So … just wondering what gear ratio everyone is using …
we have built the following, 1:25, 1:35, 1:125 and then back to the 1:75
we are looking at the 1:75 because the 1:125 is so slow … but it can support alot of mass …
Please Post What Ratios You Are Using
Cheers !
I really don’t think you will need the 1:75. That will basically make it so you have 1 dump during the match, also, when we used 1:27 we basically destroyed 3 of our high strength gears, so I’m guessing a 1:75 would do major damage. Right now our team is using 1:15 and we can lift 20 sacks with 4 motors and about 10 rubber bands on each ( we are adding more). Unless you make for sure your gears won’t skip, I wouldn’t go so high.
Wowwwwww, i dont think ive ever seen a robot at 1:35, let alone 1:125 
how long do you think it will take to lift?
We are using 1:7 currently with 4 motors and rubberbands, but can only hold about 15 - im assuming with that sort of ratio you will be lifting a whole lot more though 
That was because you didn’t support your axles! Our 1:21 last year on our scissor lift never damaged a single gear. Even when a wrench got stuck in the linear slides at the top, the structural bars of the lift were bending rather than the gears giving out! Those high-strength gears are tough when used correctly!
Wow! That’s a lot of torque you got there…
Anyway, we are using a 7:1 right now. It can lift around 8 sacks. We will probably be going to a 9:1 soon after our first few competitions.
Wow! I’ve never seen anyone use a ratio higher than 25:1 on a robot because of time, and even that takes around 5 seconds to lift depending on the load. Our team is using 25:1 because we plan on lifting 20 or more objects. I must say though, it would be awesome if you implemented that ratio and used an awesome intake to lift about 70 objects! Depending on what you want to lift, I would go for the something like 15:1 through 25:1.
I’m surprised! The only issue we had with a 25:1 last year was when our lift got caught on a goal, causing some of the teeth to deform. I didn’t think it was that easy to destroy those! Lol
i will upload a picture / videos of these 2morrow … after i have filmed them … but basically … i have double blocked all sides, new axels, standard gears, and i use 1 x 269 motor for each side … i tested it by putting 10 sacks, and a small 1kg fire extinguisher and it didn’t make a difference with the 1:75 or the 1:125 … but it works really well …
but yeh … going well so far … will keep you updated as we go along !
btw with gear breakages … i have never come across this … not from mechanical … from human error yes … but not from arms doing it themselves
But … as i have said … will upload pics … keep posting !
oh about speed … our arm can go upto 45" … not needed but nice … to get to the 45", it takes …
1:75 - about 8 seconds
1:125 … well about 15 seconds …
so tbh … takes about 5/6secs to get to high …
and about 10-12 secs for the 1:125
Why? I can understand using 1 instead of two motors, but why not a 393? It will allow you to either lift more, or faster, or both…
A lot of schools only use 269’s. I just visited one and all I saw was 269 motors. It could be because they are cheap.
But I do agree that if you are going a 2 motor lift, it would be better to stick with a 393 motor.
We are currently using a 1:15 Gear Ratio with 4 393s geared for speed and can lift approximately 20 - 25 sacks so unless you need to lift more sacks than that I would say stick with a smaller gear ratio for speed purposes.
That theory doesn’t really apply here as he mentioned that they might be getting pneumatics, which are A LOT more expensive then 393’s.
Wouldn’t it be easier and more efficient to just use regular 393’s and have a lower gear ratio?
I still think 1:7 is a good ratio, seems to work well for us
Technically this would be easier however, we decided to use all high strength gears since they are less prone to break teeth. Thus in order to get the amount of torque we wanted on our lift the only way was to use a 1:15 gear ratio. We originally had these as “regular” 393s but, they seemed too slow so we switched them to speed.
Hi yeah … well we are using a 269 motor for a prototype … we have one working 393 and we are planning on get another one before end of November … but we are planning on using 393 … we just tested it with 269 motors
And yeh … out off all 20 motors at our school atm … we have 19 269 motors, and 1 393 (and like 5 servos)
at the moment we are using
2x269 for drive
2x269 for lift
2x269 for intake
2x269 for rotation of intake
2x269 for storage system
we want to use this …
2x269 for drive
2x393 for lift
2x269 for intake
2x269 for rotation of intake
2x269 for storage system
(leaving us with 2 spare 269 motors) …
It seems like you’re dividing up your motor power quite a bit. While I’m not sure what exactly your various subsystems/mechanisms look to be doing, you might want to consider simplifying. A lot of the time, a function that seems to need two subsystems can be achieved with only one. The most common VEX robot would probably have the motor distribution:
4 motors on drive
4 motors on lift
2 on intake
The most common deviations would probably be:
6 motors on drive
4 motors on lift
no intake
8 motors on drive
2 motors on lift (high torque 1:9 or higher)
no intake
Again, although I haven’t seen your specific mechanisms, you might be spreading your motors far too thin, especially on your drive train. You might want to look into using only 1 motor on your “rotation of intake” and “storage system” and focus those motors into your drive train.
You’ve already said that you’re running an extremely high ratio on your arm, but there are still limitations, especially increased friction between gears as you compound them more. That’s why arm ratios of 1:5 and 1:7 seem to be the most preferred because you don’t need compound gearing.
Hope these comments help you out, good luck this year!
Well based off of this I would suggest just buying a bunch of 393’s instead of pneumatics. The larger motors are definitely more versatile that the pneumatics kit and it seems like you might need some.
alright … we are still hoping to get some sponsorship … but at the moment we are funding ourselves, i was thinking of getting pneumatics kit out of my own money, but yeh i will consider switching for 393s … but at the moment everything seems to be working nicely, gears are doing great, rubber banded and using blocks … but everything seems to be working , i know what you mean, and we will defo consider 393 motors after we get the second one so we can substitute them in systems to see what works better.
Thanks for everyones comments !
Good Luck To Everybody In The VRC this year !
One nice thing about the compound gearing is substantially less backdriving.