[Closed] Would you use a 3D printed stem?

Shirly considering only the stem is the old fashioned approach? 3D printing gives the ability to think it terms of overall function and not assemblies of easy to manufacture parts. That has already been said but in this case wouldn't the 'future' be a combined bars and stem part which is uniquely fitted and shaped to each rider? 🙂

ahwiles - Member
i hope that when someone does try 3d printing a Ti stem, they remember to hip it...

Hiping a Stem would make very little difference due to the wall thickness; it would likely make it worse.

hexhamstu - Member
Daffy, where are you purchasing your ti powder from? we are paying more like £450/kg

LPW is one, but the quality can vary, so you need to have it independently verified. Sandvic, Alcoa, etc. Chinese powder can be had for as little as €95/k...but you get what you pay for...to a point.

A question for those that do -- @Daffy etc. How much annealing is needed on these made-from-powdered-metal 3D printed components? I would have thought quite a lot. Does the time and space within which to do that have a big effect on the total production costs?

We use a stress relieving heat treatment on the laser parts which require it, but no other heat treatment as standard for Ti parts. We do several types of heat treatment of Al and INCo. For larger parts (walls thicker than 3mm) we do tend to HIP the part to close any porosity which may be detrimental to performance. HIP of a single part in a bespoke cycle can be pricy, but cost per part in a packed cycle is vew low 10s>100s of €, nothing more.

We maintain our own heat treatment ovens (they're cheap to buy, maintain and certify), but use external for HIP due to the NADCAP certification requirements.

Thanks Daffy, interesting.

I suppose the worry with cheap 3D printed stuff (if/when it happens) would be whether the manufacturer skimpled on the heat-treatment. Much like you might not completely trust the lay-up inside cheap carbon frames.

Cost-wise, the overall process doesn't sound like it ought to be wildly different from machined metsl, if it was done on a mass-production basis.

@hexamstu metalysis in Sheffield speak to them you may be pleasantly surprised

Go big or go home

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Daffy - Member

Hiping a Stem would make very little difference due to the wall thickness; it would likely make it worse.

so [i]not[/i] hip-ing would be the safer option? - yikes!

HIP closes internal pores, but opens pores close to the surfaces, creating a greater notch-fatigue effect...not what you want on a stem. You'd be better laser polishing and then peening the surface on a thin walled structure.

Thread is delivering.

deanfbm - Member

Thread is delivering.

Daffy - Member
You'd be better laser polishing and then peening the surface on a thin walled structure.

interesting, thanks.

(how much does that cost? and can you do it to internal surfaces?)

ahwiles - Member
interesting, thanks.

(how much does that cost? and can you do it to internal surfaces?)

MUCH more difficult on internal surfaces, but if light can enter and be projected to the surface at an angle less than 45 degrees to the surface...yes.

For internal surfaces, you'd be better with a chemietch or plasma based approach, especially on a complex surface such as the geodesic stems above.

The 3D stem above is a classic case of being designed rather than engineered.

Why is every structural intersection a sharp point on a part which is subject to fatigue loads and torsion? "Because it looks ace..."

*got meself a new mancrush*

Always thought the most obvious and beneficial area 3D printing could become prolific would be medical prosthetics and the like.

Can only imagine the weight savings for aeronautical applications will usher in some very interesting/different/innovative designs in the future.

What about [url= http://pencerw.com/feed/2017/6/12/stem-prints ]this one[/url]?

[img] [/img]

The problem with both the stem (which is gorgeous) and the approach in Abaqus (via ntopology) is that [b]you're[/b] giving it mechanical properties from billet material. The problem is that when you get to really fine structures(<1mm), especially in AM/3DP, the mechanical properties may be as little as 10% of what you believe they are.

For that one, I'd really like to see it physically tested to see if it matches the computational predicted behaviour.

As there is an expert here, what would the expected cost be for printing a custom watch bezel?

And are there places offering this service?

Are you wanting a bezel designed and printed or have you already designed it?

If your serious of printing stem i've got a conservitive/ traditional model of a 50mm stem I printed in plastic.
Done a bit of designing parts for printing on my bike project and design as always seems to be a key point, the process & function still dictates design to a point.

Couple of questions.
1) in all these hollow designs how is the powder removed from the middle/ cavity? I assume a hole is left some where.

2) how do you get a job doing 3d printing/ design and validation. It's something i'd seriously consider moving to.

Couple of questions.
1) in all these hollow designs how is the powder removed from the middle/ cavity? I assume a hole is left some where.

Correct.

2) how do you get a job doing 3d printing/ design and validation. It's something i'd seriously consider moving to.

It depends upon which aspect you want to get into.
A manufacturing/mechanical engineering background for operations, mechanical engineering/numerical Methods for analysis and design,
material Science for materials. There are quite a few aspect/roles.

Would I buy one? Not how they look now - I can't think I'd ever get one clean. Until they can come out nice and shiny and polished like my CNC'd & anodised alloy version I'm not going near it. At 106g I don't see there's much to lose from my Renthal stem - certainly not on a cost/reward basis anyway.

the range of STW experts on this thread is amazing.

[i]the range of STW experts on this thread is amazing. [/i]

I'm glad I asked about this now 🙂

Are you wanting a bezel designed and printed or have you already designed it?

I have 3d files from a 6th generation prototype. Which is a little meaningless to me tbh.

[video]

3D printing definitely has its uses. We have complex templates made at work that perfectly car bodywork contour's.

We have been using 3D printed exhaust manifolds on turbo engined race car for a while now, they are running around 1000 degrees and making a lot of power