How to tween parts already in motion?

You can write your topic however you want, but you need to answer these questions:

  1. What do you want to achieve? Keep it simple and clear!
    I want to tween parts (not for motion but for rotation) while they are already moving (in a spinning motion).
    I have 3 parts here for demonstration (this is the desired motion of the crystals but they don’t move):
    These are how the crystals move right now (they are supposed to rotate but don’t)
    I have print statements in the script that tell me that it SHOULD run through the tweens
    Here is the code:
local tweenService = game:GetService("TweenService")
local forwardTweens = {}
local backwardTweens = {}

while true do
	for _, crystal in ipairs(script.Parent:GetChildren()) do
		if crystal:IsA("UnionOperation") then
			tween1 = tweenService:Create(
				crystal,, Enum.EasingStyle.Sine, Enum.EasingDirection.InOut), 
				{CFrame = crystal.CFrame * CFrame.Angles(math.rad(-47), 0, 0)}
			tween2 = tweenService:Create(
				crystal,, Enum.EasingStyle.Sine, Enum.EasingDirection.InOut),
				{CFrame = crystal.CFrame}
			table.insert(forwardTweens, tween1)
			table.insert(backwardTweens, tween2)
		print("Tweens created")
	for _, tween in ipairs(forwardTweens) do
		print("Tween1 played")
	for _, tween in ipairs(backwardTweens) do
		print("Tween2 played")
	forwardTweens = {}
	backwardTweens = {}

Can someone help me? Thanks
By the way I wrote this at like 2:30 AM so I might not respond for a bit

you could either use math, or pause tween1 then player tween2. there a video on this: Curves & Tweening - Roblox Scripting Tutorial (

Whats the point of putting your tweens into a table?

Are you already tweening the cframe of the parts? (For your spinning motion)

I would also recommend changing the orientation of the part and see if that works instead of cframe

Thanks, but this isn’t what im looking for. I want the revolution of the crystals as it is, but as they revolve i want them to tween like the three parts i show.

So i can create tweens for all 3 crystals and have all three of them saved. I need them saved because i need to play all 3 forwardtweens first before the backwardtweens start.

How would i tween the orientation instead of its cframe? I need to use tweens to get the smoothness of the turn