Vacuum Pickup

[amesmich]

Dont go by what the HP rating is on the vac the manufactures play games with those numbers. Shop vacs dont draw 15 amps. I am looking at ours thats rated for 2.5 HP peak and it draws slightly less than 8 and is rated at 9 amps. Still not close to 350w.

[cgmv123]

Most multimeters should be able to measure the average current draw.

[Tom Line]

Originally Posted by cgmv123

Most multimeters should be able to measure the average current draw.

Careful. Most multimeters have an internal fuse and are very limited in the amount of current they can measure. You will probably need an ammeter if you're using a 12V motor.

We tried to use a single fisher price for vacuum since the centrifugal fan that came from our 12V shop vac was rated at 16,000 rpm. However, the fan was enough load that the constant motion destroyed the FP. I remember another team that geared up cims and used 2 to create enough suction to hold the soccer ball.

I can't remember which team it was, but they did post the pictures here on Delphi.

Here's a part of the thread where they discuss the model number:

http://www.chiefdelphi.com/forums/sh...cim+impell er

[Ty Tremblay]

I helped design 190's 2008 suction cup. A neat thing we learned is that current goes down significantly when the ball is captured. This is because there is less air getting in the way of the impeller blades.

Additionally, we learned that rate of removal is more important than the actual vacuum you draw. Those fabric covers are mighty porous.

[nuggetsyl]

You can use a model airplane prop to pull a ball in. Then just turn it off and kick the ball.

[Nathan Streeter]

In 2010 we also used a vacuum to hold the soccer ball. It had an excellent grip on the soccer ball (combination of suction force, area applied on ball, and "mechanical advantage" of how wide your grip on the ball is).

We used a two-stage system to pull a stronger vacuum, both stages were identical, using an impeller and impeller housing from a hand-held mini-vac with the stock motor replaced by a Fisher Price. That year we used a large, soft toilet plunger as the suction cup... I'd recommend something comparable in size to the bucket used in this video though.

Some design recommendations:
- Make sure your method of getting the cup to the ball is effective... even if the vacuum works perfectly, it will help you little if your drivers are always fumbling to acquire the ball. Iterate this, and don't underestimate it.

- Use a "suction cup" with a large diameter, but minimize the volume inside it so the vacuums don't have to evacuate as much air to get a good grip

- Find some cheap vacuums (shop vac or hand-held, probably) which you can salvage the impeller and impeller housing from. Carefully disassemble them and press your own motor on (RS550 would be my recommendation, given the high free speed, stall-less application, and excellent power-to-weight ratio).

A vacuum should be pretty low-power... Ours used two Fisher Price motors, but each drew only a few amps if I recall correctly. Don't worry much about the current draw... it won't require hundreds of watts.

[Kevin Thorp]

Thanks for all the great tips. We've found large diameter (=>10") vacuum cups online, but they seem to be for flat surfaces.

We have access to a 3D printer. In past years we've made molds with it & cast urethane wheel treads. I suppose we could do the same for a big vacuum cup.