running a 1-49 GEAR RATIO for a one wheel launcher

I have a 1-7 1-7 gear ratio for a one wheel launcher.
My problem is i can’t run it with the 393 motors.
I tried to run four and five motors connected by 36 teeth gears.
But the motor stall happens in only 5 seconds of spin.

Is there another way of fixing the motor stall?

Yes: reduce friction.

Seriously, just a little bit of friction at those speeds can and will cause your motors to burn out.

A good rule of thumb that others have suggested is to detach the motors and constantly remove friction one way or another until the flywheel spins freely for 15-20 seconds with no power. Then adding the motors on should be fine.

Remove the PTC’s in the motors.

Of course we all know that’s illegal for Vex competitions. And it’s stupid, too, unless you don’t mind your motors catching on fire. :frowning:

Yes reducing friction is the main way to prevent stalling. In my testing of flywheel launchers I have found that using less gears to connect the 3 to 4 motors or putting 2 motors on one axle for example can reduce stalling. Less gears means less power lost and less friction which means more speed and reduced stalling. Also, make sure to put motor mounts on each axle and make sure it is tight; a loose motor mount can create metal on metal contact which will produce a lot of friction. Another thing to make sure of is the spacing of the gears on the axle. If there are too many spacers on the axle it will create unnecessary friction. I have found that it is best if you allow the gears and flywheel a little bit of room (maybe 2 washers of space, not too much) to move side to side on the axle to ensure that there is not friction on any of your axles. Also you may want to consider a lower gear ratio on the launcher that the motors can better handle. I hope this helps you with your motor staling issues!

What’s the target rpm?

I’m working on a one wheel launcher that uses at most 25:1 with motors set to speed (ie. max free speed is 4000 rpm). While I play with velocity PID and TBH I dropped the ratio to 25:2 (max free speed 2000rpm). I use three motors, no PTC tripping at all yet.

I wouldn’t suggest a one wheel flywheel. I built one that was 2500 rpm with 4 100 motors and it shot pitifully, about 6 feet at about 45*. My other dual wheel flywheel have performed much better. My theory is that the single wheel flywheels turn too much of their energy into spin instead of linear velocity.
I tested a vertical single wheel flywheel with a 90* back plate.

Oh, and I’ve never had issues with ptc tripping with any of my flywheels and one was hitting the roof of my two story house from 16 feet away.

Also, does anyone have evidence that pinion gears produce more friction than other gears?

The difference between the 12 tooth metal gear and some of the other HS gears in terms of friction is almost comical. Try running 3 12 tooth gears in a line compared to 3 36 tooth gears in a line and you should notice the difference pretty quickly.

so Tabor473
do you mean running three metal 12 tooth with a motor on each?

jpearman i going for a least 3,600 rpm but the ratio is 3,900

Silicon


take the rpm of each side and combine plus did you have a drum?

If I am recalling this correctly Robodragon E used graphite in Skyrise. Might put some in your bearing to reduce friction – WD40 does get sticky as time goes.

yes martin is correct. We use graphite on axles sometimes to reduce friction. that can help a lot if you put it on your bearings

I have found with my flywheel that I get the least amount of friction using this grease. http://www.amazon.com/Permatex-80078-Anti-Seize-Lubricant-Bottle/dp/B000AAJTXY/ref=zg_bs_15719191_4
It is a mix of graphite, copper and aluminum grease, this cut my friction by a lot.

would sprockets reduce friction?

There has been different theorizing about whether chain and sprockets have more or less friction than gears. I don’t think anyone knows for sure, but I would think that a lot of the friction comes from the square metal axles turning very quickly in their bearings. If your gear/sprocket conversions are well made, I don’t think they should make a big difference.

Would be interesting to see a conclusive test of friction caused by gears vs sprockets & chain

Don’t be discouraged to build a one wheel launcher because of Silicon, not to be disrespectful, but we have built one and it can launch balls into the high scoring net really well from the starting area.