Timing Pulleys

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

Andy

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

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

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.

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

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

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.

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

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

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!

unless your going brushless dont worry about going to fast :P

Never rely on the teeth staying sharp. All materials regardless will eventually blunt. Some are more of a pain than other to sharpen especially at a competition. Boner has completely blunt teeth but as some will testify, they still happily pack a punch.

Quote:

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Originally Posted by typhoon_driver

Never rely on the teeth staying sharp. All materials regardless will eventually blunt. Some are more of a pain than other to sharpen especially at a competition. Boner has completely blunt teeth but as some will testify, they still happily pack a punch.

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Agreed

If i was using these pully's what width of belt should I use...? I don't know which number means what?

Pullys

http://uk.rs-online.com/web/p/products/ ... 4E4F4E4526

http://uk.rs-online.com/web/p/timing-be ... s/0745719/

belts

http://uk.rs-online.com/web/c/mechanica ... 4294958223

Or this belt??

http://uk.rs-online.com/web/p/timing-belts/4750333/

Those pulleys seem to be the same type as I use in Inertia XL.

I use the Synchroflex T5 16mm wide ones, with the 16mm Synchroflex belts (same as those on Technobots)- seems to do the job nicely.

I would advise against using the 10 tooth pulley for attaching to the speed 900- I had a few issues with keeping them attached as there was not a lot of material left to hold them onto the motor shaft with.

I found this tool to be a great help.

http://www.sdp-si.com/cd/default.htm

Gives you useful info like centre distances, and minimum suggested teeth of each pulley.