Hello Every One,
I am printing a gearset with black V2 and although the details is perfect, the gears are too brittle (glass like shattering) and so I am looking to buy another resin.
Evidently, I was looking to the Tough resin and this video (Formlabs Material Stress Test ♦ Tough resin vs Standard resin ♦ SLA 3D printer resins - YouTube) alost convinced me, but then I saw this graph:
and I thought perhaps Durable was the way to go, although I have not seen a comparable video with the Durable resin.
This gearset is going to be used in a product as a lens focus adjuster so the utmost important charasteristic must be its life expectancy.
Any thoughts on the best material for gears?
Thanks a lot
I’d think Tensile strength would be the characteristic you’d want for gears. But I’m not sure any resin will give you a particularly long life expectancy. Even fully cured, I doubt any of the resins are particularly wear-resistant. I print with Tough mostly and it’s not (friction with another printed part results in a white powdery surface. Unless you design the gears with a preload to keep them meshed, they might loosen up pretty quick.
You’re not going to get the lifespan you’d expect from nylon gears or even ABS. How long are you thinking? 100s of cycles or 1000s of cycles?
I honestly like the tough resins and would start there for gears. It’s a good compromise between hardness and flexibility.
Smaller teeth like 48p (0.6m) will really be pushing the limits of both the materials and the machine. I have printed gears this small before but they’re pretty weak and can come apart at high speeds.
Is this an external gear for a cinema lens focus or something internal to the lens? Small fine tooth internal gears won’t be very durable with pretty much any printed material. I would invest in the stuff to cast them in a printed mold (pressure casting in polyurethane).
I have to agree with @FredB, these are prototyping materials and just don’t have the same properties as traditional casting or machining materials. They are great at discovering immediate geometry questions but not adequate for stress/strain comparisons.
@FredB this is for the external lens, an “add-on” to te manual focus.
Has anyone tried printing gears with durable resin?
This is not a high load/high speed application so maybe there is no need for the Tough hardness.
I haven’t printed a gear in durable yet but I don’t see why it wouldn’t work. If the teeth are as big as the external focus gears I’ve seen durable should work fine.
If it’s a reasonably small part I can print it in durable to see how it turns out.
It’s not really evident from that chart, but durable also has the best wear resistance and lowest surface friction, so it might be the better choice for gears.
As the previous poster said, Durable is the way to go. It’s the most wear resistant material, and has a significantly lower coefficient of static friction than Tough.
I’ve handled some Durable prints and I do agree it’s got a “slippery feel” almost like Nylon. But it is also pretty flexible. Might need to take that in to consideration in the design of the teeth and however the gear will be attached to its axle…
One concern with either material is creep. If the gear is under a constant load then the parts are going to deform. Maybe this is less so with V3 - I only have V2 (maybe even V1) of the Tough material. If the gears are only used intermittently and are then unloaded you might stand a chance.
I would prototype with them in a heartbeat - they are awesome for that. But I wouldn’t expect the parts to last very long. You might be OK with casting - there are even some shops familiar with Formlabs Castable Resin that offer parts in metals. My concern there would be surface finish - it is probably going to come out relatively rough.