RC parts subject to the usual wear and impact stresses involved?

  • Like 1

Share this post


Link to post
Share on other sites

It's come a looong way.  I have been using 3D printing at work for just about 10 years now.  We started with the powder/glue printers and they were just awful.  Currently using an FDM printer with various materials and I use them a lot for RC purposes.  I actually use them more for functional products than aesthetic as you still need to do a lot of finishing to get them paint-ready, even when printed in high resolution.  My father has a small home printer and that works great also.  Parts he prints out of nylon are especially tough, we use them all the time on our crawlers.  Long story short, definitely look into it as it's come a long way.  

  • Like 2

Share this post


Link to post
Share on other sites

Shapeways printing service is even better!

(Meaning you could download these and have shapeways print them)

 

 

  • Like 2

Share this post


Link to post
Share on other sites

Yes and it reached that point of strength at least 5 years ago. But like all things, deep pockets are going to be needed for the high end setups like markforged and any kind of laser sintering. 

Homebrew setups of printing with carbon fibre impregnated ABS/nylon, regular nylon are way more common now although they aren't turnkey and will require experimentation and tweaking. 

I do fine with high infill to solid ABS and HIPs ATM but for anything that sees real abuse or needs strength I'd spring for nylon or markforged parts. 

As an additional point, how the part is designed is way more important than material. Reduce stress risers, think about part orientation so the layers work with you.

  • Like 4

Share this post


Link to post
Share on other sites

I think 3D printing by it’s nature will probably always be somewhat limited, to get into useful region of mechanical properties the home brew kits need to switch to SLS, which will probably happen at some point, look at materials like windform xt, it surpasses ABS in many ways and would be a reasonable swap for function. SLS Aluminium has come on giant leaps in recent years and being able to form hollow or matrix structures and aluminium skinned foams will present yet another giant leap in functionality. Some years back industry predicted roadside repair vehicles would rock up and simply print any parts required using multi metal SLS, of course.. they were a little off... I think by the time parts can be made to std. and not require excessive post finishing, we’ll all be in electric vehicles and the actual number of mechanical parts that can be replaced will be largely diminished or have taken another huge leap in complexity...

 

  • Like 3

Share this post


Link to post
Share on other sites
1 hour ago, Hobgoblin said:

As an additional point, how the part is designed is way more important than material. Reduce stress risers, think about part orientation so the layers work with you.

I’ve worked with a lot of parts either FEA optimised (material automatically removed from a designed NET to achieve target deflection/stress) or almost entirely grown between elements to perform a function. Both produce some really interesting results,  but currently, being brutally honest, when you see these parts sintered and actually used they are mostly to show off technology, with the exception of parts which require internal hollow and blind structure you can normally get a cheaper part out of using the results as inspiration and doing manual design. Lead time for casting, cost and material properties still outstrip those of sintered parts in the light weight category. Big fan of the Nickel based parts though apart from cost the quality and achieved properties of these is awesome. The term RP (rapid prototype) has become a bit of a joke.. since all the main suppliers of SLA/SLS would struggle to out perform a decent machine shop or investment caster for speed. Would still apply at home though, the only thing I can make in a hurry is a mess :)

 

 

  • Like 3

Share this post


Link to post
Share on other sites

FEA optimisation and generative design is an awesome party trick, and I've seen it work wonders (although not on printed parts, and certainly not on a budget) But I agree it sort of falls short of practicality.  To be fair I'm not overly sold on SLS for pure mechanical strength. Definitely not at the consumer level. 

I refer to more traditional design practices that are just common sense, like avoid sharp corners, don't have forces wanting to split your part directed along your print layers etc. 

  • Like 1

Share this post


Link to post
Share on other sites
19 minutes ago, Hobgoblin said:

I refer to more traditional design practices that are just common sense, like avoid sharp corners, don't have forces wanting to split your part directed along your print layers etc. 

Our colleagues in the mothership back in Germany did a weight saving exercise on one of our block castings, in their wisdom they reduced all the fillet sizes and even cut half the height off the crank caps, when they delivered the first off we unsurprisingly were able to sharpie all the crack here points before it was even built, and also unsurprisingly parts of the crank assy escaped and did some rather destructive laps of the Dyno. It should never have made it to build, but I guess we had to prove a point and ultimately it saved our jobs.. I think my job is safe now, but it wont be long before people that design things are replaced by people who can tell a computer to design things... 

  • Like 1
  • Sad 1

Share this post


Link to post
Share on other sites
42 minutes ago, Lee76 said:

Our colleagues in the mothership back in Germany did a weight saving exercise on one of our block castings, in their wisdom they reduced all the fillet sizes and even cut half the height off the crank caps, when they delivered the first off we unsurprisingly were able to sharpie all the crack here points before it was even built, and also unsurprisingly parts of the crank assy escaped and did some rather destructive laps of the Dyno. It should never have made it to build, but I guess we had to prove a point and ultimately it saved our jobs.. I think my job is safe now, but it wont be long before people that design things are replaced by people who can tell a computer to design things..

I've been in this situation before. Going through a time-wasting exercise to verify a design is flawed and should have been scrapped before it reached the prototype stage, usually pushed by those in managerial power or bean counters rather than actual designers or machinist with first hand knowledge and experience. Ego gets in the way of logic. Instead of getting the gratification of the "I told you so" moment though, I wind up feeling disgusted by the waste of time and resources and in some cases worse, production time.

