How to make a Dragger that snap to grid?

I am using a Dragger to move parts, the problem is when I use model, the model does not snap to grid, this is a this is a small part of the code

local dragger = Instance.new("Dragger")
dragger:mouseDown(partOrModel, Vector3.new(0,0,0), array)

while true do
    dragger:mouseMove(mouse.UnitRay) 
    wait(0.08333333)
end

if I use a normal part, Is accommodated in the grid perfectly, the model to the contrary no.

NOTE: I know it's going to sound weird, but when I change the value in roblox studio in move (Model -> Move) from 0 studs to 1 studs , it's acctualy snap to grid, and if I increace the value to 4 studs , it's move the model 4 stubs by movement.

Any help would be appreciated.