Why a spring for a hole saw?

I should have tried it first. The spring is not weak, so strong that it will make it quite hard to press the hole saw to the work, let alone through the work. I don't get it.

---------- I bought a USB charging jack designed for a car's dashboard, and designed to fit in the same size hole as a cigarette lighter.

Many versions for sale. This one, no more expensive than the others, came with a hole saw for 1 1/16", a size I don't have**. The hole saw has the shank, the center drill bit, an allen wrench, the hole saw itself, and a spring!!!

A tapered coil spring whose small diameter just fits the bit. Is that a coincidence? What is the point of the spring? I've used a hole saw before and didnt' feel a need for a spring. Is it to force out the hole after it's been cut? Have you seen this before?

Yep. John T.

On Mon, 05 Apr 2021 13:06:17 -0400, micky posted for all of us to digest...

I'd already thought to google, and duckduck results are about the same.

Here's a visual page:

The 2nd and 3rd are straight reamers and I don't know how that would work. If it goes in the hole, how can it ream, and if it won't go in the hole, how can it ream. Oh, here it is, "Blades are adjusted by loosening one nut and tightening the other Each reamer expands to the next size"

Good for precise work but a nuisance for what I want, not to mention the price.

Tapered reamers seem the way to go, what I have somewwhere in the house.

This one doesn't have slots. I'll see if the spring is too strong or not in a day or two, when I drill the hole.

Thanks all.

On Tue, 06 Apr 2021 00:40:15 -0400, micky posted for all of us to digest...

I feel you about "somewhere in the house"

Well, I was a little taken aback by the spring. I knew it was there but I still didn't understand at first what was pushing back. i thought it was the rubber mat glued to the other side of the plastic.

But when I was done, the spring did not force the cut-circle out of the saw. Becaue the spring itself cut a hole in the plastic. Twice the size of the bit in the middle, but smaller than the 1.1" hole saw. So the spring poked through the hole it made and the "plug" stayed in hole saw. It might work better with something other than 1/8" plastic.

Cutting plastic use a "fender washer" just smaller than the hole with a center hole big enough for the pilot drill