Help Please! Single Flywheel Issues

Us in team 2349A have been having serious confusion involving our flywheel. We are currently using a single flywheel connected to an intake similar to team 8059A(refer to their thread) and the robot is not working correctly. We went to our first competition with a working robot and during practice everything went south. It began to slow to a stop after about 3 balls shot. It never had this problem before and even after days of cooling it will not return. We have tried changing all the motors, changing the gear ratio, changing the brain, changing the motor controllers, and rebuilding the gear ratio. Nothing seems to be working. I don’t know what else to do. Looking for suggestions. Thinking of doing it with a smaller gear ratio, but with 6 turbo motors running at 80% instead of 4 high strength motors at 100%. Appreciate any help

I don’t think that 6 motors should be necessary. The only thing I can say without more information is that your PTC’s in your motors are most certainly Causing this. What is your gearing/ wheel size etc.
With the speeds required for a flywheel (especially a single design) you should also be cautious with the bearings you use. Some are machined weird. I always like to manually spin an axle through it before you use it to see if there is excess friction. The only other thing I would say is to take the motors off the gearing and see how smooth the gearing is by moving it with your hand. You might also open up all the motors and just double check that they are all internally geared the same way (and that they are all working).

If you post pictures, the vex community may be able to point out any other issues.

ok as said before, make sure to reduce friction, we have worked with a bunch of other teams having fly wheel issues, and the source of friction the almost always forget to check is shaft collars, is you have a shaft running between two plates with shaft collars pressed and tightened way to tight close the plate they cause lots of friction.

the other cause could be your code, how are you controlling the shooters from a programmatic standpoint?

What gear ratio are you using?

We are currently using a 5 inch wheel and the gear ratio as shown in the picture. I have tried removing the motors and spinning it and it seems to move freely with no friction. Hope this picture helps.
WIN_20151121_181951.JPG

That looks like a 3:105 (Flywheel > 1:5 > 3:7 > 1:3 > Motors) (at least, it looks like the motors have a 36-tooth to 12-tooth).
I think that might be a bit too high for four motors, so as a quick test, I would take out the 12-tooth from the 1:3 ratio and just move the motors down (or up) two/three holes for a ratio of 3:35 (Flywheel > 1:5 > 3:7 > Motors). Although that would be a bit too slow for full court, you could easily change to turbo (keep four motors) or just change the ratio to something higher (2500~3500 RPM).

I don’t know a lot about single wheel optimum ratio’s, but seems like it is in the right realm. The first thing I notice, is that you are using high torque gears. With the high speed and low torque of a flywheel, I would first recommend switching these all to the thinner gears. I would also look into making your actual wheel as close to frictionless as you can. At over 3000 rpm, friction increases quickly when it only has vex plastic gears as bearings. What is your internal gearing? Maybe you could post your code.

last thing. Its hard to tell from the picture, but with your design, is the flywheel required to grab the ball out of your intake before throwing it? This could cause a lot of unnecessary speed loss. You might also want to check if a ball has too much friction when squished between those 2 c-channels at the launching point. Maybe you could just add a plate or something between the two.

Well I just redid everything and put it back together and it runs really smooth with my hand but without even a ball going through it, the motors quit out. The internal gearing is now turbo. But it is at 100%. I don’t have the programming laptop with me atm. But will lower this once I get to school. I’m going to lower the gear ratio and post results.

Yeah, that gearing is almost double it should be. You might just try using normal HT motors (100rpm).

If you have the robot but not the computer you can always plug your flywheel motors into your chassis ports to be able to use the joystick to control the speed.

We tried lowering the motors internal gear ratio before and it still continued to do the same thing. I just lowered the gear ratio by making the 84 tooth gear another 64 tooth and kept the turbo motors and it lasted a bit longer but still did the same thing after I shot one ball.

Thank you guys for all the help. I did the thing where I plug the motors into the chassis ports to do the variable control and it actually seems to work pretty well. I do not however have access to a field now but once I get back to school I will be able to test it for real. I will put up my results after testing on Monday and will go from there with problems.

Lubrication.

Your compression is probably too much. Couod you show us a photo? Mine has issues like this until the compression was reduced.

Yeah, it used to have that problem and would lose speed as the ball passed through. But we fixed it and have been changing the spacing to find the right fit to give us enough top spin but not slow the wheel down.

Our robot has a similar design to what you are describing. Your flywheel issues could be the result of many different factors. We just had our first tournament of the year yesterday after having many problems with our flywheel. Luckily, we were able to fix them in time, so I’ll tell you what we did. One thing that helped quite a bit was reducing the friction, maybe taking out a washer or so. Just don’t reduce it too much. Another thing, if you are using turbo motors, make sure to check your motors to make sure they are all correct. We thought ours were, then we checked and realized one was a high speed motor. This can effect it a lot. Also, make sure you ALWAYS check your spacing. We realized ours was uneven, and fixing that enabled us to finally get full court high goals. Last but not least, always check your code. Out of nowhere, our robot stopped shooting full court, so we had our programmer boost our motor speed up from 95 to 100 and we were back on track. Make sure you check everything. Also our flywheel design is very similar to yours, but we are not using high strength gears, maybe that could be a factor?

Okay I see what the problem might be. Our team 1437z have built this design before, and the main problem is the friction between the gears. Make sure spacers are not too tight, give it a little wobble space. Also make sure that all motors are running at the same direction and the axles are not bent, especially the one with the flywheel.

Yeah we ran into those problems when we first made the robot and those were quickly fixed. We have changed shafts, spacing and all that stuff. I think it might be a problem with the squishing of the ball as it comes out now. But now after about a minute and a half at about half speed without shooting balls with the turbo motors it seems to slow to a stop again. Would it be a good idea to change the motors to high speed instead of turbo?

My team had the exact same problem with the exact same design*

We made the same mistake as you. It’s really hard to tell in 8059A’s picture, but there is no 12t pinion gear between the two 36t gears on the motors. The motors are geared together with 36t gears, and then the shaft from one of them continues through to the 84t gear.
It should be a relatively easy fix to move the motor up and reduce the gear ratio, and then it’ll work great!

Oh wow. Well I didn’t know that. Thank you for the input. I will try to change that. I have been wondering how they were able to turn the gears with a turbo motor. And with the pictures that I saw I didn’t know whether or not they used one.