Hi Fabio,
I took no offence from your earlier post, I understood it was a error in translation
You have to approach casting like you would sculpting or painting, it is something you cannot master in one day, you will need to practice and learn from the mistakes you make. Even when you know the basic principles of casting it still takes practice to get it right. I have been casting for quite a few years and have cast thousands of parts and even now I can make errors and the part will be badly cast and need throwing away. Learning how to sprue well is what will make life easier and that can be trial and error, you need to understand about how air can get trapped within the mould and how to sprue to prevent this. Sometimes just turning the part a different way in the mould will make a massive difference. In your case the wheel can be cast in just one way and is a relatively easy part to cast.
As Tommi has said, you need to make sure your pump can vacuum down to full vacuum, -1.0 BAR, if the resin is not bubbling up out of the mould then you are not reaching full vacuum.
Follow this method bellow.
1,Wrap tape around top of mould, make sure it is high enough that resin will not bubble over the top ( Do not over tighten tape as this can distort the mould and cause the pour vents to close, this is where very soft rubber can cause issues)
2,Place mould into vacuum chamber,
3,Mix resin together,
4,Pour resin into top of mould, enough to fill mould cavity and extra to fill some of the taped section,
5,Put lid on and vacuum to -1.0 BAR and let resin bubble for about 20-30 seconds,
6,Slowly release the valve to let air back into vacuum chamber until back to normal atmospheric(room) pressure,
7,Close valve and repeat step 5 & 6
Cheers
Steve