Material Creep and better Material Choice?


I’ve been using Grey V3/4 for a bunch of parts in my 1:16 E-100 Project - most notably in the Tracks and Running Gear - and have recently come to the point where the model would finally stand on its own wheels…

…which it has now been doing for the past few days until I continued working on it when I noticed the wheels being at an angle which at first, I assumed being caused by the slop in the wheels slightly oversized bearing pockets ( which I plan to shim using masking tape ) but then realized it actually being caused by the Swing Arms having experienced creep:

( The above picture is just as a reference to explain how they’re installed )

Picture showing the ever so slight misalignment between the Axle of the Swing Arm and the Wheel / Suspension Block:

( the Grid on the Cutting Mat is a 10x10mm one. The Wheel and Swing Arm Axles are 5mm Diameter and the Suspension Block Axle is 4mm )

CAD Cross-section:

I’d be lying if I weren’t hoping for the 3D printed Swing Arms to have worked out like that but obviously them experiencing such creeping in just a few days won’t cut it for the long term which brings me to my questions:

  1. Will such creep continue for as long as stress ( the weight of the model ) is applied to the parts or will it stop at some point? Would modelling and 3D printing the part with a negative creep angle be of any aid?
  2. What Formlabs Material would have been the better choice for the task?

Truth to be told the 2nd question is kinda superficial for the E-100 Project as I’ll now be aiming for them to be cast in Pewter to be on the safe side since the model doesn’t even have its final weight from a Battery and Gearboxes but ya never know if such knowledge may come in handy at a later time :grin:

Hey @Durahl ,

I always love seeing your printed tanks! Although I have very little personal experience with FDM 3D printing and can’t recommend much for your first question, I can say that Grey Pro is probably one of the best SLA materials to use for high precision and low creep over time. I hope that this ends up being helpful if you do not go the way of pewter swing arms. Take care!

Glad you like the model :grin:

My first question was actually still referencing the use of SLA 3D Printing in particular with the use of Formlabs Grey V4 I happened to have at hand - Mostly because at the size of the Swing Arms I’d most likely be facing even more of a structural integrity issue due to the laminated nature of an FDM Print unless I printed them with like 95-100% Infill followed by remelting them in an oven while packed in Salt - Mhh… Poor man’s Injection Molding? :thinking:

As for my plan to go with pewter instead SLA ( or FDM ) 3D Printing that is kinda set in stone… But if it is of any comfort to you, I’ll still be using Formlabs SLA 3D printing for making the Master required for the High Temperature Silicone Mould making process to cast the parts into :grin::ok_hand:

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Hey @Durahl,

I’ll do my best to not feel abandoned :rofl:

I will be honest that I don’t really have much experience with your DIY injection molding, but it does sound like an intriguing idea. I personally had almost no FDM experience before jumping into the world of SLA printing, but am always fascinated by use-case applications like this!

I hope some other users on the forums have some more helpful suggestions for you!

How are you post-curing your printed parts? Prints are still very “plastic” without a thorough post-cure. I see no mention of curing… parts are going to be mighty bendy if you didn’t complete the post-print cure completely.

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