3D Printing 924 & 944 Parts - Development and Discussion
#153
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Thread Starter
Printed the coupler using three different materials, ABS plus two others I've never had the chance to try.
From left to right: OE coupler, ABS print, N-Gen co-polyester, Polycarbonate ABS
The N-Gen (blue) produced a VERY attractive print. Excellent surface finish, feels glossy and premium. Easy to print, and no post processing required.
The PC-ABS felt a bit heavier than the ABS print.
The actual loads these will see from the shifter are quite low.
I decided to do some destructive testing using torsion. The bolt permanently deformed before the coupling failed.
ABS split between layers. I was really quite surprised how much force it took before this happened. Not a catastrophic failure either - this would probably still function if re-installed in the linkage, although, with more play than before.
The N-Gen co-polyester failed almost immediately under minimal load. ABS left showing failure between layers vs N-Gen shattering across layers.
Brittle failure, it essentially shattered and crumbled in my hands. I will not be using this material for any load bearing parts. I included this shot because it shows the 2mm shell thickness with 20% infill.
PC-ABS failed in a similar fashion to ABS, but took quite a bit more force before it did.
It took considerable force with leverage to break the ABS and PC-ABS printed couplings. PC-ABS is a bit pricey vs ABS, and I don't think the results from this test warrant the higher cost for this item.
We'll use ABS going forward. I'm going to print at least two more samples, increasing shell thickness and/or fill density. I want the final result to feel as good as the OE part.
From left to right: OE coupler, ABS print, N-Gen co-polyester, Polycarbonate ABS
The N-Gen (blue) produced a VERY attractive print. Excellent surface finish, feels glossy and premium. Easy to print, and no post processing required.
The PC-ABS felt a bit heavier than the ABS print.
The actual loads these will see from the shifter are quite low.
I decided to do some destructive testing using torsion. The bolt permanently deformed before the coupling failed.
ABS split between layers. I was really quite surprised how much force it took before this happened. Not a catastrophic failure either - this would probably still function if re-installed in the linkage, although, with more play than before.
The N-Gen co-polyester failed almost immediately under minimal load. ABS left showing failure between layers vs N-Gen shattering across layers.
Brittle failure, it essentially shattered and crumbled in my hands. I will not be using this material for any load bearing parts. I included this shot because it shows the 2mm shell thickness with 20% infill.
PC-ABS failed in a similar fashion to ABS, but took quite a bit more force before it did.
It took considerable force with leverage to break the ABS and PC-ABS printed couplings. PC-ABS is a bit pricey vs ABS, and I don't think the results from this test warrant the higher cost for this item.
We'll use ABS going forward. I'm going to print at least two more samples, increasing shell thickness and/or fill density. I want the final result to feel as good as the OE part.
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jjbunn (10-06-2019)
#154
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#155
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Have you considered freezing the ABS then seeing how it performs under load?
While not many cars will be driven in freezing weather, this could offer meaningful information given this application is under load and would be exposed (in theory) to colder temperatures.
While not many cars will be driven in freezing weather, this could offer meaningful information given this application is under load and would be exposed (in theory) to colder temperatures.
#156
Pro
Thread Starter
Have you considered freezing the ABS then seeing how it performs under load?
While not many cars will be driven in freezing weather, this could offer meaningful information given this application is under load and would be exposed (in theory) to colder temperatures.
While not many cars will be driven in freezing weather, this could offer meaningful information given this application is under load and would be exposed (in theory) to colder temperatures.
#157
Rennlist Member
I've been chatting with KVDR about producing a DIY linkage rebuild kit that would utilize these printed couplers along with roller bearings and new hardware. Is there any interest, in the $40-50 price region? The aftermarket SSK linkages are another solution but are a little more expensive and these retain an OEM throw.
#160
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I've been chatting with KVDR about producing a DIY linkage rebuild kit that would utilize these printed couplers along with roller bearings and new hardware. Is there any interest, in the $40-50 price region? The aftermarket SSK linkages are another solution but are a little more expensive and these retain an OEM throw.
#161
Pro
Thread Starter
The destructive testing shown above was extreme and used torsional forces that would be impossible to recreate using the shifter in the car, and the couplings destroyed were printed with a really low infill at 20% (shown below)
A higher infill % will greatly increase part strength for long term durability.
More to follow...
A higher infill % will greatly increase part strength for long term durability.
More to follow...
#162
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The destructive testing shown above was extreme and used torsional forces that would be impossible to recreate using the shifter in the car, and the couplings destroyed were printed with a really low infill at 20% (shown below)
A higher infill % will greatly increase part strength for long term durability.
More to follow...
A higher infill % will greatly increase part strength for long term durability.
More to follow...
#163
Pro
Thread Starter
20% was good enough to get dimensions dialed in and compare the strengths of three different materials.
Here's an ABS print that stopped last night for no good reason. G-Code error?
Anyway, this is 80% infill and 3mm shell. It is perfectly tight with the shifter linkages. I think 2mm shell will be better.
I am printing a final version for Odonnell now.
Here's an ABS print that stopped last night for no good reason. G-Code error?
Anyway, this is 80% infill and 3mm shell. It is perfectly tight with the shifter linkages. I think 2mm shell will be better.
I am printing a final version for Odonnell now.