I have read the post from Mike Barkley, glad to hear you are alright. I have also read the other topics around mandrel collars and micro chucks. I have not yet turned a wooden handle but have made foam and cork ring grips. I am a Machinist by trade with 28 plus years experience running all types of machinery. I also have 5 years experience in safety and accident investigation. I would like to mention some safety precautions for all of us and some ideas around lathes, madrels, centers, collars and RPM.

*ALWAYS, ALWAYS wear eye protection when running any machinery!!!
*NEVER, ever wear gloves when working with spinning machinery!!!
*NEVER wear loose clothing while running any equipment!!!
*REMOVE all jewelry from your hands, wrists and neck and anything else else that tickles your fancy!!!
*ALWAYS be sure to have handles covering the sharp back edge of files and shaping knives!!!
*ALWAYS have an emergency shut off for your equipment easily accessible!!!
*DO Not use damaged tooling or equipment. If your mandrel is bent, get rid of it

At 2000 RPM, small mandrels will naturaly flex from the speed alone. Add to that tool pressure and you very well could push it out of it's center. I don't know how Mike held the wood onto the mandrel but I have a hard time believing that the mandrel pushed into the chuck before the wood slipped on the mandrel.
*Keep your mandrels as short as possible
*Use as large a diameter mandrel as possible
*If you want collar stops on your mandrels but can't find them, get a nut that will slide on the mandrel and have somebody tack-weld it in place
*Be sure that you drill your centers deep enough in the mandrel so the tail-stock center seats firmly
*Speed is not always the answer, neither is pressure. Keep your tooling clean and sharp
*Do not use long narrow strips of sand paper to polish anything between centers

I seen a guy break his hand polishing a shaft with a long strip of sand paper. The paper caught on the shaft and wrapped around his hand. Luckily for him, he was able to pull his hand out of his glove before the machine dislocated his arm and shoulder!
I seen a guy running a lathe put a file right thru the palm of his hand because he did not have a handle on it!
I seen a guy holding a shaft from vibrating with his hand while turning the od. His glove caught and pinched his hand between the part and the tool post. He was very lucky that the part spun in the chuck because he had it wrapped with a brass shim to protect it. He dislocated 1 finger and damaged tendons up to his elbow.
My intent is not to offend anybody here so I hope that I have not. You all have been so helpful to me getting started in this craft, I hope that some of this helps you.

Steve Chontos

Steve, on the strip of sandpaper, what is too long and what is short enough to be safe? I sometimes use a 1in. wide strip, up to 600 grit to polish a reelseat insert or cork grip.

If at first you don't succeed, go fishing, then try, try again.

I would not use anything long enough to wrap around the part you are polishing.

Steve

Thanks for the tips, Steve

Mike (Southgate, MI)
If I don't want to, I don't have to and nobody can make me (except my wife) cuz I'm RETIRED!!

Thank you!
It never hurts to hear and listen to the advise of experienced professionals