Hi everyone,
We are trying to decide whether to use high strength gears or low strength gears on our flywheel. I think generally we tend to think of high strength gears as better (bigger is always better, right?), but I also saw on a thread somewhere that I can’t find that using high strength gears may also increase the friction when rotating. We may try both and compare, but I just wanted to see what everyone’s opinions are.
from what ive heard, the 12-tooth metal gears cause a lot of friction. besides that however i havent had any real trouble high strength gears
I have no way to prove this, but the HS gears should inherently have more friction (more surface area). So if the LS gears will function properly for your particular use, then in my opinion you should use them.
I don’t see any reason that LS gears aren’t strong enough to simply turn a flywheel. We are using them…seems fine.
That makes a lot of sense, and I was thinking along similar lines, yet many of the reveals I’ve seen, like 8059 and 929W, are using HS, so I was wondering if there was some advantage to HS that I was missing.
I would recommend using low strength gears as they offer reduced surface area and therefore reduced friction. High strength gears can be used where increased surface area is needed, but I do have to recommend you dont use them in series, especially the 12 tooth ones, as that introduce HEAPS of un-needed friction into a system.
I am going to second what everyone says about low strength gears and less friction. However, I will add that high strength gears have metal inserts, which means that they can withstand more force and strip less easily. So if your flywheel will be particularly violent in spinning things, I would recommend using high strength.
How about for a catapult like Wingus and Dingus have? VEX Nothing But Net NZ Scrimmage 3 Finals - 7682 Wingus & Dingus - 398pts combined - YouTube
High Strength or Low Strength gears?
We are using high strength right now but if anyone has another opinion on this please reply.
I think, because of the stress the gears are put under and because you wont be spinning the gears like you would spin a flywheel, high strength gears would be preferable in this situation.
If you’re making a flywheel, there will be no torque from the output axle slowing the system down or putting a huge load on the gears (besides the ball shooting, but that’s really negligible and won’t damage the gears).
If you’re making a catapult and have a rubber band or something be pulled by the motors, you’re putting a load on the output which puts more stress on the gears. Higher strength is preferable here so the gear teeth don’t crack.
I switched my gearing from high strength to low strength and found that my robot shot a huge distance further than it used to be able to.
I would recommend using high strength gears on the axle powered by the motor due to the most torque being applied there because we have broken a low strength gear there while prototyping, but generally I would use low strength gears to reduce friction between gears.
Okay we have experimented using both low strength and high strength gears.
We recommend using high strength gears. First of all, the high strength gears provided us with more torque on the flywheel. We ultimately had the fastest acceleration times with them. Also when the flywheel was spinning anywhere from 2800-3200 RPM, we found out that the high strength gears worked the best because of the metal inserts. It also doesn’t strip. When we had the low strength gears, we often burned out. This is because the gears kept on binding. It fixed as soon as the high strength gears were inserted. With the high strength gears however I had to make sure that every axle was inline properly and even had to drill custom holes. I found that the high strength gears take a little more effort to make work, but when you put that little effort in it, they work wonderfully.
David
Not to be rude, but these reasons you have stated for HS or LS gears are not actually related to HS or LS gears.
*1.) First of all, the high strength gears provided us with more torque on the flywheel. *
This isn’t possible. The only thing that affects the torque is the motor torque and gear ratio. The physical width of a gear is irrelevant. If anything the HS gears technically have less torque due to increased friction (but it should be quite small)
*2.)We ultimately had the fastest acceleration times with them. *
F=MA
HS gears have more mass, therefore slower acceleration. In reality it would be negligible, but there is definitely no way that HS gears themselves create faster accelerations
3.)When we had the low strength gears, we often burned out. This is because the gears kept on binding
This is not releated to HS or LS gears, but in fact differing build quality (axle straightness, bearing placement, friction, etc)
Not trying to nitpick, but I think it’s important for everyone to understand the science behind these statements. We don’t want people making false assumptions. I don’t doubt that your HS gearing build was better, as you say it is, but it is not better for the reasons you think it is. You must have simply built everything more squarely and therefore had less friction.
Alright seems like my claims were just debunked. We did ultimately had better results with our high strength. Probably because of the build quality. Thanks for straightening things out.
There seems to a misconception on this thread about surface area and friction. These two things are completely unrelated. Having a larger or smaller surface area, as a rule, does not affect the coefficient of friction between two surfaces.
Differences likely to occur between HS and LS gears: 1. HS gears are less flexible (they’re thicker) and deform less under a force when compared to a LS gear. This makes HS gears run more smoothly in situations where a significant force is applied. 2. HS gears can have metal inserts or can be put on HS axles while LS gears cannot. This makes HS gears last much longer–they won’t round out or lose their “square” to the axle (they rotate without wobble). Again, this makes HS run more smoothly than LS gears. 3. HS gears being wider, in addition to adding more tooth contact between gears, indirectly makes axles less likely to bend. Here’s a tip if you have a longer axle that is at risk of being bent: Use metal pinion (12 tooth) gears as spacers. You’re essentially making an axle out of the pinion gears which are made of a much stronger material and are thicker than standard axles.
So, yes, HS gears should run better than LS gears. The drawbacks of using HS gears are that they are heavier and take up more space–although I think the benefits heavily outweigh these when building a flywheel.
At first, I was slightly skeptical of this statement, but after thinking about it it makes sense. HS gears clearly have few disadvantages, which are greatly outweighed by the advantages. My only question now is if the coefficient of friction between the metal pinion gears and the acetal gears is greater than that of two acetal gears. Does anyone know what material the metal pinion gears are made of?
metal? Maybe. Can’t be sure 
This is technically true (it’s what you will read in a physics book…I teach physics), but I have never found it to be true in practice.
It depends on your gear ratio really, if it’s going for speed go for the low strength because in general the pressure on the gears is lower. If you are gearing down (for torque) then go for high strength since the pressure on the gears if far higher.
I’m not quite as sure on this, but I don’t think that the reason the metal pinion gears don’t run as smoothly as the acetal gears is the material that they’re made of. It seems that the size of the gears have a larger influence in how well they run. Larger gears are going to run better together than smaller gears. A good way to test this would be to compare how well the LS (acetal) pinion gears run to how well the HS (metal) pinion gears run. Compare the efficiencies of these two kinds of gears.
Would you mind elaborating on this more? What do you think specifically causes the lower performance of HS gears?