Why the parts of this fast and easy welding script bugs?

Updated = 1

local h = script.Parent
local g = script.Parent.Parent
local hm = nil

for i,v in pairs (g:GetChildren()) do
	if (v ~= h) and (v.ClassName == "Part") then
		v.Name = "Part"..i-1
		hm = i
	end	
end
wait(1)
for i=1,hm  do
	p = g["Part"..i]
	P0 = CFrame.new(h.Position.X,h.Position.Y,h.Position.Z)
	P1 = CFrame.new(p.Position.X,p.Position.Y,p.Position.Z)
	w = Instance.new("Weld", h)
	w.C0 = P0
	w.Part0 = h
	w.C1 = P1
	w.Part1 = p
end

This makes welding parts alot more faster. But theres a small problem. When the script runs, the parts that are associated to this script just bugs around. Can someone please help me fix this bug??

I edited it a bit.

local h = script.Parent 
local g = script.Parent.Parent
local hm = nil

for i,v in pairs (g:GetChildren()) do --starts for loop to list the parts
    if (v ~= h) and (v.ClassName == "Part") then -- if the block that was listed is not h then 
        hm = i -- makes how many parts are inside the model
    end 
end
wait(1)
for i=1,hm  do -- starts for loop
    p = g["Part"..i] --names p to the part
    w = Instance.new("Weld", h) -- makes a weld
    w.C0 = CFrame.new(h.Position.X,h.Position.Y,h.Position.Z)-- position of h
    w.Part0 = h -- what is part0 (h)
    w.C1 = CFrame.new(p.Position.X,p.Position.Y,p.Position.Z) --position of p
    w.Part1 = p -- what is part1(p)
end

It may still not work I saw 1 small thing.