A blasting machine for engraving or blasting a surface via a vacuum blasting process using an abrasive blasting media, said blasting machine comprising a container made up of three container sections including:
- an upper container section, comprising a suction head with a dry vacuum cleaner, said dry vacuum cleaner having a fine dust filter, said fine dust filter surrounded by an immersion tube on the suction head, said immersion tube holding said fine dust filter and projecting into the upper container section,
- a middle partial container section disposed below the upper container section and comprising a feed hopper, wherein the feed hopper is located under the fine dust filter for collecting used blasting media from a blasting process and has a flap at a bottom of said feed hopper,
- a lower container section disposed below the middle partial container section comprising an underlying screen with an underlying funnel-shaped storage container for the blasting media, the storage container containing a vibration unit or a sound generator for avoiding accumulation of the blasting media to resolve clogging, said funnel-shaped storage container also containing a metering device with a metering disc which has a plurality of nozzles, each with different diameters, and wherein rotation of the metering disc allows any one of said nozzles to communicate with a passage to an air flow guide,
- the blasting machine further comprising:
- a blasting hood containing a blasting lance, with one or two viewing windows, two sliding and removable cover plates to allow specific areas to be covered on the surface to be processed that are not to be hit by the blasting media and containing a hood connection for a flexible suction blasting hose and a hood connection for a flexible extraction hose,
- a container connection for the extraction hose on the upper container section of the three container sections of the container at a level or an area of the immersion tube containing the fine dust filter, and
- a container connection for the flexible suction blasting hose on the lower container section of the container below the metering device with adjoining air flow guide, wherein the air flow guide is connected to the container connection for the flexible suction blasting hose to pull, via suction, the blasting media from the metering device in the direction of the suction blasting hose,
- and wherein
- the metering disc is arranged in a body in the form of a cylindrical opening at the bottom of the lower container section, said body concurrently forms a housing of the metering device and includes the metering disc, wherein the housing contains eight ball latches on an inside wall, the ball latches are arranged offset every 45 degrees on the inside wall of the housing of the metering device and wherein the metering disc has cavities arranged correspondingly with the latches every 45 degrees on an outer edge of the metering disc and whereby balls are guided one in each corresponding cavity and the balls are pressable by means of a compression spring in the direction of the outer edge of the metering disc and wherein the balls latch in the ball latches with a corresponding rotary movement of the metering disc to align one of the metering disc nozzles with the passage to the air flow guide to obtain desired blast media flow rate.