  • Like 1

Share this post


Link to post
Share on other sites
1 minute ago, Saito2 said:

Ego gets in the way of logic

This was definitely the case, the crux of it is that a German company was badging something designed and built overseas and wanted to bring it all home. I can kind of see why they would want this but at the same time, they couldn’t admit they didn’t have the skills and were doing it anyway.. it took them 2 years to finally realise it would be better to leave us alone than it would be to replicate what we do.. It makes me laugh each time you see a TV or film reference talk about Germany’s reputation for brilliant and reliable engineering, or Honda for efficiency and even the negative ones for poor quality manufacture in the Far East, the reality is a German brand engineering product could well have been designed in the UK, the Honda in the US and both are probably being mass produced in the Far East... 

  • Like 1

Share this post


Link to post
Share on other sites

I have a cheap small printer and I'm pretty impressed with the strength of the parts I'm able to print with it even using only PLA. I wouldn't use it on a hardcore basher but for normal fun running I see it being perfectly fine. My biggest concern would be threads pulling out, but if you can put a nut on the other side I think it would be pretty decent.

  • Like 2

Share this post


Link to post
Share on other sites
1 hour ago, Lee76 said:

Our colleagues in the mothership back in Germany did a weight saving exercise on one of our block castings, in their wisdom they reduced all the fillet sizes and even cut half the height off the crank caps, when they delivered the first off we unsurprisingly were able to sharpie all the crack here points before it was even built, and also unsurprisingly parts of the crank assy escaped and did some rather destructive laps of the Dyno. It should never have made it to build, but I guess we had to prove a point and ultimately it saved our jobs.. I think my job is safe now, but it wont be long before people that design things are replaced by people who can tell a computer to design things... 

Part of my toolmaking career was dealing with the computer design. As a team of 8 we would point out the issues on paper and put our redesign to management before the computer issue became an issue.  It started as a rare occurrence but became more the norm when the old skool engineers were being replaced with the click on screen engineers. 
Passed down engineering techniques are being lost to the cad generation who have no idea at even a cut speed and feed let alone how to hold the item to machine accordingly.   

  • Like 2

Share this post


Link to post
Share on other sites
4 minutes ago, Toolmaker72 said:

Passed down engineering techniques are being lost to the cad generation who have no idea at even a cut speed and feed let alone how to hold the item to machine accordingly.

I've been here too on the operator side. I'm no engineer, but I know the importance of feed rate and chip load. Some programmers with no regard for either don't do wonders for tool life. Its no fun watching parts fly off a spoil board/vacuum table when there's no thought given to part size or start/end points.

Share this post


Link to post
Share on other sites
2 minutes ago, Toolmaker72 said:

Passed down engineering techniques are being lost to the cad generation who have no idea at even a cut speed and feed let alone how to hold the item to machine accordingly.  

I think I’m in the bridge period of this, as a graduate, I had little understanding of manufacturing and no CAD experience, so when releasing designs I’d spend the time talking to the machinists, programmers and assembly technicians so would rarely get any surprise phone calls (except for the odd missing dimension...) I also had the benefit of an office mate who didn’t go to uni, started as an apprentice in the machine shop so his and my skills and experience were from totally different ends of the spectrum and we complimented each other well. I find now, the new graduates are academically superior, straight A, 1st class honours etc.. but the selection process somehow always picks the really over confident ones who are very arrogant, they wouldn’t talk to the builders or machinists and only talk to the experienced engineers when they need digging out a hole.. You could say, they have to eat more humble pie than those naturally more humble :) 

Share this post


Link to post
Share on other sites

I’m not an expert, but the kids and I have really enjoyed learning about CAD and 3D printing this last year or so since we bought our printer. It’s really got them into design and creativity, and we’ve built and fixed lots of cool things. 
 

I couldn’t justify a high end unit, but ours does print ABS which is a bit stronger and less brittle than PLA. You can engineer extra strength in the design phase and also in the printing (infill structure). The key is trial and error, but you can move from design to prototype quickly so this is half the fun.  
 

it’s been really useful on a few projects -

 

  • Like 1

Share this post


Link to post
Share on other sites
39 minutes ago, Lee76 said:

I think I’m in the bridge period of this, as a graduate, I had little understanding of manufacturing and no CAD experience, so when releasing designs I’d spend the time talking to the machinists, programmers and assembly technicians so would rarely get any surprise phone calls (except for the odd missing dimension...) I also had the benefit of an office mate who didn’t go to uni, started as an apprentice in the machine shop so his and my skills and experience were from totally different ends of the spectrum and we complimented each other well. I find now, the new graduates are academically superior, straight A, 1st class honours etc.. but the selection process somehow always picks the really over confident ones who are very arrogant, they wouldn’t talk to the builders or machinists and only talk to the experienced engineers when they need digging out a hole.. You could say, they have to eat more humble pie than those naturally more humble :) 

Yes, exactly. Engineering demands many different skills.  Talking possible new processes with all involved does give a superior result.  Being a Toolmaker I’ve been a go between either engineer designers or machinists.  Missed dimensions are the norm.  Putting ridiculous tight tolerances on dimensions that simply are a waste of time then told oh the computer did that by default equals bad engineer.  Unfortunately my toolmaker career has ended with redundancy after 31 years with Ford Motor Company.    Manufacturers just seem to need cnc operators.  

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...