Timing Pulleys

[widow_twanky]

What size timing pulleys do people tend to use on featherweight spinners?

Andy

[typhoon_driver]

5mm pitch or thereabouts is the standard, 10mm wide

[maddox10]

After my experience with Prodigy Evo and Nebelwerfer, I prefer chain.

[Mouldy]

I use the same as Gary suggested, pulleys from technobots... Because there cheap... But I found the belts don't take as much strain as the more expensive ones hpc sell.

[typhoon_driver]

Just remembered I think I use the 5.35mm or thereabouts belts and pulleys from rs

[widow_twanky]

Ok, thanks. I assume that when ordering from Technobots that's the T5 ones then?

Also in terms of RPM what's the optimum speed for a spinner? I assume if it goes too slow it wont do any damage and if it goes too fast it'll act as a single surface so it wont make any substatial contact with the teeth?

Andy

[Ellis]

Not sure if too fast is possible! The speed would depend on the type of spinner I suppose. I think aim for as quick as you can get it.

[Mouldy]

360 has two teeth and goes around 5000rpm...grinds a bit, I wouldn't make it go much faster.

540 is effectively single tooth and does 8000rpm and has good engagement.

So depends on disc type

[typhoon_driver]

You can do a basic sum to work out the cutter bite that your disc will get in an impact. You need to work out the time that it takes for a tooth to leave a position and another take up that same position.

So for a 1000 rpm disc with two teeth, the disc takes 60/1000 seconds to complete a single rotation. As we have two teeth, this needs divided again by two. This gives a time of 0.03 seconds. If the robot is moving forward at a modest 1m/s then multiplying 0.03 by 1 will give a cutter bite of .03m or 3cm.

In this example the tooth will be able to move a full 3cm forward in the time given which should allow it a greater impact with the opponent. If you play with the numbers you will see that a faster disc results in a smaller bite,.hence more of a grinding action. This also explains why single tooth discs are more effective.

Although you also have to balance the kinetic energy as a faster disc means more energy

[PJ-27]

If you have strong sharp teeth though, it doesn't matter how fast you make it, if that digs in bad stuff is going to happen!

Just look at 360, grinds a little but when it bites!